Flame-retardant electrolyte, electrochemical energy storage device, and lithium ion secondary battery

Abstract

The invention discloses a flame-retardant electrolyte, an electrochemical energy storage device and a lithium ion secondary battery, and belongs to the technical field of lithium ion batteries. The flame-retardant electrolyte comprises a flame-retardant additive, and the flame-retardant additive is a novel phosphinic acid silicone grease compound. The electrochemical cell comprising the flame-retardant electrolyte exhibits improved high-temperature use safety and maintained performance of the electrochemical cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and more specifically, relates to a flame-retardant electrolyte, an electrochemical energy storage device, and a lithium-ion secondary battery. Background Art

[0002] With the popularization and application of clean energy, lithium-ion batteries have developed very rapidly, and researchers have made many major breakthroughs in this field. In 1990, Sony Corporation of Japan developed a lithium-ion secondary battery with lithium cobaltate as the positive electrode material and petroleum coke as the negative electrode material, and first proposed the concept of "lithium-ion battery". Since then, lithium-ion batteries have quickly entered our lives.

[0003] Although the lithium-ion battery industry has developed rapidly, there are still deficiencies, such as safety performance, high-rate performance, etc. In addition, with the expansion of the application range of lithium-ion batteries, the available energy density of currently used lithium-ion batteries cannot support durable devices. Fortunately, increasing the working voltage can effectively increase the energy density of lithium-ion batteries. However, the NCM (lithium-substituted mixed oxides of Ni, Co, and Mn) positive electrode usually exhibits structural and thermal instability at high cut-off voltages, thus significantly reducing the battery life. On the other hand, due to the possible generation of hydrogen fluoride (HF) from parasitic electrolyte oxidation decomposition reactions, high-voltage operation will deteriorate the cathode / electrolyte interface. The generated HF may corrode the cathode and cause the dissolution of transition metal ions in the positive electrode material. The transition metal ions can be transported to and deposited on the anode, resulting in a rapid decay of the capacity of the lithium-ion battery.

[0004] To address these problems, researchers have proposed methods such as coating a protective layer on the positive electrode particles and customizing the electrolyte formula. However, these methods are costly, have high costs, and have obvious disadvantages. Adding a small amount of functional additives to the electrolyte has been proven to be the simplest, cost-effective, and practical method because the additives can be preferentially oxidized to form a uniform passivation film, which can not only effectively prevent the cathode from being damaged but also inhibit the kinetic decomposition of the electrolyte at the electrode interface.

[0005] Additives in the electrolyte can be classified into film-forming, conductive, flame-retardant, and overcharge protection additives according to their functions. Most additives have relatively single performance. If it is necessary to improve the performance in multiple aspects, the synergistic effect of multiple additives is often required. For example, in the prior art with Chinese Patent Document No. CN110783626A, the high-temperature storage performance and high-voltage performance of lithium-ion batteries were improved through the combined action of alkenyldioxaborane compound additives and phosphoric anhydride cyclic additives. In the prior art with Chinese Patent Document No. CN115548438A, through the combined action of additives containing sulfonium-structured cations and carbonate additives, the volume expansion problem of silicon-based anodes was effectively reduced, and the low-temperature performance, cycle performance, and rate performance of the battery were improved.

[0006] Common additives are, for example, flame retardants, overcharge protection additives, and so-called film-forming additives that react on the electrode surface during the first charge / discharge cycle and thereby form a film on the electrode. Recently, new electrolyte additives based on P-containing acid derivatives containing additional functional groups have been developed. However, the addition of additives will cause changes in the cycle performance and rate performance of the battery to varying degrees. For example, in the prior art with Chinese Patent Document No. CN114243111A, it was disclosed that the single addition of vinyl crotonate in the electrolyte could improve the discharge capacity and capacity retention rate of the battery, but it would slightly increase the internal resistance of the battery. The combined use of several additives such as allyl acetate, tris(trimethylsilyl) phosphate, 1-(2,2,2-trifluoroethoxy)-1,1,2,2-tetrafluoroethane, and lithium bis(oxalato)borate led to an overall deterioration of the internal resistance, discharge capacity, and capacity retention rate of the battery.

[0007] Based on this, there is still a need to improve the performance and safety of electrochemical cells, especially to simultaneously improve or maintain the performance of the battery while adding as few types and amounts of additives as possible, such as achieving excellent flame retardancy, low gas release, high capacity retention, good long-term performance, etc. Summary of the Invention

[0008] 1. Problems to be Solved

[0009] The object of the present invention is to solve at least partially the problems of the prior art.

[0010] The technology disclosed in the present invention generally relates to lithium-ion (Li-ion) battery electrolytes; in particular, the present disclosure relates to compounds based on siloxane phosphinates of formula II and the use of these siloxane phosphinate compounds as flame retardant additives, electrolytes containing these siloxane phosphinate additives, and electrochemical energy storage devices containing the electrolytes, especially lithium batteries, lithium-ion batteries, and more particularly lithium-ion secondary batteries.

[0011] The first object of the present invention is to provide additives for use in electrochemical cells to improve the performance and safety of electrochemical cells, such as simultaneously improving long-term performance, high-temperature behavior, flame retardancy, high safety, and the retention of cycle performance and rate performance.

[0012] The second object of the present invention is to provide a flame-retardant electrolyte for electrochemical cells, and the flame-retardant electrolyte is applied to an electrochemical energy storage device, particularly a lithium-ion secondary battery, which has high capacity retention, good long-term performance, high safety and excellent high-temperature behavior.

[0013] The third object of the present invention is to further provide an electrochemical energy storage device, particularly a lithium-ion secondary battery, which exhibits overall good capacity retention, good long-term performance, good high-temperature behavior and high safety.

[0014] 2. Technical solution

[0015] Based on the problems of the safety and charging speed of electrochemical energy storage devices in the prior art, the present invention designs an electrolyte additive, which can realize the removal of hydrogen fluoride while realizing the flame retardant function, and further improve the charging speed of the electrochemical energy storage device.

[0016] 【1. Compounds with the structure of General Formula I】

[0017] Based on this, the first aspect of the present invention provides a class of compounds having the structure of General Formula I:

[0018]

[0019] Formula I

[0020] Wherein, R1 and R2 are each independently selected from substituted or unsubstituted C1-C12 alkyl groups, or substituted or unsubstituted C6-C14 aryl groups; wherein the hydrogen atom may be unsubstituted or may be substituted by a group selected from halogen, alkyl, alkoxy, perfluoroalkyl, silyl, silyloxy, silane, sulfoxide, amide, azo, ether and thioether groups or a combination thereof; and

[0021] R3, R4, and R5 are each independently selected from C1-C12 alkyl groups, heteroalkyl groups, perfluoroalkyl groups, alkenyl groups, phenyl groups or alkoxy groups.

