Repair and regeneration method of manganese-based lithium-ion batteries

Abstract

The present application discloses a method for repairing and regenerating a manganese-based lithium-ion battery, which relates to the technical field of lithium-ion batteries, and specifically includes: opening the liquid injection port of the battery to be repaired and injecting a destructive agent into the battery, and after standing for 10h~14h, heating the battery to 90℃~105℃, discharging the battery to 2.0V, and then cooling and injecting electrolyte, and then standing for 10h~14h to obtain a regenerated battery. The method for repairing and regenerating a manganese-based lithium-ion battery in the present application is conducive to a more thorough decomposition of the SEI film, and timely discharge of the decomposition products, which is conducive to increasing the capacity of the regenerated battery and reducing the internal resistance; at the same time, the process is simple, the cost is low, and it is conducive to industrial application.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a method for repairing and regenerating manganese-based lithium-ion batteries. Background Art

[0002] Lithium-ion batteries are widely used in 3C digital, electric vehicles, energy storage and other fields. As the battery is used, the capacity of the lithium-ion battery gradually decays, mainly due to the expansion of the electrode and the continuous damage and reconstruction of the SEI film. The thickness of the SEI film eventually increases from ~100nm to several hundred nm, accompanied by an increase in the internal resistance of the battery. Finding a method for repairing and regenerating lithium-ion batteries is an important topic for researchers and technical workers.

[0003] The traditional method mainly uses chemical or electrochemical methods to corrode the SEI film. For example, after the capacity of the lithium-ion battery is reduced, it is discharged, and then the SEI film is destroyed by chemical methods, and then the SEI film repair agent is added, and finally it is formed; for example, by making the potential of the negative electrode of the lithium-containing battery relative to the third electrode of the lithium-containing battery at 2.5 volts ≤ V ≤ 4 volts, the electrochemical decomposition of the negative electrode SEI film is stimulated. However, the traditional chemical method requires the use of acid to dissolve the SEI, but the acid and the passivation layer aluminum oxide on the surface of the current collector aluminum foil will also have a slight reaction, causing the positive electrode material on the surface of the current collector to be slightly separated from the aluminum foil, and finally the internal resistance of the battery will increase. At the same time, the reaction between the acid and SEI will generate a large amount of water, which will eventually be in the battery, seriously affecting the performance of the battery. The traditional electrochemical method requires an external three-electrode, which is more complicated to operate. At the same time, when the negative electrode potential is raised to a high oxidation state of 2.5~4V, copper dissolves and precipitates on the positive electrode.

[0004] In view of this, a lithium battery repair method that can destroy the SEI film in lithium-ion batteries while reducing the impact on the current collector is particularly necessary. Summary of the invention

[0005] The purpose of the present application is to provide a repair and regeneration method for manganese-based lithium-ion batteries to solve the problem of damage to the current collector or insufficient decomposition of the SEI film during the repair process of the lithium battery.

[0006] This application is implemented as follows:

[0007] In a first aspect, the present application provides a method for repairing and regenerating a manganese-based lithium-ion battery, comprising the following steps:

[0008] Injecting a destroying agent, opening the liquid injection port of the battery to be repaired and injecting the destroying agent into the battery, after standing for 10 hours to 14 hours, heating the battery to 90° C. to 105° C., discharging the battery to 2.0V, and then cooling; the destroying agent includes dimethyl carbonate and ethyl propionate;

[0009] Inject electrolyte into the cooled battery and let it stand for 10h~14h;

[0010] The battery into which the electrolyte has been injected is then subjected to formation and the injection port is sealed to obtain a regenerated battery.

[0011] In an optional embodiment, the method further includes testing the capacity and internal resistance of the battery to be repaired and the regenerated battery. If the capacity of the battery increases and the resistance decreases after repair, the repair is successful; otherwise, the repair fails.

[0012] In an optional embodiment, the positive electrode material of the battery to be repaired includes lithium manganese oxide.

[0013] In an optional embodiment, the relationship between the injection amount of the destructive agent and the nominal capacity of the battery is 3.0 g / Ah to 4.0 g / Ah;

[0014] And / or, the relationship between the injection amount of the electrolyte and the nominal capacity of the battery is 3.0 g / Ah to 4.0 g / Ah.

