Method for charging alkali metal battery
By applying high-current pulse discharge and hot charging combined with dynamic pressure control before charging lithium metal batteries, the problems of SEI formation and lithium deposition in lithium metal batteries are solved, extending battery life, reducing operating pressure, and improving safety and energy density.
Patent Information
- Application Number
- CN202510945044.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-11-12
- Filing Date
- 2025-07-09
- Publication Date
- 2026-01-16
AI Technical Summary
Lithium metal batteries (LMBs) face the challenge of forming a solid-electrolyte interface (SEI) during charging and discharging due to the reaction between the lithium surface and the electrolyte. This leads to a shortened battery life, increased resistance, and volume expansion, and high-pressure operation increases the difficulty of integration.
The method employs a high-current pulsed discharge before charging, combined with thermal charging and dynamic pressure control, including high temperature and high pressure during charging and low temperature and low pressure during discharging, combined with pulsed discharge technology to reduce SEI formation and lithium deposition below the SEI.
Extend battery cycle life, reduce electrolyte consumption and volume expansion, increase energy density, reduce operating stress requirements, and enhance safety.
Smart Images
Figure CN121355431A_ABST
Abstract
Description
[0001] Related Application Data
[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 669,446, filed July 10, 2024, entitled “Methods of Charging Alkali Metal Batteries,” and U.S. Provisional Patent Application Serial No. 63 / 719,299, filed November 12, 2024, entitled “Methods of Charging Alkali Metal Batteries,” each of which is incorporated by reference herein in its entirety.
[0003] TECHNICAL FIELD
[0004] The present disclosure relates generally to lithium metal batteries. In particular, the present disclosure relates to methods for charging alkali metal batteries.
[0005] BACKGROUND
[0006] Lithium metal batteries (LMBs) are a type of rechargeable battery in which each anode is a lithium metal anode. Anode-free batteries are a type of rechargeable battery that initially have no active material on each anode current collector. These batteries have high energy density and are a promising energy storage solution for various applications, including electric vehicles. However, the use of LMBs presents several challenges, one of which is that the lithium metal surface is so reactive that it reacts with the electrolyte and forms a solid-electrolyte interface or interphase (SEI). During each charge and discharge cycle, lithium deposition and stripping occurs, and the SEI is repeatedly formed. This process consumes some lithium and electrolyte cycle after cycle, leading to electrolyte drying and lithium depletion, ultimately resulting in battery failure. The continued formation of the SEI also results in an increase in electrical resistance and volume swelling, up to 50%, from the beginning of the battery’s life to the end of the life. Therefore, limiting SEI growth is important for the performance of LMBs.
[0007] Another challenge of LMBs is that the application of very high pressures (e.g., above about 100 psi) for limiting SEI formation and controlling lithium particle morphology during operation can make integration into various applications more difficult.
[0008] SUMMARY OF THE DISCLOSURE
[0009] A method of charging an alkali metal electrochemical cell includes applying a pulse discharge at a rate from about 0.5C to 5C immediately prior to initiating a recharge of the cell.
[0010] Further, a method of charging an alkali metal electrochemical cell includes discharging the cell to a depth of discharge between 0% and 95%, applying a pulse discharge after the discharging and before beginning recharging of the cell at a rate from 0.5C to 5C, and beginning recharging of the cell immediately after applying the pulse discharge.
[0011] Further, a method of charging an alkali metal electrochemical cell includes discharging the cell to a depth of discharge between 95% and 100%, applying a pulse charge after the discharging at a rate less than 0.33C until at least 5% state of charge of the cell is reached, applying a pulse discharge immediately after the pulse charge at a rate from 0.5C to 5C, and beginning recharging of the cell immediately after applying the pulse discharge.
[0012] In another aspect, a method of charging a lithium metal electrochemical cell includes regulating a temperature of the cell to a charge temperature between about 25°C and about 60°C when charging the cell, and reducing the temperature of the cell to a discharge temperature less than the charge temperature when discharging the cell.
