Non-aqueous electrolyte containing phosphino multi-element cyclic ester compound and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, provides a non-aqueous electrolyte containing a phosphino multi-element cyclic ester compound and a lithium ion battery, and solves the problems of poor high-temperature and high-pressure cycle performance and low-temperature discharge performance of the lithium ion battery in the prior art. The non-aqueous electrolyte provided by the invention contains a phosphino multi-element cyclic ester compound, the phosphino multi-element cyclic ester compound has a structure as shown in a general formula (I) # imgabs0 #, and A1, A2 and A3 are independently selected from one of C or S elements; a, b and c are independently selected from 1 or 2; n and m are independently selected from 0 or 1; the invention further provides a lithium ion battery containing the non-aqueous electrolyte, the problems in the prior art are well solved, and the non-aqueous electrolyte can be applied to the field of lithium ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a non-aqueous electrolyte containing a phosphonyl polycyclic ester compound and a lithium-ion battery. Background Art

[0002] With the rapid development of electric vehicles, consumers have higher and higher requirements for the energy density of lithium-ion batteries, and at the same time, excellent high-temperature cycling, storage and low-temperature discharge performance are required. In order to improve the energy density of lithium-ion batteries, adding a small amount of functional additives to the electrolyte to overcome the oxidation and decomposition problems of conventional electrolytes has become the most economical and effective means.

[0003] For example, CN109273766A discloses a non-aqueous electrolyte for high-temperature and high-voltage lithium nickel manganese cobalt oxide cathode materials, using phosphonoacetate compounds as additives to form a passivation film on the electrode surface, improve the electrolyte / electrode interface, inhibit the contact between the electrode and the electrolyte under high voltage, and ensure the excellent performance of the electrode at high working potentials; CN111490294B discloses a non-aqueous electrolyte functional additive, a non-aqueous electrolyte and a lithium-ion battery, and the structural formula of the functional additive is which can improve the high-voltage cycling performance, rate performance and low-temperature performance of lithium-ion batteries with lithium nickel manganese cobalt oxide as the cathode; CN116779973A discloses a high-voltage electrolyte and a lithium-ion battery, and the structural formula of the additive is: wherein X and Y independently selected from carbon, sulfur or phosphorus, can form an organic-inorganic double SEI interface at the electrode electrolyte interface, which is relatively stable at a high voltage of 4.5V, is not easily decomposed at high temperatures, and there are also many lithium-ion transport channels at low temperatures, so that the lithium-ion battery has good high-temperature storage, high-temperature cycling performance and low-temperature performance at a high voltage of 4.5V.

[0004] It can be seen that functional additives with a variety of group structures can enhance the synergistic effect between different molecular structures and more effectively improve the electrochemical performance of lithium-ion batteries. Summary of the Invention

[0005] One of the technical problems to be solved by the present invention is that in the prior art, the internal resistance of lithium-ion batteries increases at low temperatures, and the low-temperature performance is poor. At the same time, due to the decomposition of the electrolyte above a high voltage (4.2V), the cycle performance of the battery is poor. A non-aqueous electrolyte containing a phosphonyl polycyclic ester compound is provided, which can improve the discharge performance of lithium-ion batteries at low temperatures and at the same time improve the cycle life of lithium-ion batteries at high temperatures and high voltages.

[0006] The second technical problem to be solved by the present invention is to provide a lithium-ion battery corresponding to the first technical problem.

[0007] To solve one of the above technical problems, the technical solution adopted by the present invention is to provide a non-aqueous electrolyte containing a phosphono polycyclic ester compound, and the phosphono polycyclic ester compound has a structure shown in the general formula (I). Wherein, A1, A2, and A3 are independently selected from one of the elements C or S; a, b, and c are independently selected from 1 or 2; n and m are independently selected from 0 or 1.

[0008] Furthermore, the phosphono polycyclic ester compound is selected from at least one of the following structural formulas:

[0009]

[0010] Furthermore, the phosphono polycyclic ester compound is selected from at least one of the following structural formulas:

[0011]

[0012]

[0013] Furthermore, the dosage of the phosphono polycyclic ester compound is 0.1 to 5% of the total mass of the non-aqueous electrolyte.

[0014] Furthermore, the non-aqueous electrolyte further contains a lithium salt electrolyte, a non-aqueous organic solvent, and other additives, and the dosage of the other additives is 0.5 to 5% of the total mass of the non-aqueous electrolyte.

