CN109873205B - Electrolyte suitable for silicon-carbon cathode and lithium ion battery containing electrolyte - Google Patents
Electrolyte suitable for silicon-carbon cathode and lithium ion battery containing electrolyte Download PDFInfo
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- CN109873205B CN109873205B CN201910147708.2A CN201910147708A CN109873205B CN 109873205 B CN109873205 B CN 109873205B CN 201910147708 A CN201910147708 A CN 201910147708A CN 109873205 B CN109873205 B CN 109873205B
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Abstract
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte suitable for a silicon-carbon cathode and a lithium ion battery containing the electrolyte. The electrolyte comprises electrolyte lithium salt, a non-aqueous organic solvent and additives, wherein the additives comprise a negative electrode film-forming additive, a fluoro phenyl isocyanate compound additive with a structure shown in a formula I and a disilazane compound additive with a structure shown in a formula II. Compared with the prior art, the invention effectively improves the actual discharge capacity, the cycle stability and the high-temperature storage performance of the silicon-carbon cathode lithium ion battery and inhibits gas generation through the synergistic effect generated by the combined use of a plurality of additives, well solves the problems of volume expansion, pole piece pulverization and the like in the charging and discharging processes of the battery, and has better high and low temperature performance.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte suitable for a silicon-carbon cathode and a lithium ion battery containing the electrolyte.
Background
The lithium ion battery has the advantages of high specific energy, no memory effect, long cycle life and the like, and is widely applied to the fields of 3C digital, electric tools, aerospace, energy storage, power automobiles and the like, and the rapid development of electronic information technology and consumer products puts higher requirements on the energy density performance of the lithium ion battery. At present, a commercial lithium ion battery mainly uses graphite as a negative electrode material, but the maximum theoretical specific capacity of the graphite is only 372mAh/g, and the maximum theoretical specific capacity of the graphite is matched with ternary positive electrode materials such as lithium cobaltate, lithium manganate, lithium iron phosphate, nickel cobalt manganese and the like, so that the energy density of the battery is limited to be improved, and a positive and negative electrode material system with higher capacity is required for pursuing higher energy density. The theoretical gram capacity of a pure silicon-based negative electrode can reach 4200mAh/g, but the continuous shrinkage and expansion of the silicon negative electrode material in the lithium extraction process causes the breakage of particles, so that the capacity is continuously reduced in the circulation process, and the volume expansion effect of more than 300 percent is accompanied. Meanwhile, an unstable SEI film on the silicon negative electrode is gradually thickened in the circulation process, the polarization is increased, and large mechanical stress is caused, so that the electrode structure is further damaged.
In order to solve the problems, the silicon-carbon negative electrode material is formed by compounding silicon and carbon, so that the specific capacity of the material is improved, and the volume effect of the silicon-based negative electrode material can be reduced to a certain extent. Therefore, the development of electrolyte matching with the electrolyte is a necessary requirement for the industrial development. The development of the silicon-carbon cathode material electrolyte is mainly focused on solving the problems of volume expansion and cycling stability in the battery cycling process. The SEI film formed on the surface of the silicon-carbon negative electrode by the conventional electrolytic liquid system is unstable, and the SEI is easily damaged and falls off due to the volume effect problem in the charging and discharging processes, so that the capacity of the battery is quickly attenuated. In view of the above, there is a need to develop an electrolyte and an additive thereof suitable for a silicon-carbon negative electrode material, which can suppress the volume effect of silicon to a certain extent, ensure good cycle stability of a silicon-carbon negative electrode material lithium ion battery, and simultaneously give consideration to good high and low temperature performance.
Disclosure of Invention
The invention aims to provide an electrolyte suitable for a silicon-carbon negative electrode, aiming at the defects of the prior art, the electrolyte can effectively improve the actual discharge capacity, the cycle stability and the high-temperature storage performance of a silicon-carbon negative electrode lithium ion battery, inhibit gas generation, effectively solve the problems of volume expansion, pole piece pulverization and the like in the charging and discharging processes of the battery, and simultaneously has good high and low temperature performance.