[0013] Further, a method of charging a lithium metal electrochemical cell includes increasing a pressure in the cell to a charge pressure and maintaining the pressure at the charge pressure when the cell is charging, where the charge pressure is from 20 psi to 100 psi, and reducing the pressure to a discharge pressure and maintaining the pressure at the discharge pressure when the cell is discharging, where the discharge pressure is lower than the charge pressure applied during charging.
[0014] Further, a method of charging a lithium metal electrochemical cell includes regulating a temperature of the cell to a charge temperature between 25°C and 60°C when charging the cell, reducing the temperature of the cell to a discharge temperature less than the charge temperature when discharging the cell, increasing a pressure in the cell to a charge pressure and maintaining the pressure at the charge pressure when the cell is charging, where the charge pressure is from 20 psi to 100 psi, and reducing the pressure to a discharge pressure and maintaining the pressure at the discharge pressure when the cell is discharging, where the discharge pressure is lower than the charge pressure applied during charging.
[0015] Additionally, the method can include discharging the cell to a depth of discharge between 0% and 95%, applying a pulse discharge immediately after the discharging and before recharging of the cell, where a discharge pressure is applied during the pulse discharge, and beginning recharging of the cell immediately after applying the pulse discharge.
[0016] In another aspect, an alkali metal electrochemical cell system having one or more cell units includes a battery management system, one or more temperature sensors connected to the battery management system and positioned to monitor a temperature within the cell units, one or more pressure sensors connected to the battery management system and positioned to monitor a pressure within the cell units, a pressure controller connected to the battery management system and configured to control the pressure within the cell units, and a heat source connected to the battery management system and configured to control the temperature within the cell units. The battery management system is configured to control the heat source and the vent such that the temperature is maintained at a charge temperature between 25 °C and 60 °C when the battery is charging and at a discharge temperature lower than the charge temperature when the battery is discharging; to control the pressure controller such that the pressure is maintained at a charge pressure between 20 psi and 100 psi when the battery is charging and at a discharge pressure lower than the charge pressure when the battery is discharging, and to apply a pulse discharge at a rate from 0.5C to 5C after discharging and immediately prior to recharging the battery. BRIEF DESCRIPTION OF DRAWINGS
[0018] For the purpose of illustrating the present disclosure, the drawings show aspects of one or more implementations of the present disclosure. It should be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, in which:
[0019] Figure 1 is a plot of capacity retention of a battery charged and discharged at various rates versus cycle number;
[0020] Figures 2A-2C is an image from an anode of a battery after 50 cycles at 0.2C-1C charge / discharge rate;
[0021] Figure 3 is a plot showing voltage of a battery including a pulse discharge between discharging and charging over time according to an embodiment of the present disclosure;
[0022] Figures 4A-4F is an image of an electrode of a cell unit after cycling through various charge and discharge conditions;
[0023] Figure 5A is a plot of capacity retention of a battery charged and discharged at various rates versus cycle index;
[0024] Figure 5B is a plot of resistance of a battery charged and discharged at various rates versus cycle index;
[0025] Figures 6A-6Cis an image of an electrode of a battery cell after cycling using pulse discharges according to the present disclosure, where the pulse discharges occur at various depths of discharge;
[0026] Figures 7A-7F is an SEM image of an anode of a battery that was subjected to charge cycling at different pressures;
[0027] Figure 8 is a schematic of a battery management system that can be used to implement the charging scheme of the present disclosure;
[0028] Figure 9 is a process diagram outlining an embodiment of the charging scheme of the present disclosure;
[0029] Figure 10 is a process diagram outlining another embodiment of the charging scheme of the present disclosure;
[0030] Figure 11 is a graph showing the voltage of a battery as a function of time including a pulse discharge between discharging and charging according to an embodiment of the present disclosure, where the temperature and pressure are different during the charging and discharging portions; and
[0031] Figure 12 is a schematic of a battery management system that can be used to implement the charging scheme as well as the thermal charging and dynamic pressure aspects of the present disclosure.
