High-temperature formation method of lithium titanate battery and preparation method of lithium titanate battery
By using the pressure synthesis equipment to perform the high-temperature synthesis method of lithium titanate batteries at a temperature of 75-95°C, the problem of SEI membrane decomposition at high temperature and limited conductivity at low temperatures is solved, and the adequacy and capacity of lithium titanate batteries are realized.
Patent Information
- Application Number
- CN202411940662.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-05-06
AI Technical Summary
Generally, when lithium-ion batteries are formed at high temperatures, some components of the SEI film will decompose, resulting in the capacity of the lithium-ion batteries being limited, while the transformation at low temperatures will result in the conductivity of the electrolyte being limited and the transformation is insufficient.
The high-temperature synthesis method of lithium titanate batteries is adopted. At a temperature of 75-95°C, a series of constant current charging, constant voltage charging and constant current discharge are used to perform the synthesis using a pressure synthesis device to ensure the sufficiency of the synthesis process.
At high temperature, the SEI membrane will not decompose, and it can promote the full occurrence of chemical reactions, activate more active substances, and then make the lithium titanate battery more fully, which is conducive to the effective performance of capacity.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of lithium titanate batteries, and in particular to a high-temperature formation method of a lithium titanate battery and a preparation method of a lithium titanate battery. Background Art
[0002] With the growing demand for energy in modern society and the pursuit of environmentally friendly energy solutions, lithium titanate batteries have broad market prospects due to their high safety and long life. Lithium titanate batteries have high structural stability and cycle life. During the charge and discharge process, their volume changes are minimal, and the battery cycle stability is high and the service life is long. Lithium titanate batteries perform well in applications that require high power output and fast charge and discharge, such as electric vehicles, rail transit, energy storage systems, etc.
[0003] In the process of preparing lithium titanate batteries, the formation temperature is an important factor affecting the viscosity and conductivity of the electrolyte and the diffusion rate of the electrode material ions on the formation effect. The higher the formation temperature, the lower the viscosity of the electrolyte, the higher the conductivity of the electrolyte, and the faster the diffusion rate of the electrode material ions. Therefore, the smaller the polarization, the better the formation effect. However, for general lithium-ion batteries, some components of the SEI film will decompose at high temperatures, causing the SEI film to rupture, which will further consume lithium to generate a new SEI film, resulting in the capacity of the lithium-ion battery being limited.
[0004] In view of this, the present invention is proposed. Summary of the invention
[0005] The main purpose of the present invention is to provide a high-temperature formation method for a lithium titanate battery and a preparation method for a lithium titanate battery, so as to solve the problem that the SEI film formed at a high temperature of a general lithium-ion battery will decompose, further consuming lithium to generate a new SEI film, resulting in the capacity of the lithium-ion battery being limited, while the formation at a low temperature will result in the conductivity of the electrolyte being limited.
[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, the lithium titanate to be formed after the injection is allowed to stand still is placed in a pressure forming device for high-temperature formation under a forming pressure. The high-temperature formation method comprises: step S1, after a first preset time t1 is left at a first preset temperature T1, a first constant current charging is performed for a second preset time t2 using a first current I1; step S2, at the second preset temperature T2, a second constant current charging is performed to a first cut-off voltage V1 using a second current I2, and a first constant voltage charging is performed at the first cut-off voltage V1 for a third preset time t3 and then left for a fourth preset time t4; step S3, at the third preset temperature T3, a third current is used to charge the lithium titanate to a first constant current. I3 performs constant current discharge to a second cut-off voltage V2, and then performs constant voltage discharge at the second cut-off voltage V2 for a fifth preset time t5 and then leaves it for a sixth preset time t6; return to the above step S2, and cycle steps S2 to S3 at least once; step S4, at the fourth preset temperature T4, use the fourth current I4 to perform a third constant current charge to a third cut-off voltage V3, and then perform a third constant voltage charge at the third cut-off voltage V3 for a seventh preset time t7 and then leave it for an eighth preset time t8 to end the formation; wherein the first preset temperature T1, the second preset temperature T2, the third preset temperature T3 and the fourth preset temperature T4 are each independently 75-95°C.
[0007] Further, in step S1, the first preset time t1 is ≥ 30 min; preferably 120-240 min.
[0008] Furthermore, the first current I1 is 0.05-1.0C, preferably 0.1C.
