Electrolyte additive for lithium supplement agent, electrolyte, battery cell, single battery and electric equipment

Abstract

The invention discloses an electrolyte additive for a lithium supplement agent, an electrolyte, a battery cell, a single battery and electric equipment. The electrolyte additive for the lithium supplement agent is mainly used for inhibiting gas generated by adding the lithium supplement agent; the additive can improve the voltage window of the battery, actively capture HF, oxygen free radicals and oxygen, and solve the problems of interface corrosion caused by HF decomposed by trace water, capture of oxygen free radicals released by a lithium supplement agent, inhibition of gas production and the like.

Description

Technical Field

[0001] This invention relates to the technical field of electrolyte additives for lithium-ion batteries, electrolytes, battery cells, single cells, and electrical equipment, and particularly to electrolyte additives for lithium-ion batteries, electrolytes, battery cells, single cells, and electrical equipment, as well as their preparation methods and applications. Background Technology

[0002] As the application of lithium-ion batteries continues to expand, especially in the fields of new energy vehicles and energy storage, people are placing increasingly higher demands on battery performance, such as energy density and cycle life. With the research and application of new high-capacity anode materials such as silicon-based anodes, the lithium loss problem during battery charging and discharging is becoming increasingly prominent, giving rise to lithium replenishment technology.

[0003] During the first charge of a lithium-ion battery, a series of complex electrochemical reactions occur, leading to lithium loss. At the negative electrode surface, the electrolyte reacts with the negative electrode material to form a solid electrolyte interphase (SEI) film. This process consumes lithium ions, and once these ions participate in the reaction, they cannot return to the battery's normal cycle, resulting in irreversible lithium loss. Taking graphite negative electrodes as an example, the lithium ions consumed in forming the SEI film during the first charge can cause an irreversible capacity loss of over 6%. For silicon-based negative electrode materials, due to the significant volume changes during charging and discharging, the SEI film formation process is even more complex, resulting in more severe lithium loss, with irreversible capacity losses reaching as high as 10%-20% or more.

[0004] Currently, lithium replenishment agents have become the main solution to the above problems. Existing lithium replenishment agents mainly include positive electrode lithium replenishment solutions. Among them, lithium-rich materials for positive electrode lithium replenishment agents include lithium-rich lithium iron ore oxide, lithium-rich lithium manganese oxide, lithium-rich lithium nickel oxide, lithium-rich lithium cobalt oxide, lithium-rich lithium aluminum oxide, and lithium-rich lithium copper oxide. However, these materials release oxygen free radicals and oxygen during lithium replenishment, and the residues after lithium replenishment can further react with trace amounts of water and lithium salt products (HF) in the electrolyte.

[0005] The lithium replenishment mechanism of the above-mentioned lithium replenishment materials is as follows:

[0006]

[0007] Our company proposes an electrolyte additive for lithium replenishment. This electrolyte additive can actively capture HF and oxygen free radicals, inhibiting the chain decomposition reaction of the electrolyte from the source and improving thermal stability. In addition, this lithium replenishment additive can also improve the voltage window of the battery system. Summary of the Invention

[0008] The purpose of this invention is to provide an electrolyte additive for lithium replenishment, as well as a battery cell and electrical device thereof. By using an electrolyte and an electrolyte additive for lithium replenishment, gas generation during application and long-cycle operation of lithium-rich replenishment agents can be suppressed.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an electrolyte additive for lithium replenishment, a battery cell, and battery cells and electrical devices thereof, which are prepared by compounding a commercial electrolyte with an electrolyte and an electrolyte additive for lithium replenishment.

[0011] As a specific technical solution, the lithium replenishing agent uses electrolyte additives with a mass ratio of 0% to 10% of the lithium replenishing agent additives. The specific mass ratio of the lithium replenishing agent can be 0%, 1%, 2, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any of these values.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned composite material, comprising the following steps:

[0013] This invention also discloses a method for preparing an electrolyte additive for lithium replenishment, an electrolyte, a battery cell, a single battery cell, and an electrical device, characterized by comprising the following steps:

[0014] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercially available lithium iron phosphate / ternary material electrolyte.