[0022] After the compound with the structure of General Formula I is added to the electrolyte as an additive, on the one hand, it can exert the flame retardant characteristics of its hydrocarbyl phosphonate to improve safety, and on the other hand, it can react with the generated HF to effectively remove HF and improve the charging speed of the electrochemical energy storage device. Based on this, the compound with the structure of General Formula I can be used as a bifunctional additive with hydrogen fluoride scavenging function and flame retardant effect.

[0023] However, in the research of the present invention, it is found that among the compounds with the structure of General Formula I, when some compounds are added to the electrolyte as additives, the battery will bloat when the battery generates heat during use (for example, above 50 °C), which hinders the application of these compounds as additives in the battery electrolyte.

[0024] Through further research, the present invention finds that the reason for the battery to bloat under heating conditions is that when R3, R4, and R5 are all methyl groups, the product of the reaction between the compound with the structure of General Formula I and HF is trimethylfluorosilane, whose boiling point is too low, being 16.4 °C. When the battery operates under high voltage or for a long time and generates heat, it reaches the boiling point of trimethylfluorosilane, thus causing the battery to bloat.

[0025] 【2. Compounds with the structure of General Formula II】

[0026] In order to further avoid the problem of battery bloating under heating conditions, the second aspect of the present invention provides a class of compounds with the structure of General Formula II:

[0027]

[0028] Formula II

[0029] Wherein, R1 and R2 each independently selected from substituted or unsubstituted C1-C12 alkyl groups, or substituted or unsubstituted C6-C14 aryl groups; wherein the hydrogen atom may be unsubstituted or may be substituted by a group selected from halogen, alkyl, alkoxy, perfluoroalkyl, silyl, silyloxy, silane, sulfoxide, amide, azo, ether, and thioether groups or a combination thereof; and

[0030] R3, R4, and R5 each independently selected from C1-C12 alkyl groups, heteroalkyl groups, perfluoroalkyl groups, alkenyl groups, phenyl groups, or alkoxy groups, provided that R3, R4, and R5 cannot be methyl groups simultaneously.

[0031] Compared with the compounds with the structure of General Formula I, R3, R4, and R5 of the compounds with the structure of General Formula II cannot be methyl groups simultaneously, that is, it avoids the formation of low-boiling trimethylfluorosilane after the reaction of the compounds with the structure of General Formula II as additives with HF in the electrolyte, thereby effectively avoiding the problem of battery bloating under heating conditions.

[0032] Furthermore, the present invention finds that by increasing the chain length of R3, R4, and R5, although the problem of battery bloating under heating conditions can be effectively avoided, too long a chain length also brings the problem of decreased battery cycling performance and rate performance.

[0033] Based on this, the present invention provides a class of preferred compounds within the scope of the structure of General Formula II, with the structure of General Formula II:

[0034]

[0035] Formula II

[0036] Wherein, R1 and R2 are each independently selected from substituted or unsubstituted C1-C6 alkyl groups, or substituted or unsubstituted C6-C14 aryl groups; wherein the hydrogen atom may be unsubstituted or may be substituted by a group selected from halogen, alkyl, alkoxy, perfluoroalkyl, silyl, siloxy, silane, sulfoxide, amide, azo, ether and thioether groups or a combination thereof; and

[0037] R3, R4, and R5 are each independently selected from C1-C4 alkyl groups, provided that R3, R4, and R5 cannot all be methyl at the same time.

[0038] Compared with the compounds of the broad Formula II structure, the preferred compounds of the Formula II structure have R3, R4, and R5 selected from C1-C4 alkyl groups, provided that R3, R4, and R5 cannot all be methyl at the same time, that is, it avoids the problem of the decline in the battery cycle performance and rate performance caused by the addition of the compounds of the broad Formula II structure as additives in the electrolyte, and enables the battery to have flame retardant performance, fast charging performance, high safety, and excellent battery cycle performance and rate performance.

[0039] As a preference of any one of the embodiments in the second aspect of the present invention, R1 and R2 are each independently selected from C1-C4 alkyl groups; R3, R4, and R5 are each independently selected from C2-C4 alkyl groups.

[0040] As a preference of any one of the embodiments in the second aspect of the present invention, the compound is selected from one or more of the following:

[0041] Triethylsilyl diethylphosphinate, tripropylsilyl diethylphosphinate, tert-butyldimethylsilyl diethylphosphinate, n-butyldimethylsilyl diethylphosphinate, trimethylsilyl diphenylphosphinate, triethylsilyl diphenylphosphinate, tripropylsilyl diphenylphosphinate, tert-butyldimethylsilyl diphenylphosphinate, n-butyldimethylsilyl diphenylphosphinate, and mixtures thereof.

[0042] As a preference of any one of the embodiments in the second aspect of the present invention, the compound has a structural formula selected from the following:

[0043]

[0044] II-b

[0045]

[0046] II-c

[0047]

[0048] II-d

[0049]

[0050] II-e

[0051]

[0052] II-f.

[0053] 【3. Use as a flame retardant additive in the electrolyte】

[0054] The third aspect of the present invention provides the use of one or more of the compounds described in any one of the first aspect or the second aspect of the present invention as a flame retardant additive in the electrolyte.

[0055] Preferably, in any embodiment of the third aspect of the present invention, R1 and R2 are each independently selected from C1-C4 alkyl groups; R3, R4, and R5 are each independently selected from C2-C4 alkyl groups.

[0056] Preferably, in any embodiment of the third aspect of the present invention, the compound is selected from one or more of the following:

[0057] Triethylsilyl diethylphosphinate, tripropylsilyl diethylphosphinate, tert-butyldimethylsilyl diethylphosphinate, n-butyldimethylsilyl diethylphosphinate, trimethylsilyl diphenylphosphinate, triethylsilyl diphenylphosphinate, tripropylsilyl diphenylphosphinate, tert-butyldimethylsilyl diphenylphosphinate, n-butyldimethylsilyl diphenylphosphinate, and mixtures thereof.