In order to achieve the above object, the electrolyte solution for silicon-carbon negative electrodes according to the present invention comprises an electrolyte lithium salt, a non-aqueous organic solvent and additives, wherein the additives comprise a negative electrode film-forming additive, a fluoro phenyl isocyanate compound additive having a structure of formula i, and a disilazane compound additive having a structure of formula ii, wherein the fluoro phenyl isocyanate compound additive having a structure of formula i has a general formula as follows:
wherein R is1-R5Respectively selected from any one of hydrogen atom, fluorine atom, alkyl with carbon content more than or equal to 1, alkylene, alkoxy or aromatic group, and R1-R5At least one of which is substituted by a fluorine atom;
the general formula of the disilazane compound additive with the structure of the formula II is as follows:
wherein, X1-X6Each independently selected from alkyl with 1-5 carbon atoms or a substitute thereof, and M is any one of Li or H.
Preferably, the content of the fluoro phenyl isocyanate compound with the structure of formula I accounts for 0.5-5.0 wt% of the total mass of the electrolyte; the content of the disilazane based compound with the structure shown in the formula II accounts for 0.1-1.0 wt% of the total mass of the electrolyte.
Further preferably, the fluoro phenyl isocyanate compound with the structure of formula I is selected from A1-A5One or more of:
the disilazane compound with the structure of formula II is selected from B1-B5One or more of:
in the invention, the negative film forming additive is fluoroethylene carbonate (FEC) or/and sulfate/sulfite compounds; preferably, the content of the fluoroethylene carbonate (FEC) and the content of the sulfate/sulfite compounds respectively account for 2.0-15.0 wt% and 0.1-2.0 wt% of the total mass of the electrolyte.
Preferably, the sulfate/sulfite compound comprises one or more of ethylene sulfate, 1, 3-propylene glycol cyclic sulfate (PCS), vinyl sulfite, dimethyl sulfate, methyl ethyl sulfate, dipropyl sulfate and diisopropyl sulfate.
More preferably, the negative electrode film forming additive contains 4.0-6.0 wt% of fluoroethylene carbonate (FEC) based on the total mass of the electrolyte and 0.4-0.6 wt% of 1, 3-propylene glycol episulfide (PCS) based on the total mass of the electrolyte; for example, fluoroethylene carbonate (FEC) in an amount of 5.0 wt% based on the total mass of the electrolyte and 1, 3-propanediol episulfide (PCS) in an amount of 0.5 wt% based on the total mass of the electrolyte.
In the present invention, the electrolyte lithium salt is lithium hexafluorophosphate (LiPF)6) Lithium bis (oxalato) borate (LiBOB) and lithium tetrafluoroborate (LiBF)4) One or more of lithium difluoro oxalato borate (LiDFOB), lithium bis (fluorosulfonyl) imide (LiTFSI) and lithium bis (fluorosulfonyl) imide (LiFSI).
Preferably, the content of the boron-containing lithium salt compound in the electrolyte lithium salt accounts for 0.1-10 wt% of the total mass of the electrolyte, and lithium hexafluorophosphate (LiPF)6) The content of the electrolyte accounts for 12.5-15.0 wt% of the total mass of the electrolyte.
More preferably, the electrolyte lithium salt contains 11.5 to 13.5 wt% of lithium hexafluorophosphate (LiPF) based on the total mass of the electrolyte6) 0.4 to 0.6 wt% of lithium bis (oxalato) borate (LiBOB) based on the total mass of the electrolyte and 2.0 to 3.0 wt% of lithium difluoro (oxalato) borate (LiDFOB) based on the total mass of the electrolyte; for example, 12.5 wt% of lithium hexafluorophosphate (LiPF) based on the total mass of the electrolyte6) 0.5 wt% of lithium bis (oxalato) borate (LiBOB) based on the total mass of the electrolyte and 2.5 wt% of lithium difluoro (oxalato) borate (LiDFOB) based on the total mass of the electrolyte.