[0015] S2. Add the above electrolyte to a 3Ah soft-pack battery cell with lithium replenishment agent, let it stand for several hours, then test the gas production capacity.

[0016] As a specific technical solution, in step S2 of the preparation method of the electrolyte additive for lithium replenishment, the molar concentration of lithium salt is 0.5 mol / L ≤ molar concentration of lithium salt ≤ 12 mol / L; for traditional lithium-ion batteries, the molar concentration can be further optimized to 0.8 mol / L ≤ molar concentration of lithium salt ≤ 1.5 mol / L; for high-concentration lithium salt electrolytes in lithium metal battery systems, the concentration can be optimized to 3 mol / L ≤ molar concentration of lithium salt ≤ 12 mol / L; for locally high-concentration lithium salt electrolytes in lithium metal battery systems, the concentration can be optimized to 1 mol / L ≤ molar concentration of lithium salt ≤ 5 mol / L; the additive content of 0% ≤ total mass addition of additive ≤ 30% can be optimized to 0% ≤ total mass addition of additive ≤ 20%, and can be further optimized to 1% ≤ total mass addition of additive ≤ 15%.

[0017] Thirdly, the present invention also provides the application of lithium-replenishing electrolyte additive materials prepared by methods for preparing lithium-replenishing electrolyte additives, electrolytes, battery cells and their battery cells and electrical devices in batteries, wherein the batteries include any one of lithium-ion batteries and semi-solid-state batteries.

[0018] Compared with existing technologies, the electrolyte additives used in lithium replenishment are compounded with the electrolyte. During lithium replenishment, oxygen free radicals and oxygen are released, and the residues after lithium replenishment will further react with trace amounts of water and lithium salt products HF in the electrolyte.

[0019] Our company proposes an electrolyte additive for lithium replenishment. This electrolyte additive can actively capture HF and free radicals, inhibiting the chain decomposition reaction of the electrolyte from the source and improving thermal stability. In addition, this lithium replenishment additive can also improve the voltage window of the battery system. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the experimental methods used in the examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0022] The present invention will be further described in detail below through detailed embodiments.

[0023] Example 1

[0024] This embodiment provides a method for preparing an electrolyte additive for lithium replenishment, a battery cell, and its battery cells and electrical equipment. The additive for lithium replenishment is diethyl[4-(trifluoromethyl)benzyl]phosphonate, added at a concentration of 1%. The electrolyte ratio is: lithium iron phosphate electrolyte. The amount of electrolyte is determined by multiplying the cell capacity by 2.3 Ah / g. The preparation method of the electrolyte for this lithium replenishment additive is as follows:

[0025] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercial lithium iron phosphate electrolyte.

[0026] S2. Add the above electrolyte to a 3Ah soft-pack lithium iron phosphate cell containing 3% lithium iron phosphate supplementer in the positive electrode, let it stand for several hours, then test the gas production capacity and test the gas production.

[0027] Example 2

[0028] This embodiment provides a method for preparing an electrolyte additive for lithium replenishment, a battery cell, and its battery cells and electrical equipment. The additive for lithium replenishment is diethyl[4-(trifluoromethyl)benzyl]phosphonate, added at a concentration of 2%. The electrolyte ratio is: lithium iron phosphate electrolyte. The amount of electrolyte is determined by multiplying the cell capacity by 2.3 Ah / g. The preparation method of the electrolyte for this lithium replenishment additive is as follows:

[0029] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercial lithium iron phosphate electrolyte.

[0030] S2. Add the above electrolyte to a 3Ah soft-pack lithium iron phosphate cell containing 3% lithium iron phosphate supplementer in the positive electrode, let it stand for several hours, then test the gas production capacity and test the gas production.

[0031] Example 3

[0032] This embodiment provides a method for preparing an electrolyte additive for lithium replenishment, a battery cell, and its battery cells and electrical equipment. The additive for lithium replenishment is diethyl[4-(trifluoromethyl)benzyl]phosphonate, added at 3%. The electrolyte ratio is: lithium iron phosphate electrolyte. The amount of electrolyte is determined by multiplying the cell capacity by 2.3 Ah / g. The preparation method of the electrolyte for this lithium replenishment electrolyte additive is as follows:

[0033] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercial lithium iron phosphate electrolyte.