[0058] Preferably, in any embodiment of the third aspect of the present invention, the compound has a structural formula selected from the following:

[0059]

[0060] II-b

[0061]

[0062] II-c

[0063]

[0064] II-d.

[0065] 【4. Flame retardant electrolyte】

[0066] The fourth aspect of the present invention provides a flame retardant electrolyte comprising one or more of the compounds described in any one of the first aspect or the second aspect of the present invention.

[0067] Preferably, in any of the embodiments of the fourth aspect of the present invention, R1 and R2 are each independently selected from C1-C4 alkyl; R3, R4, and R5 are each independently selected from C2-C4 alkyl.

[0068] Preferably, in any of the embodiments of the fourth aspect of the present invention, the compound is selected from one or more of the following:

[0069] Triethylsilyl diethylphosphinate, tripropylsilyl diethylphosphinate, tert-butyldimethylsilyl diethylphosphinate, n-butyldimethylsilyl diethylphosphinate, trimethylsilyl diphenylphosphinate, triethylsilyl diphenylphosphinate, tripropylsilyl diphenylphosphinate, tert-butyldimethylsilyl diphenylphosphinate, n-butyldimethylsilyl diphenylphosphinate, and mixtures thereof.

[0070] Preferably, in any of the embodiments of the fourth aspect of the present invention, the compound has a structural formula selected from the following:

[0071]

[0072] II-b

[0073]

[0074] II-c

[0075]

[0076] II-d.

[0077] Preferably, in any of the embodiments of the fourth aspect of the present invention, the flame-retardant electrolyte further comprises:

[0078] Aprotic organic solvent; and

[0079] An electrolyte, preferably a metal salt. More preferably a lithium salt.

[0080] Preferably, in any of the embodiments of the fourth aspect of the present invention, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, or lithium perchlorate. Further preferably, the lithium salt is lithium hexafluorophosphate.

[0081] Preferably, in any of the embodiments of the fourth aspect of the present invention, the concentration of the lithium salt is 0.5 to 2.0 M. For example, the concentration of the lithium salt is 0.5 M, 1.0 M, 1.5 M, or 2.0 M. Preferably, the concentration of the lithium salt is 1 to 1.2 M.

[0082] As a preferred embodiment of any one of the fourth aspects of the present invention, the mass fraction of the lithium salt in the flame-retardant electrolyte is 10 wt % to 30 wt %.

[0083] As a preferred embodiment of any of the fourth aspects of the present invention, the compound selected from formula II, formula II-b, formula II-c or formula II-d in the electrolyte is present in the flame retardant electrolyte at a mass concentration of 0.5% to 5%. For example, the compound selected from formula II, formula II-a, formula II-b, formula II-c, formula II-d is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%.

[0084] From the perspective of improving the flame retardant performance as much as possible and considering the effect of the compound on the battery performance, preferably, the compound selected from Formula II, Formula II-b, Formula II-c, Formula II-d is added at a mass concentration of 3.0 to 5.0%, more preferably 4 to 5%.

[0085] From the perspective of maintaining the cycle performance and rate performance of the battery as much as possible, preferably, the compound selected from Formula II, Formula II-b, Formula II-c, Formula II-d is added at a mass concentration of 0.5 to 3.0%, more preferably 1 to 3%.

[0086] In general, preferably, the compound selected from Formula II, Formula II-b, Formula II-c, Formula II-d is added at a mass concentration of 1.0 to 3.0%, more preferably 1.5 to 3.0%, and even more preferably 2.0 to 3.0%.

[0087] As a preferred embodiment of any one of the fourth aspects of the present invention, the aprotic organic solvent is present in the flame retardant electrolyte at a mass concentration of 60% to 90%. Preferably, the aprotic organic solvent is present in the flame retardant electrolyte at a mass concentration of 70% to 90%.

[0088] As a preferred embodiment of any of the fourth aspects of the present invention, the aprotic organic solvent comprises a solvent selected from one or more of the following: open-chain or cyclic carbonates, carboxylates, nitrites, ethers, sulfones, ketones, lactones, dioxolanes, glycol dimethyl ethers, crown ethers, siloxanes, phosphates, phosphites, monophosphazenes or polyphosphazenes.

[0089] Further, the aprotic organic solvent includes a solvent selected from one or more of the following: dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, bis(trifluoroethyl) carbonate, bis(pentafluoropropyl) carbonate, trifluoroethyl methyl carbonate, pentafluoroethyl methyl carbonate, heptafluoropropyl methyl carbonate, perfluorobutyl methyl carbonate, trifluoroethyl ethyl carbonate, pentafluoroethyl ethyl carbonate, heptafluoropropyl ethyl carbonate, perfluorobutyl ethyl carbonate, etc., fluorinated oligomers, methyl propionate, ethyl propionate, butyl propionate, dimethoxyethane, triglyme, dimethyl vinylene carbonate, tetraethylene glycol, dimethyl ether, polyethylene glycol, triphenyl phosphate, tributyl phosphate, hexafluorocyclotriphosphazene, 2-ethoxy-2,4,4,6,6-pentafluoro-1,3,5,2,5,4,5,6,5 - pentaazatriphenylene, triphenyl phosphite, sulfolane, dimethyl sulfoxide, ethyl methyl sulfone, ethyl vinyl sulfone, allyl methyl sulfone, divinyl sulfone, fluorophenyl methyl sulfone, and γ-butyrolactone.

[0090] Further, the electrolyte is a liquid electrolyte, a solid polymer electrolyte, or a gel polymer electrolyte.

[0091] 【5. Solid electrolyte】

[0092] The fifth aspect of the present invention provides a solid electrolyte, which includes one or more of the compounds described in any embodiment of the second aspect of the present invention.

[0093] As a preference of any embodiment in the fifth aspect of the present invention, it further includes:

[0094] a polymer matrix; and

[0095] a conductive lithium salt;

[0096] Preferably, the polymer matrix is selected from one or more mixtures of the following substances: polyethylene oxide, polyethylene glycol, poly(ethylene carbonate), poly(propylene carbonate), polyacrylonitrile, poly(methyl methacrylate), or poly(vinylidene fluoride); and / or

[0097] Preferably, the conductive lithium salt is selected from one or more mixtures of the following substances: lithium hexafluorophosphate, lithium difluorophosphate, lithium tris(pentafluoroethyl)trifluorophosphate, lithium tetrafluoroxalate phosphate, lithium trioxalate phosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluorooxalate borate, lithium pentafluoroethyltrifluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, or lithium trifluoromethanesulfonate.