In the invention, the non-aqueous organic solvent is selected from carbonate or/and carboxylate compounds, preferably, the carbonate compound is selected from cyclic carbonate or/and chain carbonate; further preferably, the cyclic carbonate is at least one of Ethylene Carbonate (EC) and Propylene Carbonate (PC), and the chain carbonate is one or more selected from diethyl carbonate (DEC), ethyl methyl carbonate (DMC), dimethyl carbonate (EMC) and Methyl Propyl Carbonate (MPC).
Preferably, the content of the cyclic carbonate accounts for 25.0-45.0 wt% of the total mass of the electrolyte, and the content of the chain carbonate accounts for 40.0-70.0 wt% of the total mass of the electrolyte.
Preferably, the non-aqueous organic solvent is selected from the group consisting of ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, and more preferably, the mass ratio of the ethylene carbonate, diethyl carbonate and ethyl methyl carbonate is (1-3): (2-4): (2-4), for example, 2: 3: 3.
another object of the present invention is to provide a lithium ion battery comprising the electrolyte of the present invention, wherein the lithium ion battery comprises a cell formed by laminating or winding a positive plate, a separation film and a negative plate, and the electrolyte suitable for a silicon-carbon negative electrode of the present invention.
Preferably, the positive electrode active material of the positive electrode sheet is LiNi1-x-y-zCoxMnyAlzO2Wherein: x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, z is more than or equal to 0 and less than or equal to 0 and x + y + z is more than or equal to 1; the negative active material of the negative plate is nano silicon or SiOwA silicon-carbon composite material compounded with graphite, wherein: w is more than 1 and less than 2.
Compared with the prior art, the invention has the following remarkable advantages:
1. the fluoroethylene carbonate in the negative electrode film-forming additive can be preferentially reduced on the surface of a negative electrode and decomposed on the surface of a silicon-carbon negative electrode to form a stable and tough SEI film, so that the volume expansion of silicon in the repeated charge and discharge process of a battery is improved, the decomposition process of an electrolyte can be effectively prevented, and the reversible capacity performance, the cycle performance and the safety performance of the battery are improved; the sulfate or sulfite compounds in the negative film forming additive can reduce the irreversible capacity of the silicon-carbon negative battery and improve the discharge capacity of the battery, and the sulfate or sulfite compounds can also participate in the formation of an SEI film of the silicon-carbon negative electrode and inhibit the decomposition of fluoroethylene carbonate and the battery flatulence, so that the silicon-carbon negative lithium ion battery has good high and low temperature performance;
2. the fluoro phenyl isocyanate compound additive with the structure shown in the formula I can form a compact and stable SEI film on the surface of a silicon-carbon negative electrode in preference to a solvent, inhibit the reductive decomposition of an organic solvent and reduce the interface impedance of the SEI film; meanwhile, the compound contains F element, which is beneficial to improving the flash point of the electrolyte, and the flame retardant property of the F element is also beneficial to improving the safety performance of the high specific energy battery under heating and overcharging; in addition, isocyanate groups in the compound participate in and change the composition of an SEI film, homopolymerization reaction is carried out on the interface of a silicon-carbon negative electrode to form a passive film reaction layer, and the formed polymer can effectively inhibit volume expansion and internal resistance change of a silicon-carbon negative electrode lithium ion battery in the charge-discharge process, reduce the loss of active lithium and enable the battery to have good cycle performance and capacity recovery rate at high temperature;
3. the disilazane-based compound additive with the structure shown in the formula II can be used as an HF acid adsorbent to effectively reduce the HF acid content in the electrolyte, inhibit the corrosion of HF acid on silicon, improve the storage stability and the thermal stability of the lithium ion battery electrolyte, and improve the electrochemical performance and the cycling stability of the battery;
4. according to the invention, by using a novel conductive lithium salt lithium bis (oxalato) borate (LiBOB) or lithium difluoro (oxalato) borate (LiDFOB) with good film forming characteristics, the generation of water in the electrolyte can be effectively inhibited at high temperature, and the content of HF acid is reduced, so that the corrosion to silicon is reduced; meanwhile, LiBOB or LiDFOB has good film-forming performance, can form a stable SEI film with the silicon-carbon negative electrode, and inhibits the volume effect of the silicon-carbon negative electrode to a certain extent; adopts a plurality of novel film-forming lithium salts to be combined and used together with LiPF6Blend to make up LiPF6Compared with the single use of LiPF (lithium ion PF)6The storage and cycle performance, the rate capability and the safety performance of the battery at high temperature are improved;
5. the inventor finds that the common use of a plurality of additives of the invention in the electrolyte can affect each other, and compared with a single additive, the performance of the electrolyte can be mutually improved, and the additive plays a role of 1+1+1+1 > 4.