[0032] DETAILED DESCRIPTION
[0033] In an embodiment, a method for extending the cycle life of an LMB and reducing its need to operate at very high pressures includes applying a high current pulse discharge prior to initiating recharge of the LMB. The fast discharge is important to the cycle life of the LMB because the fast discharge can remove lithium isolated in the SEI, making it non-conductive, so that more lithium can be deposited underneath. The high current pulse discharge prior to charging can also remove lithium isolated in the SEI and cause lithium to be deposited underneath the SEI. This pre-charge pulse discharge is effective after a conventional discharge to almost any depth of discharge and for a range of pulse durations and current densities. The resulting improved SEI quality and lithium deposition underneath the SEI slows the accumulation of the SEI. And because this effect occurs even at lower pressures, the LMB can be operated at relatively low pressures.
[0034] In another embodiment, a thermal charge is applied, where a high temperature is present during charging of the battery cell (compared to the temperature during discharging). In addition, a lower pressure can be applied during discharging compared to the pressure present during charging. In addition, the higher temperature and pressure can be applied together during charging, and the higher temperature and pressure for charging can be applied in combination with the application of the pulsed discharge described above, where the pulsed discharge is applied before initiating charging, where the discharging temperature and pressure will be present during the pulsed discharge, and the elevated temperature and / or pressure will be present during the subsequent charging.
[0035] Pulsed discharging
[0036] The cycle life of LMBs is closely related to the charge / discharge rate. As shown in Figure 1 , for a battery with the same cathode loading (3 mAh / cm 2 in this example) and sufficient electrolyte, a battery applying fast charging, slow discharging (1.1 C - 0.33 C, line 116 in Figure 1 ) only lasts for 160 cycles. A battery with symmetric charging / discharging at moderate rates (0.33 C - 0.33 C, line 112 in Figure 1 ) lasts for 440 cycles. Batteries cycled under slow charging / fast discharging conditions (0.2 C - 1 C, line 108 and 0.2 C - 3 C, line 104) show better performance, lasting for 700 cycles and 1075 cycles, respectively.
[0037] Figures 2A-2C is an image from the anode of a battery after 50 cycles using 0.2 C - 1 C charge / discharge. Figure 2A shows the anode with a black surface instead of a shiny metallic color. Figure 2B is a top view SEM image of the anode, where the bright parts are SEI and the dark parts are lithium. Figure 2C is a cross-sectional image of the anode at 100% SOC, showing SEI on top of the deposited lithium. These images indicate that under slow charging / fast discharging conditions, lithium is deposited underneath the SEI with a thin layer of SEI on top. This can be attributed to the fact that faster discharging can remove the isolated lithium in the SEI, making the electronic conductivity of the SEI worse. As a result, lithium can be deposited underneath the SEI, which is more electronically insulating, resulting in fewer side reactions between lithium and electrolyte, and thus slower electrolyte consumption.
[0038] Although lithium can deposit under the SEI and can extend cycle life under slow charge / fast discharge, continuous fast discharge is not always practical, for example for electric vehicles (EVs). Lithium can deposit under the SEI because fast discharge tends to pull lithium out of the SEI, making the SEI less electronically conductive. Using a high current fast discharge (or pulse discharge) before each recharge to remove lithium isolated in the SEI can have a similar effect. Figure 3 is a plot 150 of the voltage of the LMB as a function of time (shown at trace 160), where the LMB is used for applications where discharging occurs at a relatively slow rate during a discharge period 154 until at any given depth of discharge (DOD) between 0% and 95%, the user decides to initiate a charging scenario. At this point, a high current pulse discharge is applied before the charging process begins, which can last for a period of time (156) of, for example, between 10 seconds and 20 minutes, and preferably between 10 seconds and 3 minutes. The discharge rate of the pulse can be in the range from 0.5C to 10C. After the pulse discharge, a charging period 158 begins. The recharge can begin at a typical charge rate, or by first using a lower charge rate for a short period of time (for example, between 10 minutes and 20 minutes) before switching to a typical charge rate for the remainder of the recharge.
