CN105514487A - Method for matching organic silicon electrolyte with silicon-based electrode material for use - Google Patents

Abstract

The invention relates to a method for cooperating an organosilicon electrolyte with a silicon-based electrode material. The silicon-based negative electrode material is silicon powder, silicon oxide or a silicon-carbon composite electrode material, and the organosilicon electrolyte contains lithium salt, electrolyte additives and Organosilicon compound, described organosilicon compound is as shown in following general formula: Among them, R', R", R"' are selected from the same or different C1-C10 alkyl, alkoxy or halogen substituents (-F); M is C1-C20 alkyl or the structure is -(CH ₂ ) A segment of _n O[(CH ₂ ) _m O]x(CH ₂ )y structure, n and m are integers from 0 to 10, x and y are integers from 0 to 10; FG is cyano, carbonate, poly Ether chain, or tertiary amino functional group. The invention utilizes the "similar and compatible" properties of organic silicon electrolyte and silicon-based electrode materials, and the manufactured battery has low impedance, excellent cycle stability and rate performance, and safety.

Description

A method for cooperating use of organic silicon electrolyte and silicon-based electrode material

technical field

The invention belongs to the technical field of electrochemical energy storage, and in particular relates to a method for cooperating an organic silicon electrolyte and a silicon-based electrode material.

Background technique

With the depletion of fossil energy and the deterioration of the earth's climate, the development of new clean energy and the strengthening of energy conservation and emission reduction have become the key development directions of countries all over the world. In recent years, with the accelerated construction of hybrid electric vehicles, pure electric vehicles and new energy (solar, wind power) grid-connected power station projects, high-performance power (energy storage) batteries have become one of the core technologies for vigorous development. At present, lithium-ion batteries are due to Its advantages such as high voltage, large capacity, good cycle performance and low pollution have become the most competitive power solution. The development of anode materials with excellent performance is one of the keys to improving the performance of lithium-ion batteries. Carbon materials are the earliest anode materials widely used in commercial lithium batteries. However, the disadvantages of low capacitance density, large irreversible loss, low safety at high temperature, and easy short circuit during overcharging limit the development of carbon anode materials. Therefore, it is imminent to develop new lithium-ion battery anode materials with high capacity density, excellent cycle performance and excellent safety performance.

Among the many new lithium-ion battery anode materials, silicon-based anode materials have the advantage of high capacity (Li ₂₂ Si ₅ , theoretical lithium storage capacity 4200mAh/g), which is unmatched by other anode materials, and is recognized as the next generation of anode materials with commercial prospects Material. Silicon-based negative electrode materials are 11 times the theoretical capacity of current commercial carbon negative electrode materials. The potential of lithium intercalation into silicon (less than 0.5V) is lower than the co-intercalation voltage of general solvent molecules, and higher than the precipitation potential of lithium. Therefore, silicon-based anode materials can solve the problems of solvent molecule intercalation and lithium dendrite precipitation. However, the conductivity of silicon-based materials is poor, and at the same time, there is a serious volume effect in the process of intercalation and extraction of lithium, and the volume change rate is about 400%, which will cause powdering of electrode materials and separation of electrode materials and current collectors. The above-mentioned defects of silicon-based materials severely limit their commercial applications. In order to overcome the volume effect of silicon, people often use silicon-based materials with nanostructures, silicon thin film materials, porous silicon materials and silicon-based composite materials to improve the cycle performance of silicon-based electrode materials, but the silicon in these composite materials will be exposed. In the electrolyte, due to the volume effect during the charging and discharging process, the silicon-based electrode material continuously forms a fresh surface, so the electrolyte is continuously consumed to form an SEI film, which reduces the cycle performance of the electrode material. In recent years, there have also been reports on electrolytes that match silicon-based electrode materials, such as AurbachD., MullinsCB found that fluoroethylene carbonate can greatly improve the cycle performance of nano-silicon-based electrode lithium-ion batteries when they are used as a solvent for the electrolyte (J . Langmuir, 2012, 28, 965-976; 2014, 30, 7414-7424; Chem. Commun. 2012, 48, 7268-7270). Therefore, by developing an electrolyte system that matches silicon-based electrode materials to improve the electrochemical performance of silicon-based negative electrode lithium-ion batteries, and then develop new lithium-ion batteries with high specific capacity, high charge-discharge efficiency, and long cycle life, it has a certain The theoretical value and practical significance are undoubtedly of great significance to promote the technological upgrading of the lithium-ion battery industry and the development of the new energy industry, electric vehicles and hybrid electric vehicles.

