Low-internal-resistance electrolyte and lithium ion battery

Abstract

The invention relates to the technical field of batteries, in particular to a low-internal-resistance electrolyte and a lithium ion battery, and the electrolyte comprises the following components: a solvent system, which is composed of fluorocarboxylate and asymmetric cyclic carbonate, the asymmetric cyclic carbonate is prepared by mixing fluoroethylene carbonate and vinylene carbonate according to a mass ratio of 3: 1; the lithium salt combination comprises lithium bis (fluorosulfonyl) imide and lithium difluoro (oxalato) borate, the concentration of the lithium bis (fluorosulfonyl) imide is 1.2-1.8 mol / L, and the concentration of the lithium difluoro (oxalato) borate is 0.3-0.7 mol / L; the multifunctional additive is prepared from ethylene trithiocarbonate, tetrabutyl ammonium hexafluorophosphate and 2, 6-butylated hydroxytoluene; the nano dispersed phase is a boron nitride nanosheet subjected to surface hydroxylation treatment, and the-OH coverage rate of the boron nitride nanosheet is greater than or equal to 15%. The lithium ion battery comprises a frame structure, a battery monomer and a protective seat, and the battery monomers adopt a lifting type mounting structure. And the purposes of reducing the internal resistance of the electrolyte and reducing the harm caused by electrolyte leakage are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a low internal resistance electrolyte and a lithium ion battery. BACKGROUND

[0002] Lithium ion batteries are widely used in electric vehicles, energy storage systems, consumer electronics and aerospace due to their high energy density, long cycle life and lightweight advantages. As the medium for ion transmission in lithium ion batteries, the conductivity of electrolyte directly affects the power output, rate performance and low temperature characteristics of the battery. Traditional electrolyte usually uses a combination of carbonate solvents and LiPF6 lithium salt, but in high-rate charging or low-temperature environments, the ionic conductivity of the electrolyte decreases significantly, resulting in a sharp increase in battery internal resistance. The increase in internal resistance not only reduces energy efficiency, but also causes local overheating, accelerates battery aging, and even triggers thermal runaway.

[0003] At the same time, in the battery pack, due to the influence of packaging process or battery use environment, there is a problem of electrolyte leakage in the battery monomer, and the electrolyte leakage of a single battery monomer may trigger a chain reaction, seriously affecting the safety and reliability of the entire system. The main reasons for electrolyte leakage at present include mechanical abuse, thermal runaway, long-term aging, etc. Once the electrolyte leaks, it may cause a short circuit risk, and the electrolyte is corrosive, the organic solvent and lithium salt in the electrolyte may corrode metal parts, circuit boards or heat dissipation structures, and cause thermal runaway to spread. At present, the industry mainly alleviates the risk of electrolyte leakage by optimizing the battery packaging process, but it cannot effectively and actively reduce the harm caused by electrolyte leakage. SUMMARY

[0004] The purpose of the present application is to provide a low internal resistance electrolyte and a lithium ion battery to reduce the internal resistance of the electrolyte and reduce the harm caused by electrolyte leakage, to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a low internal resistance electrolyte, comprising the following components: Solvent system: composed of fluoro carboxylic acid ester and asymmetric cyclic carbonate, wherein the fluoro carboxylic acid ester is 2,2-difluoroethyl acetate, and the asymmetric cyclic carbonate is a mixture of fluoroethylene carbonate and vinylene carbonate in a mass ratio of 3:1; Lithium salt combination: containing lithium bisfluorosulfonylimide and lithium difluoro(oxalato)borate, wherein the concentration of lithium bisfluorosulfonylimide is 1.2-1.8 mol / L, and the concentration of lithium difluoro(oxalato)borate is 0.3-0.7 mol / L; Multifunctional additive: containing trithioethylene carbonate, tetrabutylammonium hexafluorophosphate and 2,6-di-tert-butyl-p-cresol; Nanodispersed phase: surface hydroxylated boron nitride nanoplatelets with -OH coverage of > 15%.