[0039] In an example, when a pre-charge high current pulse discharge is applied at 2C for 2 minutes before initiating charging, 4mAh / cm2cycled at C / 3-C / 3 rate 2 High cathode loading batteries were at 90% DOD. After 50 cycles at 100% SOC, the batteries that had the pre-charge pulse discharge applied and the batteries that did not have the pre-charge pulse discharge applied were disassembled and the lithium electrodes were observed. As can be seen in Figures 4A-4F the brighter lithium surface (160) from the electrode of the battery that did not have the pre-charge pulse discharge applied compared to the darker surface (150) from the electrode of the battery that had the pre-charge pulse discharge applied. This difference in appearance reflects the difference in the amount of lithium deposition when the pre-charge pulse discharge is applied. In particular, the darker surface indicates that lithium has been deposited under the SEI, while the brighter surface is due to lithium deposition on the SEI surface and formation of new SEI. A surface SEM of the electrode was also taken to observe the morphological differences. For the battery without the pre-charge pulse discharge (160), lithium particles are present on the top surface, while for the battery with the pre-charge pulse discharge (150), the surface is mostly covered by SEI and lithium is only sparsely dispersed on the surface. Cross-sectional images show that for the battery without the pre-charge pulse discharge (170), the lithium is present in the bulk of the electrode, while for the battery with the pre-charge pulse discharge (160), the lithium is present on the surface of the electrode. Figure 4A Figure 4B Figure 4C Figure 4D Figure 4E ), the lithium layer and SEI deposited on the surface accumulate with each cycle. In contrast, for batteries with pre-charge pulse discharges ( Figure 4F ), the SEI is at the surface and thus much less lithium is exposed to the electrolyte.
[0040] Figures 5A-5B is a graph showing the effect of applying a pre-charge pulse discharge on the cycle performance of LMBs. In Figure 5A , the capacity retention versus cycle index is shown for three sets of batteries cycled at C / 3-C / 3 rate. The first set, line 212, has a pre-charge pulse discharge applied at a cutoff voltage of 3.6 V. The second set, line 208, has no pre-charge pulse discharge applied and has a cutoff voltage of 3.6 V. The third set, line 204, has no pre-charge pulse discharge applied and has a cutoff voltage of 2.5 V. The batteries cycled without pre-charge pulse discharge decay faster than the batteries with pre-charge pulse discharge. The difference in cycle performance is attributed to the difference in resistance of the batteries, which is shown in Figure 5B . For the batteries with no pre-charge pulse discharge applied (as shown by line 216 and line 220), the capacity decay is mainly attributed to the increase in resistance. The batteries with pre-charge pulse discharge (line 224) show both the highest capacity retention and the smallest resistance growth, indicating that SEI growth is inhibited.
[0041] The pre-charge pulse discharge can be applied at any DOD, i.e., at any time the battery is being charged. Figures 6A-6C is a photo of the electrode of a battery after 10 cycles. In Figure 6A , the battery was charged after pre-charge pulse discharge at 50 DOD, and the electrode has more dark portions compared to Figure 6C , where no pre-charge pulse discharge was applied and the electrode showed a shiny lithium surface. Figure 6B is a photo of the electrode from a battery charged after pre-charge pulse discharge at 90 DOD, showing similar dark portions to Figure 6A . This indicates that pre-charge pulse discharge at any DOD is beneficial for lithium deposition under the SEI.
[0042] In addition to reducing SEI formation, another advantage of applying a pre-charge pulse discharge is to allow lower pressure operation of LMBs. Unlike C / 3 cycling, which requires much higher pressure to achieve dense lithium deposition, batteries with pre-charge pulse discharge applied only require about half the pressure to cycle, as lithium can be deposited under the SEI even at lower pressures. This allows for more flexible battery designs that can be suitable for a variety of applications, and provides opportunities for integrating LMBs into space-constrained applications such as electric vehicles, airplanes, submarines, and spacecraft. Figures 7A-7F includes SEM images of the anode of batteries cycled at different pressures:Figure 7A , Figure 7B and Figure 7C are images of a zero SOC anode operating at 50 psi, 100 psi, and 150 psi; and Figure 7D , Figure 7E and Figure 7F are images of a 100 SOC anode operating at 50 psi, 100 psi, and 150 psi. As can be seen, for the electrodes of the battery that were discharged with pre-charge pulses, even when operating at these relatively low pressures, lithium is deposited under the SEI and there is less lithium exposed to the surface.