[0015] In an optional embodiment, the battery is discharged to 2.0V at a current corresponding to 0.05C-0.2C;

[0016] and / or, the current used in the formation step is 0.05C~0.2C corresponding current;

[0017] and / or, cooling the battery to below 55° C. before injecting the electrolyte;

[0018] And / or, the injecting of the breaking agent is performed at an ambient dew point of ≤-30°C.

[0019] In an optional embodiment, the electrolyte includes a lithium salt, a solvent and a water-removing and acid-removing additive, and the water-removing and acid-removing additive is selected from at least one of trimethylsilyl phosphate, 1,3,6-hexanetrinitrile and tetravinylsilane; the mass fraction of the water-removing and acid-removing additive in the electrolyte is less than 1%.

[0020] In an optional embodiment, the solvent includes a cyclic solvent and a chain solvent, the mass fraction of the cyclic solvent in the electrolyte is 20% to 40%, and the mass fraction of the chain solvent in the electrolyte is 40% to 60%.

[0021] In an optional embodiment, the cyclic solvent is selected from at least one of ethylene carbonate and propylene carbonate;

[0022] And / or, the chain solvent is selected from at least one of dimethyl carbonate and ethyl methyl carbonate.

[0023] In an optional embodiment, the mass fraction of the lithium salt in the electrolyte is 10% to 15%.

[0024] In an optional embodiment, the electrolyte further includes a film-forming additive, and the film-forming additive is selected from at least one of vinylene carbonate, propylene sulfite, lithium difluorooxalatoborate and lithium disoxalatoborate; the mass fraction of the film-forming additive in the electrolyte is less than 2%.

[0025] This application has the following beneficial effects:

[0026] The repair and regeneration method of the manganese-based lithium-ion battery in the present application is conducive to a more thorough decomposition of the SEI film and timely discharge of the decomposition products, which is conducive to increasing the capacity of the regenerated battery and reducing the internal resistance; at the same time, the process is simple and the cost is low, which is conducive to industrial application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0028] The present application provides a method for repairing and regenerating a manganese-based lithium-ion battery, comprising the following steps:

[0029] Injecting a destroying agent, opening the liquid injection port of the battery to be repaired and injecting the destroying agent into the battery, after standing for 10 hours to 14 hours, heating the battery to 90° C. to 105° C., discharging the battery to 2.0V, and then cooling; the destroying agent includes dimethyl carbonate and ethyl propionate;

[0030] Inject electrolyte into the cooled battery and let it stand for 10h~14h;

[0031] The battery into which the electrolyte has been injected is then subjected to formation and the injection port is sealed to obtain a regenerated battery.

[0032] The SEI film only decomposes a small amount at 60~90℃, and can decompose by exothermic reaction at above 90℃. At this time, when the battery is discharged, lithium ions will escape from the negative electrode, solvate at the SEI membrane, and impact the SEI membrane, thereby accelerating the decomposition of SEI.

[0033] Furthermore, the destructive agent has a suitable boiling point, such as the boiling point of dimethyl carbonate is 91°C. When dimethyl carbonate with a boiling point that coincides with the SEI spontaneous exothermic decomposition reaction temperature is injected into the battery, the organic components in the SEI film (such as alkyl lithium carbonate ROCO2Li) will decompose and produce gas between 90 and 105°C. The produced gas can be taken out of the battery along with the boiling and vaporization of dimethyl carbonate, reducing the residual gas inside the battery that affects the battery performance; at the same time, the gas produced by the decomposition of organic matter and the gas produced by the vaporization of dimethyl carbonate will impact the inorganic matter in the SEI film (such as lithium carbonate, LiF, Li2O, LiOH), thereby causing some inorganic matter to be stripped off the negative electrode surface and a small amount to be taken out of the battery. When the temperature reaches 110°C, the battery separator begins to shrink, which will cause the positive and negative electrodes to directly contact and cause a short circuit, so the heating temperature should not be too high. In comparison, the boiling point of ethyl propionate is 99°C. Although it can also coincide with the SEI spontaneous exothermic decomposition reaction temperature, its effect in this application is less than that of dimethyl carbonate due to its slightly higher boiling point.