[0006] Preferably, the ethyl 2,2-difluoroacetate accounts for 30-40% of the total mass of the electrolyte, and the total amount of fluoroethylene carbonate and vinylene carbonate accounts for 20-30% in the solvent system. In the multifunctional additive, ethylene thiocarbamate accounts for 2-4% of the total mass of the electrolyte, tetrabutylammonium hexafluorophosphate accounts for 1-3%, and 2,6-di-tert-butyl-p-cresol accounts for 0.5-1%. The particle size of the boron nitride nanoplatelets is 50-200 nm, the thickness is ≤5 nm, and the dispersion concentration in the electrolyte is 0.3-0.6 wt%.

[0007] A lithium ion battery using the above low-resistance electrolyte, the battery pack comprises: The frame structure is composed of a battery bottom plate, a base, a side frame and a top seat, and the base is a frame structure and is arranged and installed on the battery bottom plate; The battery monomer is arranged and installed between the base and the top seat; The protection seat is fixed below the battery bottom plate, and the protection seat is provided with a storage tank for collecting leaked electrolyte and providing a sinking space for the battery monomer; The battery monomer adopts a lifting type installation structure, and the bottom of the battery monomer is provided with a lifting seat with a bottom block, and a support seat is installed in the storage tank through a spring guide rod, and the battery monomer is supported through the contact between the support seat and the bottom block, and the support seat is kept in the supporting state through a floating type latch, and the buoyancy generated when the electrolyte leaks can unlock the latch; The storage tank is provided with a sleeve with a movable sealing ring, and the top seat is provided with a pop-up type glue box with a sealing plate, and the sleeve and the glue box can be used to close the bottom and top of the battery monomer after sinking, and after the glue box is closed on the top of the battery monomer, the glue can be cured to close the side wall of the battery monomer.

[0008] Preferably, the bottom block adopts a conical structure, and the protection seat is provided with a storage tank for each battery monomer, and the two sides of the storage tank are provided with horizontal spring guide rods, and a sliding seat is slidingly installed on the spring guide rod, and the support seat is installed through the sliding seat, and the support seat adopts an inclined block type structure, and the bottom block is supported by two support seats.

[0009] Preferably, the spring force of the spring guide rod can move the sliding seat and the support seat to both sides, and a vertical latch is movably installed on the sliding seat, and a limiting seat is arranged at the bottom of the storage tank, and the latch can be connected with the limiting seat to keep the sliding seat in the extended state, and a floating plate is arranged at the bottom of the latch.

[0010] Preferably, the side wall of the storage tank is provided with a liquid storage bag, which is filled with diluent or neutralizer, and the liquid storage bag can be broken when the support seat moves to the two sides.

[0011] Preferably, the base is a frame structure, and the battery base plate is provided with a guide groove at the position of each base, and the lifting seat is located in the guide groove, and the side of the guide groove is provided with a leakage hole.

[0012] Preferably, the sleeve is below the battery monomer, and the inner wall of the sleeve is provided with a slope, and the sealing ring is connected with a bottom support, and when the bottom block falls on the bottom support, the sealing ring can be pulled down, so that the sealing ring is in close contact with the outer wall of the battery monomer.

[0013] Preferably, the top seat is fixedly installed with a guide seat on the two sides below, the glue box is movably installed through the guide seat, and the glue box is fixedly connected with an elastic piece, the elastic piece can make the glue box pop up on the guide seat, and the bottom of the glue box is installed with a sealing plate.

[0014] Preferably, the glue box is provided with two, which are respectively filled with A glue and B glue, and the two kinds of glue can be cured after mixing, and the side wall of the battery monomer is closed.

[0015] Preferably, the glue box is provided with two, which are respectively filled with A glue and B glue, and the two kinds of glue can be cured after mixing, and the side wall of the battery monomer is closed.

[0016] Preferably, the glue head is installed with an inclined groove, and the bottom of the guide seat is provided with a mixing ring, the mixing ring is sleeved on the battery monomer, and the mixing ring is provided with an upward inlet pipe and a downward glue outlet hole.

[0017] Preferably, the two ends of the battery monomer are respectively provided with upper and lower terminals, and the contact type power connection mode is adopted, the top seat is provided with an upper power connector, and the bottom seat is provided with a lower power connector.

[0018] Compared with the prior art, the beneficial effects of the present application are: 1. The lithium ion battery of the present application has an active leakage protection mechanism, through the lifting type installation structure and the buoyancy trigger device, the electrical connection of the battery monomer is automatically disconnected when the electrolyte leaks, effectively preventing the short circuit and heat runaway diffusion caused by leakage, improving the overall safety of the battery pack, and the battery monomer after sinking realizes the bottom closure through the sleeve sealing ring, and the top glue box is closed to form a sealing layer, and the A / B glue curing technology is combined to actively block the side wall leakage point, realizing all-round leakage isolation.

