CN112103556A - Secondary battery and repairing method thereof - Google Patents

Abstract

The invention discloses a secondary battery and a repairing method thereof. The secondary battery comprises a casing; a positive electrode and a negative electrode separated by a diaphragm are arranged in the casing; Electrolyte; the negative electrode contains alloy particulate material. In the present invention, alloy lithium (or alloy sodium) is used instead of metal lithium (or sodium) as the lithium source (or sodium source); the alloy powder is mixed with the negative electrode active material to prepare a negative electrode pole piece containing the alloy powder, which is paired with the positive electrode; The addition of lithium- or sodium-containing alloys to the negative electrode of secondary batteries can supplement more active Li ⁺ or Na ⁺ ions. Due to the use of alloys, the activity of metal lithium/sodium is reduced, and the safety performance of the battery is improved.

Description

A kind of secondary battery and its repairing method

technical field

The invention belongs to the technical field of batteries, and in particular relates to a secondary battery and a repairing method thereof.

Background technique

Secondary batteries are widely used in 3C electronic products, electric vehicles, and energy storage due to their excellent charge-discharge cycle characteristics. Secondary batteries (such as lithium-ion batteries and sodium-ion batteries) are mainly composed of a positive electrode, a negative electrode, a separator, an electrolyte and a shell. Energy storage and release. The slower the capacity decay of the secondary battery, the better its cycle life performance. There are many reasons for the decline of battery capacity. For example, the solid electrolyte film (SEI film) formed on the surface of the negative electrode sheet during the first charging process of the secondary battery will consume part of the lithium from the positive electrode, resulting in the loss of lithium from the positive electrode material; during charging, the negative electrode precipitates metal. (lithium or sodium), and during the charging and discharging cycle of the secondary battery, side reactions occur, resulting in the decomposition of the electrolyte, the decrease in conductivity, the increase in internal resistance after cycling, and the decrease in capacity. Therefore, the consumption of electrolyte and active ions is one of the main reasons for battery capacity decay and performance degradation.

In view of the above-mentioned capacity fading problem in the prior art, an important method at present is to pre-supplement the negative electrode with lithium (or sodium ions), that is, to find a lithium source (or sodium source) outside the positive electrode material to supplement the consumed lithium ions, The active ions consumed during the formation of the SEI film are replenished, thereby increasing the capacity of the lithium-ion battery.

In order to supplement the loss of active ions during charging and discharging overcharge, some methods have also been reported in patents and literatures. The Chinese patent application with the application number of 201210350770.X discloses "a method for replenishing lithium to the positive electrode sheet of a lithium ion battery"; the specific scheme is to use the organic lithium solution as the n-hexane solution of n-butyl lithium and the n-hexane solution of t-butyl lithium. At least one of the alkane solution and the n-hexane solution of phenyllithium, in an inert atmosphere, spray or drop the organic lithium solution on the surface of the positive electrode sheet, so that the lithium ions in the organic lithium solution are reduced to metal lithium and embedded in the positive electrode in the film. All n-butyllithium, tert-butyllithium and phenyllithium can be dissolved in n-hexane to form a homogeneous solution, which is convenient for spraying or dropping operations on the positive electrode sheet. The method uses a wet method to replenish lithium, so that the lithium powder is distributed on the surface of the pole piece, and the uneven distribution of the lithium powder in the pole piece is avoided. Since the active metal lithium is directly added, it is easy to cause an exothermic reaction with oxygen and moisture in the surrounding environment, causing the danger of combustion and explosion; and the organic lithium source is a highly toxic substance, which is not conducive to actual production operations.