[0043] Furthermore, applying a pulse discharge prior to each recharge can also improve the safety of the battery. If lithium is deposited under the SEI, the risk of uncontrolled lithium growth or dendrite formation, which can lead to safety hazards such as short circuits and thermal runaway, can be reduced.
[0044] Applying a pre-charge pulse discharge prior to each charge facilitates the deposition of lithium under the SEI. These pre-charge pulse discharges can be applied at any DOD in the range of 0-95% and have a variety of advantages, including minimizing electrolyte / lithium consumption, which improves the life of the battery; reducing volume expansion, increasing energy density, and enhancing structural integrity; allowing operation at lower pressures; and improving safety due to reduced opportunities for isolated lithium and lower dendritic lithium formation.
[0045] An exemplary battery management system 300 is shown schematically in Figure 8 and can include one or more battery cells 304, a battery management microcontroller 308, a battery system interface 312, battery power supply terminals 316, a battery system interface 318, and a sensor 320 for determining SOC. The battery management microcontroller 308 can monitor and control the charging and discharging of the one or more battery cells 304.
[0046] In operation, as Figure 9The process outlined in the overview of process chart 400, whenever a recharge request is received from a user such as through a battery system interface (402), at step 404 the current DOD of the battery is determined, for example via a sensor, and at decision point 406 it is determined whether the DOD is between 0% and 95%. If the DOD is between 0% and 95% (preferably, the percentage to be discharged by the pulse discharge is subtracted from the current DOD for this determination), the battery management microcontroller discharges the battery at a high current pulse discharge rate for a pulse discharge time period (e.g., 10 seconds to 20 minutes) at step 408, or to a cutoff voltage of 3.5V to 2V as determined at step 410. The pulse discharge can occur at the charger or prior to being connected to the charger. The pulse discharge can be applied in a single discharge, or can be applied as a series of discharges. Further, the pulse discharge rate need not be constant during the pulse discharge phase. For example, the pulse discharge phase can be a multi-step pulse discharge with different currents at each step, or a continuous pulse with a constantly varying discharge current. For example, the pulse discharge can be at 2C for 2 minutes, or at 2C for 1 minute and then change to 1C for 1 minute. After the pulse discharge time period is complete, the recharge process begins at step 411 and continues until it is determined at step 412 that the charge is complete or otherwise to stop charging. The recharge can begin at the typical charge rate, or a lower charge rate can be applied for a short period of time (e.g., 10 seconds to 20 minutes) prior to completing the recharge at the typical charge rate.
[0047] Further, as Figure 10As outlined in the process diagram 500, in the event that the DOD is greater than 95%, a pulse charge can be applied at 0.33C rate until 5% SOC is reached, and then immediately after the pulse charge a pulse discharge is applied as described above, for example, at a rate from 0.5C to 5C. The battery is recharged immediately after the pulse discharge is applied. In this example, such as by receiving (502) a recharge request by the battery system interface, the current DOD of the battery is determined at step 504, for example, via sensors, and it is determined at decision point 506 whether the DOD is between 0% and 95%. If the DOD is between 0% and 95%, the battery management microcontroller discharges the battery at a high current pulse discharge rate for a pulse discharge time period (e.g., 10 seconds to 20 minutes), or to a cutoff voltage of 3.5V to 2V, as determined at step 510, at step 508. The pulse discharge can occur at the charger or before being connected to the charger. After the pulse discharge time period is complete, the recharging process begins at step 512 and continues until it is determined at step 514 that the charge is complete, or if not, the charge continues at step 516. If it is determined at step 518 that the DOD is not between 0% and 95%, if it is greater than 95%, a pulse discharge is applied at step 520 until 5% (or 10%) SOC is reached, at which point the pulse discharge is applied at step 508, and the recharging process continues as described above.