Organosilicon compounds have the advantages of excellent thermal stability, high electrical conductivity, non-toxicity, low flammability, and high decomposition voltage. Compared with the current commercial organic carbonate electrolyte, they have better safety performance and are used in electrochemical energy storage The device has great commercial application prospects. The inventor of this patent has applied for a series of organosilicon electrolyte materials for lithium-ion batteries in recent years, including organosilicon cyanide compounds (ZL201010182978.6), organosilicon ionic liquids (CN102372732A), organosilicon carbonates (ZL201210358351.0, PCTCN2012084205) , organosilicon amine compounds (ZL201010607369.0 and US9,085,591B2), organosilicon fluoropolyether compounds (CN2012103896591/PCLBN2012084192). In view of the fact that silicon-based electrode materials are the next generation of high-capacity anodes that may be commercialized on a large scale, and the huge market for lithium-ion batteries using silicon-based electrode materials, it is also particularly important to use organosilicon compounds as electrolytes for silicon-based electrodes.

Contents of the invention

The present invention utilizes the "similar and compatible" properties of organosilicon electrolyte materials and silicon-based electrode materials to modify them with different functional groups (such as cyano groups, carbonate groups, polyether chains, halogen groups, tertiary amino groups, etc.) To improve the compatibility of organosilicon compounds and silicon-based negative electrodes, and provide a method for the use of organosilicon electrolytes and silicon-based electrode materials in combination, organosilicon compounds as electrolytes have outstanding technical effects when applied to silicon-based electrodes, and have Low impedance, excellent cycle stability and rate performance, and safety.

For realizing the above-mentioned purpose of the invention, the technical scheme of the present invention is as follows:

A method in which an organosilicon electrolyte is used in conjunction with a silicon-based electrode material, the silicon-based electrode material being silicon powder, silicon oxide or a silicon-carbon composite electrode material, the organosilicon electrolyte comprising a lithium salt, an electrolyte additive And organosilicon compound, described organosilicon compound is as shown in following general formula:

Among them, R', R", R"' are selected from the same or different C1-C10 alkyl, alkoxy or halogen substituents (-F), wherein the alkoxy group is the following structure -(CH ₂ ) _n O (CH ₂ CH ₂ O) _m CH ₃ , n and m are integers from 0 to 10; M is C1-C20 alkyl or the structure is -(CH ₂ ) _n O[(CH ₂ ) _m O]x(CH ₂ ) is a chain segment of y structure, n and m are integers of 0-10, x and y are integers of 0-10; FG is a functional group such as cyano group, carbonate ester, polyether chain, or tertiary amino group.

Preferably, the structural formula of the organosilicon compound is a cyano-containing organosilicon compound:

Among them, R ₁ , R ₂ , R ₃ are selected from the same or different C1-C10 alkyl, alkoxy or halogen substituents (-F), wherein the alkoxy is the following structure -(CH ₂ ) _n O(CH ₂ CH ₂ O) _m CH ₃ , n and m are integers from 0 to 10; R ₄ is a C1-C20 alkyl group. Cyano-containing organosilicon compounds include the following structures:

Preferably, the structural formula of the organosilicon compound is a halosilane functionalized carbonate organosilicon compound:

Wherein, R ₅ is selected from the following groups: [-(CH ₂ ) _m -, m=1~3] or [-(CH ₂ ) _m O(CH ₂ ) _n -, m, n=1~3]; R ₆ , R ₇ , R ₈ are selected from the following groups: [-(CH ₂ ) _m CH ₃ , m=0~3], aryl or substituted aryl, or halogen substituent, and R ₆ , R ₇ , R ₈ has at least one halogen substituent. The halosilane functionalized carbonate organosilicon compound preferably has the following structure:

Preferably, the structural formula of the organosilicon compound is a halosilane functionalized polyether organosilicon compound:

Wherein, R ₉ , R ₁₀ , R ₁₁ are selected from the same or different -(CH ₂ )xCH ₃ , x=0~5, or halogen substituents, the halogen is selected from F or Cl, and R ₉ , R ₁₀ , R ₁₁ has at least one halogen substituent; R ₁₂ is a tertiary amino group with the structural formula -NR ₁₃ R ₁₄ , R ₁₃ and R ₁₄ are selected from the same or different C1-C5 alkyl groups; m is an integer of 1-20 , n is an integer of 0-5. The halosilane functionalized polyether organosilicon compound preferably has the following structure:

Preferably, the structural formula of the organosilicon compound is an organosilicon amine compound containing a polyether chain:

Among them, R ₁₅ and R ₁₆ are selected from the same or different C1-C10 alkyl groups; A is a polyether chain segment such as (CH ₂ ) _n O[(CH ₂ ) _m O]x(CH ₂ )y structure, n , m is an integer of 0-10, x is an integer of 1-10; R ₁₇ , R ₁₈ and R ₁₉ are selected from the same or different C1-C10 alkyl or alkoxy groups, or the structure is equivalent to ANR ₁₅ R ₁₆ , or -O-SiR ₂₀ R ₂₁ R ₂₂ , R ₂₀ , R ₂₁ and R ₂₂ are the same or different C1-C10 alkyl groups. The polyether chain-containing organosilicon amine compound preferably has the following structure:

Preferably, the lithium salt is selected from one or more of LiClO ₄ , LiPF ₆ , LiBF ₄ , LiTFSI, LiFSI, LiBOB, LiODFB, LiCF ₃ SO ₃ , LiAsF ₆ ; the electrolyte additive is selected from fluorinated One or more of ethylene carbonate, propane sultone, vinylene carbonate, succinonitrile, LiBOB, LiODFB.

Preferably, the organosilicon compound is present in the organosilicon electrolyte as an electrolyte additive or co-solvent. Organosilicon compound is used for the mass content of electrolyte solvent of 1-100%, and all the other solvents are common carbonate organic solvents (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, etc.), ether organic solvents (such as 1,3-dioxolane, dimethoxymethane, 1,2-dimethoxyethane, diglyme, etc.) any one or more of them.

Preferably, the method is applied to electrochemical energy storage devices, including sulfur-based lithium batteries, metal-ion batteries, metal-air batteries and supercapacitors using silicon-based electrode materials. The battery produced by using the organosilicon electrolyte and the silicon-based electrode material has low impedance, excellent cycle stability and rate performance, and safety.

Preferably, the method is applied to lithium-ion batteries.

The beneficial effects of the present invention are: the present invention utilizes the "similar and compatible" properties of silicon-based negative electrode materials and organosilicon electrolyte materials, and organosilicon compounds are used as electrolytes to show outstanding technical effects when applied to silicon-based negative electrodes. The battery has low impedance, excellent cycle stability and rate performance, and safety.

Description of drawings

Figure 1: Si/C electrode using battery charge and discharge cycle performance test curve with different content of BNS electrolyte;

Accompanying drawing 2: Electrolyte 1MLiPF ₆ /BNS tests the CV curve of Si negative electrode;

Figure 3: Si and Si/C electrodes use electrolyte LB303, LB303+10%FEC, LB303+10%BNS battery cycle test curves;

Figure 4: Impedance test of electrolyte LB303 and Si/Li half-cell with 10wt.% SN1 added

Figure 5: Impedance test of electrolyte LB303 and Si/Li half-cells with 1wt.%, 5wt.% SN1 added

Figure 6: Si electrode using electrolyte LB303, LB303+0.1wt.% DMSCN battery cycle test curve

Figure 7: Electrolyte LB303, and Si/Li half-cell charge-discharge cycle performance test curves with FEC, MFGC, and TFGC added

Figure 8: Electrolyte LB303, and Si/Li half-cell charge-discharge cycle performance test curve with 5wt% TN2 added

Figure 9: Impedance test of electrolyte LB303 and Si/Li half-cells with 0.5wt.%, 1wt.% DN1 added

Figure 10: Si electrode using electrolyte LB303, LB303+0.5wt.% DN2 battery cycle test curve;

Figure 11: Electrolyte LB303, and Si/Li half-cell charge-discharge cycle performance test curves with 5wt% and 10wt% DFSM2 added.

detailed description

Below in conjunction with specific example, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention, not to limit the protection scope of the present invention. Improvements and adjustments made by skilled personnel according to the present invention in practical applications still belong to the protection scope of the present invention.

