Method and apparatus for charging rechargeable cells

0001The invention relates to a method for charging a rechargeable battery, particularly a lithium ion battery or a lithium battery. Furthermore, the present invention relates to a device for charging such a battery.

0002Recent trends in the generation of electrical energy based on renewable energy sources, especially by methods such as photovoltaic or wind power, have been generated to make available the stored electrical energy in the required amount and when needed. It demands more and more efficient storage of energy. In addition, there is a clear increase in the number of rechargeable batteries and portable battery-powered devices powered by batteries, especially for communications and the construction industry. In these devices, the capacity of the rechargeable battery represents an essential functional feature. Factors that affect the capacity of rechargeable batteries, on the one hand, are geometric dimensions, which have traditionally been achieved by increasing the geometric size of batteries and batteries. On the other hand, durability and maximum number of rechargeable cycles play a major role. This is because in normal battery-powered equipment, the battery or battery fails first, that is, when it comes to the durability of the components of such equipment, rechargeable batteries or batteries are among them. This is because it has the shortest useful life.

0003Also, when it comes to embracing the rapidly evolving new technologies in the field of electric mobility using hybrid and electric vehicles, the capacity, durability and capacity of rechargeable batteries, batteries and storage modules Characteristics such as charging time are particularly important. Again, the geometric dimensions and weight of the rechargeable battery play a very important role.

0004Over the last few months, lithium-ion batteries have proven to be particularly advantageous among rechargeable batteries. This is because lithium-ion batteries have a higher number of charge cycles and a longer life than other technologies. In addition, the lithium ion battery has a higher storage capacity than other rechargeable batteries.

0005In the case of lithium-ion batteries, the battery is discharged to 30% of its capacity, depending on the design, in other words, 30% of the inherent energy stored in the battery is not available to the user. This is because discharging the battery below the 30% threshold can lead to irreparable destruction of the lithium-ion battery. When the battery is discharged below this threshold, ions are desorbed from the electrode material (Cu, Al), thereby destroying the electrode.

0006Moreover, batteries, including today's lithium-ion batteries, can only be charged to 80% of their capacity. This is because it takes a lot of time exponentially to charge the battery to 100%. This is because the current is usually under a limit as it approaches the end-of-charge voltage, under which the last 20% of capacity is smaller amperage so that less energy is stored or loaded in the battery in time. This is because it is charged with.

0007Thus, under the prior art of rechargeable batteries, the inherent capacity of the battery was not utilized.

0008U.S. Pat. No. 5,481174 describes a method for charging a lithium-ion battery, in which positive and negative pulses are used and a positive current pulse is reached after a predetermined maximum voltage has been reached. The height is reduced, resulting in a longer charging process.

<p num="0009"> Based on this situation, the subject of the invention is that the capacity of the battery can be optimally utilized, the charging time can be significantly reduced, the durability of the battery can be extended, and / or the capacity of the battery can be increased. It is to propose a method for charging a lithium-based battery and a device for charging a lithium-based battery.</p>