[0009] Furthermore, the second preset time t2≥5min, preferably 10-15min.
[0010] Further, in step S2, the second current I2 is 0.2-2.0C, preferably 0.5-1.5C.
[0011] Furthermore, the first cut-off voltage V1 ≥ 2.6V, preferably 2.6-3.0V.
[0012] Further, in step S2, the third preset time t3 is ≥ 30 min, preferably 30-240 min.
[0013] Furthermore, the fourth preset time t4≥5min, preferably 5-15min.
[0014] Further, in step S3, the third current I3 is 0.2-2.0C, preferably 0.8-1.2C.
[0015] Furthermore, the second cut-off voltage V2≤1.8V, preferably 1.5-1.8V.
[0016] Further, in step S3, the fifth preset time t5 ≥ 30 min, preferably 30-240 min.
[0017] Furthermore, the sixth preset time t6 is ≥5 min, preferably 5-15 min.
[0018] Further, step S2 to step S3 are cycled multiple times, preferably 2-6 times.
[0019] Further, in step S4, the fourth current I4 is 0.2-2.0C, preferably 0.8-1.2C.
[0020] Furthermore, the third cut-off voltage is ≥2.6V, preferably 2.6-3.0V.
[0021] Further, in step S4, the seventh preset time t7 is ≥ 30 min, preferably 120-240 min.
[0022] Furthermore, the eighth preset time t8 is ≥5 min, preferably 5-15 min.
[0023] Furthermore, the formation pressure is 2.0-4.0 MPa. To achieve the above object, according to another aspect of the present invention, a method for preparing a lithium titanate battery is provided, the method comprising the high temperature formation method for a lithium titanate battery provided in the first aspect.
[0024] By applying the technical solution of the present application, the high-temperature formation method of the lithium titanate battery provided by the present application utilizes the unique wide temperature resistance of the lithium titanate material and performs the formation at 75-95°C. Not only will it not cause the decomposition of the SEI film, but it can also promote the chemical reaction to occur more fully, and more active substances will be activated, thereby making the lithium titanate battery more fully formed and more conducive to capacity utilization. DETAILED DESCRIPTION
[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.
[0026] As analyzed in the background technology of this application, at present, the formation of general lithium-ion batteries at high temperatures will cause some components of the SEI film to decompose, causing the SEI film to rupture, resulting in the capacity of the lithium-ion battery being limited, while the formation at low temperatures will lead to slow ion diffusion, limited conductivity of the electrolyte, and insufficient formation. In order to solve this problem, the present application provides a high-temperature formation method for a lithium titanate battery and a preparation method for a lithium titanate battery.
[0027] In a first typical embodiment of the present application, a high-temperature formation method for a lithium titanate battery is provided, wherein the lithium titanate battery to be formed after being injected and allowed to stand is placed in a pressure formation device for high-temperature formation under a formation pressure, and the high-temperature formation comprises the following steps: step S1, after being left at a first preset temperature T1 for a first preset time t1, a first current I1 is used to perform a first constant current charging for a second preset time t2; step S2, at a second preset temperature T2, a second current I2 is used to perform a second constant current charging to a first cut-off voltage V1, and a first constant voltage charging is performed at the first cut-off voltage V1 for a third preset time t3 and then left for a fourth preset time t4; step S3, at At the third preset temperature T3, the third current I3 is used to discharge at a constant sulfur current to the second cut-off voltage V2, and then the second cut-off voltage V2 is discharged at a constant voltage for a fifth preset time t5 and then the sixth preset time t6 is set aside; return to step S2, and cycle steps S2 to S3 at least once; step S4, at the fourth preset temperature T4, the fourth current I4 is used to charge at a constant current to the third cut-off voltage V3, and then the third cut-off voltage V3 is charged at a constant voltage for a seventh preset time t7 and then the eighth preset time t8 is set aside to end the formation; wherein the first preset temperature T1, the second preset temperature T2, the third preset temperature T3 and the fourth preset temperature T4 are each independently 75-95°C.
[0028] The high-temperature formation method of the lithium titanate battery provided in the present application utilizes the unique wide temperature resistance of the lithium titanate material and has excellent applicability within 75-95°C. It not only does not cause the decomposition of the SEI film, but also can promote the chemical reaction to occur more fully, more active substances are activated, and thus the lithium titanate battery is formed more fully and is more conducive to capacity utilization.