Unless otherwise specified, the equipment and reagents used in the present invention are conventional commercial products in the technical field.

Fabrication of Nano-Si and Si/C Composite Battery Negative Electrodes

In the experiments carried out, nano-Si (30-50nm) and Si/C materials were used as active materials, CMC as binder, and acetylene black as conductive agent, mixed at a mass percentage of 7:1:2, and ball milled for 1 h The mixed slurry was prepared, the coating film was placed on the copper foil base fluid, and dried in a vacuum oven at 80°C for 24 hours to prepare Si and Si/C electrodes.

Example 1

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add BNS accounting for 5%, 10% and 20% of the total mass of the electrolyte to the above basic electrolyte to prepare a mixed electrolyte, then use Si or Si/C negative as the working electrode, and lithium sheet as the counter electrode, Using polyethylene film as a diaphragm, the button half-cells (CR2025) were prepared with mixed electrolytes. The specific test method of the battery: at room temperature 25 ° C, the silicon-based negative half-cell was subjected to constant current on the Shenzhen Xinwei battery charge and discharge test system Charge and discharge test, charge and discharge cut-off voltage range is 0 ~ 1.5V, charge and discharge current density is 400mA/g, cycle 100 times. The test results are shown in Figure 1 and Figure 2.

Figure 1 is the charge-discharge cycle performance test curve of the battery with Si/C electrodes added with different contents of BNS electrolyte. It can be seen from the figure that the battery with 10% BNS has the best cycle performance, the first coulombic efficiency is 82%, and the first discharge specific capacity is 1389mAh/ g, the specific capacity after 100 cycles is 1035mAh/g, and the capacity retention rate is 74.5%. Figure 2 is the CV curve of the Si negative electrode tested with the electrolyte 1MLiPF ₆ /BNS. It can be seen in the figure that during the first cycle reduction process of the electrolyte, there are obvious reduction peaks at 1.7V and 1.1V. It should be that BNS decomposes on the electrode surface to form SEI membrane, and disappears in the second loop cycle.

Comparative example 1

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte. Then with Si or Si/C negative electrode as working electrode, with lithium sheet as counter electrode, with polyethylene film as diaphragm, prepare button half cell (CR2025) with this basic electrolyte.Battery specific test method is with embodiment 1. The test results are shown in Figure 3.

Comparative example 2

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte: add fluoroethylene carbonate (FEC) accounting for 10% of the total mass of the electrolyte to the above-mentioned basic electrolyte to prepare a mixed electrolyte, then use Si or Si/C as the negative electrode as the working electrode, and the lithium sheet as the counter electrode, With polyethylene film as diaphragm, button type half cell (CR2025) is prepared with this mixed electrolyte.Battery specific test method is the same as embodiment 1, and test result is shown in Fig. 3.

Figure 3 is the battery cycle test curves of Si and Si/C electrodes using electrolyte LB303, LB303+10%FEC, LB303+10%BNS. It can be seen from the figure that using electrolyte LB303, LB303+FEC, LB303+BNS, Si electrode batteries The first discharge specific capacities are 3509, 3575, 3894mAh/g, the first coulombic efficiencies are 77.1, 86.4, 86.2%, and after 100 cycles, the discharge specific capacities are 136, 1305, 2047mAh/g, and the capacity retention rates are respectively 5.0, 41.7, 60.8%. For the Si/C electrode battery after 100 cycles, the discharge specific capacity is 502, 876, 1035mAh/g, and the capacity retention rate is 46.9, 78.6, 88.1%. So for both Si and Si/C electrodes, the LB303+BNS electrolyte battery has the best cycle performance.

Example 2

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add BNS accounting for 3% of the total mass of the electrolyte to the above-mentioned basic electrolyte to prepare a mixed electrolyte, and then use silicon oxide as a negative electrode as a working electrode (silicon oxide comes from Shenzhen Beiterui Company, Si/Carbonblack/ Binder=60/30/10), using lithium sheet as the counter electrode, polyethylene film as the diaphragm, and mixed electrolytes to prepare button half-cells (CR2025). The specific test method of the battery: at room temperature 25 ° C, put The silicon half-cell was subjected to a constant current charge-discharge test on the Shenzhen Xinwei battery charge-discharge test system, the charge-discharge cut-off voltage range was 0-1.5V, and the charge-discharge current density was 100mA/g. The test results are shown in Table 1.