[0015] Furthermore, the other additives are selected from at least one of unsaturated carbonates, halogenated carbonates, sulfates, sulfites, sulfonates, phosphates, phosphites, borates, acid anhydrides, polycyanides, phosphonitriles, silanes, or lithium salt additives.

[0016] Further, the other additives are selected from at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (DTD), bis(ethylene sulfate) (BESA), ethylene sulfite (ES), methylene methanedisulfonate (MMDS), 1,3 - propane sultone (PS), 1,3 - propylene sultone (PST), tris(trimethylsilyl) phosphate (TMSP), tris(trimethylsilyl) phosphite (TMSPi), tris(trimethylsilyl) borate (TMSB), succinic anhydride (SA), succinonitrile (SN), adiponitrile (ADN), ethoxypentafluorocyclotriphosphazene (PFPN), tetravinylsilane (TVSi), dimethyldivinylsilane (DMDV), lithium difluorophosphate (LiPO2F2), lithium bis(oxalate) borate (LiBOB), lithium difluoro(oxalate) borate (LiODFB), lithium bis(oxalate) difluorophosphate (LiDFBP), lithium tetrafluoro(oxalate) phosphate (LiOTFP), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), or lithium 2 - (trifluoromethyl) - 4,5 - dicyanoimidazole (LiTDI).

[0017] Further, the non - aqueous organic solvent is selected from at least one of carbonate solvents or carboxylate solvents.

[0018] Further, the non - aqueous organic solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, 2,2,2 - trifluoroethyl methyl carbonate, bis(trifluoroethyl) carbonate, 2,2,2 - trifluoroethyl acetate, or 2,2 - difluoroethyl acetate.

[0019] Further, the lithium salt electrolyte is lithium hexafluorophosphate, and the concentration of the lithium salt electrolyte in the non - aqueous electrolyte is 0.8 - 1.5 mol / L.

[0020] In a specific embodiment, the phosphine - based polycyclic ester compound (I) in the non - aqueous electrolyte provided by the present invention can be prepared by a publicly known method in the prior art or purchased commercially, or can be prepared by the following route:

[0021] S1a: Compound A is esterified to obtain compound B;

[0022] S1b: Compound B is oxidized to obtain compound C. This step can be selected or not after S1a;

[0023]

[0024] S2a: Compound B and / or compound C are esterified to obtain compound (I), that is, the phosphine - based polycyclic ester;

[0025] S2b: The compound (I) is further oxidized to obtain the oxidized phosphine polycyclic ester (I), which is an optional step after S2a and can be performed or not.

[0026]

[0027] Among them, the esterification described in steps S1a and S2a is an ester exchange or dehalogenation reaction; A, A1, A2, and A3 are independently selected from C or S elements; p, n, and m are independently selected from 0 or 1; a, b, c, d, and e are independently selected from 1 or 2.

[0028] Furthermore, when the esterification described in steps S1a and S2a is a dehalogenation reaction, the esterification reagent used is selected from at least one of carbonyl halides, thionyl halides, or sulfuryl halides; a tertiary amine compound is used as an acid-binding agent during the reaction to promote the reaction; the molar ratio of the acid-binding agent to compound A in step S1a is 0.8 - 3.0:1; the molar ratio of the acid-binding agent to the total hydroxyl groups in compound B and compound C in step S2a is 0.5 - 2.5:1.

[0029] Furthermore, the esterification reagent is selected from at least one of phosgene, diphosgene, triphosgene, carbonyl fluoride, carbonyl bromide, thionyl fluoride, thionyl chloride, thionyl bromide, sulfuryl chloride, or sulfuryl fluoride; the tertiary amine compound is selected from at least one of trimethylamine, triethylamine, N,N - diisopropylethylamine, N,N - dimethylcyclohexylamine, N,N - dimethylaniline, pyridine, 4 - dimethylaminopyridine, or 2,6 - di - tert - butylpyridine.

[0030] Furthermore, when the esterification described in steps S1a and S2a is an ester exchange, the esterification reagent used is selected from at least one of carbonates, sulfites, or sulfates; a catalyst is used to promote the reaction during the reaction, and the catalyst is selected from at least one of metal oxides, metal hydroxides, metal salts, metal organic compounds, transition metal complexes, solid acids, or molecular sieve catalysts.