[0029] In the present application, the first preset temperature T1, the second preset temperature T2, the third preset temperature T3 and the fourth preset temperature T4 can be the same or different, as long as they are all controlled within 75-95° C. Specifically, the first preset temperature T1, the second preset temperature T2, the third preset temperature T3 and the fourth preset temperature T4 can each independently be 75° C., 78° C., 80° C., 82° C., 85° C., 88° C., 90° C., 92° C., 95° C. or a range consisting of any two values.
[0030] In some embodiments, in step S1, the first preset time t1 is ≥ 30 min, so as to facilitate the electrolyte to be formed inside the lithium titanate battery to be dispersed more fully. In particular, when the first preset time t1 is 120-240 min, it is more conducive to saving energy while making the electrolyte more fully infiltrated inside the lithium titanate battery. Specifically, the first preset time t1 can be 30 min, 60 min, 90 min, 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, 150 min, 180 min or a range of any two values.
[0031] In some embodiments, the first current I1 is 0.05-1.0C to facilitate constant current charging with a small current, which is more conducive to the activation of active materials, especially when the first current I1 is 0.08-0.12C, it is more conducive to improving the efficiency of constant current charging. Specifically, the first current I1 can be 0.05C, 0.08C, 0.09C, 0.1C, 0.12C, 0.15C, 0.2C, 0.5C, 1.0C or a range of any two values.
[0032] In some embodiments, the second preset time t2 is ≥ 5 min, so that the active material is more fully activated during the low-current constant-current charging process, especially when the second preset time is 10-15 min, it is more conducive to reducing energy consumption while activating the active material. Specifically, the second preset time can be 5 min, 8 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, or a range of any two values.
[0033] In some embodiments, in the above step S2, the second current I2 is 0.2-2.0C to facilitate constant current charging through a large current to further activate the active material, especially when the second current I2 is 0.5-1.5C, it is more conducive to improving the efficiency of large current constant current charging. Specifically, the second current I2 can be 0.2C, 0.4C, 0.6C, 0.8C, 0.9C, 1.0C, 1.1C, 1.2C, 1.5C, 1.8C, 2.0C or a range of any two values.
[0034] In some embodiments, the first cut-off voltage V1 is ≥ 2.6V, so as to facilitate more sufficient activation of the active material, especially when the first cut-off voltage V1 is 2.6-3.0V, it is more conducive to saving energy while improving the efficiency of high-current constant-current charging. Specifically, the first cut-off voltage V1 can be 2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 2.95V, 3.0V, or a range of any two values.
[0035] In some embodiments, the third preset time t3 ≥ 30 min is more conducive to promoting the chemical reaction in the first constant voltage charging, especially when the third preset time t3 is 30-240 min, it is more conducive to improving the efficiency of the first constant voltage charging. Specifically, the third preset time t3 can be 30 min, 60 min, 90 min, 120 min, 130 min, 140 min, 150 min, 180 min, 210 min, 240 min or a range of any two values.
[0036] In some embodiments, the fourth preset time t4 is ≥ 5 min, so as to facilitate a more complete chemical reaction in the electrolyte, especially when the fourth preset time t4 is 5-15 min, it is more conducive to improving the efficiency of high temperature formation. Specifically, the fourth preset time t4 can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 15 min or a range consisting of any two values.
[0037] In some embodiments, in the above step S3, the third current I3 is 0.2-2.0C, so as to facilitate the use of high-current constant-current discharge to further activate the chemical substances, especially when the third current I3 is 0.8-1.2C, it is more conducive to improving the efficiency of high-current constant-current discharge. Specifically, the third current I3 can be 0.2C, 0.4C, 0.6C, 0.8C, 0.9C, 1.0C, 1.1C, 1.2C, 1.5C, 2.0C or a range of any two values.
[0038] In some embodiments, the second cut-off voltage V2 is ≤1.8V, so as to facilitate the chemical reaction to fully occur, especially when the second cut-off voltage is 1.5-1.8V, it is more conducive to improving the efficiency of large current constant current discharge. Specifically, the second cut-off voltage can be 1.5V, 1.55V, 1.6V, 1.65V, 1.7V, 1.75V, 1.8V or a range of any two values.