Comparative example 3

The same method as in Example 2 was used to make the battery, and the cycle performance of the battery was tested by adding 3% vinylene carbonate (VC) as a comparison. The test results are shown in Table 1. Table 1 shows that the silicon oxide electrode uses LB303, LB303+3%VC , the circulation data of LB303+3%BNS, as shown in Table 1.

Table 1

It can be seen from Table 1 that after the addition of 3% BNS, the silicon oxide battery has outstanding effects in terms of initial capacity and charge-discharge efficiency.

Example 3

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add SN1 accounting for 10% of the total mass of the electrolyte to the above basic electrolyte to prepare a mixed electrolyte, then use the Si negative electrode as the working electrode, the lithium sheet as the counter electrode, and the polyethylene film as the separator. The button half-cells (CR2025) were prepared respectively. The specific test method of the battery: at room temperature 25 ° C, the impedance test of the silicon negative half-cell was carried out on the electrochemical workstation. The test results are shown in Figure 4. After adding SN1, the impedance of the battery decreased significantly .

Example 4

Using DESCN and DMSCN as additives, the electrolyte was configured according to the method of Example 1, a battery was fabricated, and tested. The test results are shown in Figures 5 and 6. Figure 5 shows the AC impedance test of the Si electrode using the electrolyte LB303 and adding the DESCN electrolyte after 3 charge and discharge cycles. It can be seen from the impedance spectrum that after adding DESCN, the impedance value of the battery is significantly reduced: the impedance value of the battery containing 1% DESCN is about 36Ω; the impedance value of the battery containing 5% DESCN is about 80Ω. The LB303 battery membrane impedance value is about 200Ω. Smaller membrane resistance is conducive to the rapid transport of lithium ions.

Fig. 6 is the electrolyte LB303, and the Si/Li half-cell charge-discharge cycle performance test curve with 0.1% DMSCN added. It can be seen from the figure that with the addition of 0.1% DMSCN, the charging specific capacities before and after 33 cycles are 3130mAh/g and 1921mAh/g respectively, while the charging specific capacities of the LB303 battery before and after cycles are 2440mAh/g and 1502mAh/g respectively. It can be seen that adding a small amount of DMSCN can significantly increase the capacity of the battery and improve the performance of the battery.

Example 5

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add MFGC accounting for 3% of the total mass of the electrolyte to the above-mentioned basic electrolyte, then use the Si negative electrode as the working electrode, the lithium sheet as the counter electrode, and the polyethylene film as the diaphragm, and use the electrolyte to prepare a button type Half-battery (CR2025).Battery specific test method: At room temperature 25°C, the silicon-based negative electrode half-battery is subjected to a constant current charge-discharge test on the Shenzhen Xinwei battery charge-discharge test system. The charge-discharge cut-off voltage range is 0-1.5V. The charge and discharge current density is 500mA/g, and the cycle is 100. The test results are shown in Figure 7.

Example 6

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303: Add TFGC accounting for 3% of the total mass of the electrolyte to the basic electrolyte. The battery assembly and test are the same as in Example 1. The test results are shown in Figure 7.

Comparative example 4

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte. Battery assembly and testing are the same as in Example 1, and the test results are shown in Figure 7.

Comparative example 5

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303: Add FEC accounting for 3% of the total mass of the electrolyte to the basic electrolyte. Battery assembly and testing are the same as in Example 1, and the test results are shown in Figure 7.

Figure 7 is the electrolyte LB303, and the Si/Li half-cell charge-discharge cycle performance test curves with FEC, MFGC, and TFGC added. It can be seen from the figure that the electrolyte LB303, and the first discharge specific capacity of the battery with FEC, MFGC, and TFGC are respectively 2945.7, 3039, 260.4, 2720.9mAh/g, the discharge specific capacity after 100 cycles is 808.9, 1149.6, 1127.1, 1458.6mAh/g, and the capacity retention rate is 27.5, 37.8, 38.0, 53.6%. Adding TFGC has significantly improved the cycle performance of the battery, showing the best cycle stability. The specific capacities of FEC and MFGC are close after 100 cycles, but both are higher than that of LB303 without additives. It shows that all three additives can improve the cycle performance of the battery.