In summary, according to the electrolyte additive system and the electrolyte provided by the invention, through the synergistic effect of the fluoro phenyl isocyanate compound additive, the disilazane compound additive, the negative electrode film forming additive and the novel conductive lithium salt additive, the film forming performance of the electrolyte on the surface of the silicon-carbon negative electrode is excellent, the formed SEI film has small impedance overall, and the components and the structure of the SEI film are stable. The electrolyte can effectively improve the actual discharge capacity, the cycle stability and the high-temperature storage performance of the silicon-carbon negative lithium ion battery, inhibit gas generation, effectively solve the problems of volume expansion, pole piece pulverization and the like in the charging and discharging processes of the battery, and simultaneously has good high and low temperature performance.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. It is to be understood that the following description is only illustrative of the present invention and is not to be construed as limiting the present invention.
The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.
When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.
Further, the technical features of the embodiments of the present invention may be combined with each other as long as they do not conflict with each other.
Example 1
Preparing electrolyte: in a glove box filled with argon, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate are mixed according to the mass ratio of EC: DEC: EMC 2: 3: 3 and then slowly adding 12.5 wt% of lithium hexafluorophosphate (LiPF) based on the total mass of the electrolyte to the mixed solution6) 0.5 wt% of lithium bis (oxalato) borate (LiBOB) based on the total mass of the electrolyte and 2.5 wt% of lithium difluoro (oxalato) borate (LiDFOB) based on the total mass of the electrolyte, and finally 2.0 wt% of a fluorophenyl isocyanate compound having a structure represented by formula I, 0.5 wt% of a disilazane compound having a structure represented by formula II, 5.0 wt% of fluoroethylene carbonate (FEC) and 0.5 wt% of 1, 3-Propanediol Cyclic Sulfate (PCS) based on the total mass of the electrolyte were added and uniformly stirred to obtain the electrolyte for the lithium ion battery of example 1.
Preparing a soft package battery: stacking the prepared positive plate, the diaphragm and the negative plate in sequence, enabling the diaphragm to be positioned between the positive plate and the negative plate, and winding to obtain a bare cell; and (3) placing the bare cell in an outer package, injecting the prepared electrolyte into the dried battery, packaging, standing, forming, shaping and grading to finish the preparation of the lithium ion soft package battery (the full battery material is NCM 111/SiC).
Examples 2 to 12 and comparative examples 1 to 8
Examples 2 to 12 and comparative examples 1 to 8 were the same as example 1 except that the electrolyte composition was changed to additives shown in Table 1.
TABLE 1 composition ratios of the components of the electrolytes of examples 1-12 and comparative examples 1-8
The following performance tests were performed on the full cells obtained in examples 1 to 12 and comparative examples 1 to 8:
1) and (3) testing the normal-temperature cycle performance: at 25 ℃, the battery after capacity grading is charged to 4.2V at constant current and constant voltage according to 1C, the current is cut off at 0.05C, then the battery is discharged to 3.0V at constant current according to 1C, and the capacity retention rate of the 1000 th cycle is calculated after 1000 cycles of charge/discharge according to the cycle, and the calculation formula is as follows:
the 1000 th cycle capacity retention ratio (%) (1000 th cycle discharge capacity/first cycle discharge capacity) × 100%.