[0031] Furthermore, the esterification reagent is selected from at least one of dimethyl carbonate, diethyl carbonate, bis(trifluoromethyl) carbonate, bis(2,2,2 - trifluoroethyl) carbonate, diphenyl carbonate, dimethyl sulfite, diethyl sulfite, dimethyl sulfate, or diethyl sulfate; the catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, sodium acetate, triethylamine, pyridine, 4 - dimethylaminopyridine, aluminum trichloride, titanium tetrachloride, sodium methoxide, sodium ethoxide, sodium tert - butoxide, potassium tert - butoxide, p - toluenesulfonic acid, acidic clay, tetraisopropyl titanate, n - butyl titanate, metal - loaded modified molecular sieve, acidic ion exchange resin, basic ion exchange resin, cobalt carbonyl, or samarium trifluoromethanesulfonate.

[0032] Further, in the esterification step S1a, the reaction temperature is -30 to 110°C, and the molar ratio of the esterification reagent to compound A is 0.5 to 2:1; in the esterification step S2a, the reaction temperature is -30 to 110°C, and the molar ratio of the esterification reagent to the total hydroxyl groups in compound B and compound C is 0.4 to 3.0:1; in steps S1b and S2b, the oxidizing agent used is selected from at least one of hypochlorous acid, hypochlorite, peroxide, ozone, oxygen, air, or metal oxide.

[0033] Further, the oxidizing agent used in steps S1b and S2b is selected from at least one of aqueous hypochlorous acid, sodium hypochlorite, calcium hypochlorite, hydrogen peroxide, peracetic acid, persulfuric acid, sodium peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, potassium hydrogen persulfate, sodium percarbonate, oxygen, potassium permanganate, or sodium dichromate.

[0034] Further, the prepared phosphono polycyclic ester is purified by at least one of crystallization or column chromatography.

[0035] To solve the second of the above technical problems, the technical solution adopted by the present invention is: to provide a lithium-ion battery, comprising a positive electrode material, a separator, a negative electrode material, and a non-aqueous electrolyte containing the above-mentioned phosphono polycyclic ester compound.

[0036] Further, the positive electrode material includes, but is not limited to, at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium nickel manganate, lithium cobaltate, lithium nickel cobalt manganate, or lithium nickel cobalt aluminate materials.

[0037] Further, the negative electrode material includes, but is not limited to, at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon-based materials, or lithium metal materials.

[0038] The beneficial effects of the present invention are:

[0039] The present invention adds the phosphono polycyclic ester compound as an additive to the non-aqueous electrolyte, which can simultaneously form a thin and dense CEI and SEI film at the positive and negative electrode interfaces of the battery, having a lower internal resistance. The CEI film formed on the positive electrode can inhibit the dissolution of transition metals, avoid the oxidation and decomposition of the electrolyte, improve the cycle performance of the battery, and at the same time, the alkyl phosphine in the CEI film can promote the migration of lithium ions. The SEI film on the negative electrode can inhibit the reduction and decomposition of the electrolyte, avoid the enrichment of reduction products on the negative electrode side, resulting in an increase in internal resistance. Therefore, the lithium-ion battery provided by the present invention has excellent low-temperature discharge performance and a long cycle life at high temperature and high voltage, achieving good technical effects. Detailed Embodiments

[0040] The technical solution of the present invention will be further explained and illustrated below in conjunction with specific embodiments. However, the following examples are only illustrative examples of this application and do not limit the content of this application. Those skilled in the art can make improvements or modifications without creative contributions to the content of the present invention according to the inspiration of this specification, and all fall within the protection scope of the present invention.

[0041] The following further details this application in conjunction with examples.

[0042]

Preparation Example

[0043] The phosphino polycyclic esters used in the examples can be prepared by the method routes of the prior art or directly purchased commercially, or can be prepared by the following routes:

[0044]

[0045]

[0046] Taking Ⅰ-11 and Ⅰ-18 as examples, the preferred preparation routes adopted in this embodiment are briefly described as follows, and the preparation of other compounds is similar:

[0047] Ⅰ-11: Add 63.0 g of trimethylolphosphine oxide, 59.0 g of diethyl carbonate, 3.15 g of potassium carbonate and toluene into the reaction flask, reflux at 100-105 °C for 2 h, remove the by-products, cool after the reaction, distill under reduced pressure, and recrystallize to obtain 53.1 g of compound B-2. Then add toluene, 2.0 g of p-toluenesulfonic acid and 27.6 g of dimethyl sulfite, react at 95-98 °C for 5 h, separate out the by-products, distill under reduced pressure after the reaction, and purify by recrystallization to obtain 26.7 g of compound Ⅰ-11.