[0048] Thermal charging and dynamic pressure
[0049] In another embodiment, a method of charging an alkali metal, such as lithium metal, electrochemical cell includes charging the cell at an elevated charging temperature between 25°C and 60°C, and then discharging the cell at a discharge temperature that is lower than the charging temperature. Preferably, the discharge temperature can be about 25% lower than the charging temperature. For example, if the charging temperature is 45°C, the discharge temperature can be lower than 34°C. These thermal charging conditions can be applied throughout the charging process or for various lengths of time during any phase of the charging. For example, if the charging time is three hours, the thermal charging can be applied for the full three hours, or only for a portion of the charging time, for example, one hour.
[0050] Additionally, a lower pressure can be applied to the cell during discharge than during charging. For example, a charge pressure from 20 psi (137895 Pa) to 100 psi (689476 Pa) can be applied during the charging process, and then a discharge pressure that is lower than the charge pressure is applied when the cell is discharged. For example, the discharge pressure can be from about 10 psi (68948 Pa) to about 80 psi (551581 Pa).
[0051] The elevated temperature for charging can be provided by any suitable heat source, such as one or more thermoelectric modules. One or more temperature sensors can be positioned to monitor the temperature, and a controller that can be part of the battery management system can be used to control the heat source based on readings from the temperature sensors and the determined state of charge or state of discharge. During discharging, the heat source will be inactive, and if needed, based on the current temperature determination, a fan or similar can be used to accelerate and / or maintain the temperature in the desired lower range. With these arrangements in the context of a battery system, the temperature can be adjusted in a relatively short timeframe (e.g., a few seconds) so that no significant delay is needed when switching from charging to discharging or from discharging to charging.
[0052] A pressure controller can be used to adjust the pressure in the battery, and one or more pressure sensors can be used to monitor the pressure. The pressure controller and pressure sensors can be connected to the battery management system, which is used to control the pressure based on readings from the pressure sensors and the determined state of charge or state of discharge.
[0053] These temperature variations and pressure variations can be applied in conjunction with the above-described pulsed discharging techniques, such that the discharging temperature and discharging pressure will be applied during the discharging time period and during the pulsed discharging, and then the charging temperature and charging pressure will be applied during the subsequent charging. As Figure 11 As illustrated by the graph 600 shown, during the discharging time period 604, the temperature 620 and / or the pressure 622 can be maintained. As described above, a pulsed discharge can be applied during the pulsed discharging time period 608, and then one or both of a higher temperature 621 and a higher pressure 623 can be applied during the charging time period 612.
[0054] The example battery system 700 is in Figure 12A battery system 700 is schematically illustrated and can include one or more battery cells 704, a battery management microcontroller 708, a battery system interface 712, battery power terminals 716, a battery system interface 718, and sensors 720 for determining SOC. The battery management microcontroller 708 can monitor and control the charging and discharging of the one or more battery cells 704 according to pulse discharge techniques. Additionally, the system 700 can include a temperature sensor 726 and a pressure sensor 706 for determining temperature and pressure in the system, each connected to the battery management microcontroller 708. A heating element 702 can be connected to and controlled by the battery management microcontroller 708 to raise the temperature of the battery cells 704 during recharging. A pressure device 722 can be connected to and controlled by the battery management microcontroller 708 to raise the pressure of the battery cells 704 during recharging. A valve 728 can be connected to and controlled by the battery management microcontroller 708 such that heat and pressure can be released from the system 700 when needed, such as during a discharging period. A fan can also be included to facilitate cooling and temperature control.
[0055] As used herein, the term "immediately" means that no other discharging operation or charging operation is performed between the referenced discharging operation or charging operation. For example, if battery recharging occurs immediately after applying a pulse discharge, no other discharging operation or charging operation occurs between the pulse discharge and the recharging.
[0056] The term "about," as used herein when used in connection with a quantity, is meant to encompass ±20% of the stated value, typically ±10% of the stated value, often ±5% of the stated value, and most often ±2% of the stated value. In some embodiments, the term "about" can be considered to be an exact indication of the actual value.