<p num="0010"> The invention is based on the idea of charging rechargeable batteries and batteries faster and / or better than before. For this purpose, a charging preparation stage is provided in which the battery is prepared or activated for the pulse charging stage. In order to achieve the above object, the charging preparation step according to the invention may be required only. Similarly, only the pulse charging step may be required to achieve the above objectives.</p><p num="0011"> First, the pulse charging stage according to the invention will be described in detail. During the pulsed charging phase, a pulsed charging process is used, in which the battery charges current I._LCharged with, charging current I_LIs the certified nominal charging current of the battery I_LmaxIs over. Pulsed charging current I_LConsists of a positive pulse and a negative pulse. The pulse charging method is described with respect to current. The relevant voltage characteristics are described with reference to the drawings. Negative pulses constitute a limited load on the battery, in other words, the battery releases energy or current flows in the opposite direction. Positive pulses are referred to as charge pulses, while negative pulses can be referred to as load pulses or stress pulses. The term reverse pulse is also sometimes used.</p><p num="0012"> In order to provide a charge current greater than the certified nominal charge current, the storage of energy in the battery is faster than when the nominal charge current is applied. As a result, more ions are carried from one electrode to the other and then conversely when loaded. If energy storage at a charging current greater than the certified nominal charging current is continuously performed for a long period of time, the battery will heat up and the safety mechanism (PTC, molten fuse, outgassing valve, balancer) will charge such a charge. Interrupt the process. Continuous charging has the effect of the dendrites growing continuously on the electrodes, while increasing the internal resistance of the battery and causing a voltage rise in the battery. On the other hand, increasing the number of dendrites reduces the number of rechargeable cycles.</p><p num="0013"> However, according to the invention, it is proposed to have a load pulse after the charge pulse. During this load pulse, the battery releases energy again, causing current to flow in the battery in the opposite direction. Therefore, the residue deposited during the charge pulse is reduced during the subsequent load pulse. The load pulse has the effect of removing dendrites and crystals that have accumulated during the charge pulse. Crystals and dendrites can stick to the separator between the cathode and anode, which in the worst case can lead to short circuits. The load pulse causes the deposited crystals to be repeatedly removed. Therefore, during the next charging pulse, the battery can be charged with a charging pulse higher than the certified nominal charging current without overheating. During a positive pulse, a higher charging current causes more energy to be stored in the battery than traditional charging methods. Subsequent load pulses soften the continuous formation of dendrites and allow the battery to be recharged with a higher charging current. The height of the load pulse is smaller than that of the charge pulse, in other words, the absolute value of the amperage during the load pulse is smaller. Therefore, the path in the separator is cleared for ion exchange, however, this leaves increased energy in the battery due to the higher charging current.</p><p num="0014"> The separator is formatted (initialized) by a short, high charging current according to the invention, followed by a load pulse. On the one hand, this prevents uneven distribution or deposition of lithium on one electrode. In addition, short, high charge and load pulses prevent the battery from rising in temperature. Because these pulses are short in both current directions, the temperature at the electrodes cannot rise. Moreover, the possible temperature rise at the electrodes drops again in the time between pulses. The increase in temperature can cause a non-uniform distribution of resistance at the electrodes, which can ultimately result in a non-uniform deposition of lithium at the electrodes.</p><p num="0015"> In batteries, the lug terminals are usually arranged diagonally to each other, i.e., especially in wound batteries, the line resistance at the electrodes is different. Due to the long and small charging current, especially the slowly pulsed charging current, the lithium ions try to move in the direction of the minimum resistance, in other words, instead of taking the shortest route to the opposite electrode. , Try to move directly towards the lug terminal on the opposite pole. However, this will have the effect of unevenly depositing lithium on the electrodes. However, the non-uniform deposition of lithium on the electrodes leads to a reduction in life and battery capacity. This is because the entire surface of the electrode is no longer available for chemical reactions.</p><p num="0016"> However, according to the short charge pulse with increased current and according to the load pulse, the ion does not have time to look for the path of the minimum resistance and must choose the shortest route between the electrodes, thus the electrode length. The entire current is available for ion exchange, and lithium deposits remain evenly distributed between the electrodes.</p><p num="0017"> Preferably, during the charging pulse, the charging current is greater than 1.5 times the nominal charging current of the battery, eg, twice or more of the nominal charging current. A charging current of up to 5 times the nominal charging current is possible. The charge or discharge current supplied during the pulse charge phase is limited only by the PCT in both current directions, and its conductivity depends on temperature. Depending on the battery design, the PTC is configured to accommodate 5 to 10 times the nominal charging current. When a larger current flows, the PTC cuts off the current.</p><p num="0018"> After a predetermined charging time, after a correspondingly large number of charging pulses, the voltage U in the battery_zCharge end voltage U during the charge pulse_LmaxExceed. Then, with conventional batteries, the current is limited, as in US Pat. No. 5,481174. However, according to the invention, the charging current is the charging end voltage U._LmaxNot restricted when you reach. In other words, the voltage in the battery is the charge end voltage U_LmaxFurther rising beyond, the level of charging current is maintained during the charging pulse. In conventional charging methods, the current is limited when about 80% of the capacity of the battery is achieved. Because, at that time, the maximum charge end voltage U has already been reached._LmaxIs achieved. Maximum charge end voltage U_LmaxVoltage rises above are achieved by short, high charge and load pulses. This is because, in particular, short and strong pulses do not raise the temperature of the battery, which softens the non-uniform distribution of electrode resistance and the non-uniform distribution of lithium deposits on the electrodes.</p><p num="0019"> Preferably, the battery is discharged with a load pulse between the positive charge pulses. As already explained, this causes the removal of the formed dendrites. However, other charging patterns are possible, in which a pause occurs between the two load pulses, and the other load pulse does not occur until after two or more charge pulses. However, this affects the charging time. This is because, as a result, the charging current between the charging pulses cannot be increased as in the case where the load pulse continues between all the charging pulses.</p><p num="0020"> In a preferred embodiment, the height of the charge pulse and / or the height of the load pulse depends on the state of the battery, in particular the internal resistance of the battery. In other words, the height of the charge pulse may increase with increasing charge to remove residues. The adaptive determination of the height of the charge pulse and load pulse allows for anomalies such as the effects of external temperature during the charging operation. Similarly, there is a deviation in the voltage trend between the charge pulse and / or the load pulse. This is caused by the non-uniform deposition of lithium and the short-term temperature rise of the electrodes.</p><p num="0021"> To assess the condition of the battery, a voltage measurement on the battery is made between at least one load pulse and / or a charge pulse. The voltage is measured during the load pulse because the voltage measurement on the battery is done under load to get a near-true result for the state of the battery. It is particularly advantageous that the voltage is measured at the end of the load pulse. This is because then the most stable state of the battery is achieved. In other words, the voltage is measured at some point before the load pulse leaves its maximum value and before the current flows in the zero direction. The result of voltage measurements without load can be voltage values that are no longer achieved under load. This is because, at that time, the voltage rises extremely and the current collapses. For better control of charge pulses and / or load pulses, and especially for better control of pulse height or duration, voltage deviations, especially in the ascending direction, during charge pulses. It is advantageous to measure the voltage of the battery to detect.</p><p num="0022"> Preferably, a discharge current of up to 20-25% of the charge current flows during the load pulse. The result is that the energy recovered from the battery during the load pulse is less than the energy stored during the charge pulse.</p><p num="0023"> The level of charging current in continuous charging pulses may vary, in other words, may be adapted to the state of the battery, where, for example, voltage measurements and / or temperature measurements determine the state. It may be used for recording.