[0098] Preferably, in any of the embodiments of the fifth aspect of the present invention, the solid electrolyte is in the form of a film with a thickness of 1 μm to 100 μm.

[0099] 【6. Electrochemical energy storage device】

[0100] The sixth aspect of the present invention provides an electrochemical energy storage device, comprising:

[0101] a cathode; an anode; a separator; and

[0102] a flame-retardant electrolyte according to any one of the embodiments of the fourth aspect of the present invention.

[0103] 【7. Lithium battery】

[0104] The seventh aspect of the present invention provides a lithium battery, comprising:

[0105] a cathode; an anode; a separator; and

[0106] a flame-retardant electrolyte according to any one of the embodiments of the fourth aspect of the present invention.

[0107] Preferably, in the embodiment of the seventh aspect of the present invention, the lithium battery is selected from a lithium-ion battery or a lithium-sulfur battery.

[0108] 【8. Lithium-ion secondary battery】

[0109] The eighth aspect of the present invention provides a lithium-ion secondary battery, comprising:

[0110] a cathode; an anode; a separator; and

[0111] a flame-retardant electrolyte according to any one of the embodiments of the fourth aspect of the present invention.

[0112] Preferably, in any of the embodiments of the eighth aspect of the present invention, after the lithium-ion secondary battery is charged and discharged in a cycle at a rate of 1C between 3.0 V and 4.2 V for 200 cycles, the capacity retention rate is greater than or equal to 90%.

[0113] Preferably, in any of the embodiments of the sixth, seventh, or eighth aspect of the present invention, the cathode comprises a cathode active component, a conductive agent, a binder, and an aluminum foil current collector; the cathode active component comprises a lithium metal oxide.

[0114] Preferably, the lithium metal oxide is selected from any one or more of lithium iron phosphate, lithium manganate, lithium cobaltate, nickel cobalt manganese ternary materials, and nickel cobalt aluminum ternary materials.

[0115] Preferably, the lithium metal oxide is selected from one or two of spinel type and olivine type.

[0116] Preferably, the spinel-type and olivine-type lithium metal oxides are carbon-coated materials.

[0117] More preferably, the lithium metal oxide is any one or more selected from lithium iron phosphate, lithium manganate, lithium cobaltate, nickel cobalt manganese ternary materials, and nickel cobalt aluminum ternary materials.

[0118] As a preference of any implementation manner in the sixth, seventh, or eighth aspect of the present invention, the anode comprises a lithium metal and a composite anode.

[0119] Preferably, the composite anode comprises an anode active component, a conductive agent, and a binder;

[0120] More preferably, the anode active component includes one or more selected from graphite materials, amorphous carbon, lithium titanate, tin alloys, silicon, silicon alloys, silicon-carbon composite materials, and intermetallic compounds.

[0121] Preferably, the intermetallic compound is selected from one or more of NiSi2, TiSi2, Li 17 Si4, Li13Si4, Li 12 Si7, Mg2Si, CuSn, Cu6Sn5, Ni3Sn4, Ni3Sn2, Co3Sn2, Mn2Sn, FeSn2, YSn2, TiSnSb, InSb, SnSb, CoSb, CoSb2, CoSb3, NiSb, NiSb2, Sb2C, Cu2Sb, ZnSb, Cu6Sb5.

[0122] Even more preferably, the anode active component is selected from any one or more of graphite materials, lithium titanate, and silicon-carbon composite materials.

[0123] As a preference of any implementation manner in the sixth, seventh, or eighth aspect of the present invention, the separator is a porous separator, the porous separator is a microporous polymer membrane, and the microporous polymer membrane comprises any one or more copolymers or blends of nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, and polybutene.

[0124] 【9. Lithium-ion secondary battery】

[0125] The ninth aspect of the present invention provides another lithium-ion secondary battery, comprising:

[0126] a cathode; an anode; and

[0127] the solid electrolyte according to any one of the fifth aspect of the present invention.

[0128] 3. Beneficial effects

[0129] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0130] (1) A class of silane phosphinates of formula II disclosed in the present invention, when added to an electrolyte, can not only achieve a flame retardant effect, but also maintain the cycle performance and rate performance of the battery due to its excellent HF removal ability; further, while removing HF, it avoids the problem of battery swelling under heating caused by the addition of trimethyl phosphate in the prior art, thus further improving the safety of the battery.

[0131] (2) A class of silane phosphinates of formula II disclosed in the present invention, preferably with the number of carbon atoms of R3-R5 not exceeding 4, not only avoids the problem of battery swelling under heating, but also avoids the problem of decline in the cycle performance and rate performance of the battery caused by too long carbon chains, and further ensures the maintenance of the cycle performance and rate performance of the battery while solving the swelling problem.

[0132] (3) The present invention discloses an electrolyte for a lithium-ion battery having a silane phosphinate of formula II as an electrolyte additive. The silane phosphinate of formula II as an electrolyte additive can improve the safety of the lithium-ion battery while achieving the purpose of flame retardancy, and the cycle performance and rate performance of the battery are maintained.

[0133] (4) The technology disclosed in the present invention is based on a novel electrolyte additive containing silane phosphinate, which can improve the stability of the electrolyte during operation in a wide temperature range. Even when used at a low weight addition amount, after the addition of the silane phosphinate compound, it will preferentially decompose over the electrolyte during the charge and discharge process of the battery, and the decomposition products are deposited on the electrode surface, thereby forming a solid electrolyte interface different from that of a battery without an additive. Description of the Drawings

[0134] Figure 1 1H NMR spectrum of trimethylsilyl diethylphosphinate prepared in Preparation Example 1;

[0135] Figure 2 1H NMR spectrum of triethylsilyl diethylphosphinate prepared in Preparation Example 2;

[0136] Figure 3 1H NMR spectrum of tripropylsilyl diethylphosphinate prepared in Preparation Example 3;

[0137] Figure 4 1H NMR spectrum of tert-butyldimethylsilyl diethylphosphinate prepared in Preparation Example 4;

[0138] Figure 5 1H NMR spectrum of trimethylsilyl diphenylphosphinate prepared in Preparation Example 5;

[0139] Figure 6 1H NMR spectrum of triethylsilyl diphenylphosphinate prepared in Preparation Example 6