[0034] In summary, the repair and regeneration method of manganese-based lithium-ion batteries in the present application is conducive to a more thorough decomposition of the SEI film and timely discharge of the decomposition products, which is conducive to increasing the capacity of the regenerated battery and reducing the internal resistance; at the same time, the process is simple and the cost is low, which is conducive to industrial application.

[0035] In an optional embodiment, the method further includes testing the capacity and internal resistance of the battery to be repaired and the regenerated battery. If the capacity of the battery increases and the resistance decreases after repair, the repair is successful; otherwise, the repair fails.

[0036] Generally, after repair and regeneration, the battery capacity will be greater than before repair and regeneration, and the battery internal resistance will be smaller than before repair and regeneration. Such batteries can be used with confidence. Otherwise, they can be identified as abnormal batteries with hidden dangers, and wet extraction of metal elements is recommended.

[0037] In an optional embodiment, the positive electrode material of the battery to be repaired includes lithium manganese oxide.

[0038] Due to the characteristics of lithium manganese oxide, manganese-based lithium-ion batteries containing it decay quickly in the early stages of the cycle, the excess of the negative electrode relative to the positive electrode is aggravated, and there is no problem of insufficient NP ratio, so this type of battery is easy to repair and regenerate. However, the commonly mentioned spinel lithium manganese oxide LiMn2O4 will generate lithium-rich lithium manganese oxide Li2Mn2O4 after being discharged to below 2.0V. This phase is a tetragonal phase, and manganese is trivalent. The generation of lithium-rich lithium manganese oxide will cause material deformation and electrochemical irreversibility, so lithium manganese oxide is generally not lower than 2.0V.

[0039] In an optional embodiment, the relationship between the injection amount of the destructive agent and the nominal capacity of the battery is 3.0 g / Ah to 4.0 g / Ah;

[0040] And / or, the relationship between the injection amount of the electrolyte and the nominal capacity of the battery is 3.0 g / Ah to 4.0 g / Ah.

[0041] In manganese-based lithium-ion batteries, the amount of electrolyte and destructive agent that fills the pores in the battery is 3.0~4.0g / Ah. Too little addition cannot fill the pores in the positive and negative electrodes and the diaphragm. Too much addition will not only lead to a waste of electrolyte but also the battery cannot store too much electrolyte.

[0042] In an optional embodiment, the battery is discharged to 2.0V at a current corresponding to 0.05C-0.2C;

[0043] And / or, the current used in the formation step is 0.05C~0.2C corresponding current.

[0044] The formation and decomposition of the SEI film are both slow processes. Therefore, in the present application, both the SEI film decomposition and the SEI film regeneration use a small current corresponding to a rate of 0.05C~0.2C, which is conducive to a more thorough decomposition of the SEI film during the decomposition process or a relatively uniform SEI film during the formation process.

[0045] In an optional embodiment, the battery is cooled to below 55° C. before injecting the electrolyte to avoid excessive temperature difference between the battery and the electrolyte to be injected, which would cause the electrode and the diaphragm to shrink rapidly and cause performance degradation.

[0046] In an optional embodiment, the injection of the destructive agent is performed at an ambient dew point of ≤-30° C. to avoid introducing moisture into the battery as much as possible.

[0047] In an optional embodiment, the repair and regeneration method of a manganese-based lithium-ion battery comprises the following steps:

[0048] Charge and discharge the battery at a rate of 0.5C to test the battery capacity C1 and internal resistance R1;

[0049] In an environment with a dew point of ≤-30°C, dimethyl carbonate DMC solvent was injected into the lithium-ion battery. After standing for 12 hours, the battery was heated to 90°C~105°C and discharged to 2.0V with a small current.

[0050] Leave the heating environment, wait for the battery to cool down to below 55°C, inject electrolyte into the battery, and let it stand for 12 hours;

[0051] Use a small current to perform formation, repair and regeneration on the battery, and seal the battery after formation;

[0052] Charge and discharge the battery at a rate of 0.5C to test the battery capacity C2 and internal resistance R2;

[0053] If C2>C1 and R2<R1, it is determined that the battery repair and regeneration is successful, otherwise the battery repair and regeneration fails.