[0034] S2. Add the above electrolyte to a 3Ah soft-pack lithium iron phosphate cell containing 3% lithium iron phosphate supplementer in the positive electrode, let it stand for several hours, then test the gas production capacity and test the gas production.

[0035] Example 4

[0036] This embodiment provides a method for preparing an electrolyte additive for lithium replenishment, a battery cell, and its battery cells and electrical equipment. The additive for lithium replenishment is diethyl[4-(trifluoromethyl)benzyl]phosphonate, added at 3%. The electrolyte ratio is: lithium iron phosphate electrolyte. The amount of electrolyte is determined by multiplying the cell capacity by 2.3 Ah / g. The preparation method of the electrolyte for this lithium replenishment electrolyte additive is as follows:

[0037] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercial lithium iron phosphate electrolyte.

[0038] S2. Add the above electrolyte to a 3Ah soft-pack lithium iron phosphate cell containing 3% lithium cobalt oxide as a lithium supplement agent in the positive electrode. After standing for several hours, perform composition and test the gas production.

[0039] Example 5

[0040] This embodiment provides a method for preparing an electrolyte additive for lithium replenishment, a battery cell, and its battery cells and electrical equipment. The additive for lithium replenishment is diethyl[4-(trifluoromethyl)benzyl]phosphonate, added at 3%. The electrolyte ratio is: lithium iron phosphate electrolyte. The amount of electrolyte is determined by multiplying the cell capacity by 2.3 Ah / g. The preparation method of the electrolyte for this lithium replenishment electrolyte additive is as follows:

[0041] S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in a commercially available high-nickel ternary silicon anode electrolyte.

[0042] S2. Add the above electrolyte to a 3Ah soft-pack battery cell containing a high-nickel ternary 811 silicon anode (450mAh / g) with 3% lithium iron phosphate as the positive electrode, let it stand for several hours, then test the gas production capacity.

[0043] Comparative Example 1

[0044] A 3Ah soft-pack lithium iron phosphate battery with 3% lithium iron phosphate lithium supplementer and no lithium supplementer electrolyte additive; battery testing of gas production during formation and gas production in the later stages of cycling.

[0045] Comparative Example 2

[0046] It has a 3Ah soft pack with 3% lithium iron ferrite lithium supplement, high nickel ternary silicon anode (450mAh / g), and no lithium supplement electrolyte additive; the battery test shows the amount of gas generated during formation and the amount of gas generated in the later stage of cycling.

[0047] The batteries from Examples 1-5 and Comparative Examples 1-2 were further tested at a 0.1C rate cycle to measure their gas production and gas production in the later stages of the cycle.

[0048] Table 1 Test data of batteries made in different embodiments

[0049] Example Gas production rate (ml / g) Gas production after 2000 cycles 1 49.2 20.2 2 27.5 4.6 3 20.7 1.2 4 30.5 6.8 5 45.2 3.6 Comparative Example 1 59.5 38.2 Comparative Example 2 68.8 43.3

[0050] As shown in Table 1 above, in the ternary silicon anode system, and as seen in Comparative Example 2, with the presence of 3% lithium-rich material as a lithium supplement and without any additives to suppress gas production, the initial gas production during formation was very high at 68.8 ml / g, and the gas production after cycling was also nearly 43.3 ml / g. However, in Example 5, the electrolyte system with 3% diethyl[4-(trifluoromethyl)benzyl]phosphonate reduced the gas production during formation to 45.2 ml / g, and the gas production after cycling also decreased to 3.6 ml / g, significantly suppressing gas production.

[0051] Similar trends were observed in the lithium iron phosphate graphite system. In Comparative Example 1, with the presence of 3% lithium-rich material as a lithium supplement and without any additives to suppress gas production, the initial gas production during formation was high at 59.5 ml / g, and the post-cycle gas production was also nearly 38.2 ml / g. However, in Examples 1, 2, and 3, electrolyte systems with 1%, 2%, and 3% diethyl[4-(trifluoromethyl)benzyl]phosphonate added, respectively, the gas production during formation decreased to […].