Example 7

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303: Add 5% TN2 of the total mass of electrolyte to the above basic electrolyte to prepare mixed electrolyte. Battery assembly and testing are the same as in Example 1, and the test results are shown in Figure 8.

Comparative example 6

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303. Battery assembly and testing are the same as in Example 1, and the test results are shown in FIG. 8 .

Figure 8 is the electrolyte LB303, and the Si/Li half-cell charge-discharge cycle performance test curve with 5wt% TN2 added. It can be seen from the figure that the cycle capacity of the battery added with TN2 is significantly improved in the first 40 cycles, which is higher than that of the basic electrolyte, but its attenuation is faster, and the capacity after 40 cycles is equal to that of the basic electrolyte.

Example 8

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add DN1 accounting for 0.5% of the total mass of the electrolyte to the above basic electrolyte to prepare a mixed electrolyte, then use the Si negative electrode as the working electrode, the lithium sheet as the counter electrode, and the polyethylene film as the separator. The button-type half-cell (CR2025) was prepared separately. The specific test method of the battery: at a room temperature of 25 ° C, the impedance test of the silicon negative half-cell was carried out on the electrochemical workstation, and the test results are shown in Figure 9.

Example 9

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; In above-mentioned basic electrolyte, add and account for 0.5% DN of electrolyte gross mass Prepare mixed electrolyte.Battery assembly is the same as embodiment 7, constant current charge-discharge test on Shenzhen Xinwei battery charge-discharge test system, charge-discharge The cut-off voltage range is 0-1.5V, the charge-discharge current density is 500mA/g, and the cycle is 200 times. The test results are shown in Figure 10.

Figure 9 is the impedance test diagram of the electrolyte LB303 and the Si/Li half-cell with 0.5wt% DN1 added before cycling. It can be seen from the figure that the impedance of the battery is significantly reduced after the addition of DN1. Figure 10 is the electrolyte LB303, and the Si/Li half-cell charge-discharge cycle performance test curves with 0.5wt% DN2 added. It can be seen from the figure that the initial cycle capacity of charging and discharging is the same as that of the basic electrolyte, but the cycle stability has been significantly improved, and the 60-cycle cycle capacity is still much higher than that of the basic electrolyte.

Example 10

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303; add 5% and 10% DFSM2 to the above basic electrolyte to prepare a mixed electrolyte, then use Si as the negative electrode as the working electrode, lithium sheet as the counter electrode, and polyethylene film as the separator. Prepare button half-cells (CR2025) with mixed electrolytes. The specific battery test method: at room temperature 25 ° C, the silicon-based negative electrode half-cells are subjected to constant current charge-discharge tests on the Shenzhen Xinwei battery charge-discharge test system, and the charge-discharge cut-off The voltage range is 0-1.5V, the charge and discharge current density is 500mA/g, and the cycle is 200. The test results are shown in Figure 11.

Comparative example 7

In an argon glove box with moisture and oxygen content less than 10ppm, prepare lithium-ion battery electrolyte: use 1MLiPF ₆ /(EC:DEC:DMC (v:v:v=1:1:1) electrolyte as the basis Electrolyte LB303. Battery assembly and testing are the same as in Example 1, and the test results are shown in FIG. 11 .

Figure 11 is the electrolyte LB303, and the Si/Li half-cell charge-discharge cycle performance test curves added with 5wt% and 10wt% DFSM2. It can be seen from the figure that the cycle performance of the battery is significantly improved by adding DFSM2. LB303, the first discharge specific capacities of the batteries added with 5wt% and 10wt% DFSM2 were 2702.7, 2263.8, 2883.7mAh/g, and the capacity retention rates after 100 cycles were 32.8, 52.6, 55% (86 cycles). Especially after adding 10% DFSM2, it is obviously better than the basic electrolyte in terms of discharge capacity and cycle stability.

The above detailed description is a specific description of the feasible embodiment of the present invention. This embodiment is not used to limit the patent scope of the present invention. Any equivalent implementation or change that does not deviate from the present invention should be included in the patent protection of this case. in range.