[0054] In an optional embodiment, the electrolyte includes a lithium salt, a solvent and a water-removing and acid-removing additive, and the water-removing and acid-removing additive is selected from at least one of trimethylsilyl phosphate, 1,3,6-hexanetrinitrile and tetravinylsilane; the mass fraction of the water-removing and acid-removing additive in the electrolyte is less than 1%.

[0055] When the battery filling port is opened, it will come into contact with the electrolyte. Even in a dew point environment, water will inevitably be introduced. Therefore, a small amount of water-removing and acid-removing additives are added to the electrolyte. Otherwise, water will continue to react with lithium hexafluorophosphate inside the lithium battery to generate hydrofluoric acid, which will eventually lead to a decrease in battery performance.

[0056] In some embodiments, if the ambient dew point is controlled below -40°C, it is not necessary to add water-removing and acid-removing additives.

[0057] In an optional embodiment, the solvent includes a cyclic solvent and a chain solvent, the mass fraction of the cyclic solvent in the electrolyte is 20% to 40%, and the mass fraction of the chain solvent in the electrolyte is 40% to 60%.

[0058] In an optional embodiment, the cyclic solvent is selected from at least one of ethylene carbonate and propylene carbonate;

[0059] And / or, the chain solvent is selected from at least one of dimethyl carbonate and ethyl methyl carbonate.

[0060] In an optional embodiment, the mass fraction of the lithium salt in the electrolyte is 10% to 15%.

[0061] In an optional embodiment, the electrolyte further includes a film-forming additive, and the film-forming additive is selected from at least one of vinylene carbonate, propylene sulfite, lithium difluorooxalatoborate and lithium disoxalatoborate; the mass fraction of the film-forming additive in the electrolyte is less than 2%.

[0062] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0063] Example 1

[0064] This embodiment provides a method for repairing and regenerating a manganese-based lithium-ion battery, which specifically includes the following steps:

[0065] Take two square aluminum shell battery products 15119-24Ah (nominal capacity is 24Ah, actual initial capacity is about 25Ah, initial internal resistance is about 0.95mΩ, battery thickness is 15mm, width is 119mm, height is 208mm) produced by Xingheng Power Co., Ltd. and conduct a repair and regeneration experiment. After the battery has been charged and discharged at room temperature and 0.5C, the capacity has decayed to about 20Ah, which is about 83% of the nominal capacity.

[0066] The two batteries were charged and discharged at a rate of 0.5C to test the capacity and internal resistance of the batteries before repair.

[0067] At an ambient dew point of -30°C, 72g of DMC was injected into each of the two batteries. After standing for 12 hours, the batteries were heated to 90°C, discharged to 2.0V with a current of 0.05C, and then left the heating environment.

[0068] When the battery is cooled to below 55°C, 72g of electrolyte is injected into the battery and left to stand for 12 hours. The electrolyte composition is as follows: the content of lithium salt LiPF6 is 13.5%, the sum of cyclic solvents ethylene carbonate EC and propylene carbonate PC is 35%, the sum of chain solvents dimethyl carbonate DMC and ethyl methyl carbonate EMC is ~50%, the sum of film-forming additives vinylene carbonate VC, propylene sulfite PS, lithium difluorooxalate borate LiODFB and lithium bisoxalate borate LiBOB is 1%, and the sum of water and acid removal additives trimethylsilyl phosphate TMSP, 1,3,6-hexane trinitrile HTCN and tetravinylsilane is 0.5%.

[0069] Then use a small current of 0.05C to repair and regenerate the battery, and seal the battery after formation.

[0070] The two batteries were then charged and discharged at a rate of 0.5C to test the battery capacity and internal resistance.

[0071] The battery capacity and internal resistance before and after repair are shown in Table 1. After repair and regeneration, the capacity of the two batteries increased by 18.62% and 18.41% respectively, and the internal resistance decreased by 25.17% and 25.90% respectively. After repair and regeneration, the capacity of the battery is still slightly different from the initial capacity. This is mainly due to the loss of battery capacity. In addition to the repeated expansion and reconstruction of SEI and the increase in the activated internal resistance, there is also the expansion of the electrode to form a dead zone and the collapse of the material structure. Therefore, this application is mainly used to repair the capacity loss and internal resistance increase caused by SEI film damage and thickening.