[0019] 2. By placing neutralizer or diluent in the liquid storage bag, the corrosiveness of the leaked electrolyte is automatically released when the support seat moves, reducing the harm to metal parts and the environment.

[0020] 3. The frame structure of the present application adopts a detachable base and top seat layout, facilitating the maintenance or replacement of individual battery monomers, avoiding overall scrapping due to local failure, and reducing the harm caused by battery monomer electrolyte leakage.

[0021] 4. The low internal resistance electrolyte provided by the present application significantly improves ion conductivity and Li⁺ transference number by adopting a fluorinated carboxylic acid ester and an asymmetric cyclic carbonate composite solvent system, in combination with a double lithium salt and a functional additive; the electrolyte can reduce interface impedance and has flame retardant properties. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the overall structure of the battery pack of the present application.

[0023] Figure 2 is a schematic diagram of the arrangement structure of the battery pack of the present application.

[0024] Figure 3 is a schematic diagram of the installation of the battery monomer structure of the present application.

[0025] Figure 4 is a schematic diagram of the battery monomer structure of the present application.

[0026] Figure 5 is a first schematic diagram of the top seat structure of the present application.

[0027] Figure 6 is a second schematic diagram of the top seat structure of the present application.

[0028] Figure 7 is a schematic diagram of the adhesive box structure of the present application.

[0029] Figure 8 is a schematic diagram of the protective seat structure of the present application.

[0030] Figure 9 is a schematic diagram of the storage tank structure of the present application.

[0031] Figure 10 is a schematic diagram of the support seat structure of the present application.

[0032] Figure 11 is a schematic diagram of the sleeve structure of the present application.

[0033] In the figure: 1, battery bottom plate; 2, base; 3, side frame; 4, top seat; 5, battery monomer; 6, upper terminal; 7, lower terminal; 8, upper electrical connector; 9, lower electrical connector; 10, lifting seat; 11, bottom block; 12, protection seat; 13, storage groove; 14, spring guide rod; 15, sliding seat; 16, support seat; 17, bolt; 18, limit seat; 19, floating plate; 20, liquid storage bag; 21, guide groove; 22, leakage hole; 23, sleeve; 24, slope; 25, sealing ring; 26, bottom support; 27, guide seat; 28, glue box; 29, elastic member; 30, sealing plate; 31, glue outlet head; 32, opening assembly; 33, inclined groove; 34, mixing ring; 35, inlet pipe; 36, glue outlet hole. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with the drawings and specific embodiments. It should be noted that the embodiments described below or the technical features thereof can be combined with each other to form new embodiments without conflict. It should be understood that the described embodiments are only part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0035] Please refer to Figures 1 to 11 The application provides a technical solution: a low internal resistance electrolyte, which belongs to a lithium ion battery electrolyte, and comprises the following components: A solvent system composed of fluoro carboxylic acid ester and asymmetric cyclic carbonate, wherein the fluoro carboxylic acid ester is 2,2-difluoroethyl acetate (EDFA), and the asymmetric cyclic carbonate is a mixture of fluoroethylene carbonate (FEC) and vinylene carbonate (VEC) in a mass ratio of 3:1; A lithium salt combination containing lithium bisfluorosulfonylimide (LiFSI) and lithium difluoro(oxalato)borate (LiDFOB), wherein the concentration of LiFSI is 1.2-1.8 mol / L, and the concentration of LiDFOB is 0.3-0.7 mol / L; A multifunctional additive containing trithioethylene carbonate (TTS), tetrabutylammonium hexafluorophosphate (TBAPF6) and 2,6-di-tert-butyl-p-cresol (BHT); A nanodispersed phase of surface hydroxylated boron nitride nanosheet (BNNS) with an -OH coverage of ≥15%.

[0036] EDFA accounts for 30-40% of the total mass of the electrolyte in the solvent system, and FEC and VEC together account for 20-30%.

[0037] TTS accounts for 2-4% of the total mass of the electrolyte in the multifunctional additive, TBAPF6 accounts for 1-3%, and BHT accounts for 0.5-1%.