Claims (10)

1. the method for an organosilicon electrolyte and the use of silicon based electrode material fit, it is characterized in that, described silicon based anode material is silica flour, is oxidized sub-silicon or silico-carbo combination electrode material, described organosilicon electrolyte comprises lithium salts, electrolysis additive and organo-silicon compound, and described organo-silicon compound are as shown in following general formula:

Wherein, R ', R ", R " ' be selected from identical or different C1-C10 alkyl, alkoxy or halogen substituting group (-F), wherein alkoxy grp is following structure-(CH ₂) _no (CH ₂cH ₂o) _mcH ₃, n, m are the integer of 0-10; M is C1-C20 alkyl or structure is-(CH ₂) _no [(CH ₂) _mo] x (CH ₂) segment of y structure, n, m are the integer of 0-10, and x, y are the integer of 0-10; FG is cyano group, carbonic ester, polyether chain or tertiary amine groups functional group.

2. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, the structural formula of described organo-silicon compound is cyano-containing organo-silicon compound:

Wherein, R ₁, R ₂, R ₃be selected from identical or different C1-C10 alkyl, alkoxy or halogen substituting group (-F), wherein alkoxyl is following structure-(CH ₂) _no (CH ₂cH ₂o) _mcH ₃, n, m are the integer of 0-10; R ₄for C1-C20 alkyl.

3. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, the structural formula of described organo-silicon compound is halosilanes functionalized carbon acid esters organo-silicon compound:

Wherein, R ₅be selected from following group: [-(CH ₂) _m-, m=1 ~ 3] or [-(CH ₂) _mo (CH ₂) _n-, m, n=1 ~ 3]; R ₆, R ₇, R ₈be selected from following group: [-(CH ₂) _mcH ₃, m=0 ~ 3], aryl or substituted aryl, or halogenic substituent (-F), and R ₆, R ₇, R ₈has a halogen substiuted group at least.

4. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, the structural formula of described organo-silicon compound is halosilanes functionalization polyethers organo-silicon compound:

Wherein, R ₉, R ₁₀, R ₁₁be selected from identical or different-(CH ₂) xCH ₃, x=0 ~ 5, or halogenic substituent, described halogen is selected from F or Cl, and R ₉, R ₁₀, R ₁₁in have a halogenic substituent at least; R ₁₂for alkoxyl or structural formula are-NR ₁₃r ₁₄tertiary amine groups, R ₁₃, R ₁₄be selected from the alkyl of identical or different C1-C5; M is the integer of 1-20, and n is the integer of 0-5.

5. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, is characterized in that, the structural formula of described organo-silicon compound is for containing polyether chain organic silicon amine compounds:

Wherein, R ₁₅, R ₁₆be selected from identical or different C1-C10 alkyl; A is as (CH ₂) _no [(CH ₂) _mo] x (CH ₂) polyether segment of y structure, n, m are the integer of 0-10, and x is the integer of 1-10; R ₁₇, R ₁₈and R ₁₉be selected from alkyl or the alkoxy grp of identical or different C1-C10, or structure is equal to ANR ₁₅r ₁₆, or-O-SiR ₂₀r ₂₁r ₂₂group, R ₂₀, R ₂₁and R ₂₂for the alkyl of identical or different C1-C10.

6. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, described lithium salts is selected from LiClO ₄, LiPF ₆, LiBF ₄, LiTFSI, LiFSI, LiBOB, LiODFB, LiCF ₃sO ₃, LiAsF ₆in one or more; Described electrolysis additive is selected from fluorinated ethylene carbonate, one or more in propane sultone, vinylene carbonate, succinonitrile, LiBOB, LiODFB.

7. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, described organo-silicon compound are present in described organosilicon electrolyte as additive agent electrolyte or cosolvent.

8. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, the method is applied to electrochemical energy storing device.

9. the method for organosilicon electrolyte according to claim 8 and the use of silicon based electrode material fit, it is characterized in that: described electrochemical energy storing device employs silicon based electrode material, comprise sulfenyl lithium battery, metal ion battery, metal-air cell and super capacitor.

10. the method for organosilicon electrolyte according to claim 1 and the use of silicon based electrode material fit, it is characterized in that, the method is applied to lithium ion battery.