</p><p num="0024"> Further, the level and scale of the discharge current in the continuous load pulse may be changed.</p><p num="0025"> If the voltage measurement shows a voltage rise during the charging pulse, this indicates anomalies during charging. The anomaly may have been caused by an increased buildup of dendrites, which results in an increase in the internal resistance of the battery. To mitigate this voltage rise, the height of the next charge pulse may be reduced compared to the previous charge pulse. In other words, when the voltage rises sharply in the battery, the current is reduced at the closest charging pulse. Preferably, if the previous charge pulse doubles the charge current, then for this charge pulse, about 50% of the previous charge current will be charged so that it will be charged with the same charge current as the nominal charge current. There is a reduction.</p><p num="0026"> Preferably, the load pulse following the reduced charge pulse may also be reduced by 50% compared to the previous load pulse. From the voltage measured during the load pulse, it can be found whether the next positive charge pulse should also be reduced or can be performed again with an increased charge current. If the voltage between the load pulses at the reduced load is again within the preset tolerance, the next positive charge pulse will be again at the previously applied increased charge current. Will be executed. Then, in order to discharge the battery in a short period of time and prepare the battery for the next positive charge pulse with the increased charge current, the next load pulse is also performed with the previously applied load. Can be done.</p><p num="0027"> The voltage of the battery may rise, for example, when the internal resistance of the battery becomes too high due to a defect in the PTC or due to overheating of the electrodes. At that time, both the charge pulse and the load pulse are preferably reduced until the battery voltage returns to a preset voltage trend.</p><p num="0028"> In a preferred embodiment, voltage measurements are performed on all discharge pulses.</p><p num="0029"> Preferably, the length of the load pulse corresponds to about half the length of the charge pulse. This not only provides a higher current during the charge pulse than during the load pulse, but is also longer and higher during the charge pulse than during the load pulse where energy is drawn from the battery. Current is supplied. A ratio of 2/3 for charge pulses and 1/3 for load pulses is possible. Do not select load pulses that are too long. Otherwise, the battery charge will be unnecessarily long. In a preferred embodiment, the duration of the pulses and their respective ratios can be adjusted.</p><p num="0030"> In a more preferred embodiment, charging of the battery is terminated when the measured voltage matches the charging termination voltage of the battery by a preset number of load pulses.</p><p num="0031"> This is especially advantageous if the last load pulse before the battery charge reaches 100% is about 25% greater than the previous load pulse. This is because the battery residue, which increases due to the rising voltage, is removed by the larger load pulse.</p><p num="0032"> Moreover, or instead, if the voltage reaches the charge termination voltage during the load pulse, the current of the next charge pulse is reduced. Preferably, the next charge pulse is halved, which continues for a long time until the charge end voltage stabilizes in subsequent load pulses. As a result, the battery is nearly 100% charged.</p><p num="0033"> It is advantageous to measure the battery temperature continuously or periodically in all method steps. This further provides information on whether the battery being charged behaves normally during charging. If the temperature is below a preset limit, charging will continue. Temperature rise below a preset limit can be mitigated by reducing the height or duration of the charge pulse and / or load pulse. Temperature should be monitored, at least during charging or load pulses. Preset temperature T_maxHowever, if the preset time is exceeded, the battery charging operation is stopped at one or more charging pulses, for example at 45 ° C. The critical temperature for both high energy and high current batteries is 47-48 degrees.</p><p num="0034"> Moreover, or instead, when the preset voltage of the battery is exceeded and the charging operation is stopped or interrupted, the voltage of the battery is increased to obtain further information about the state of the battery. Measured continuously or periodically during charging. If the battery voltage rises above the preset battery voltage, the battery has an anomaly and is charged to adjust the charging current level or load current level or, in extreme cases, to cool the battery. By aborting or interrupting the process, the anomaly is considered during further charging.</p><p num="0035"> The charging process has been described above only for the pulse charging stage. The pulse charging step described above, on the one hand, achieves a great deal of time savings while focusing on the battery, and on the other hand, the battery can be charged to 100% of its capacity in a short time. This is because the charge current is not reduced and the scale of the charge current is maintained during the charge pulse even when the maximum charge end voltage is reached and when the charge end voltage is exceeded. Thereby, according to the charging method according to the invention, 100% of the capacity of the battery can be charged within 20% of the normal charging time without the battery becoming hot or permanently damaged. The resistance of the electrodes also remains the same, which prevents the battery from rising by rapidly switching between high charge and load pulses to alleviate the non-uniform distribution of lithium.</p><p num="0036"> The charging preparation step described below is used to activate the battery. It is especially important to slowly prepare a deeply discharged battery for the pulse charging process. However, even if the charging preparation stage is applied alone, it will lead to improvements during the charging of the lithium battery.</p><p num="0037"> Batteries usually consist of several batteries connected in parallel or in series. This type of battery or power pack is usually provided with a balancer to prevent deep discharge of the battery. With conventional batteries, the battery is said to be "discharged" even though it still has 30% of its capacity. If the battery is discharged deeper than 30%, this is called a "deep discharge". This occurs because the balancer is defective, or the battery is loaded or discharged at an extremely low temperature and stored at a very low temperature.</p><p num="0038"> The charge preparation stage is performed before the pulse charge stage. The pre-charging phase specifically includes a first measurement of the voltage of the battery, with no load, in other words, without the previously supplied current. If the battery does not show voltage, the conclusion is drawn that the battery is defective. Then, the level of charging current is set according to the measured voltage. During the charge preparation phase, the charge current level is limited due to the first rise stage of the maximum nominal charge current level. In addition, an increase or time is set, at which the charging current increases from zero or a low initial value to a specified charging current level. If the voltage measurement shows a very low voltage, typically 50% of the nominal charging current is supplied in the first ascending phase, in other words, the increasing charging current is smaller due to the lower voltage.</p><p num="0039"> Then, within the first linear ascent step, the battery continues to be charged at the set charging current for a preset time, eg, 1 minute, up to a preset charging current level, eg 1A. At this time, the maximum charging current corresponds to the nominal charging current of the battery. This charge is used to activate the battery so that the ions slowly start moving from one electrode to the other. small.</p><p num="0040"> After reaching the set charging current level, a pause is provided in which no charging current is supplied. Battery voltage can be measured as quickly as possible in this regard. The battery voltage is then measured at a preset load. The preset load is close to or equal to the load pulse at the pulse charging stage. In addition, a pause without current supply may be inserted before and / or after the load pulse to measure the voltage.</p><p num="0041"> The first ascending step is repeated depending on the battery voltage measured under load. Repeating is important if the voltage under load has not yet shown the desired value. For example, the first ascending step is repeated if the discharge end voltage of the battery has not yet been achieved. This first ascending step with a charging current that matches the nominal charging current at its maximum value can be repeated several times, depending on the type of battery and the condition of the battery.</p><p num="0042"> If the battery has a voltage that is 5% or more higher than the discharge end voltage under load, preferably a second ascending step can be performed. In the second ascending phase, the battery is charged while linearly increasing to a preset charging current higher than the nominal charging current. For example, the battery may be charged up to twice the nominal charging current during the second ascending phase. Then, at the end of the second ascent phase, the battery voltage is measured again under load. At this time, if the voltage consisting of the preset values is achieved, the battery is suitable for undergoing the pulse charging stage, and the charging preparation stage is completed. If the discharge end voltage is achieved after one or several first rise steps, the second rise step may be omitted.</p><p num="0043"> The required conditions are also met by the device to charge the battery. The device comprises a controller applied to perform the steps described above.</p>