[0072] Table 1

[0073] Cycle times / times Capacity before repair / Ah Internal resistance before repair / mΩ Capacity after repair / Ah Internal resistance after repair / mΩ Battery 1 1050 20.2 1.51 23.9 1.13 Battery 2 1080 20.1 1.53 23.8 1.14

[0074] Example 2

[0075] This embodiment provides a method for repairing and regenerating a manganese-based lithium-ion battery, which specifically includes the following steps:

[0076] Take two square aluminum shell battery products 15119-24Ah (nominal capacity is 24Ah, actual initial capacity is about 25Ah, initial internal resistance is about 0.95mΩ, battery thickness is 15mm, width is 119mm, height is 208mm) produced by Xingheng Power Co., Ltd. for repair and regeneration experiment. After the battery is charged and discharged at room temperature and 0.5C, the capacity has decayed to about 19Ah, which is about 79% of the nominal capacity.

[0077] The two batteries were charged and discharged at a rate of 0.5C to test the capacity and internal resistance of the batteries before repair.

[0078] At an ambient dew point of -30°C, 96 g of DMC was injected into each of Battery 3 and Battery 4. After standing for 12 hours, the batteries were heated to 105°C, discharged to 2.0 V with a current of 0.05C, and then left the heating environment.

[0079] When the battery is cooled to below 55° C., 96 g of the electrolyte in Example 1 is injected into the battery and allowed to stand for 12 h.

[0080] Then use a small current of 0.05C to repair and regenerate the battery, and seal the battery after formation.

[0081] Then, battery 3 and battery 4 were charged and discharged at a rate of 0.5C to test the battery capacity and internal resistance.

[0082] The battery capacity and internal resistance before and after repair are shown in Table 2. After repair and regeneration, the capacity of the two batteries increased by 22.80% and 24.21% respectively, and the internal resistance of the batteries decreased by 25.32% and 26.09% respectively.

[0083] Table 2

[0084] Cycle times / times Capacity before repair / Ah Internal resistance before repair / mΩ Capacity after repair / Ah Internal resistance after repair / mΩ Battery 3 1200 19.3 1.59 23.7 1.18 Battery 4 1250 19.0 1.61 23.6 1.19

[0085] Comparative Example 1

[0086] This comparative example provides a repair and regeneration method for a manganese-based lithium-ion battery, which specifically includes the following steps:

[0087] Take two square aluminum shell battery products 15119-24Ah (nominal capacity is 24Ah, actual initial capacity is about 25Ah, initial internal resistance is about 0.95,mΩ, battery thickness is 15mm, width is 119mm, height is 208mm) of Xingheng Power Co., Ltd. for repair and regeneration comparison experiment. After the battery is charged and discharged at room temperature and 0.5C, the capacity has decayed to about 20Ah, which is about 83% of the nominal capacity.

[0088] The two batteries were charged and discharged at a rate of 0.5C to test the capacity and internal resistance of the batteries before repair. Referring to the heating method of Example 1 of Chinese invention patent CN103187595B, the batteries were discharged to a voltage of 3.0V, the batteries were placed in a 60°C thermostat for 24 hours after the valve was opened, and then cooled to room temperature, the electrolyte in Example 1 was added, the batteries were placed for 8 hours, and then charged at a constant current of 0.05C to form, and the batteries were sealed after formation.

[0089] Then, the comparison battery 1 and comparison battery 2 were charged and discharged at a rate of 0.5C to test the battery capacity and internal resistance. The capacity and internal resistance of the battery before and after repair and regeneration are shown in Table 3. The battery capacity increased by 6.00% and 7.00%, and the battery internal resistance decreased by 1.97% and 2.00%.

[0090] Table 3

[0091] Cycle times / times Capacity before repair / Ah Internal resistance before repair / mΩ Capacity after repair / Ah Internal resistance after repair / mΩ Comparison battery 1 1000 20.1 1.52 21.3 1.49 Comparison Battery 2 1100 20.0 1.50 21.4 1.47

[0092] Combining Example 1 and Comparative Example 1, it can be seen that the decomposition of SEI is less under heating at 60°C, resulting in less capacity improvement after repair and less reduction in internal resistance.