[0038] The particle size of the BNNS is 50-200 nm, the thickness is ≤5 nm, and the dispersion concentration in the electrolyte is 0.3-0.6 wt%.

[0039] Preparation method of hydroxylated BNNS: The BN nanosheet (Aldrin reagent, purity > 99%) is mixed with 30% hydrogen peroxide at a mass ratio of 1:10, refluxed at 80°C for 6 hours, centrifuged and washed to neutral, and then vacuum dried to obtain BNNS with an -OH coverage of ≥15% (determined by XPS).

[0040] The preparation method of the above electrolyte comprises the following steps: S1. Mix EDFA, FEC and VEC under an argon atmosphere, and stir for 30-60 min; S2. Add LiFSI and LiDFOB in sequence, and heat to dissolve at 40°C; S3. Add TTS, TBAPF6 and BHT, and ultrasonically treat for 20 min; S4. Add BNNS and ultrasonically disperse for 30 min at a power of 300 W.

[0041] Example 1: Preparation of low-resistance electrolyte Formulation composition: Solvent system (75 wt%): Ethyl 2,2-difluoroacetate (EDFA): 35% Fluoroethylene carbonate (FEC): 24% Vinylene carbonate (VEC): 8% Lithium salt (20 wt%): LiFSI: 1.5 mol / L (corresponding to 18% of the total mass of the electrolyte) LiDFOB: 0.5 mol / L (corresponding to 2%) Additives (4.5 wt%): Thiolyte (TTS): 3% Tetrabutylammonium hexafluorophosphate (TBAPF6): 1.2% BHT: 0.3% Nanodispersed phase (0.5 wt%): Hydroxylated boron nitride nanosheet (BNNS, -OH coverage 18%, particle size ~100 nm) Preparation steps: In an argon glove box (H2O <1 ppm, O2 <1 ppm), mix EDFA, FEC and VEC, and magnetically stir for 40 min; LiFSI and LiDFOB were added in three times, and heated to complete dissolution in 40℃ water bath; TTS, TBAPF6 and BHT were added in turn, and ultrasonic treatment (40 kHz, 20 min) was performed; BNNS was added, and dispersed for 30 min under 300 W probe ultrasonic treatment. After standing for 12 h, filtration was performed (0.22 μm PTFE membrane).

[0042]

[0043] Table 1 The above table is the performance test results of the electrolyte prepared in Example 1 and the control example, wherein the control example is a conventional electrolyte commonly used in a lithium ion battery randomly selected from the market.

[0044] Example 2: Matching battery assembly Electrode and battery configuration: Positive electrode: Active material: single crystal LiNi0.8Mn0.1Co0.1O2 (coated with 5 nm Li2ZrO3) Coating parameters: surface load 18 mg / cm2, compaction density 3.4 g / cm3 Negative electrode: Active material: pre-lithiated 12% SiOx@C (x = 1.0) Coating parameters: surface load 8 mg / cm2, compaction density 1.6 g / cm3 Separator: PE-based ceramic composite separator (pore size 0.1 μm, porosity 45%) Electrolyte: electrolyte prepared in Example 1, injection amount 0.3 g / Ah Battery assembly: The positive and negative electrode sheets were dried at 120℃ for 12 h under vacuum; The lamination was completed in a drying room (dew point <-40℃); After injecting the electrolyte, aging was performed for 48 h (25℃); Formation system: 0.1C constant current charging to 4.2V, and then constant voltage to current ≤0.05C.

[0045] The electrolyte realizes the balance of low internal resistance, wide temperature range, long service life and high safety through four-dimensional optimization of solvent-lithium salt-additive-nanophase, and is especially suitable for power batteries, fast charging equipment and extreme environment applications.

[0046] A lithium ion battery using the above low internal resistance electrolyte, the battery pack includes a frame structure for battery monomer 5 installation, the frame structure includes a battery bottom plate 1, the battery bottom plate 1 is arranged and installed on the base 2, and the battery bottom plate 1 is installed on the top seat 4 through the side frame 3, wherein the battery bottom plate 1 is a flat plate type structure, the base 2 is a frame type structure, the side frame 3 is a support structure of the top seat 4, and the top seat 4 is composed of a plurality of arranged connecting frames, the base 2 and the connecting frame one-to-one, the battery monomer 5 is installed between the base 2 and the connecting frame, the two ends of the battery monomer 5 are respectively provided with an upper terminal 6 and a lower terminal 7, a contact type power connection mode is adopted, the line connection is avoided, at the same time, the top seat 4 is provided with an upper power connector 8, and the base 2 is provided with a lower power connector 9, which are respectively used for connecting the upper terminal 6 and the lower terminal 7 of the two battery monomers 5, and the electrical connection of all battery monomers 5 is completed.