0044Hereinafter, embodiments of the invention will be described with reference to the drawings.<figref num="1">The configuration of a commonly used lithium ion battery is shown.</figref><figref num="2">The lithium-ion battery in a wound state is shown.</figref><figref num="3">A schematic diagram of the current signal characteristics of the charging method according to the invention for high energy batteries is shown.</figref><figref num="4">The current characteristics of the pulse charging method according to the invention for high current batteries are shown.</figref><figref num="5">The current, voltage and temperature characteristics of other embodiments of the charging method according to the invention are shown.</figref><figref num="6">The current, voltage and temperature characteristics of still another embodiment of the charging method according to the invention are shown.</figref><figref num="7">A part of the current, voltage and temperature characteristics according to Fig. 5 is shown.</figref><figref num="8a">The flowchart of the charging method which concerns on invention is shown.</figref><figref num="8b">The flowchart of the charging method which concerns on invention is shown.</figref><figref num="9">Examples of signal characteristics during the charging preparation stage according to another embodiment are shown.</figref><figref num="10">The configuration of the charging device for applying the pulse charging method according to the present invention is schematically shown.</figref>

0045FIG. 1 schematically shows the configuration of a lithium ion battery having a cathode and an anode. During the charging operation, lithium ions move from the positive electrode to, for example, a negative electrode covered with lithium graphite. During the discharge operation, lithium ions move in the opposite direction from the negative electrode to the positive electrode. The two electrodes are separated from each other by a separator. Lithium ions move through the separator.