2) And (3) testing the thickness expansion and capacity residual recovery rate at high temperature of 60 ℃: firstly, the battery is placed at normal temperature and is circularly charged and discharged for 1 time (4.2V-3.0V) at 0.5C, and the discharge capacity C before the battery is stored is recorded0Then charging the battery to 4.2V full-voltage state with constant current and constant voltage, and using vernier caliper to test the thickness d of the battery before high-temperature storage1(the two diagonals of the battery are respectively connected through a straight line, and the intersection point of the two diagonals is a battery thickness test point), then the battery is placed in a 60 ℃ incubator for storage for 7 days, and after the storage is finished, the battery is taken out and the thermal thickness d of the stored battery is tested2Calculating the expansion rate of the thickness of the battery after the battery is stored for 7 days at a constant temperature of 60 ℃; after the battery is cooled for 24 hours at room temperature, the battery is discharged to 3.0V at a constant current of 0.5C, then charged to 4.2V at a constant current and a constant voltage of 0.5C, and the discharge capacity C after the battery is stored is recorded1And a charging capacity C2And calculating the capacity residue of the battery after the battery is stored for 7 days at the constant temperature of 60 DEG CThe residual rate and the capacity recovery rate are calculated according to the following formula:
thickness expansion ratio (%) of the battery after 7 days of storage at 60 ℃ ═ d2-d1)/d1*100％；
Capacity remaining ratio (%) C after 7 days of high-temperature storage at 60 DEG C1/C0*100％；
Capacity recovery (%) of C after 7 days of high-temperature storage at 60 DEG C2/C0*100％。
3) -20 ℃ low temperature discharge performance test: charging the batteries after capacity grading to 4.2V at constant current and constant voltage of 0.2C, stopping current to 0.02C, then discharging to 3.0V at constant current of 0.2C, and recording discharge capacity D0(ii) a Charging to 4.2V at 0.2C, stopping current at 0.02C, standing at-20 deg.C for 7h, discharging to 3.0V at constant current of 0.2C, and recording low-temperature 0.2C discharge capacity D1And calculating the discharge efficiency of the battery after discharging at the low temperature of-20 ℃ and 0.2C, wherein the calculation formula is as follows:
discharge efficiency (%) after-20 ℃ low-temperature 0.2C discharge1/D0*100％。
The results of the above performance tests are shown in table 2.
Table 2 lithium ion battery electrical performance test results
As can be seen from a comparison of the test results of comparative examples 1 to 8 and examples 1 to 12 in Table 2: the invention jointly acts in the electrolyte through the synergistic effect of the fluoro phenyl isocyanate compound additive, the disilazane compound additive, the negative electrode film forming additive and the novel conductive lithium salt additive, the electrolyte has excellent film forming performance on the surface of an electrode, the actual discharge capacity, the cycle stability and the high-temperature storage performance of the silicon-carbon negative electrode lithium ion battery are effectively improved, the gas generation is inhibited, the problems of volume expansion, pole piece pulverization and the like in the charging and discharging processes of the battery are well solved, and meanwhile, the invention has good high and low temperature performance.