There is also a method of pre-embedding and replenishing lithium in the prior art; specifically, the metal lithium sheet is embedded in the battery, and the operator in the process of preparing the battery, the metal lithium sheet and the negative electrode of the battery are pasted together in advance, or the metal lithium The powder is directly added to the graphite negative electrode to provide a lithium source for the later battery pre-lithium. The Chinese patent with the bulletin number CN 1290209 C also reported a method of "dry method" supplementing lithium to the negative electrode, in which the metal lithium powder is directly added to the graphite negative electrode. The Chinese patent with the publication number of CN 207558931 U provides a method of pasting the metal lithium sheet and the negative electrode of the battery together in advance. Metal lithium is very active in the air, and will be quickly oxidized and deteriorated in the air. Lithium sheets in the air will also react violently and catch fire, causing danger. At the same time, the metal lithium powder must be isolated from the air during the actual operation, so the operation is difficult and it is not easy to produce on a large scale. Moreover, in the lithium-inserted negative electrode sheet obtained by this method, the lithium powder is distributed in the middle of the negative electrode material. After the lithium powder is partially dissolved, it is easy to cause the lithium powder to form an arc-standing state, which is electronically insulated from the negative electrode, forming dead lithium and unable to participate in the electrochemical reaction.

In the above-mentioned prior art, active lithium is directly added to the electrode active material to obtain a lithium-replenishing negative electrode sheet. However, these organolithiums may cause combustion and explosion, and alkyl lithiums are highly toxic substances, so there are great safety problems in their production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a secondary battery and a repair method thereof to solve the problems of unsafe lithium (sodium) supplementation, high toxicity of lithium (sodium) sources, and inability to recover capacity and performance in the later stage of the battery in the prior art. . In the present invention, in the later stage of battery cycle, the electrolyte and additives are replenished through the reserved injection holes on the battery shell, and then the SEI film damaged in the early stage of the battery is repaired according to a certain charging strategy, so as to improve the battery capacity and electrochemical performance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A secondary battery comprises a casing; a positive electrode and a negative electrode separated by a diaphragm are arranged in the casing; an electrolyte solution is filled between the positive electrode and the diaphragm, and between the negative electrode and the diaphragm; the negative electrode contains alloy particulate material;

The casing is provided with a liquid injection hole for supplementing the electrolyte;

After the secondary battery runs for a period of time, the supplementary solution injected through the injection hole is composed of electrolyte and functional additives for repairing the SEI film; the functional additives are composed of DTD, VC, FEC, LiDFOB, and TTSPi.

A further improvement of the present invention is that: the secondary battery is a lithium battery; the alloy particle material is alloy lithium.

A further improvement of the present invention is that the alloy lithium is specifically lithium aluminum alloy, lithium magnesium alloy, lithium magnesium aluminum alloy or lithium boron alloy.

A further improvement of the present invention is that the lithium battery is specifically a lithium iron phosphate battery, a ternary lithium ion battery or a lithium titanate battery.

A further improvement of the present invention is that: the secondary battery is a sodium battery; and the alloy particle material is alloy sodium.

A further improvement of the present invention is that the alloy sodium is specifically a sodium-aluminum alloy or a sodium-magnesium alloy.

A further improvement of the present invention is that the sodium battery is specifically a Prussian blue-like sodium ion battery, an iron-based phosphate system sodium ion battery or a vanadium-based phosphate system sodium ion battery.

A further improvement of the present invention is that: the particle size range of D ₅₀ of the alloy particulate material is: 200nm≦D ₅₀ ≦80μm.

A further improvement of the present invention is that the weight of the alloy particle material is 1% to 10% of the weight of the entire negative electrode material.

The further improvement of the present invention is: the mass percentages of DTD, VC, FEC, LiDFOB and TTSPi in the supplementary solution are respectively: 0~6%, 0~12%: 0~10%, 0~8%, 0~6%, 0~13%.

A method for repairing a secondary battery, comprising:

After the secondary battery runs for a period of time, a supplementary solution is added to the secondary battery; the supplementary solution is composed of an electrolyte and a functional additive; the functional additive is composed of DTD, VC, FEC, LiDFOB, and TTSPi;

After replenishing the replenishing liquid, remediately charge and discharge the secondary battery.

The further improvement of the present invention is: the percentages of the added mass of DTD, VC, FEC, LiDFOB and TTSPi in the mass of the supplementary solution are respectively: 0~6%, 0~12%: 0~10%, 0~8%, 0~8% 6%, 0~13%.

A further improvement of the present invention is that: the temperature at which the repairing charge and discharge is performed is 15°C to 30°C.

A further improvement of the present invention is that the charge-discharge cycle for repairing charge-discharge is one or more times.