0046Lithium-ion batteries have the characteristics that they have no memory effect and have very little self-discharge as compared with other rechargeable batteries. The normal end-of-charge voltage of a lithium-ion battery is about 4.2V, based on a nominal voltage of 3.6V. Lithium ion batteries include, for example, lithium polymer batteries, lithium iron sulfate batteries, lithium graphite batteries, and lithium. Includes cobalt batteries.

0047FIG. 2 shows a wound lithium-ion battery. The anode 21 and the cathode 22 are arranged so as to face each other and are separated from each other by a separator 23. The lug terminals 24 and 25 attached to the electrodes 21 and 22 are arranged diagonally opposite to each other. That is, the electrical resistance at the electrode increases as the path length increases. Therefore, the electrical resistance of the electrode increases as the distance to the lug terminal increases. Therefore, lithium ions try to take the path with the lowest electrical resistance when moving from the positive electrode to the negative electrode. The resistance of the path, however, is not formed by the directly opposed electrodes, but exists between the electrodes through the battery, as shown by 27. Battery nominal charging current I_LmaxHigher charging current I_LDue to the short charge pulse at, lithium ions are driven to other electrodes without having time to find the path with the lowest electrical resistance. Therefore, the separator 23 is knitted to allow uniform ion exchange between the two opposing electrodes 21 and 22. Further, the temperature rise of the electrodes 21 and 22 is prevented by the time limitation of the charging pulse similar to the load pulse. Otherwise, it causes an increase in the internal resistance of the electrode, which in turn leads to a non-uniform resistance distribution. This, on the one hand, causes a further temperature rise of the electrodes and, on the other hand, alters the distribution of lithium in the battery, resulting in a non-uniform distribution of lithium deposits. The heterogeneous deposition of lithium leads to no longer having a complete chemical reaction surface available between the electrodes. Lithium deposits, on the other hand, grow non-uniformly on one electrode and eventually reach the separator, piercing and causing a short circuit. Short charge or load pulses have the effect of softening this, and prevention of excessive temperature rise is very important. Reference numeral 27 indicates a lithium ion path that attempts to take the path with the lowest electrical resistance. If the battery is not charged or discharged with a short, high charge or load pulse, the lithium ions will try to follow the path indicated by reference numeral 27, leading to an uneven distribution of lithium deposits on the electrodes.

0048FIG. 3 shows the signal characteristics over time in the charging method according to the invention using the charging preparation stage and the pulse charging stage. The charging method shown here is an example for a high energy battery with a capacity of 2.3 Ah.

0049In this charging method, the battery is charged during the pre-charging phase, which comprises a first ascending step 33 with a charging current that increases from 0 to 1 A within 1 minute. After this 1 minute, the charging operation is stopped for a period of 2s, in other words, the battery is no longer supplied with charging current, where the voltage of the battery is first unloaded and then with a given load. , Measured. After 2 seconds have passed and a voltage higher than the 3.0 V discharge end voltage has been measured, the charging preparation stage is completed and the pulse charging process can be started.