[0047] In the lithium ion battery of the application, the battery monomer 5 adopts a lifting type installation structure, which can automatically sink to complete the disconnection in the case of electrolyte leakage, the bottom of the battery monomer 5 is provided with a lifting seat 10, the bottom surface of the lifting seat 10 is provided with a bottom block 11, the bottom block 11 adopts a conical structure, the battery bottom plate 1 is fixedly installed on a protection seat 12, the protection seat 12 can be used as a support structure, a storage groove 13 is arranged for each battery monomer 5, which is used as an absorption structure for the leaked electrolyte, and can also be used as a sinking space for the battery monomer 5, horizontal spring guide rods 14 are arranged on both sides of the storage groove 13, sliding seats 15 are slidably installed on the spring guide rods 14, the sliding seats 15 are used for installing support seats 16, the support seats 16 adopt inclined block type structures, two support seats 16 can support the bottom block 11, lift the battery monomer 5, and make the upper terminal 6 and the lower terminal 7 of the battery monomer 5 connected with the upper power connector 8 and the lower power connector 9 respectively, when the electrolyte leaks, the support seats 16 can be withdrawn to both sides, the support effect of the bottom block 11 disappears, the battery monomer 5 can fall, the electrical connection is released, and the safety of the battery pack as a whole is avoided.

[0048] The spring of the spring guide rod 14 can act on the sliding seat 15, so that the sliding seat 15 has a tendency to move the supporting seat 16 to both sides, meanwhile, the vertical pin 17 is movably arranged on the sliding seat 15, the bottom of the storage groove 13 is correspondingly provided with the limiting seat 18, the pin 17 can be connected with the limiting seat 18, so that the sliding seat 15 is kept in the extended state, the spring of the spring guide rod 14 is stretched, the supporting seat 16 can support the bottom block 11, the bottom of the pin 17 is provided with the floating plate 19, when the electrolyte of a certain battery monomer 5 leaks into the storage groove 13, the generated buoyancy can make the floating plate 19 rise, so that the pin 17 is disconnected with the limiting seat 18, the sliding seat 15 drives the supporting seat 16 to move at this time, so that the battery monomer 5 falls, further, the sidewall of the storage groove 13 is provided with the liquid storage bag 20, which is loaded with diluent or neutralizing agent, when the supporting seat 16 moves to both sides, the liquid storage bag 20 can be pressed to break, so that the medicine in it flows out, neutralizes or dilutes the electrolyte in the storage groove 13, reduces the harm of the electrolyte leakage to the environment.

[0049] The floating plate 19 is made of polypropylene foam plate with a density lower than that of the electrolyte, the density is 0.2 g / cm3, the bottom of the storage groove is provided with an inclined flow guide groove, the leaked electrolyte can be concentrated below the floating plate 19, and the pin 17 is also made of common lightweight material, so that the floating plate 19 can drive the pin 17 to rise under the action of the buoyancy of the electrolyte.

[0050] The base 2 of the application is a frame structure, which can prevent the leaked electrolyte of the battery monomer 5 from flowing to other positions, meanwhile, the battery bottom plate 1 is provided with the guide groove 21 at the position of each base 2, which is used for the passing of the battery monomer 5, and the side of the guide groove 21 is provided with the leakage hole 22, which can make the electrolyte enter the storage groove 13.

[0051] The sleeve 23 for temporarily closing the bottom of the battery monomer 5 is arranged in the storage groove 13, the sleeve 23 is below the battery monomer 5, after the supporting seat 16 moves to both sides, the bottom of the battery monomer 5 and the lifting seat 10 can fall into the sleeve 23, the inner wall of the sleeve 23 is provided with the slope 24, and the sleeve 23 is provided with the sealing ring 25, the sealing ring 25 is connected with the bottom support 26, under normal circumstances, the sealing ring 25 falls on the upper part of the slope 24, in a relaxed state, so as not to affect the entry of the battery monomer 5, when the bottom block 11 falls on the bottom support 26, the sealing ring 25 can be pulled down, so that the sealing ring 25 moves below the slope 24, and tightly contacts with the outer wall of the battery monomer 5, in the case that the bottom of the battery monomer 5 leaks, the electrolyte can be further prevented from flowing out, and is limited in the sleeve 23.