[0140] Figure 7 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE1, EE2, EE3, EE4 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0141] Figure 8 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE5, EE6, EE7, EE8 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0142] Figure 9 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE9, EE10, EE11, EE12 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0143] Figure 10 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE13, EE14, EE15, EE16 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0144] Figure 11 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE17, EE18, EE19, EE20 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0145] Figure 12 Cycling life curves of NCM811||Li half-cells with electrolyte formulations of EE21, EE22, EE23, EE24 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 1C after activation at 0.1C for 3 cycles

[0146] Figure 13 Rate performance curves of NCM811||Li half-cells with electrolyte formulations of EE1, EE2, EE3, EE4 and CE1 in lithium-ion coin cells; voltage range: 3.0 - 4.2 V, cycled at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C and 0.1C for 3 cycles

[0147] Figure 14 Rate performance graphs of the NCM811||Li half-cell when the electrolyte formulation in the lithium-ion button cell is EE5, EE6, EE7, EE8, and CE1; voltage range: 3.0 - 4.2 V, cycling 3 loops at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, 0.1C respectively;

[0148] Figure 15 Rate performance graphs of the NCM811||Li half-cell when the electrolyte formulation in the lithium-ion button cell is EE9, EE10, EE11, EE12, and CE1; voltage range: 3.0 - 4.2 V, cycling 3 loops at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, 0.1C respectively;

[0149] Figure 16 Rate performance graphs of the NCM811||Li half-cell when the electrolyte formulation in the lithium-ion button cell is EE13, EE14, EE15, EE16, and CE1; voltage range: 3.0 - 4.2 V, cycling 3 loops at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, 0.1C respectively;

[0150] Figure 17 Rate performance graphs of the NCM811||Li half-cell when the electrolyte formulation in the lithium-ion button cell is EE17, EE18, EE19, EE20, and CE1; voltage range: 3.0 - 4.2 V, cycling 3 loops at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, 0.1C respectively;

[0151] Figure 18 Rate performance graphs of the NCM811||Li half-cell when the electrolyte formulation in the lithium-ion button cell is EE21, EE22, EE23, EE24, and CE1; voltage range: 3.0 - 4.2 V, cycling 3 loops at 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, 0.1C respectively;

[0152] Figure 19 19F NMR spectra of the effect of removing hydrogen fluoride from electrolyte CE1;

[0153] Figure 20 19F NMR spectra of the effect of removing hydrogen fluoride from electrolyte EE1;

[0154] Figure 21 19F NMR spectra of the effect of removing hydrogen fluoride from electrolyte EE5;

[0155] Figure 2219F NMR spectrum of electrolyte EE9 for HF removal effect

[0156] Figure 23 19F NMR spectrum of electrolyte EE13 for HF removal effect. Detailed implementation mode

[0157] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs; the term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0158] For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0159] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement, or value. Those skilled in the art can easily determine the degree of flexibility of a specific variable.

[0160] Concentrations, amounts, and other numerical data may be presented herein in a range format. It should be understood that such range formats are used merely for convenience and brevity and should be interpreted flexibly as including not only the explicitly recited values as the limits of the range, but also all individual values or sub-ranges subsumed within the stated range as if each value and sub-range were explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted as including not only the explicitly recited limits of 1 to about 4.5, but also the individual numbers (such as 2, 3, 4) and sub-ranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that recite only one numerical value, such as "less than about 4.5", which should be interpreted as including all of the above values and ranges. In addition, this interpretation should apply regardless of the breadth of the range or feature described.

[0161] The present invention will be further described below in conjunction with specific embodiments.

[0162] Preparation Example 1

[0163] This preparation example is for the synthesis of trimethylsilyl diethylphosphinate

[0164]

[0165] Weigh 10 g of diethylphosphinic acid into a flask, add 10 ml of pure water to dissolve and dilute it, and dropwise add ammonia water while stirring until the solution is weakly alkaline (pH value ranges from 7 to 9). After removing most of the pure water by vacuum distillation, transfer it to a vacuum oven and dry it at 110 °C overnight to obtain 11.4 g of diethylammonium phosphinate.

[0166] Add 10 g of ammonium diethylphosphinate prepared above to a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane thereto. After displacing the air in the two-necked flask with nitrogen, slowly add 8 g of trimethylchlorosilane dropwise with stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution, and rotary evaporate the obtained filtrate to remove the solvent, obtaining 9.9 g of a liquid containing trimethylsilyl diethylphosphinate.

[0167] The liquid containing trimethylsilyl diethylphosphinate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then distilled under reduced pressure to obtain 8.3 g of trimethylsilyl diethylphosphinate, which is stored in a glove box. The 1H NMR spectrum of trimethylsilyl diethylphosphinate is as Figure 1 shown.

[0168] Preparation Example 2

[0169]

[0170] This preparation example is for the synthesis of triethylsilyl diethylphosphinate

[0171] Weigh 10 g of diethylphosphinic acid into a flask, add 10 ml of pure water to dissolve and dilute it, and slowly add ammonia water dropwise with stirring until the solution is weakly alkaline (pH value ranges from 7 to 9). After removing most of the water by vacuum distillation, transfer it to a vacuum oven and dry it at 110 °C overnight to obtain 11.4 g of ammonium diethylphosphinate.

[0172] Add 10 g of ammonium diethylphosphinate prepared above to a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane thereto. After displacing the air in the two-necked flask with nitrogen, slowly add 12 g of triethylchlorosilane dropwise with stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution, and rotary evaporate the obtained filtrate to remove the solvent, obtaining 10.2 g of a liquid containing triethylsilyl diethylphosphinate.

[0173] The liquid containing triethylsilyl diethylphosphinate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then distilled under reduced pressure to obtain 7.9 g of triethylsilyl diethylphosphinate, which is stored in a glove box. The 1H NMR spectrum of triethylsilyl diethylphosphinate is as Figure 2 shown.

[0174] Preparation Example 3

[0175] This preparation example is for the synthesis of tripropylsilyl diethylphosphinate

[0176]

[0177] Weigh 10 g of diethylphosphinic acid into a flask, add 10 mL of pure water to dissolve and dilute it, and slowly add ammonia water dropwise while stirring until the solution is weakly alkaline (pH value ranges from 7 to 9). After removing most of the water by vacuum distillation, transfer it to a vacuum oven and dry it at 110 °C overnight to obtain 11.4 g of ammonium diethylphosphinate.

[0178] Add 10 g of the ammonium diethylphosphinate prepared above to a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane to it. After displacing the air in the two-necked flask with nitrogen, slowly add 15 g of tripropylchlorosilane dropwise while stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution and rotary evaporate the obtained filtrate to remove the solvent, obtaining 9 g of a liquid containing tripropylsilyl diethylphosphinate.