[0093] Comparative Example 2

[0094] This comparative example provides a repair and regeneration method for a manganese-based lithium-ion battery, which specifically includes the following steps:

[0095] Take two square aluminum shell battery products 15119-24Ah (nominal capacity is 24Ah, actual initial capacity is about 25Ah, initial internal resistance is about 0.95,mΩ, battery thickness is 15mm, width is 119mm, height is 208mm) of Xingheng Power Co., Ltd. for repair and regeneration comparison experiment. After the battery is charged and discharged at room temperature and 0.5C, the capacity has decayed to about 19Ah, which is about 79% of the nominal capacity.

[0096] The two batteries were charged and discharged at a rate of 0.5C to test the capacity and internal resistance of the batteries before repair. Referring to the method of Example 6 of Chinese invention patent CN103187595B, the battery was discharged to 3.0V, and after opening the valve, a 0.6% mass ratio of methyl methacrylate monomer was added as a destroyer. After standing for 8 hours, the electrolyte of Example 1 was charged and formed at a constant current of 0.05C, and the batteries were sealed after formation. Subsequently, the comparison batteries 3 and 4 were charged and discharged at a rate of 0.5C to test the battery capacity and internal resistance.

[0097] The capacity and internal resistance of the battery before and after repair and regeneration are shown in Table 4. The battery capacity increased by 14.06% and 14.14%, and the battery internal resistance decreased by 16.88% and 16.98%.

[0098] Table 4

[0099] Cycle times / times Capacity before repair / Ah Internal resistance before repair / mΩ Capacity after repair / Ah Internal resistance after repair / mΩ Comparison battery 3 1230 19.2 1.60 21.9 1.33 Comparison Battery 4 1240 19.1 1.59 21.8 1.32

[0100] Combining Example 2 and Comparative Example 2, it can be seen that SEI can be chemically etched by acrylic acid, but SEI decomposition is not sufficient because methyl methacrylate only reacts with inorganic substances (lithium carbonate, Li2O, LiOH) and cannot react with organic substances (alkyl lithium carbonate ROCO2Li). In addition, the hydrogen element introduced by the acid will eventually form water and remain in the battery, which will reduce the first effect during formation and lead to a decrease in discharge capacity, while the internal resistance of the battery will increase.

[0101] In summary, compared with traditional heating methods and chemical corrosion methods, the present application is more conducive to improving battery capacity and reducing battery internal resistance.

[0102] Comparative Example 3

[0103] This comparative example provides a repair and regeneration method for a manganese-based lithium-ion battery, which is different from Example 1 only in that DMC is replaced by ethyl methyl carbonate EMC.

[0104] In addition to the above-mentioned dimethyl carbonate DMC and ethyl propionate EP, the boiling points of other common electrolyte solvents for lithium batteries are ethylene carbonate EC at 248°C, propylene carbonate PC at 242°C, ethyl methyl carbonate EMC at 110°C, diethyl carbonate DEC at 126°C, and ethyl acetate EA at 77°C. In the range of 90~105°C, ethyl acetate EA has already been vaporized, while ethylene carbonate EC, propylene carbonate PC, ethyl methyl carbonate EMC, and diethyl carbonate DEC have not yet reached the boiling point.

[0105] Comparative Example 4

[0106] This comparative example provides a repair and regeneration method for a manganese-based lithium-ion battery, which is different from Example 1 only in that the battery is heated to 80° C. and discharged to 2.0V with a current of 0.05C.

[0107] Comparative Example 5

[0108] This comparative example provides a repair and regeneration method for a manganese-based lithium-ion battery, which is different from Example 1 only in that the electrolyte does not contain water-removing and acid-removing additives.

[0109] The capacity and internal resistance of the batteries before and after repair in the above embodiments and comparative examples 3-5 were tested, and the results are summarized in Table 5.