A further improvement of the present invention is that the charge-discharge cycle for repairing charge-discharge is more than 3 times.

A further improvement of the present invention is that: the charging method for repairing charging and discharging is: charging with a small current of 0.01C-0.1C.

A further improvement of the present invention is that: the charging method for repairing charging and discharging is: using intermittent and stepped current charging.

A further improvement of the present invention is that: the intermittent and stepped current charging is specifically: the current in the first 1/3 time period is 0.01C~0.1C; the current in the middle 1/3 time period is 0.1C~0.3C; /3 time period current is 0.01C.

A further improvement of the present invention is that the additive can play the function of repairing the SEI film damaged during the cycle.

The further improvement of the present invention lies in that: performing reparative charge and discharge is beneficial to remove interface damaged substances, and repair the damaged SEI film to be smoother, denser and more complete.

Compared with the prior art, the present invention has the following beneficial effects:

In the present invention, alloy lithium (or alloy sodium) is used instead of metal lithium (or sodium) as the lithium source (or sodium source); the alloy powder is mixed with the negative electrode active material to prepare a negative electrode pole piece containing the alloy powder, which is paired with the positive electrode; The addition of lithium- or sodium-containing alloys to the negative electrode of secondary batteries can supplement more active Li ⁺ or Na ⁺ ions. Due to the use of alloys, the activity of metal lithium/sodium is reduced, and the safety performance of the battery is improved.

Further, the present invention is provided with a refilling hole, and after the secondary battery has been operated for a period of time, the refilling liquid is added to the secondary battery; the functional additives in the refilling liquid are combined with a specific repairing charging and discharging method to enhance the lithium ion of the battery. The conductive ability and the role of repairing damaged SEI film can significantly improve battery capacity and prolong battery cycle life.

Further, the internal resistance of the battery repaired by the present invention is significantly reduced, and the cycle life is increased by 1500 to 2000 times (80% DOD).

Detailed ways

The following detailed descriptions are all exemplary descriptions and are intended to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention.

Example 1

The invention provides a secondary battery, comprising a casing; a positive electrode and a negative electrode separated by a diaphragm are arranged in the casing; electrolyte solution is filled between the positive electrode and the diaphragm, and between the negative electrode and the diaphragm. The casing is provided with a liquid injection hole that can add electrolyte into the casing, which is used to open the liquid injection junction in the later stage of battery cycle, release the gas therein, and add a certain amount of electrolyte and functional additives.

The negative electrode is prepared by the following methods: grinding the alloy material to obtain alloy material particles; the _D50 particle size range of the alloy particles is: _{200nm≤D50≤80μm} ; the alloy material particles and the negative electrode active material are mixed uniformly to prepare an alloy Negative electrode sheet; the weight of alloy particles is 1% to 10% of the weight of the entire negative electrode material. When a lithium alloy is used as the alloy material, a lithium-containing alloy negative electrode sheet is obtained; when a sodium alloy is used as the alloy material, a sodium-containing alloy negative electrode sheet is obtained. The secondary battery is pre-supplemented with lithium/sodium through an alloy negative electrode sheet.

In the present invention, alloy lithium (or alloy sodium) is used instead of metal lithium (or sodium) as the lithium source (or sodium source), or the carbon material is combined with lithium/sodium; the alloy powder is mixed with the negative electrode active material to prepare an alloy containing The negative electrode of the powder is paired with the positive electrode; by adding an alloy containing lithium or sodium to the negative electrode of the secondary battery, more active Li ⁺ or Na ⁺ ions can be supplemented. Due to the use of the alloy, the activity of the metal lithium/sodium is reduced, and the increase battery safety.

In the present invention, alloy lithium (or alloy sodium) includes lithium aluminum alloy, lithium magnesium alloy, lithium magnesium aluminum alloy, and lithium boron alloy (sodium aluminum alloy, sodium magnesium alloy).

The secondary battery in the present invention refers to a lithium ion battery and a sodium ion battery. The secondary battery system includes: lithium iron phosphate battery, ternary lithium ion battery, lithium titanate battery; Prussian blue-like sodium ion battery, iron-based phosphate system sodium ion battery, vanadium-based phosphate system sodium ion battery.