[0179] The liquid containing tripropylsilyl diethylphosphinate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then distilled under reduced pressure to obtain 6.5 g of tripropylsilyl diethylphosphinate, which is stored in a glove box. The nuclear magnetic resonance hydrogen spectrum of tripropylsilyl diethylphosphinate is as Figure 3 shown.

[0180] Preparation Example 4

[0181] This preparation example is for the synthesis of tert-butyldimethylsilyl diethylphosphinate

[0182]

[0183] Weigh 10 g of diethylphosphinic acid into a flask, add 10 mL of pure water to dissolve and dilute it, and slowly add ammonia water dropwise while stirring until the solution is weakly alkaline (pH value ranges from 7 to 9). After removing most of the water by vacuum distillation, transfer it to a vacuum oven and dry it at 110 °C overnight to obtain 11.4 g of ammonium diethylphosphinate.

[0184] Add 10 g of the ammonium diethylphosphinate prepared above to a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane to it. After displacing the air in the two-necked flask with nitrogen, slowly add 12 g of tert-butyldimethylchlorosilane dropwise while stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution and rotary evaporate the obtained filtrate to remove the solvent, obtaining 10.2 g of a liquid containing tert-butyldimethylsilyl diethylphosphinate.

[0185] The liquid containing tert-butyldimethylsilyl diethylphosphinate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then distilled under reduced pressure to obtain 7.6 g of tert-butyldimethylsilyl diethylphosphinate, which is stored in a glove box. The nuclear magnetic resonance hydrogen spectrum of tert-butyldimethylsilyl diethylphosphinate is as Figure 4 shown.

[0186] Preparation Example 5

[0187]

[0188] This preparation example is for the synthesis of trimethylsilyl diphenylphosphinate

[0189] Weigh 10 g of diphenylphosphinic acid into a beaker, add ammonia water and stir continuously until diphenylphosphinic acid is completely dissolved. After removing most of the water by vacuum distillation, transfer it to a vacuum oven and keep it overnight at 110 °C to obtain 10.78 g of ammonium diphenylphosphinate

[0190] Add 10 g of ammonium diphenylphosphinate prepared above into a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane to it. After displacing the air in the two-necked flask with nitrogen, slowly dropwise add 7 g of chlorotrimethylsilane while stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution. The filtrate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then the solvent is removed by rotary evaporation to obtain 11.1 g of a liquid containing trimethylsilyl diphenylphosphinate. This liquid solidifies into a solid at room temperature

[0191] Recrystallize the obtained solid with dehydrated toluene to obtain 4.2 g of white crystals (trimethylsilyl diphenylphosphinate). The nuclear magnetic resonance hydrogen spectrum of trimethylsilyl diphenylphosphinate is as Figure 5 shown

[0192] Preparation Example 6

[0193] This preparation example is for the synthesis of triethylsilyl diphenylphosphinate

[0194]

[0195] Weigh 10 g of diphenylphosphinic acid into a beaker, add ammonia water and stir continuously until diphenylphosphinic acid is completely dissolved. After removing most of the water by vacuum distillation, transfer it to a vacuum oven and keep it overnight at 110 °C to obtain 10.78 g of ammonium diphenylphosphinate

[0196] Add 10 g of ammonium diphenylphosphinate prepared above into a 100 mL two-necked flask equipped with a magnetic stirrer, then add 50 mL of dichloromethane to it. After displacing the air in the two-necked flask with nitrogen, slowly dropwise add 10 g of chlorotriethylsilane while stirring. After the addition is complete, heat the mixed solution in the two-necked flask to 60 °C and keep it warm for 6 h. Then filter the mixed solution. The filtrate is deacidified with anhydrous potassium carbonate and dehydrated with calcium hydride, and then the solvent is removed by rotary evaporation to obtain 13.1 g of a liquid containing triethylsilyl diphenylphosphinate. This liquid solidifies into a solid at room temperature

[0197] The obtained solid was recrystallized using toluene after water removal to obtain 3.8 g of white crystals (triethylsilyl diphenylphosphinate). The 1H NMR spectrum of triethylsilyl diphenylphosphinate is as shown in Figure 6 shown below.

[0198] Preparation Example 7

[0199] This preparation example is for the preparation of an electrolyte formulation, and the preparation process is carried out in a dry argon-filled glove box.

[0200] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3:7 to obtain a liquid mixture. Then lithium hexafluorophosphate (LiPF6) was added and dissolved in the liquid mixture as a Li-ion conducting salt to obtain a basic electrolyte formulation, and at this time the concentration of lithium hexafluorophosphate (LiPF6) was 1.2 M. Various phosphinous acid silyl esters prepared in Preparation Examples 1-4 were used as additive materials and added to the above basic electrolyte formulation at 1 wt%, 2 wt%, 3 wt%, and 4 wt% of the electrolyte formulation respectively to obtain the electrolyte formulations shown in Examples 1-16 of Table 1. Considering the poor solubility of the phosphinous acid silyl esters prepared in Preparation Examples 5-6, various phosphinous acid silyl esters prepared in Preparation Examples 5-6 were used as additive materials and added to the above basic electrolyte formulation at 0.25 wt%, 0.5 wt%, 1 wt%, and 2 wt% of the electrolyte formulation respectively to obtain the electrolyte formulations shown in Examples 17-24 of Table 1. At the same time, a basic electrolyte formulation without additives was used as a control group.

[0201] All of the above electrolyte components were stirred and mixed in a glass vial for 24 hours to ensure that all solids were completely dissolved.

[0202] Table 1 Electrolyte formulations with different addition ratios of phosphinous acid silyl esters

[0203]

[0204]

[0205] Test Example 1

[0206] This test example is for the flame retardancy test of electrolyte formulations with different addition ratios of phosphinous acid silyl esters.

[0207] In this test example, the preparation process of the electrolyte formulations used was carried out in a dry argon-filled glove box.

[0208] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed evenly in a volume ratio of 3:7 to obtain a liquid mixture. Then, lithium hexafluorophosphate (LiPF6) was added and dissolved in the liquid mixture as the Li-ion conductive salt to obtain a basic electrolyte formulation. At this time, the concentration of lithium hexafluorophosphate (LiPF6) was 1.2 M. Various silane phosphinates prepared in Preparation Examples 1 to 4 were added as additive materials to the above basic electrolyte formulation at mass concentrations of 0 wt%, 3 wt%, 5 wt%, 10 wt%, and 20 wt% of the electrolyte formulation to obtain the electrolyte formulations shown in Table 2. At the same time, a basic electrolyte formulation without additives was used as a control group.