0050In the pulse charging stage, the pulse period of the positive charging pulse 31 is initially 1 s and the period of the load pulse 32 is 0.5 s. During the load pulse 32, the battery receives a load of 300 mA, where the battery voltage U_zIs measured during one load pulse 32. During this load, if the voltage is greater than 4.2V, the charging operation is terminated.

0051During the charging operation according to the invention, the following occurs in the battery. During the charge pulse 31, crystals formed in the battery damage the battery separator. This causes the battery to lose charge and capacity. In addition, the crystals impede the movement of ions between the electrodes 21 and 22, resulting in a significant reduction in battery life. However, in the load pulse 32 according to the invention existing between the charge pulses 31, the load causes these crystals to be immediately reduced again immediately, negating the negative effects of the crystals. This constitutes a major advantage of the charging method according to the invention. According to the charging method of the invention of FIG. 3, a 5A charging pulse 13 is adopted during the pulse charging phase, which is about twice the magnitude of the 2.3A nominal charging current for high energy batteries. is there.

0052In the charging method according to the invention, during the charging pulse 31, the specified charging end voltage U is set aside from the increased current value._LmaxHigher voltages are also applied or allowed. Charging end voltage U_LmaxIs preset for each battery, in which case it is specified as 4.2V for high energy batteries. By this method, a high current can be maintained up to the final charging pulse 31, and the battery can be charged to 100% or more in a very short time as compared with the conventional charging method.

0053In other conventional charging methods, the charging current used is constant, but this is the end-of-charge voltage U._LmaxIs reduced when is achieved. Charging end voltage U_LmaxDue to the current subduction when is achieved, a clearly increased charging time is required, especially to charge the remaining 20% of the battery's capacity. In the conventional charging method, the voltage is further measured during the interruption of the charging pulse. Therefore, no load pulse is applied, and crystals and dendrites that damage the separator 23 are formed and are not removed during charging. Due to the fact that these crystals are not removed again, a commonly used charging method is the charging end voltage U._LmaxNever use constant elevated charging currents and voltages above.

0054There is also a charging method that continuously increases the charging current, however, the continuously increasing charging current I._LCauses deterioration of the battery, especially when the battery is charged to 100%. In addition, a considerable temperature rise is also observed.

0055According to the charging method according to the invention, a set subduction is used during the load pulse 32 to remove crystals and dendrites and to mitigate the temperature rise, so that the charging end voltage U_LmaxCharge current I during charge pulse 31 even when_LCan maintain a constant charging current I_LAnd charge end voltage U_LmaxBatteries can be charged even at higher voltages. Crystals and dendrites that are continuously removed during the load pulse allow higher voltage and uniform current pulses to be used, resulting in a dramatic reduction in charging time. The short pulses avoid temperature rise and the battery is charged in a very careful manner, despite higher voltage and current values, which never compromises battery life.

0056Furthermore, since there are no crystals, there is almost no self-discharge, and even if a battery charged to 100% is not used or separated, it has the effect of not discharging, and therefore does not deteriorate. And even after several years of storage, sufficient capacity can be withdrawn.

0057The signal characteristics in Fig. 3 are 2.3Ah capacity and 4.2V charge end voltage U._Lmax, 3.7V nominal voltage, 3.0V discharge end voltage U_EL, 2.3A nominal charging current I_Lmax, With a maximum discharge current of 4.2A and a continuous discharge current of 3.5A.

0058FIG. 4 shows a charging method according to the invention for a high current battery having a capacity of 2.3 Ah. Further characteristic data of the high current battery is the charge end voltage U of 4.1V._Lmax, 3.3V nominal voltage, 2.0V discharge end voltage U_EL, 10A nominal charging current I_Lmax, 50A maximum discharge current, and 25A continuous discharge current.

0059Compared to the charging method of FIG. 3, in a high current battery, charging is performed with an absolutely clearly higher current of 20A during the charging pulse 41 in the pulse charging stage. The load pulse 42 between the charge pulses 41 is also absolutely clearly large (2A).