[0039] In some embodiments, the fifth preset time t5 of constant voltage discharge is ≥ 30 min, so as to facilitate the full activation of the active material, especially when the fifth preset time t5 is 30-240 min, it is more conducive to improving the efficiency of constant voltage discharge. Specifically, the fifth preset time of constant voltage discharge can be 30 min, 60 min, 90 min, 120 min, 130 min, 140 min, 150 min, 180 min, 210 min, 240 min or a range of any two values.
[0040] In some embodiments, the sixth rest time t6 after constant voltage discharge is ≥ 5 min, so as to facilitate more sufficient activation of the active material, especially when the sixth rest time t6 after constant voltage discharge is 5-15 min, it is more conducive to improving the efficiency of high temperature formation. Specifically, the sixth rest time t6 after constant voltage discharge can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 15 min or a range of any two values.
[0041] In order to further improve the formation efficiency, it is preferred to cycle step S2 to step S3 multiple times, preferably 2-6 times, such as 2 times, 3 times, 4 times, 5 times or 6 times.
[0042] In order to further improve the high-temperature formation efficiency, in some embodiments, in the above step S4, the fourth current I4 is 0.2-2.0C, so as to facilitate more sufficient formation through a large current, especially when the fourth current is 0.8-1.2C, it is more conducive to improving the third constant current charging efficiency. Specifically, the fourth current I4 can be 0.2C, 0.4C, 0.6C, 0.8C, 0.9C, 1.0C, 1.1C, 1.2C, 1.5C, 2.0C or a range of any two values.
[0043] In some embodiments, the third cutoff voltage V3 ≥ 2.6V, preferably 2.6-3.0V, to further promote a more complete formation. Specifically, the third cutoff voltage V3 can be 2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 2.95V, 3.0V, or a range of any two values.
[0044] In some embodiments, the seventh preset time t7 of the third constant voltage charging is ≥ 30 min, preferably 30-240 min, so as to improve the efficiency of the third constant voltage charging. Specifically, the seventh preset time of the third constant voltage charging can be 30 min, 60 min, 90 min, 120 min, 130 min, 140 min, 150 min, 180 min, 210 min, 240 min or a range of any two values.
[0045] In some embodiments, the eighth preset time t8 after the third constant voltage charging is set aside for ≥5 min, so as to make the electrolyte in the lithium titanate battery more uniform and sufficient, especially when the eighth preset time t8 is 5-15 min, it is more conducive to improving the formation effect. Specifically, the eighth preset time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 15 min or a range of any two values.
[0046] In order to further improve the capacity of lithium titanate batteries, in some embodiments, the above-mentioned high-temperature formation method is preferably carried out under a formation pressure of 2.0-4.0 MPa. Specifically, the formation pressure can be 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa or a range value consisting of any two values.
[0047] In a second typical embodiment of the present application, a method for preparing a lithium titanate battery is provided, and the method includes the high-temperature formation method of the lithium titanate battery provided in the first typical embodiment.
[0048] The preparation method of the lithium titanate battery provided in the present application utilizes the unique wide temperature resistance of the lithium titanate material and is formed at 75-95°C. Not only will it not cause the decomposition of the SEI film, but it can also promote the chemical reaction to occur more fully, and more active substances will be activated, thereby making the lithium titanate battery more fully formed and more conducive to capacity utilization.
[0049] In some specific embodiments, the positive electrode of the lithium titanate battery includes a positive electrode active material, a conductive agent and a binder, and the positive electrode active material includes but is not limited to lithium cobalt oxide, lithium manganate, lithium iron phosphate, etc.; the negative electrode includes a negative electrode active material, a conductive agent and a binder, and the negative electrode active material is such as lithium titanate, etc.; the electrolyte is generally a lithium salt solution, and the lithium salt is such as lithium hexafluorophosphate, lithium borate, etc.; the solvent is DMC (dimethyl carbonate), EC (ethylene carbonate) and EMC (ethyl methyl carbonate), etc., and the preferred solution is DMC, EC and EMC in a volume ratio of 1:1:1; the diaphragm is a PE (polyethylene) wet diaphragm or a PP (polypropylene) dry diaphragm.
[0050] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.
[0051] It should be noted that the specific composition of the 2AhLTO soft-pack lithium titanate battery used in the following embodiments and comparative examples is as follows: Positive electrode: Lithium nickel cobalt manganese oxide, Ketjen black, carbon nanotubes and PVDF (polyvinylidene fluoride) are mixed and coated in a ratio of 95:2:3.