As can be seen from a comparison of the results of the electrical property tests of comparative example 4 and examples 1-3 in Table 2: in the embodiment, the fluorinated phenyl isocyanate compound additive with the structure shown in the formula I is added, so that the normal and low temperature cycle performance of the NCM111/SiC battery is obviously improved, probably because the additive can preferentially form excellent interface protective films on the surfaces of a positive electrode and a negative electrode, the reaction activity of an electrode material and an electrolyte is reduced, the reduction decomposition of an organic solvent is inhibited, the interface impedance of an SEI film is reduced, and the normal and low temperature cycle performance of the battery is improved; meanwhile, with the increase of the content of the additive of the compound with the structure shown in the formula I, the silicon-carbon negative electrode battery has the advantages that the battery thickness expansion rate is reduced and the capacity residual recovery rate is increased after the silicon-carbon negative electrode battery is stored at the high temperature of 60 ℃ for 7 days, on one hand, the F element in the compound is favorable for improving the flash point of an electrolyte, and the flame retardant property of the F element is also favorable for improving the safety performance of the high-specific energy battery under heating and overcharging, on the other hand, the isocyanate group in the compound participates in and changes the composition of an SEI film, homopolymerization reaction is carried out on a silicon-carbon negative electrode interface to form a passive film reaction layer, so that the volume expansion and internal resistance change of the silicon-carbon negative electrode lithium ion battery in the charging and discharging process are inhibited. However, when the content of the additive of the compound with the structure shown in the formula I is too high, the normal temperature and high and low temperature performances of the silicon-carbon cathode battery are integrally reduced.
Further, compared with comparative example 5 in which no disilazide additive with the structure of formula ii is added, the appropriate amount of the disilazide additive in the embodiments of the present invention can effectively improve the normal temperature cycle performance and the high temperature storage performance of the NCM111/SiC battery, which is probably because the compound additive can effectively reduce the HF acid content in the electrolyte, inhibit the corrosion of HF acid to silicon, and improve the storage stability and the thermal stability of the lithium ion battery electrolyte, thereby improving the electrochemical performance and the cycle performance of the battery. However, with the increase of the content of the additive with the structure shown in the formula II, the interface impedance of the silicon-carbon cathode is increased, and the low-temperature performance is deteriorated; and when the content of the compound additive with the structure shown in the formula II is too high, the performance of the silicon-carbon cathode lithium ion battery is in an integral decline trend.
Further, compared with examples 7 and 9 in which fluoroethylene carbonate or sulfate/sulfite compounds are used alone and comparative example 6 in which fluoroethylene carbonate and sulfate/sulfite compounds are not added, other examples in the present invention can be decomposed to form a stable and tough SEI film on the surface of the silicon-carbon negative electrode preferentially by the combined use of fluoroethylene carbonate and sulfate/sulfite compounds, thereby effectively improving the volume expansion of silicon during the repeated charge and discharge of the battery, preventing the decomposition process of the electrolyte, improving the reversible capacity, cycle performance and safety performance of the battery, and enabling the silicon-carbon negative electrode lithium ion battery to have good high and low temperature performance.
Further, in comparison with comparative example 2 in which no nitrogen-containing lithium salt was added, the addition of the novel conductive lithium salt LiBOB or lidob having good film-forming characteristics in each example of the present invention effectively suppressed the generation of moisture in the electrolyte at high temperature, and reduced the HF acid content, thereby reducing the corrosion of silicon. Meanwhile, both LiBOB and LiDFOB have good film forming performance, and can form a stable SEI film with the silicon-carbon negative electrode, so that the volume effect of the silicon-carbon negative electrode is inhibited to a certain extent. The invention adopts a plurality of novel film-forming lithium salts for combined use and is combined with LiPF6Mixing to make up for LiPF6Compared with the single use of LiPF (lithium ion PF)6The method is favorable for improving the storage and cycle performance, the rate capability and the safety performance of the battery under high voltage.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any modifications, substitutions or alterations obvious to those skilled in the art based on the present invention are intended to be included within the scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (15)
1. An electrolyte suitable for a silicon-carbon cathode, the electrolyte comprises electrolyte lithium salt, a non-aqueous organic solvent and an additive, and the additive comprises a cathode film forming additive, a fluoro phenyl isocyanate additive with a structure shown in formula I and a disilazane additive with a structure shown in formula II, wherein the fluoro phenyl isocyanate additive with a structure shown in formula I has the following general formula:
wherein R is1-R5Respectively selected from any one of hydrogen atom, fluorine atom, alkyl with carbon content more than or equal to 1, alkylene, alkoxy or aromatic group, and R1-R5At least one of which is substituted by a fluorine atom;
the general formula of the disilazane compound additive with the structure of the formula II is as follows:
wherein, X1-X6Each independently selected from alkyl with 1-5 carbon atoms or a substitute thereof, and M is any one of Li or H; the negative film-forming additive is fluoroethylene carbonate and 1, 3-propylene glycol episulfide; the electrolyte lithium salt is a mixed lithium salt of lithium hexafluorophosphate, lithium bis (oxalato) borate and lithium difluoro (oxalato) borate.