[0052] The concentrations were 49.2 ml / g, 27.5 ml / g, and 20.7 ml / g, respectively. Furthermore, the gas production after circulation also decreased to 20.2 ml / g, 4.6 ml / g, and 1.2 ml / g, respectively.

[0053] The same trend was observed in Example 4, where a 3% lithium supplement was used in the lithium-rich cobalt oxide material.

[0054] Therefore, it can be seen that adding electrolyte additives with lithium replenishment materials can improve the battery voltage window, actively capture HF and free radicals, solve problems such as HF corrosion of the interface due to trace water decomposition, capture oxygen free radicals released by lithium replenishment agents, and suppress gas production.

[0055] The present invention provides an electrolyte additive for lithium replenishment, an electrolyte, a battery cell, a single battery cell, and an electrical device, which can be applied to batteries such as lithium-ion batteries, semi-solid-state batteries, lithium metal batteries, and negative electrode-free batteries.

[0056] The above embodiments are merely illustrative of the concept and technical solution of the present invention and are not intended to limit the present invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. The invention discloses an electrolyte additive for lithium replenishment, an electrolyte, a battery cell, a single battery cell and an electrical device. The general structural formula of the electrolyte additive for lithium replenishment is (R1O)2P(A)R2Ar-R3, where Ar is an aryl group. It is mainly used as an electrolyte additive, and the mass percentage of its addition is 0% < addition amount < 10%.

2. As described in claim 1, characterized in that, The position of R3 can be 2, 3, 4, 5, or 6 on the benzene ring. R3 can be CX3 (X = F, Cl, Br, I); R3 can also be CH3, OCH3, CH2CH3, NO2, or CN; R3 can be OCX3.

3. According to claim 1, the feature is that, The Ar aromatic ring can be a benzene ring, naphthalene, anthracene, phenanthrene, or a five-membered ring: such as furan (containing oxygen), pyrrole (containing nitrogen), thiophene (containing sulfur); a six-membered ring: such as pyridine (containing nitrogen), pyrimidine (containing nitrogen); and benzo[5] five-membered rings such as indole (benzene ring + pyrrole ring), benzo[furan], benzo[thiophene]; benzo[6] six-membered rings: such as quinoline (benzene ring + pyridine ring), quinazoline, phthalazine; and nitrogen-containing heterocycles: which can be further divided into basic (such as pyridine, quinoline, where the lone pair electrons of the nitrogen atom do not participate in conjugation) and non-basic (such as pyrrole, indole, where the lone pair electrons of the nitrogen atom participate in conjugation); and metal aromatic rings: certain metal atoms (such as bismuth) can also form aromatic ring structures.

4. According to claim 1, the feature is that, R1 can be methyl, propyl, isopropyl, butyl, aromatic hydrocarbons, or their halogenated hydrocarbon groups.