[0052] Negative electrode: Lithium titanate, acetylene black and PVDF are mixed and coated in a ratio of 93:4:3.
[0053] Electrolyte: 1 mol / L lithium hexafluorophosphate (1 mol / L) lithium salt solution, the solvent is a mixture of DEC (dimethyl carbonate), EC (ethylene carbonate) and EMC (ethyl methyl carbonate) in a volume ratio of 1:1:1.
[0054] Diaphragm: Dry PP (polypropylene) diaphragm.
[0055] Example 1
[0056] This embodiment provides a formation method for a 2AhLTO soft-pack lithium titanate battery, which is performed according to the following steps:
[0057] (1) placing the lithium titanate battery to be formed after the injection and standing still on a pressure forming device, and setting the formation pressure to 2.0 MPa;
[0058] (2) setting the temperature of the pressure forming equipment to 85°C, and placing the lithium titanate battery to be formed for 120 minutes after the temperature reaches 85°C;
[0059] (3) Charge the battery at a constant current of 0.1C for 10 minutes;
[0060] (4) Increase the current to 1.0C and charge the battery to 2.8V at a constant current;
[0061] (5) Charge at 2.8V constant voltage for 120min;
[0062] (6) After standing for 5 minutes, discharge the battery to 1.5V using a 1.0C constant current;
[0063] (7) Discharge at 1.5V constant voltage for 120min and let stand for 5min;
[0064] (8) Repeat steps (4) to (7) for a total of 3 cycles;
[0065] (9) Charge at a high constant current of 1C to 2.8V, then charge at a constant voltage of 2.8V for 120min, let stand for 5min, and the formation is complete.
[0066] Example 2
[0067] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the pressure forming equipment is set to 95°C.
[0068] Example 3
[0069] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the pressure forming equipment is set to 75°C.
[0070] Example 4
[0071] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the pressure forming equipment is set to 95°C, the current of constant current charging in steps (4) and (9) is 1.5C, and the current of constant current discharging in step (6) is also 1.5C.
[0072] Example 5
[0073] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the pressure forming equipment is set to 95°C, the current of constant current charging in steps (4) and (9) is 0.5C, and the current of constant current discharging in step (6) is also 0.5C.
[0074] Example 6
[0075] This embodiment provides a formation method for a 2AhLTO soft-pack lithium titanate battery, which is performed according to the following steps:
[0076] (1) placing the lithium titanate battery to be formed after the injection and standing still on a pressure forming device, and setting the formation pressure to 2.1 MPa;
[0077] (2) setting the temperature of the pressure forming equipment to 85°C, and placing the lithium titanate battery to be formed for 240 minutes after the temperature reaches 85°C;
[0078] (3) Charge the battery at a constant current of 0.08C for 15 minutes;
[0079] (4) Increase the current to 0.5C and charge the battery to 3.0V at a constant current;
[0080] (5) Charge at 3.0V constant voltage for 30min;
[0081] (6) After standing for 15 minutes, discharge the battery to 1.8V using a 0.8C constant current;
[0082] (7) Discharge at 1.8V constant voltage for 240min and let stand for 15min;
[0083] (8) Repeat steps (4) to (7) for a total of 3 cycles;
[0084] (9) Charge at a high constant current of 1.2C to 2.6V, then charge at a constant voltage of 2.6V for 240min, let stand for 15min, and the formation is complete.
[0085] Example 7
[0086] This embodiment provides a formation method for a 2AhLTO soft-pack lithium titanate battery, which is performed according to the following steps:
[0087] (1) placing the lithium titanate battery to be formed after the injection and standing still on a pressure forming device, and setting the formation pressure to 2.0 MPa;
[0088] (2) setting the temperature of the pressure forming equipment to 85°C, and placing the lithium titanate battery to be formed for 120 minutes after the temperature reaches 85°C;
[0089] (3) Charge the battery at a constant current of 0.12C for 10 minutes;
[0090] (4) Increase the current to 1.5C and charge the battery to 2.6V at a constant current;
[0091] (5) Charge at 2.6V constant voltage for 240min;
[0092] (6) After standing for 5 minutes, discharge the battery to 1.5V using a 1.2C constant current;
[0093] (7) Discharge at 1.5V constant voltage for 30min and let stand for 5min;
[0094] (8) Repeat steps (4) to (7) for a total of 3 cycles;
[0095] (9) Charge at a high constant current of 0.8C to 3.0V, then charge at a constant voltage of 3.0V for 120min, let stand for 5min, and the formation is complete.