The present invention also provides a method for repairing a secondary battery, comprising:

After the secondary battery has been running for a period of time, the injection hole is opened to inject supplementary liquid; the supplementary liquid is composed of electrolyte and functional additives; after the battery is injected with liquid, repair charge and discharge are carried out, and the SEI film damaged in the early stage of the secondary battery is repaired. Make repairs to restore battery capacity and improve electrochemical performance.

The composition of the electrolyte in the supplementary solution is consistent with the composition of the electrolyte originally filled in the battery; the functional additives can repair the damaged SEI film during the cycle; the functional additives include: ethylene sulfate (DTD), vinylene carbonate ( VC), fluoroethylene carbonate (FEC), lithium difluorooxalate borate (LiDFOB), and tris(trimethylsilyl) phosphite (TTSPi).

The percentages of the added mass of DTD, VC, FEC, LiDFOB and TTSPi to the mass of the supplementary solution are: 0~6%, 0~12%: 0~10%, 0~8%, 0~6%, 0~13% .

The remedial charging and discharging method includes: charging and discharging the secondary battery in an environment of 15° C. to 30° C.; the number of charging and discharging times is more than 1 charge and discharge cycle; preferably, it is more than 3 charge and discharge cycles. The specific method of charging is: charging with a small current of 0.01C~0.1C, or using intermittent and stepped current charging; the intermittent and stepped current charging is specifically: the current in the first 1/3 time period is 0.01C~0.1C ; The current in the middle 1/3 time period is 0.1C~0.3C; the current in the last 1/3 time period is 0.01C.

Example 2

The invention relates to a method for repairing a secondary battery, comprising: after the secondary battery has been operated for a period of time, opening a liquid injection hole to inject a supplementary liquid; the supplementary liquid is composed of electrolyte and functional additives; after the battery is injected with liquid, repairing Charge and discharge, repair the damaged SEI film in the early stage of the secondary battery, restore the battery capacity and improve the electrochemical performance.

The composition of the electrolyte in the supplementary solution is consistent with the composition of the electrolyte originally filled in the battery; the functional additive can repair the damaged SEI film during the cycle; the functional additive includes: DTD, VC, FEC, LiDFOB, TTSPi. The percentages of the added mass of DTD, VC, FEC, LiDFOB, and TTSPi to the mass of the supplementary solution were: 1%, 10%: 5%, 8%, 6%, and 2%, respectively.

The remedial charging and discharging method includes: charging and discharging the secondary battery in an environment of 15°C to 30°C; the number of charging and discharging is 5 charge-discharge cycles.

Example 3

The difference between the present invention and Example 2 is that the added mass of DTD, VC, FEC, LiDFOB, TTSPi accounts for the percentage of the supplementary liquid mass: 5%, 12%: 1%, 2%, 2%, 13%, respectively.

The remedial charging and discharging method includes: charging and discharging the secondary battery in an environment of 15°C~30°C; the number of charging and discharging is 3 charge-discharge cycles.

Example 4

The difference between the present invention and Example 2 is that the added mass of DTD, VC, FEC, LiDFOB, and TTSPi accounts for the percentages of the supplementary liquid mass: 6%, 1%, 5%, 1%, 4%, and 6%, respectively.

The remedial charging and discharging method includes: charging and discharging the secondary battery in an environment of 15°C~30°C; the number of charging and discharging is 3 charge-discharge cycles.

Example 5

The difference between Example 5 and Example 2 is that the specific charging method is intermittent, stepped current charging: the current in the first 1/3 time period is 0.01C; the current in the middle 1/3 time period is 0.1C; 1/3 time period current is 0.01C.

Example 5

The difference between Example 5 and Example 2 is that the specific method of charging is intermittent, stepped current charging: the current in the first 1/3 time period is 0.05C; the current in the middle 1/3 time period is 0.1C; 1/3 time period current is 0.01C.

Example 6

The difference between Example 6 and Example 2 is that the specific method of charging is intermittent, stepped current charging: the current in the first 1/3 time period is 0.01C; the current in the middle 1/3 time period is 0.3C; 1/3 time period current is 0.01C.