5. According to claim 1, the feature is that, R2 can be (CH2) n n = 1, 2, 3, etc.; it can also be CH (CH3).

6. According to claim 1, the feature is that, A can be O, S, etc.

7. According to claim 1, the feature is that, The electrolyte is composed of solvent, lithium salt, and positive and negative electrode film-forming additives. The solvent mainly consists of carbonate solvents and organic ether solvents, as well as other solvents and diluents. The carbonate solvents include cyclic carbonates, chain carbonates, and carboxylic acid esters. Cyclic carbonates include ethylene carbonate (EC) and propylene carbonate (PC); chain carbonates include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC); carboxylic acid esters include ethyl propionate (EC), methyl formate (MF), ethyl acetate (EA), MA, EP, and one or more of these compounds. The organic ether solvents include chain ether solvents and cyclic ether solvents. Chain ether solvents can be, for example, 1. 2-Dimethoxypropane (DMP), dimethoxymethane (DMM), and ethylene glycol dimethyl ether (DME) and cyclic ethers such as tetrahydrofuran (THF) and 2-methyltetrahydrofuran (2-Me-THF); other solvents may include trimethyl phosphate (TMPa), dimethylacetamide (DMA), cyclosulfonyl ether (TMS), and acetonitrile (AN). Other diluents may include 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), hydrofluoroether (HFE), H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether (OFE), and 2,2,2,-trifluoroethyl ether (BTFE). The lithium salt can be one or more of the following: lithium decafluoropentane (HFC), 1,2-difluorobenzene (dFBn); the lithium salt can be lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2). Organic lithium salts are obtained by introducing electron-withdrawing groups to regulate inorganic lithium salts. Common examples include lithium bis(oxalato)borate (LiBOB), LiDFOP, lithium difluorooxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)amino (Li[TFSA]), LiBTFSI (N-phenylbis(trifluoromethanesulfonyl)imide), lithium bis(difluoromethanesulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); etc.The positive and negative electrode film-forming additives may be vinylene carbonate (Vc), fluorinated vinyl carbonate (FEC), vinyl sulfate (VEC), ES, VES, propylene sulfite (PS), lithium bis(oxalato)borate (LiBOB), lithium difluorooxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)amino (Li[TFSA]), lithium bis(difluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorophosphate (LiPO2F2), trifluoroacetate (TFAE), terephthalonitrile (PTMN) and p-dimethylbenzoic acid (DMTB), flame retardant additives such as trimethyl phosphate (TMP), ethyl hexafluorophosphate (FEP) and propyl pentafluorophosphate (FPP), triethyl phosphate (TEP), dimethyl methyl phosphate (DMMP) and diethyl ethyl phosphate (DEEP), tris(2-chloropropyl) phosphate, PFPN, DOPO (9,10-dichloropropyl) phosphate, etc. Hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide), ammonium polyphosphate (APP), ethoxy(pentafluoro)cyclotriphosphazene (PFPN); tri(2-chloroethyl) phosphate (TCEP), tris(1,3-dichloroisopropyl) phosphate (TDCPP), polydiphenoxyphosphazene; dehydrating additives: mainly represented by amines (ethanolamine, aromatic amines), thiocyanates, DCC; wetting agents: nonionic surfactants, such as carbonates, phosphates, fluorinated ethers, silane compounds; vinyl sulfate (DTD), methylene disulfonate (MMDS), lithium difluorophosphate (LiDFP); one or more of the following: tri(trimethylsilyl) phosphate (TMSPA), tri(trimethylsilane) phosphate (TMSP), tri(trimethylsilane) borate (TMSB); 8. According to claim 1, the feature is that, The lithium replenishing agent can be lithium iron phosphate, lithium manganese phosphate, lithium nickel phosphate, lithium cobalt phosphate, lithium aluminum phosphate, lithium copper phosphate, or other lithium-rich lithium replenishing agents doped or coated with other metal or non-metal elements. The amount of lithium replenishing agent in the cathode material is 0 ≤ lithium replenishing dose ≤ 10. The suitable cathode materials include ternary, lithium iron phosphate, lithium manganese iron phosphate, lithium-rich manganese-based, etc., and can be matched with any anode including graphite, silicon, lithium metal, and anode-free materials.

9. This invention also discloses a method for preparing an electrolyte additive for lithium replenishment, an electrolyte, a battery cell, a single battery cell, and an electrical device, characterized in that... Includes the following steps: S1. Dissolve the above-mentioned lithium replenishing agent and electrolyte additive in a certain proportion in commercially available lithium iron phosphate, ternary material, or liquid metal electrolyte (locally high concentration or high concentration electrolyte system). S2. Add the above electrolyte to a 3Ah soft-pack battery cell with lithium replenishment agent, let it stand for several hours, then test the gas production capacity.

10. The electrolyte additive for lithium replenishment according to claim 1 or the electrolyte additive material for lithium replenishment prepared by any one of claims 1 to 9 can be matched with all battery systems and applied in electrode sheets, batteries, battery packs, and electrical equipment, wherein the battery includes any one of lithium-ion batteries, solid-state batteries, lithium metal batteries, negative electrode-free batteries, and semi-solid-state batteries.

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