[0209] Specifically, 100 μl of the prepared electrolyte formulation was respectively dipped with a quartz wool ball with a diameter of 0.5 cm, and then ignited in a candle flame for 2 s and then taken away and timed. The timing was stopped until the flame went out, and the self-extinguishing time of the quartz wool ball was recorded. The results are shown in Table 2.

[0210] Table 2 Self-extinguishing time of electrolytes containing a certain amount of additives

[0211]

[0212] Compared with the control group without silane phosphinate added, the silane phosphinate additives can effectively shorten the self-extinguishing time of the electrolyte and improve the safety of the battery.

[0213] Test Example 2

[0214] This test example was to test various performances of a lithium-ion battery using the electrolyte formulation prepared in Preparation Example 7 as the electrolyte in a button battery.

[0215] Specifically, 1 g of lithium nickel manganese cobalt oxide (NMC811), polyvinylidene fluoride (PVDF), and conductive carbon black (Super P) were weighed in a mass ratio of 8:1:1, placed in a quartz mortar and ground thoroughly, then transferred to a 5 ml weighing bottle, 1500 μL of N-methylpyrrolidone was added, and after magnetic stirring for 24 h, it was coated on an aluminum foil with a thickness of 100 μm. After drying in a forced-air oven at 80 °C for 8 h, it was transferred to a vacuum oven and dried at 120 °C for 10 h. After drying, a pole piece with a diameter of 12 mm was cut and used as the cathode, a lithium sheet was used as the anode, and a polypropylene (pp) membrane was used to assemble a half-cell.

[0216] Specifically, place the lithium sheet in the negative electrode case. Use a pipette to transfer 35 μL of the electrolyte formulation prepared in Preparation Example 7 to the center of the lithium sheet. After covering the electrolyte formulation with a separator, use a pipette to transfer another 35 μL of the electrolyte formulation prepared in Preparation Example 7 to the center of the separator. Take a cathode, place the coated electrode material mixture facing downwards in the center of the separator. Then, stack a stainless-steel gasket, a stainless-steel spring piece, and a positive electrode case on top of the cathode in sequence to complete the assembly. Place the assembled battery in a dedicated hydraulic press and apply pressure to 50 kg / cm 2 Keep it for 10 s for sealing. Then, leave the sealed lithium-ion button battery in an incubator at 25 °C for 12 h to allow the electrolyte to infiltrate the separator.

[0217] 2.1 Test of remaining capacity and capacity retention rate of the battery

[0218] Charge and discharge the above lithium-ion button battery 3 times at a rate of 0.1C between 3.0V and 4.2V, and then perform charge and discharge cycles on the lithium-ion button battery at a rate of 1C between 3.0V and 4.2V. Record the remaining capacity and capacity retention rate. The specific results are shown in Table 3, and the data records of the specific measurement process are as Figures 7 - 12 shown.

[0219] Table 3 Remaining capacity and capacity retention rate of the battery

[0220]

[0221]

[0222] Compared with the comparative examples, the additives and their addition amounts corresponding to Examples 5, 9, and 11 can improve the capacity retention rate of the half-cell and improve the cycle life of the battery. At the same time, the capacity retention rates of the batteries with the additives and their addition amounts corresponding to Examples 1, 2, 3, 5, 6, 7, 9, 11, and 15 are higher than 80%. When the silicate hypophosphite additive has the dual effects of flame retardancy and hydrogen fluoride removal, the impact on the capacity retention rate and cycle life of the lithium-ion battery is still within an acceptable range. However, it was found during this experimental process that the lithium-ion button battery prepared with trimethylsilyl diethylphosphinate prepared in Preparation Example 1 as an additive material would react with the generated hydrogen fluoride during the cycling process to form trimethylfluorosilane. Trimethylfluorosilane has a very low boiling point of only 16.4 °C and is volatile at room temperature, which is likely to cause the battery to swell.

[0223] 2.2 Rate performance test

[0224] In the voltage range of 3 - 4.2V, perform rate performance tests on the above lithium-ion button battery by cycling 3 times at charge and discharge rates of 0.1C, 0.5C, 1C, 2C, 3C, 5C, 7C, 10C, and 0.1C. The specific results are as Figures 13 - 18as shown

[0225] The additives and their addition amounts corresponding to Examples EE7, EE9, EE15, and EE17 can improve the rate performance of the half-cell and enhance the fast charging function of the lithium-ion battery. Among them, the battery assembled with electrolyte formulation EE9 has an average discharge capacity of 79.3 mAh / g after three cycles at a rate of 10C, which is higher than the discharge capacity of 67.8 mAh / g of the battery assembled with electrolyte formulation CE1, indicating that the phosphinic acid silicone additive can improve the fast charging performance of the lithium-ion battery to a certain extent. At the same time, when the phosphinic acid silicone additive has the dual effects of flame retardancy and hydrogen fluoride removal, the impact on the rate performance and fast charging function of the lithium-ion battery is still within an acceptable range.

[0226] Test Example 3

[0227] This test example is for the hydrogen fluoride removal test of the basic electrolyte formulation CE1 and electrolyte formulations EE1, EE5, EE9, and EE14.

[0228] In the glove box, an acetonitrile solution with a water content of 1‰ was prepared using anhydrous acetonitrile and ultrapure water for standby. Appropriate amounts of the basic electrolyte formulation CE1 and electrolyte formulations EE1, EE5, EE9, and EE14 were respectively placed in 5 glass bottles, and the aforementioned acetonitrile solution with a water content of 1‰ was added to each to dilute the basic electrolyte formulation and each electrolyte formulation by 10 times, so that the water content was 100 ppm. After stirring evenly, it was left standing for one day. After the standing ended, F 19 NMR test was carried out.

[0229] The test results are as Figures 19 - 23 shown, Figure 19 the peak at 190 ppm in it indicates that HF is generated in the electrolyte without additives after adding water, Figures 20 - 23 the absence of a peak at this chemical shift in it, and the newly emerged F-Si peak at 160 ppm indicate that the addition of the additive removes HF. The results show that the phosphinic acid silicone additive can effectively remove HF in the lithium-ion battery and protect the electrode from corrosion by HF.