Example 7

The difference between Example 7 and Example 2 is that the specific charging method is intermittent, stepped current charging: the current in the first 1/3 time period is 0.1C; the current in the middle 1/3 time period is 0.2C; 1/3 time period current is 0.01C.

The internal resistance of the battery repaired by the invention is significantly reduced, and the cycle life is increased by 1500 times to 2000 times (80% DOD).

It is known from the technical common sense that the present invention can be realized by other embodiments without departing from its spirit or essential characteristics. Accordingly, the above-disclosed embodiments are, in all respects, illustrative and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims (18)

1. A secondary battery, comprising a case; a positive electrode and a negative electrode which are separated by a diaphragm are arranged in the shell; electrolyte is filled between the anode and the diaphragm and between the cathode and the diaphragm; the negative electrode contains alloy particle materials;

the shell is provided with a liquid injection hole for supplementing electrolyte;

after the secondary battery runs for a period of time, the supplementary liquid injected through the liquid injection hole consists of electrolyte and functional additives for repairing SEI films; the functional additive is composed of DTD, VC, FEC, LiDFOB and TTSPi.

2. The secondary battery according to claim 1, wherein the secondary battery is a lithium battery; the alloy particle material is alloy lithium.

3. A secondary battery according to claim 2, characterized in that the alloyed lithium is in particular a lithium aluminium alloy, a lithium magnesium aluminium alloy or a lithium boron alloy.

4. A secondary battery according to claim 2, characterized in that the lithium battery is in particular a lithium iron phosphate battery, a ternary lithium ion battery or a lithium titanate battery.

5. The secondary battery according to claim 1, wherein the secondary battery is a sodium battery; the alloy particle material is alloy sodium.

6. A secondary battery as claimed in claim 5, characterized in that the alloy sodium is in particular a sodium-aluminium alloy or a sodium-magnesium alloy.

7. The secondary battery according to claim 5, wherein the sodium battery is a Prussian-like blue sodium ion battery, an iron-based phosphate system sodium ion battery, or a vanadium-based phosphate system sodium ion battery.

8. The secondary battery according to claim 1, wherein D of the alloy particulate material₅₀The particle size range is as follows: d is not more than 200nm₅₀≤80μm。

9. The secondary battery of claim 1, wherein the weight of the alloy particle material is 1-10% of the total weight of the anode material.

10. The secondary battery of claim 1, wherein the mass percentages of DTD, VC, FEC, LiDFOB and TTSPi in the supplementary liquid are respectively as follows: 0-6%, 0-12%: 0-10%, 0-8%, 0-6%, 0-13%.

11. A method of repairing a secondary battery, comprising:

supplementing a supplementary liquid to the secondary battery after the secondary battery operates for a period of time; the supplementary liquid consists of electrolyte and functional additives for repairing SEI films; the functional additive consists of DTD, VC, FEC, LiDFOB and TTSPi;

and performing reparative charging and discharging on the secondary battery after the supplement liquid is supplemented.

12. The method for repairing a secondary battery according to claim 11, wherein the mass percentages of the DTD, VC, FEC, lidfeed, and TTSPi added to the replenishment solution are: 0-6%, 0-12%: 0-10%, 0-8%, 0-6%, 0-13%.

13. The method of claim 11, wherein the temperature at which the replenishing charge and discharge is performed is 15 ℃ to 30 ℃.

14. The method according to claim 11, wherein the charge-discharge cycle for the restorative charge-discharge is 1 or more times.

15. The method according to claim 11, wherein the charge-discharge cycle for the restorative charge-discharge is 3 times or more.

16. The method for repairing a secondary battery according to claim 11, wherein the charging method for performing the repairing charging and discharging includes: charging by adopting micro current of 0.01-0.1C.

17. The method for repairing a secondary battery according to claim 11, wherein the charging method for performing the repairing charging and discharging includes: intermittent and stepped current charging is adopted.

18. The method for repairing a secondary battery as claimed in claim 17, wherein the intermittent, step-current charging is specifically: the current is 0.01-0.1C in 1/3 time periods before the beginning; the current in the middle 1/3 time period is 0.1-0.3C; the current was 0.01C during the post 1/3 time period.