[0048] Ⅰ-18: Add 42.0 g of trimethylolphosphine oxide, 63.7 g of triethylamine and tetrahydrofuran into the reaction flask, cool down, dropwise add 37.1 g of thionyl chloride, keep the reaction at -10 to -5 °C for 6 h, filter to remove salts, distill under reduced pressure, and purify the crude product to obtain 39.1 g of compound B-4. Then dissolve it in toluene, add 19.0 g of pyridine, cool down and dropwise add 14.3 g of thionyl chloride, keep the process at -15 to 10 °C, reflux at 105 °C for 2 h after dropping, filter to remove salts after the reaction, distill under reduced pressure, and purify to obtain 33.4 g of intermediate product. Then, add the intermediate product to dichloromethane, cool down, dropwise add 30% hydrogen peroxide solution, keep the process at -15 to -5 °C, keep the temperature for 6 h, separate the liquid, dry, distill under reduced pressure, and purify by column chromatography to obtain 32.9 g of compound Ⅰ-18.

[0049]

Example 1

[0050] (1) Preparation of non-aqueous electrolyte

[0051] In a glove box filled with nitrogen or argon where the water and oxygen contents are both ≤ 0.1 ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1. Lithium hexafluorophosphate is added to the prepared non-aqueous solvent and thoroughly mixed and dissolved to prepare a 1 mol / L lithium hexafluorophosphate solution.

[0052] Based on the total mass of the electrolyte being 100%, 2% by mass of fluoroethylene carbonate (FEC), 1% of lithium difluorophosphate (LiPO2F2) and 1% of 1,3 - propane sultone (PS) are added to the lithium hexafluorophosphate solution. Finally, 1% of a phosphino polycyclic ester compound having the structure shown in formula (Ⅰ-1) is added, and after thorough dissolution and mixing, a non-aqueous electrolyte is obtained.

[0053] (2) Fabrication of the lithium-ion battery

[0054] Preparation of the positive electrode sheet:

[0055] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) are added in a mass ratio of 96:2:2 and dispersed in N-methyl-2-pyrrolidone (NMP), and thoroughly mixed to obtain a positive electrode slurry; the positive electrode slurry is coated on a double-sided carbon-coated aluminum foil, and after drying, rolling, and cutting, a positive electrode sheet is obtained. Preparation of the negative electrode sheet:

[0056] The negative electrode active material artificial graphite, conductive carbon black Super-P, binder sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) are added in a mass ratio of 96:1.5:1.5:1 and dispersed in deionized water, and thoroughly mixed to obtain a negative electrode slurry. The negative electrode slurry is coated on both sides of a copper foil, and after drying, rolling, and cutting, a negative electrode sheet is obtained.

[0057] Dry cell assembly:

[0058] The positive electrode sheet, polypropylene porous separator membrane, and negative electrode sheet are stacked to prepare an electrode assembly, and aluminum electrode tabs and nickel electrode tabs are welded to the positive electrode and the negative electrode respectively using an ultrasonic spot welder. Then, the electrode assembly is placed in an aluminum foil bag and thoroughly dried under vacuum at 85 °C to obtain a lithium-ion battery dry cell.

[0059] In a glove box filled with nitrogen or argon where the water and oxygen contents are both ≤ 0.1 ppm, the prepared non-aqueous electrolyte is injected into the above-assembled dry cell. After the injection is completed, it is sealed, left standing, formed, aged, secondarily sealed, and capacity-divided to obtain the lithium-ion battery used in Example 1. The electrochemical performance of this lithium-ion battery is tested, and the results are shown in Table 2.

[0060]

Examples 2 to 12

[0061] The non-aqueous electrolyte was prepared and the lithium-ion battery was fabricated according to the method steps of Example 1, except that the combination and dosage of additives in the non-aqueous electrolyte were different, as specifically shown in Table 1.

[0062] The fabricated lithium-ion battery was subjected to electrochemical performance testing, and the results are shown in Table 2.

[0063]

Comparative Example 1

[0064] (1) Preparation of non-aqueous electrolyte

[0065] In a glove box filled with nitrogen or argon with the water and oxygen content both ≤ 0.1 ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were mixed well in a volume ratio of 1:1:1. Lithium hexafluorophosphate was added to the prepared non-aqueous solvent and fully mixed and dissolved to form a 1 mol / L lithium hexafluorophosphate solution.