2. The electrolyte suitable for silicon-carbon negative electrode according to claim 1, wherein the fluorinated phenyl isocyanate compound having the structure of formula I is selected from A1-A5One or more of:
the disilazane compound with the structure of formula II is selected from B1-B5One or more of:
3. the electrolyte suitable for the silicon-carbon cathode is characterized in that the content of the fluoro phenyl isocyanate compound with the structure shown in the formula I is 0.5-5.0 wt% of the total mass of the electrolyte; the content of the disilazane based compound with the structure shown in the formula II accounts for 0.1-1.0 wt% of the total mass of the electrolyte.
4. The electrolyte for the silicon-carbon negative electrode according to claim 1, wherein the content of the boron-containing lithium salt compound in the electrolyte lithium salt is 0.1-10 wt% of the total mass of the electrolyte, and the content of the lithium hexafluorophosphate is 12.5-15.0 wt% of the total mass of the electrolyte.
5. The electrolyte suitable for the silicon-carbon negative electrode according to claim 1, wherein the electrolyte lithium salt comprises 11.5-13.5 wt% of lithium hexafluorophosphate based on the total mass of the electrolyte, 0.4-0.6 wt% of lithium bis (oxalato) borate based on the total mass of the electrolyte, and 2.0-3.0 wt% of lithium difluoro (oxalato) borate based on the total mass of the electrolyte.
6. The electrolyte suitable for the silicon-carbon negative electrode according to claim 5, wherein the electrolyte lithium salt contains 12.5 wt% of lithium hexafluorophosphate based on the total mass of the electrolyte, 0.5 wt% of lithium bis (oxalato) borate based on the total mass of the electrolyte, and 2.5 wt% of lithium difluoro (oxalato) borate based on the total mass of the electrolyte.
7. The electrolyte suitable for the silicon-carbon negative electrode according to claim 1, wherein the non-aqueous organic solvent is selected from carbonate compounds and/or carboxylate compounds.
8. The electrolyte suitable for the silicon-carbon negative electrode according to claim 7, wherein the carbonate compound is selected from cyclic carbonates and/or chain carbonates.
9. The electrolyte suitable for the silicon-carbon negative electrode according to claim 8, wherein the cyclic carbonate is at least one of ethylene carbonate and propylene carbonate, and the chain carbonate is one or more selected from diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate and propyl methyl carbonate.
10. The electrolyte for the silicon-carbon negative electrode according to claim 8, wherein the content of the cyclic carbonate accounts for 25.0-45.0 wt% of the total mass of the electrolyte, and the content of the chain carbonate accounts for 40.0-70.0 wt% of the total mass of the electrolyte.
11. The electrolyte suitable for a silicon-carbon anode according to claim 7, wherein the non-aqueous organic solvent comprises ethylene carbonate, diethyl carbonate and ethyl methyl carbonate.
12. The electrolyte suitable for the silicon-carbon negative electrode according to claim 11, wherein the mass ratio of the ethylene carbonate, the diethyl carbonate and the ethyl methyl carbonate is (1-3): (2-4): (2-4).
13. The electrolyte suitable for the silicon-carbon negative electrode according to claim 12, wherein the mass ratio of the ethylene carbonate, the diethyl carbonate and the ethyl methyl carbonate is 2: 3: 3.