[0052] Meanwhile, the top base 4 is further provided with a sealing structure for temporarily sealing the top and side wall of the battery monomer 5, which includes guide seats 27 installed on both sides below the top base 4, glue boxes 28 movably installed through the guide seats 27, elastic members 29 fixedly connected to the glue boxes 28, which can make the glue boxes 28 pop up on the guide seats 27, and sealing plates 30 provided at the bottom of the glue boxes 28. When the battery monomer 5 is used, the glue boxes 28 are clamped on both sides of the battery monomer 5 and cannot be closed, while when the battery monomer 5 sinks due to electrolyte leakage, the two glue boxes 28 can be closed on the top surface of the battery monomer 5 to achieve a sealing effect through the sealing plates 30, so as to avoid further electrolyte leakage. Further, the glue boxes 28 are provided with two glue boxes, which are respectively filled with A glue and B glue. The two kinds of glue can be cured within a certain time after mixing, so as to seal the side wall of the battery monomer 5. Usually, the curing time is controlled to be about one minute.

[0053] The side surface of each glue box 28 is provided with a glue outlet head 31 as a glue leakage point. The glue outlet head 31 is provided with an opening assembly 32, which includes a weak point and a needle provided on the glue outlet head 31. When the two glue boxes 28 are close to each other, the opening assemblies 32 on the two glue boxes 28 contact each other, the needle pierces the weak point, and the glue outlet head 31 is further provided with an inclined groove 33, through which the glue can flow down. Meanwhile, the bottom of the guide seat 27 is provided with a mixing ring 34, which is sleeved on the battery monomer 5 and is provided with an upward inlet pipe 35 and a downward glue outlet hole 36. After the two glue boxes 28 are close to each other, the glue in the two glue boxes 28 flows into the inlet pipe 35 from the inclined groove 33, so as to enter the mixing ring 34, gather in the mixing ring 34, and then flow out of the glue outlet hole 36, so as to cover the surface of the battery monomer 5 and seal the damaged point of the side wall of the battery monomer 5, thereby preventing further electrolyte leakage.

[0054] In order to ensure the sealing effect of the glue, the A glue is epoxy resin with a viscosity of 200 cP and contains a delayed curing agent, and the B glue is an amine curing agent with a viscosity of 150 cP. The inclined groove 33 has a width of 2 mm and an inclination angle of 30°, and the mixing ring 34 has a volume of 0.5 mL, so as to ensure that the glue completes the flow and curing within 60±5 seconds.

[0055] Although the embodiments of the present application have been shown and described, it should be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A low internal resistance electrolyte, characterized in that: Includes the following components: Solvent system: composed of fluorocarboxylate and asymmetric cyclic carbonate, wherein the fluorocarboxylate is ethyl 2,2-difluoroacetate, and the asymmetric cyclic carbonate is a mixture of fluoroethylene carbonate and vinylene carbonate in a mass ratio of 3:1; Lithium salt combination: comprising lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate, wherein the concentration of lithium bis(fluorosulfonyl)imide is 1.2-1.8 mol / L and the concentration of lithium difluorooxalatoborate is 0.3-0.7 mol / L; Multifunctional additive: contains ethylene trithiocarbonate, tetrabutylammonium hexafluorophosphate and 2,6-di-tert-butyl-p-cresol; Nano-dispersed phase: Boron nitride nanosheets with surface hydroxylation treatment, whose -OH coverage is ≥15%.

2. The low internal resistance electrolyte according to claim 1, characterized in that: In the solvent system, ethyl 2,2-difluoroacetate accounts for 30-40% of the total mass of the electrolyte, and fluoroethylene carbonate and vinylene carbonate account for 20-30% in total; In the multifunctional additive, ethylene trithiocarbonate accounts for 2-4% of the total mass of the electrolyte, tetrabutylammonium hexafluorophosphate accounts for 1-3%, and 2,6-di-tert-butyl-p-cresol accounts for 0.5-1%; The boron nitride nanosheets have a particle size of 50-200 nm, a thickness of ≤5 nm, and a dispersion concentration of 0.3-0.6 wt % in the electrolyte.