0060FIG. 5 shows the signal characteristics of the voltage, current, capacity and temperature of the charging method according to the invention. According to FIG. 5, the lithium-ion battery is fully charged in about 18 minutes without the temperature of the battery rising. The temperature is shown at the bottom of Figure 5 and remains in the region below 35 ° C from the start to the end of the charging operation. The current and voltage characteristics show the pulse of the battery at a 5A charge pulse, each charge pulse followed by one load pulse less than 1A, preferably the load pulse used is up to 300mA. Is. The voltage is shown at the top of Figure 5. At the beginning of the charging process the battery voltage is below 3.7V and during the first charging pulse the voltage U_zIs lower than 4.2V at the beginning. Looking at the characteristics of the voltage over the entire time of the charging process, however, the voltage U in the battery_zIs a relatively short time, after about 2.5 minutes, the charging end voltage U of the lithium-ion battery_LmaxIt can be seen that it has reached 4.25V, which is higher than.

0061In commonly used charging methods, the current level is reduced during the charging pulse. In the charging method according to the invention, the nominal charging current I_LmaxVery short charging pulse above is used, battery voltage U_zCharge end voltage U without the need to reduce the amperage of the charging current_LmaxEven when it exceeds_、Can rise further than. Therefore, the charging time can be dramatically reduced without increasing the temperature or deteriorating the battery in various forms. Voltage U of about 4.5V_zWhen it reaches, the current begins to decrease during the charging pulse. Because the charge end voltage U_LmaxApproximately 4.1V voltage U corresponding to_zHowever, it was measured with several consecutive load pulses.

0062In addition, both the height of the charge pulse and the height of the discharge pulse are the measured voltage U of the battery._zIt can be admitted that it is changing in response to. It can be seen that due to the increase in voltage during the load pulse, the stress or load current is gradually reduced until the voltage between the load pulses is again within the specified range, which follows a downward trend in voltage. .. Therefore, the temperature rise at the electrode can be avoided.

0063FIG. 6 shows further signal characteristics of the charging method according to the invention. With this charging method, 100% charging of the battery is achieved in 25 minutes. Similar to the charging method in Figure 5, the voltage is found to rise relatively quickly above the charge termination voltage of 4.2V without the need to use current reduction during the charging pulse. The charge pulse is the battery voltage U_zDoes not decrease until about 17 minutes after reaching 4.5V. After reaching the voltage of 4.5V, in the load pulse, a voltage greater than 4V has already appeared in the battery. That is, the battery is almost fully charged. To avoid further temperature rise, at a preset voltage of 4.5V, the amperage begins to decrease during the charging pulse, however, the height of the load pulse does not change. Voltage U during load pulse_zFurther rises, and the battery charge end voltage U_LmaxIt can be clearly seen that a voltage of 4.2V is reached, which is consistent with. Due to this signal characteristic, the temperature of the battery hardly changes and does not rise above 35 ° C anyway.

0064FIG. 7 shows the signal characteristics of current, voltage, capacitance and temperature in the charging process. At the beginning of the pulse charging phase, a 5A charging pulse is given. This is the current I for high energy batteries_LmaxCorresponds to a value somewhat greater than twice. Voltage U_zIs measured during both load and charge pulses. In the first charge pulse of 5A, the voltage U of about 4.2V in the battery_zIs achieved. The first charge pulse is followed by a first load pulse less than 500 mA, which discharges the battery. The current of the load pulse is about 3% to 6% of the current during the charge pulse.

0065The display in FIG. 7 clearly shows that the height of the load pulse is changing. In the center of the display, it can be seen that the voltage suddenly rises to just below 3.8V or 4V during the load pulse. This sudden voltage rise is mitigated by the load pulse that follows after the amperage has been reduced. Initially, the load pulse is halved from 300mA to 150mA. If the voltage rises further, it is possible to apply a load pulse with an amperage of less than 50mA. After the height of the load pulse is reduced, the voltage U_zHowever, it is found that the voltage trend returns during the load pulse, resulting in the voltage being in the range below 3.75V during the load pulse.

0066The display of FIG. 7 shows a part of the time of the charging method of FIG. 5 or 6, however, only about 1 minute is displayed. Therefore, no change in temperature or capacity has been detected.

00678a and 8b show a flowchart of the charging method according to the invention, in which both the charging preparation stage and the pulse charging stage are executed. After the charging process is started in step S301, the voltage U_zIs measured first (S302). Voltage U_zIs the charging end voltage U_LmaxWhen it is greater than, in other words, when it appears in the battery above 4.2V in the case of a high energy battery, the battery is fully charged and the charging process is terminated.

0068Voltage U_zIs the charging end voltage U_LmaxWhen less than, the battery voltage is the discharge end voltage U_ELAn inspection is performed in step S303 to see if it is greater than. High energy battery discharge end voltage U_ELIs about 3V, and that of a high current battery is about 2V. Battery voltage U_zIs the discharge end voltage U_ELWhen above, the pulse charging process of Figure 8b is immediately continued. However, the battery discharge end voltage U_ELLess than voltage U_zWhen having, the pre-charging stage must be performed to activate the battery.