[0057] Many modifications and additions can be made to the embodiments described herein without departing from the spirit and scope of this disclosure. Each of the various embodiments described above can be appropriately combined with features of other described embodiments to provide a variety of combinations of features in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present disclosure. Furthermore, while a particular method can be illustrated and / or described as being performed in a particular order, ordering is highly variable within the scope of ordinary skill to achieve aspects of the present disclosure. Therefore, the description is intended to be illustrative only and not limiting of the scope of the application.
Claims
1. A method of charging an alkali metal electrochemical cell, comprising: applying a pulse discharge at a rate from about 0.5C to about 5C immediately prior to initiating a recharge of the cell.
2. The method of claim 1, wherein the rate is from about 1C to about 5C.
3. The method of claim 2, wherein the pulse discharge has a duration in a range from about 10 seconds to about 20 minutes.
4. The method of claim 3, wherein the pulse discharge is applied at a depth of discharge between 0% and 95%.
5. The method of claim 3, wherein an operating pressure of the cell is between 0 psi and 300 psi.
6. The method of claim 3, further comprising recharging the cell at a charge rate from 0.1C to 5C immediately after applying the pulse discharge.
7. The method of claim 3, wherein a cycle temperature of the cell is between about 10°C and about 60°C.
8. The method of claim 6, further comprising repeating the application of the pulse discharge for each cell cycle.
9. The method of claim 1, wherein the alkali metal electrochemical cell comprises a lithium metal oxide cathode or a lithium iron phosphate oxide cathode, an anode, a separator between the cathode and the anode, and an electrolyte comprising lithium ions or other alkali metal ions.
10. The method of claim 1, wherein the alkali metal electrochemical cell is a pouch cell, a prismatic cell, or a cylindrical cell having a capacity in a range from 0.2 Ah to 100 Ah.
11. The method of claim 1, wherein applying the pulse discharge comprises applying a series of pulse discharges, each pulse discharge applied at a different rate.
12. The method of claim 1, wherein applying the pulse discharge comprises applying a continuous pulse discharge at a varying rate.
13. The method of claim 1, further comprising initiating a recharge of the cell at a first charge rate for a period of time and completing the recharge of the cell at a second charge rate, wherein the first charge rate is lower than the second charge rate and the period of time is between about 10 seconds and about 20 minutes.
14. The method of claim 13, further comprising initiating a recharge of the cell at a first charge rate for a period of time and completing the recharge of the cell at a second charge rate, wherein the first charge rate is lower than the second charge rate and the period of time is between about 10 seconds and about 20 minutes.
15. The method of claim 1, further comprising applying a pulse charge at a rate less than 0.33C prior to applying the pulse discharge until a state of charge of at least 10% of the cell is reached.
16. The method of claim 1, further comprising: adjusting a temperature of the cell to a charge temperature between about 25°C and about 60°C when charging the cell; and lowering the temperature of the cell to a discharge temperature less than the charge temperature when discharging the cell. 17. The method of claim 16, wherein the discharge temperature is about 25% lower than the charge temperature.
18. The method of claim 16, wherein the charge temperature is maintained throughout the charge period.
19. The method of claim 1, further comprising: increasing a pressure in the battery to a charge pressure and maintaining the pressure at the charge pressure while the battery is charging, wherein the charge pressure is from about 20 psi to about 100 psi; and decreasing the pressure to a discharge pressure and maintaining the pressure at the discharge pressure while the battery is discharging, wherein the discharge pressure is lower than the charge pressure applied during charging.
20. The method of claim 19, wherein the discharge pressure is from about 10 psi to about 80 psi.
21. The method of claim 1, further comprising: adjusting a temperature of the battery to a charge temperature between about 25 °C and about 60 °C while the battery is being charged; decreasing the temperature of the battery to a discharge temperature that is less than the charge temperature while the battery is being discharged; increasing a pressure in the battery to a charge pressure and maintaining the pressure at the charge pressure while the battery is charging, wherein the charge pressure is from about 20 psi to about 100 psi; and decreasing the pressure to a discharge pressure and maintaining the pressure at the discharge pressure while the battery is discharging, wherein the discharge pressure is lower than the charge pressure applied during charging.
22. The method of claim 21, wherein the discharge pressure is from about 10 psi to about 80 psi.