3. A lithium-ion battery using the low internal resistance electrolyte according to claim 2, characterized in that: The battery pack includes: The frame structure is composed of a battery bottom plate, a base, a side frame and a top seat. The base is a frame structure and is arranged and installed on the battery bottom plate; Battery cells, the battery cells are arranged and installed between the base and the top seat; The protective seat is fixed under the battery bottom plate. The protective seat is provided with a storage tank for collecting leaked electrolyte and providing a sinking space for the battery cells; The battery cell adopts a lifting installation structure, and a lifting seat with a bottom block is provided at the bottom of the battery cell. A support seat is installed in the storage tank via a spring guide rod, and the battery cell is supported by the support seat and the bottom block. The support seat is maintained in a supporting state by a floating latch. When the electrolyte leaks, the buoyancy generated can unlock the latch. A sleeve with a movable sealing ring is provided in the storage tank, and a pop-up glue box with a sealing plate is provided on the top seat. The sleeve and the glue box can be used to seal the bottom and top of the battery cell after sinking, respectively. After the glue box is sealed on the top of the battery cell, the glue can be cured to seal the side wall of the battery cell.

4. A lithium-ion battery according to claim 3, characterized in that: The bottom block adopts a conical structure, and a storage slot is provided in the protective seat for each battery cell. Horizontal spring guide rods are provided on both sides of the storage slot, and a slide is slidably installed on the spring guide rod. The support seat is installed through the slide. The support seat adopts an inclined block structure, and the bottom block is supported by two support seats.

5. A lithium-ion battery according to claim 4, characterized in that: The elastic force of the spring guide rod can make the slide and the support seat move to both sides, and a vertical pin is movably installed on the slide. A limit seat is provided at the bottom of the storage tank. The pin can be connected to the limit seat to keep the slide in an extended state, and a floating plate is provided at the bottom of the pin.

6. A lithium-ion battery according to claim 5, characterized in that: A liquid storage capsule is provided on the side wall of the storage tank, in which a diluent or a neutralizer is loaded. When the support seat moves toward both sides, the liquid storage capsule can be crushed.

7. The lithium-ion battery according to claim 3, wherein: The base is a frame structure, and the battery bottom plate is provided with a guide groove at the position of each base, and the lifting seat is located in the guide groove, and the side of the guide groove is provided with a leakage hole.

8. The lithium-ion battery according to claim 3, wherein: The sleeve is located below the battery cell, and the inner wall of the sleeve is provided with a slope. The sealing ring is connected to the bottom bracket. When the bottom block falls on the bottom bracket, the sealing ring can be pulled down so that the sealing ring is in close contact with the outer wall of the battery cell.

9. The lithium-ion battery according to claim 3, wherein: Guide seats are fixedly installed on both sides below the top seat, and the plastic box is movably installed through the guide seats. An elastic member is fixedly connected to the plastic box, and the elastic member can make the plastic box pop out on the guide seat. A sealing plate is installed at the bottom of the plastic box.

10. The lithium-ion battery according to claim 3, characterized in that: There are two glue boxes, each containing glue A and glue B. The two glues can be solidified after mixing to seal the side walls of the battery cell.

11. A lithium-ion battery according to claim 10, characterized in that: A glue dispensing head is installed on the side of the glue box, and an opening component is provided on the glue dispensing head. The opening component includes a weak point and a needle provided on the glue dispensing head. When two glue boxes are close to each other, the opening components thereon contact each other, and the needle can puncture the weak point.

12. A lithium-ion battery according to claim 11, characterized in that: The glue discharge head is provided with an inclined groove, and the bottom of the guide seat is provided with a mixing ring, which is sleeved on the battery monomer and is provided with an upward inlet pipe and a downward glue discharge hole.

13. The lithium-ion battery according to claim 3, characterized in that: The two ends of the battery cell are respectively provided with an upper terminal and a lower terminal, and a contact-type power connection method is adopted. The top seat is provided with an upper electrical connection, and the base is provided with a lower electrical connection.

Images