14. a lithium ion battery, comprising a cell formed by stacking or winding a positive electrode sheet, a separator and a negative electrode sheet, and the electrolyte solution for a silicon-carbon negative electrode according to any one of claims 1 to 13.
15. The lithium ion battery according to claim 14, wherein the positive electrode active material of the positive electrode sheet is LiNi1-x-y-zCoxMnyAlzO2Wherein: x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, z is more than or equal to 0 and less than or equal to 0.5, and x + y + z is more than or equal to 0 and less than or equal to 1; the negative active material of the negative plate is nano silicon or SiOwA silicon-carbon composite material compounded with graphite, wherein: w is more than 1 and less than 2.
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| CN112510256B (en) * | 2019-09-16 | 2023-08-29 | 浙江省化工研究院有限公司 | Lithium ion battery electrolyte and lithium ion battery containing same |
| CN110336076B (en) * | 2019-06-19 | 2021-08-06 | 东莞东阳光科研发有限公司 | Lithium ion battery electrolyte and lithium ion battery |
| CN110336078B (en) * | 2019-08-09 | 2021-02-09 | 深圳市天劲新能源研究院 | Silicon-based negative electrode electrolyte and lithium ion power battery |
| CN110994022B (en) * | 2019-11-27 | 2022-07-29 | 惠州锂威新能源科技有限公司 | Electrolyte for silicon-carbon cathode and lithium ion battery |
| CN111454661A (en) * | 2020-06-18 | 2020-07-28 | 广东睿智环保科技有限责任公司 | Wear-resistant self-lubricating anti-icing, anti-fogging coating and preparation method thereof |
| CN111534196A (en) * | 2020-06-23 | 2020-08-14 | 广东睿智环保科技有限责任公司 | Epoxy anticorrosive antifogging coating and preparation method thereof |
| CN111834671A (en) * | 2020-07-27 | 2020-10-27 | 香河昆仑化学制品有限公司 | Electrolyte suitable for silicon-carbon cathode and lithium ion battery |
| CN111883838B (en) * | 2020-08-03 | 2023-05-12 | 香河昆仑新能源材料股份有限公司 | Nonaqueous electrolyte and lithium ion battery |
| CN114122513A (en) * | 2020-08-28 | 2022-03-01 | 天津中电新能源研究院有限公司 | Functional electrolyte additive, battery electrolyte and sodium ion battery |
| CN114583243A (en) * | 2020-11-30 | 2022-06-03 | 深圳新宙邦科技股份有限公司 | Lithium ion battery |
| CN114583241A (en) * | 2020-11-30 | 2022-06-03 | 深圳新宙邦科技股份有限公司 | Lithium ion battery |
| CN112531211B (en) * | 2020-12-03 | 2022-06-14 | 惠州亿纬锂能股份有限公司 | Electrolyte, preparation method thereof and lithium ion battery |
| CN113140792B (en) * | 2021-03-30 | 2022-05-24 | 山东海容电源材料有限公司 | High-energy-density lithium ion battery electrolyte and application thereof |
| CN113130998B (en) * | 2021-03-30 | 2022-05-24 | 山东海容电源材料有限公司 | Electrolyte flame-retardant additive and lithium ion battery electrolyte containing same |
| CN113964384B (en) * | 2021-10-18 | 2024-01-05 | 南京航空航天大学 | Multifunctional organic silicon electrolyte suitable for lithium ion battery based on silicon negative electrode and preparation and application thereof |
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| CN105336984B (en) * | 2014-07-31 | 2018-05-22 | 东莞新能源科技有限公司 | Lithium ion battery and its electrolyte |
| CN106602143A (en) * | 2016-12-27 | 2017-04-26 | 石家庄圣泰化工有限公司 | Electrolyte used for silicon negative electrode lithium battery |
| CN109216759B (en) * | 2018-09-13 | 2020-06-19 | 湛江市金灿灿科技有限公司 | Lithium ion battery electrolyte and lithium ion battery |
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