[0096] Example 8
[0097] This embodiment provides a formation method for a 2AhLTO soft-pack lithium titanate battery, which is performed according to the following steps:
[0098] (1) placing the lithium titanate battery to be formed after the injection and standing still on a pressure forming device, and setting the formation pressure to 2.0 MPa;
[0099] (2) setting the temperature of the pressure forming equipment to 85°C, and placing the lithium titanate battery to be formed for 120 minutes after the temperature reaches 85°C;
[0100] (3) Charge the battery at a constant current of 0.05C for 15 minutes;
[0101] (4) Increase the current to 0.2C and charge the battery to 3.0V at a constant current;
[0102] (5) Charge at 3.0V constant voltage for 30min;
[0103] (6) After standing for 15 minutes, discharge the battery to 1.8V using a 0.2C constant current;
[0104] (7) Discharge at 1.5V constant voltage for 120min and let stand for 5min;
[0105] (8) Repeat steps (4) to (7) for a total of 3 cycles;
[0106] (9) Charge at a high constant current of 0.2C to 2.6V, then charge at a constant voltage of 2.6V for 120min, let stand for 5min, and the formation is complete.
[0107] Example 9
[0108] This embodiment provides a formation method for a 2AhLTO soft-pack lithium titanate battery, which is performed according to the following steps:
[0109] (1) placing the lithium titanate battery to be formed after the injection and standing still on a pressure forming device, and setting the formation pressure to 2.0 MPa;
[0110] (2) setting the temperature of the pressure forming equipment to 85°C, and placing the lithium titanate battery to be formed for 120 minutes after the temperature reaches 85°C;
[0111] (3) Charge the battery at a constant current of 1.0C for 5 minutes;
[0112] (4) Increase the current to 2.0C and charge the battery to 2.6V at a constant current;
[0113] (5) Charge at 2.6V constant voltage for 150min;
[0114] (6) After standing for 15 minutes, discharge the battery to 1.5V using a 2.0C constant current;
[0115] (7) Discharge at 1.5V constant voltage for 120min and let stand for 5min;
[0116] (8) Repeat steps (4) to (7) for a total of 3 cycles;
[0117] (9) Charge at a high constant current of 2.0C to 3.0V, then charge at a constant voltage of 3.0V for 120min, let stand for 5min, and the formation is complete.
[0118] Example 10
[0119] The difference between this embodiment and embodiment 1 is that in step (1), the formation pressure is set to 2.5 MPa.
[0120] Embodiment 11
[0121] The difference between this embodiment and embodiment 1 is that in step (1), the formation pressure is set to 4.0 MPa.
[0122] Example 12
[0123] The difference between this embodiment and embodiment 1 is that in step (1), the formation pressure is set to 1.5 MPa.
[0124] Example 13
[0125] The difference between this embodiment and embodiment 1 is that in step (1), the formation pressure is set to 5.0 MPa.
[0126] Comparative Example 1
[0127] The difference between this comparative example and Example 1 is that in step (2), the temperature of the pressure forming equipment is set to 60°C.
[0128] Comparative Example 2
[0129] The difference between this comparative example and Example 1 is that in step (2), the temperature of the pressure forming equipment is set to 105°C.
[0130] Comparative Example 3
[0131] The difference between this comparative example and Example 1 is that step (3) is not performed to directly charge the battery to 2.8V with a current of 1C, and step (7) is not performed to start the cycle to directly charge the battery to 2.8V with a current of 1C after constant current discharge to 1.5V.
[0132] Performance Testing
[0133] The lithium titanate batteries obtained after the formation of the embodiment and the comparative example were tested for capacity, internal resistance and 3000 cycle retention rate at room temperature. The results are shown in Table 1 below.
[0134] Among them, (1) the capacity test method is: at room temperature (25°C), the battery is charged to 2.9V at 1C on a charge and discharge cabinet, left to stand for 10 minutes, and then discharged to 1.5V at 1C, and the battery capacity during the discharge process is recorded.
[0135] (2) The internal resistance test method is: when the battery is half-charged, a voltage internal resistance meter is used to apply a sine wave AC signal with a frequency of 1kHz and a current of 100mA to both ends of the battery, and the AC response of the battery is measured and processed and calculated.