0069Therefore, in step 304, the first ascending step is performed. After the battery is charged in the first charging stage, the battery voltage U under load_zIs measured. In other words, under load, the voltage U on the battery_zLevel is checked. Voltage U_zHowever, depending on the battery currently used, the discharge end voltage U is 2V or 3V._ELWhen greater than, the pulse charging step can be initiated. Otherwise, in steps S306 and S307, the first ascending step is repeated and the voltage measurement is also repeated. After repeating the first rising step, the battery voltage is still the discharge end voltage U_ELNominal charging current I when below_LmaxGreater charging current I_LThe second ascending phase is performed using. Although not shown in Figure 8a, the battery voltage U after the end of the second ascending phase_zIs the discharge end voltage U_ELCan be checked to see if it has reached. Battery voltage U_zIs still the discharge end voltage U after the second rising stage_ELWhen it has not reached, the battery is defective and cannot be charged further. In the pulse charging stage shown in Figure 8b, the discharge end voltage U_ELCan only be started on the condition that is achieved. After the pulse charging phase has begun, the charging pulse initially has a nominal charging current I_LmaxGreater charging current I_LIs given only time t1. A load pulse is given after the charge pulse. The load pulse is preferably half the length of the charge pulse and during the load pulse the nominal charge current I_LmaxDischarge current I, which is about 25% of_LastThe load is given to the battery. Battery voltage U during the load pulse_zIs measured and the battery voltage U_zIs the charging end voltage U_LmaxCan be checked if it is larger than. Battery voltage U_zHowever, the charging end voltage U has already been reached._LmaxWhen it is larger than, it is checked whether the charge end voltage is achieved three times in step S315 and S316 or S317. If so, the battery is fully charged. As is clear from the signal characteristics of FIGS. 5, 6 and 7, the battery voltage U in step S313._zWhen is less than the discharge end voltage, the height of the next charge or load pulse is the voltage U measured during the load pulse._z(S314), then the process is continued in steps S311 or S312.

0070FIG. 9 shows the detailed charging preparation stage. At the top of Figure 9, it can be seen that the battery is initially charged with a current that rises linearly up to 1A amperage, during which time the voltage on the battery rises from about 3.5V to 3.7V. The voltage measurement is performed again during the subsequent load application. After the first rising stage, the voltage U in the battery_zIs the discharge end voltage U for high current batteries_ELIt is lower than 2.0V, which is smaller than 2.0V, so a further first ascent step needs to be taken. Because, in the pulse charging stage, the discharge end voltage U_ELBecause it can only be started on the basis of. After repeating the first ascending step, another voltage measurement is performed, at the end of which the first ascending step is repeated, the battery discharge end voltage U._ELIt shows that it has a higher voltage of 2.1V. From now on, depending on each embodiment, the nominal charging current I_LmaxA second ascending step may be performed while the battery is charged to an amperage above. Instead, the pulse charging step can be performed immediately.

0071FIG. 10 shows a device for performing the charging method. Usually, the device for performing the charging method is referred to as a charging device. The charging device for executing the charging method can give a set subduction and a set load pulse to the battery as compared with the conventional charging device. The charging device 100 is connected to the battery 140. A temperature sensor 160 connected to the charging device 100 is connected to the battery 140 for continuous or periodic temperature monitoring. The charging device 100 includes a CPU 110 that executes the charging method according to the invention. The CPU 110 is connected to a memory 120 and a display 130 for outputting the measured value. Further, the charging device includes an input unit 150 through which the charging device can be affected. The memory 120 has various parameters stored in itself for the charging method. The parameters are characteristic data such as capacity, end-of-charge voltage, nominal voltage, end-of-discharge voltage, maximum charge current, maximum discharge current, and continuous discharge current, or only a few of them, for a battery. Is. Based on these values, the height of the charge pulse and load pulse is calculated. Further, the memory 120 stores a limit temperature value in relation to each battery. The charging device may preferably include a detection device to identify the battery to be charged.

0072Similarly, the battery type can be input via the input means 150. The CPU 110 of the charging device measures the voltage and / or current in the charging pulse or the load pulse according to the charging method. Preferably, the charging device 100 has at least one capacitor used to provide charge for the charging pulse. Similarly, it is possible to use at least one capacitor for discharge during the load pulse, and the stored charge is then discharged through the resistor.