[0110] Table 5

[0111]

[0112] By comparing Example 1 with Comparative Example 3, it can be seen that in this application, after DMC is replaced with EMC, since the boiling point of EMC is 110°C, it is accompanied by SEI decomposition at 90°C, and EMC cannot play the function of gasification and taking away the SEI decomposition products, resulting in incomplete SEI decomposition and residue inside the battery, which ultimately makes the battery capacity increase and internal resistance reduction after repair not as good as Example 1. By comparing Example 1 with Comparative Example 4, it can be seen that after lowering the battery heating temperature to 80°C, since SEI has not reached the decomposition temperature, the injected dissolution and electrolyte can only achieve the effect of wetting the battery, and cannot decompose and repair SEI, so the capacity and internal resistance after repair are almost unchanged, and the repair effect cannot be achieved. By comparing Example 1 with Comparative Example 5, it can be seen that the presence of water-removing and acid-removing additives is also very necessary to ensure the repair effect of the battery. When the battery injection port is opened, it will come into contact with, and even in a dew point environment, it is inevitable to introduce moisture, so a trace amount of water-removing and acid-removing additives is added to the electrolyte. Otherwise, water will continue to react with lithium hexafluorophosphate inside the lithium battery to generate hydrofluoric acid, causing corrosion, resulting in decreased adhesion between the positive and negative electrode active materials and the current collector, increased internal resistance, and reduced charge and discharge capacity. Comparative Example 5 shows a lower level of capacity improvement and internal resistance reduction than Example 1.

[0113] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for repairing and regenerating a manganese-based lithium-ion battery, characterized in that: The following steps are involved: Injecting a destructive agent, opening the liquid injection port of the battery to be repaired and injecting the destructive agent into the battery, after standing for 10 hours to 14 hours, heating the battery to 90°C to 105°C, discharging the battery to 2.0V, and then cooling; the destructive agent includes dimethyl carbonate; the positive electrode material of the battery to be repaired includes lithium manganese oxide; between 90 and 105°C, the organic components in the SEI film will decompose to generate gas, and the generated gas can be taken out of the battery together with the boiling and vaporization of dimethyl carbonate; at the same time, the gas generated by the decomposition of organic matter and the gas generated by the vaporization of dimethyl carbonate will impact the inorganic matter in the SEI film, thereby causing part of the inorganic matter to be stripped off the surface of the negative electrode; Inject electrolyte into the cooled battery and let it stand for 10h~14h; The battery into which the electrolyte has been injected is then subjected to formation and the injection port is sealed to obtain a regenerated battery.

2. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: The method also includes testing the capacity and internal resistance of the battery to be repaired and the regenerated battery. If the capacity of the battery increases and the resistance decreases after repair, the repair is successful; otherwise, the repair fails.

3. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: The relationship between the injection amount of the destructive agent and the nominal capacity of the battery is 3.0 g / Ah ~ 4.0 g / Ah; And / or, the relationship between the injection amount of the electrolyte and the nominal capacity of the battery is 3.0 g / Ah to 4.0 g / Ah.

4. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: Discharge the battery to 2.0V at a current of 0.05C~0.2C; And / or, the current used in the formation step is 0.05C~0.2C corresponding current.

5. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: The battery was cooled to below 55° C. before the electrolyte was injected.

6. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: The injection of the destructive agent is carried out at an ambient dew point of ≤-30°C.

7. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 1, characterized in that: The electrolyte comprises a lithium salt, a solvent and a water-removing and acid-removing additive, wherein the water-removing and acid-removing additive is selected from at least one of trimethylsilyl phosphate, 1,3,6-hexanetrinitrile and tetravinylsilane; and the mass fraction of the water-removing and acid-removing additive in the electrolyte is less than 1%.

8. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 7, characterized in that: The solvent includes a cyclic solvent and a chain solvent. The mass fraction of the cyclic solvent in the electrolyte is 20% to 40%, and the mass fraction of the chain solvent in the electrolyte is 40% to 60%.

9. The method for repairing and regenerating a manganese-based lithium-ion battery according to claim 8, characterized in that: The cyclic solvent is selected from at least one of ethylene carbonate and propylene carbonate; And / or, the chain solvent is selected from at least one of dimethyl carbonate and ethyl methyl carbonate; And / or, the mass fraction of lithium salt in the electrolyte is 10% to 15%; And / or, the electrolyte further includes a film-forming additive, and the film-forming additive is selected from at least one of vinylene carbonate, propylene sulfite, lithium difluorooxalatoborate and lithium disoxalatoborate; the mass fraction of the film-forming additive in the electrolyte is less than 2%.

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