[0136] (3) The test method for the 3000-cycle retention rate at room temperature is as follows: the test battery is first initialized at room temperature (25°C) by discharging at 1C to 1.5V and letting it stand for 30 minutes; then at room temperature (25°C), the battery is charged at 2C to a termination voltage of 2.9V, let it stand for 30 minutes, and then discharged at 2C to a termination voltage of 1.5V and let it stand for 30 minutes; the discharge capacity at the first time and at the 3000th cycle is recorded and the cycle retention rate is calculated.
[0137] Table 1
[0138]
[0139]
[0140] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the high-temperature formation method of the lithium titanate battery provided in the present application utilizes the unique wide temperature resistance of the lithium titanate material and is formed at 75-95°C, which not only does not cause the decomposition of the SEI film, but also can promote the chemical reaction to occur more fully, more active substances are activated, and thus the lithium titanate battery is formed more fully and is more conducive to capacity utilization.
[0141] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A high temperature formation method for a lithium titanate battery, characterized in that: The lithium titanate battery to be formed after the injection is allowed to stand is placed in a pressure forming device for high temperature formation under formation pressure. The high temperature formation method comprises: Step S1, after being left at a first preset temperature T1 for a first preset time t1, a first constant current charging is performed using a first current I1 for a second preset time t2; Step S2, at the second preset temperature T2, using the second current I2 to perform a second constant current charging to the first cut-off voltage V1, performing a first constant voltage charging at the first cut-off voltage V1 for a third preset time t3 and then suspending for a fourth preset time t4; Step S3, at the third preset temperature T3, using the third current I3 to perform constant current discharge to the second cut-off voltage V2, and then performing constant voltage discharge at the second cut-off voltage V2 for a fifth preset time t5 and then suspending for a sixth preset time t6; returning to the above step S2, and looping steps S2 to S3 at least once; Step S4, at the fourth preset temperature T4, using the fourth current I4 to perform a third constant current charging to a third cut-off voltage V3, and then performing a third constant voltage charging at the third cut-off voltage V3 for a seventh preset time t7 and then suspending for an eighth preset time t8 to end the formation; The first preset temperature T1, the second preset temperature T2, the third preset temperature T3 and the fourth preset temperature T4 are independently 75-95°C.
2. The high temperature chemical formation method according to claim 1, characterized in that: In step S1, the first preset time t1 is ≥ 30 min; preferably 120-240 min; and / or, the first current I1 is 0.05-1.0C, preferably 0.08-0.12C; And / or, the second preset time t2≥5min, preferably 10-15min.
3. The high temperature chemical formation method according to claim 1, characterized in that: In step S2, the second current I2 is 0.2-2.0C, preferably 0.5-1.5C; And / or, the first cut-off voltage V1 ≥ 2.6V, preferably 2.6-3.0V.
4. The high temperature chemical formation method according to claim 1, characterized in that: In step S2, the third preset time t3 is ≥ 30 min, preferably 30-240 min; And / or, the fourth preset time t4≥5min, preferably 5-15min.
5. The high temperature chemical formation method according to claim 1, characterized in that: In step S3, the third current I3 is 0.2-2.0C, preferably 0.8-1.2C; And / or, the second cut-off voltage V2≤1.8V, preferably 1.5-1.8V.
6. The high temperature chemical formation method according to claim 1, characterized in that: In step S3, the fifth preset time t5 is ≥ 30 min, preferably 30-240 min; And / or, the sixth preset time t6 ≥ 5 min, preferably 5-15 min; And / or, cycle step S2 to step S3 multiple times, preferably 2-6 times.
7. The high temperature chemical formation method according to any one of claims 1 to 6, characterized in that: In step S4, the fourth current I4 is 0.2-2.0C, preferably 0.8-1.2C; And / or, the third cut-off voltage is ≥2.6V, preferably 2.6-3.0V.
8. The high temperature chemical formation method according to any one of claims 1 to 6, characterized in that: In step S4, the seventh preset time t7 is ≥ 30 min, preferably 30-240 min; And / or, the eighth preset time t8≥5 min, preferably 5-15 min.
9. The high temperature chemical formation method according to any one of claims 1 to 6, characterized in that: The formation pressure is 2.0-4.0 MPa.
10. A method for preparing a lithium titanate battery, characterized in that: The method for preparing the lithium titanate battery comprises the high-temperature formation method for the lithium titanate battery according to any one of claims 1 to 9.