[0230] The above content is a schematic description of the present invention and its implementation manners. This description is not restrictive. What is shown in the embodiments is only one of the implementation manners of the present invention, and the actual implementation manners are not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design implementation manners and embodiments similar to this technical solution without creative efforts without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A compound, characterized in that, Has the structure of general formula II: Wherein, R1 and R2 are each independently selected from substituted or unsubstituted C1-C12 alkyl groups, or substituted or unsubstituted C6-C14 aryl groups; wherein the hydrogen atom may be unsubstituted or may be substituted by a group selected from halogen, alkyl, alkoxy, perfluoroalkyl, silyl, silyloxy, silane, sulfoxide, amide, azo, ether and thioether groups or a combination thereof; and R3, R4, and R5 are each independently selected from C1-C12 alkyl, heteroalkyl, perfluoroalkyl, alkenyl, phenyl or alkoxy, provided that R3, R4, and R5 cannot all be methyl at the same time.

2. The compound according to claim 1, wherein In formula II: R1 and R2 are each independently selected from substituted or unsubstituted C1-C6 alkyl groups; wherein the hydrogen atom may be unsubstituted or may be substituted by a group selected from halogen, alkyl, alkoxy, perfluoroalkyl, silyl, silyloxy, silane, sulfoxide, amide, azo, ether and thioether groups or a combination thereof; and R3, R4, and R5 are each independently selected from C1-C4 alkyl.

3. The compound according to claim 2, wherein In formula II: R1 and R2 are each independently selected from C1-C4 alkyl groups; R3, R4, and R5 are each independently selected from C2-C4 alkyl.

4. The compound according to claim 1, characterized in that, The compound is selected from one or more of the following: Triethylsilyl diethylphosphinate, tripropylsilyl diethylphosphinate, tert-butyldimethylsilyl diethylphosphinate, n-butyldimethylsilyl diethylphosphinate, trimethylsilyl diphenylphosphinate, triethylsilyl diphenylphosphinate, tripropylsilyl diphenylphosphinate, tert-butyldimethylsilyl diphenylphosphinate, n-butyldimethylsilyl diphenylphosphinate and mixtures thereof.

5. The compound according to claim 1, characterized in that, The compound has a structural formula selected from the following:

6. Use of one or more of the compounds according to any one of claims 1 to 5 as a flame retardant additive in an electrolyte.

7. Flame-retardant electrolyte, characterized in that, Contains one or more of the compounds according to any one of claims 1 to 5.

8. The flame-retardant electrolyte according to claim 7, characterized in that, Further contains: Aprotic organic solvent; and Lithium salt.

9. The flame retardant electrolyte according to claim 8, characterized in that The concentration of the lithium salt is 0.5 to 2 M; or the mass fraction of the lithium salt in the flame retardant electrolyte is 10 wt% to 30 wt%; The compound selected from formula II, formula II-b, formula II-c or formula II-d in the electrolyte is present in the flame retardant electrolyte at a mass concentration of 0.5% to 5%; The aprotic organic solvent is present in the flame retardant electrolyte at a mass concentration of 60% to 90%.

10. The flame-retardant electrolyte according to claim 8, wherein, The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate or lithium perchlorate; and / or The aprotic organic solvent contains one or more solvents selected from the following: open-chain or cyclic carbonates, carboxylates, nitrites, ethers, sulfones, ketones, lactones, dioxolanes, ethylene glycol dimethyl ethers, crown ethers, siloxanes, phosphates, phosphites, monophosphazenes or polyphosphazenes.

11. A solid electrolyte, characterized in that, Contains one or more of the compounds according to any one of claims 1 to 5.

12. The solid electrolyte according to claim 11, characterized in that, Further contains: Polymer matrix; and Conductive lithium salt; Preferably, the polymer matrix is selected from one or a mixture of more than one of the following substances: polyethylene oxide, polyethylene glycol, poly(ethylene carbonate), poly(propylene carbonate), polyacrylonitrile, polymethyl methacrylate, or poly(vinylidene fluoride); and / or Preferably, the conductive lithium salt is selected from one or a mixture of more than one of the following substances: lithium hexafluorophosphate, lithium difluorophosphate, lithium tris(pentafluoroethyl)trifluorophosphate, lithium tetrafluoroxalate phosphate, lithium trioxalate phosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium pentafluoroethyltrifluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, or lithium trifluoromethanesulfonate.

13. The solid electrolyte according to claim 11, characterized in that, The solid electrolyte is in the form of a film with a thickness of 1 μm to 100 μm.

14. Electrochemical energy storage device, characterized in that, Comprising: a cathode; an anode; a separator; and the flame-retardant electrolyte according to any one of claims 7 to 10.

15. A lithium ion secondary battery, characterized in that, Comprising: a cathode; an anode; a separator; and the flame-retardant electrolyte according to any one of claims 7 to 10.

16. The lithium-ion secondary battery according to claim 15, wherein: After the lithium-ion secondary battery is charged and discharged cyclically 200 times at a rate of 1C between 3.0 V and 4.2 V, the capacity retention rate is greater than or equal to 90%.

17. The electrochemical energy storage device according to claim 14 or the lithium-ion secondary battery according to claim 15, wherein: The cathode comprises a cathode active component, a conductive agent, a binder, and an aluminum foil current collector; the cathode active component comprises a lithium metal oxide; Preferably, the lithium metal oxide is selected from any one or more of lithium iron phosphate, lithium manganate, lithium cobaltate, nickel cobalt manganese ternary materials, and nickel cobalt aluminum ternary materials.

18. The electrochemical energy storage device according to claim 14 or the lithium-ion secondary battery according to claim 15, wherein: The anode comprises a lithium metal and a composite anode; The composite anode comprises an anode active component, a conductive agent, and a binder; Preferably, the anode active component includes one or more selected from graphite materials, amorphous carbon, Li4Ti5O 12 , tin alloys, silicon, silicon alloys, and intermetallic compounds.

19. The electrochemical energy storage device according to claim 14 or the lithium-ion secondary battery according to claim 15, wherein: The separator is a porous separator, the porous separator is a microporous polymer membrane, and the microporous polymer membrane comprises any one or more copolymers or blends of nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, poly(vinylidene fluoride), polypropylene, polyethylene, and polybutene.

20. A lithium ion secondary battery, characterized in that, Comprising: a cathode; an anode; and the solid electrolyte according to any one of claims 11 to 13.

Images