[0066] Based on the total mass of the electrolyte being 100%, 2% (by mass) of fluoroethylene carbonate (FEC), 1% of lithium difluorophosphate (LiPO2F2) and 1% of 1,3-propanesultone (PS) were added to the lithium hexafluorophosphate solution, and fully dissolved and mixed to obtain the non-aqueous electrolyte.

[0067] (2) Fabrication of lithium-ion battery

[0068] Preparation of positive electrode sheet:

[0069] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) were added and dispersed in N-methyl-2-pyrrolidone (NMP) in a mass ratio of 96:2:2, and fully mixed and homogenized to obtain a positive electrode paste; the positive electrode paste was coated on a double-sided carbon-coated aluminum foil, and after drying, rolling and cutting, a positive electrode sheet was obtained.

[0070] Preparation of negative electrode sheet:

[0071] The negative electrode active material artificial graphite, conductive carbon black Super-P, binder sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) were added and dispersed in deionized water in a mass ratio of 96:1.5:1.5:1, and fully mixed and homogenized to obtain a negative electrode paste. The negative electrode paste was coated on both sides of a copper foil, and after drying, rolling and cutting, a negative electrode sheet was obtained.

[0072] Dry cell assembly:

[0073] Stack the positive electrode plate, polypropylene porous separator, and negative electrode plate to prepare an electrode assembly. Use an ultrasonic spot welder to weld aluminum tabs and nickel tabs on the positive and negative electrodes respectively. Then, place the electrode assembly in an aluminum foil bag and dry it thoroughly under vacuum at 85°C to obtain a dry lithium-ion battery cell.

[0074] In a glove box filled with nitrogen or argon with the water and oxygen content both ≤ 0.1 ppm, inject the prepared non-aqueous electrolyte into the above-assembled dry battery cell. After the injection is completed, seal it, let it stand, form, age, seal it again, and perform grading to obtain the lithium-ion battery used in Comparative Example 1. Conduct electrochemical performance tests on this lithium-ion battery, and the results are shown in Table 2.

[0075]

Comparative Examples 2 - 4

[0076] Refer to the method steps of Comparative Example 1 for the preparation of the non-aqueous electrolyte and the production of the lithium-ion battery, with the only difference being the combination and dosage of the additives in the non-aqueous electrolyte, as specifically shown in Table 1.

[0077] Conduct electrochemical performance tests on the fabricated lithium-ion battery, and the results are shown in Table 2.

[0078] Table 1 Composition and Dosage of the Non-aqueous Electrolyte in Examples 1 - 12 and Comparative Examples 1 - 4

[0079]

[0080] The performance detection method of the lithium-ion battery involved in this application is as follows:

[0081] (1) Low-temperature discharge test

[0082] At room temperature (25°C), charge the above-graded lithium-ion battery at a constant current of 0.5C and a constant voltage of 4.5V until the cut-off current is 0.05C, and then discharge it at a constant current of 0.5C until 3V, and record the room-temperature discharge capacity. Then, charge the battery at a constant current of 0.5C and a constant voltage of 4.5V until the cut-off current is 0.05C to fully charge it. Place the fully charged battery in a low-temperature chamber at -20°C and keep it at a constant temperature for 10h. After the constant temperature, discharge the battery at a constant current of 0.5C to 3V in an environment of -20°C, and record the low-temperature discharge capacity.

[0083] Discharge capacity retention rate at -20°C = Discharge capacity at -20°C / Room-temperature discharge capacity × 100%

[0084] (2) High-temperature and high-voltage cycle test

[0085] At high temperature (45°C), charge the above-graded lithium-ion battery at a constant current of 1C until 4.5V, and then discharge it at a constant current of 1C until 3V. Perform 500 charge-discharge cycles, and calculate the discharge capacity retention rate after the 500th cycle:

[0086] Discharge capacity retention rate (%) = Discharge capacity at the 500th cycle / Discharge capacity at the first cycle × 100%

[0087] Table 2 Test results of the performance of lithium-ion batteries in Examples 1 - 12 and Comparative Examples 1 - 4

[0088]

[0089]

[0090] It can be seen from the performance data in the above table that in Comparative Examples 1 - 3, a series of other additives were added to the electrolyte. Compared with Comparative Example 4 without additives, the low-temperature discharge performance and high-temperature cycle performance of the battery have been greatly improved, indicating that adding a variety of functional additives is one of the most effective and convenient ways to improve the electrochemical performance of lithium-ion batteries.

[0091] In the batteries of Examples 1 - 12, a phosphine-based polycyclic ester compound was further added to the electrolyte. Compared with Comparative Examples 1 - 3 without the phosphine-based polycyclic ester compound, the low-temperature discharge performance and high-temperature cycle performance of the battery were further improved. This is because the phosphine-based polycyclic ester can simultaneously form thin and dense CEI and SEI films at the positive and negative electrode interfaces of the battery, which can better inhibit the decomposition of the electrolyte and the dissolution of transition metals, avoiding the deposition of electrolyte decomposition products and transition metals on the electrode surface, resulting in an increase in internal resistance, thereby improving the cycle performance of the battery. Moreover, a large amount of inorganic components in the generated CEI and SEI films can reduce the internal resistance and promote the migration of lithium ions, thus improving the low-temperature performance of the battery.

[0092] Therefore, using the non-aqueous electrolyte and lithium-ion battery containing the phosphine-based polycyclic ester compound provided by the present invention can effectively improve the high-temperature and high-pressure cycle performance and low-temperature discharge performance of lithium-ion batteries, and has good technical effects.

Claims

1. A non-aqueous electrolyte containing a phosphono polycyclic ester compound, characterized in that, The phosphono polycyclic ester compound described has the structure shown in general formula (I), wherein A1, A2, and A3 are independently selected from one of the elements C or S; a, b, and c are independently selected from 1 or 2; n and m are independently selected from 0 or 1.

2. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 1, characterized in that, The phosphino polycyclic ester compound is selected from at least one of the following structural formulas:

3. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 1, characterized in that, The dosage of the phosphino polycyclic ester compound is 0.1 to 5% of the total mass of the non-aqueous electrolyte.

4. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 1, wherein The non-aqueous electrolyte further contains a lithium salt electrolyte, a non-aqueous organic solvent, and other additives. The dosage of the other additives is 0.5 to 5% of the total mass of the non-aqueous electrolyte.

5. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 4, wherein The non-aqueous organic solvent is selected from at least one of carbonate solvents or carboxylate solvents; the other additives are selected from at least one of unsaturated carbonates, halogenated carbonates, sulfates, sulfites, sulfonates, phosphates, phosphites, borates, acid anhydrides, polynitriles, phosphazenes, silanes, or lithium salt additives.

6. The non-aqueous electrolyte containing a phosphono polycyclic ester compound as described in claim 5, characterized in that, The other additives are selected from at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (DTD), bis(ethylene sulfate) (BESA), ethylene sulfite (ES), methylene methanedisulfonate (MMDS), 1,3-propane sultone (PS), 1,3-propene sultone (PST), tris(trimethylsilyl) phosphate (TMSP), tris(trimethylsilyl) phosphite (TMSPi), tris(trimethylsilyl) borate (TMSB), succinic anhydride (SA), succinonitrile (SN), adiponitrile (ADN), ethoxypentafluorocyclotriphosphazene (PFPN), tetravinylsilane (TVSi), dimethyldivinylsilane (DMDV), lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), lithium bis(oxalato)difluorophosphate (LiDFBP), lithium tetrafluoro(oxalato)phosphate (LiOTFP), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), or lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI).

7. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 4, characterized in that, The non-aqueous organic solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, 2,2,2-trifluoroethyl methyl carbonate, bis(trifluoroethyl) carbonate, 2,2,2-trifluoroethyl acetate, or 2,2-difluoroethyl acetate.

8. The non-aqueous electrolyte containing a phosphono polycyclic ester compound according to claim 4, characterized in that, The lithium salt electrolyte is lithium hexafluorophosphate, and the concentration of the lithium salt electrolyte in the non-aqueous electrolyte is 0.8 to 1.5 mol / L.

9. A lithium-ion battery, comprising a positive electrode material, a separator, and a negative electrode material, characterized in that, It further includes the non-aqueous electrolyte containing the phosphino polycyclic ester compound according to any one of claims 1 to 8.

10. The lithium-ion battery according to claim 9, characterized in that, The positive electrode material includes, but is not limited to, at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium nickel manganate, lithium cobaltate, lithium nickel cobalt manganate, and lithium nickel cobalt aluminate materials; the negative electrode material includes, but is not limited to, at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon-based materials, and lithium metal materials.

Images