Electrolyte for anodeless batteries and anodeless batteries

Abstract

This invention provides an electrolyte for anodeless batteries that exhibits excellent reversibility in the lithium elution reaction. [Solution] The electrolyte for anodeless batteries contains a solvent, a lithium salt, and an additive. The additive includes a compound represented by the following general formula (1), and one or more compounds 1 to 2 represented by the following chemical formulas. However, n is an integer between 1 and 10. TIFF2026141808000025.tif43170 TIFF2026141808000026.tif64170

Description

Technical Field

[0001] The present application relates to an electrolytic solution for anodeless batteries that is excellent in reversibility of lithium dissolution and deposition reactions, and to an anodeless battery using the electrolytic solution.

Background Art

[0002] As a non-aqueous electrolyte secondary battery using lithium ions as charge carriers, an anodeless battery that does not use metallic lithium as a negative electrode active material is known (Patent Document 1). Since the negative electrode of an anodeless battery is composed only of a current collector, it has higher safety in the manufacturing process compared to metallic lithium secondary batteries. An anodeless battery is in the research stage: during charging, lithium ions (Li + ) released from the positive electrode are deposited as metallic lithium (Li) on the negative electrode current collector, and the reverse reaction is utilized during discharging.

[0003] Improving the efficiency of the dissolution and deposition reaction of metallic lithium is the key to the practical application of anodeless batteries. As a means to this end, development of electrolytic solutions for anodeless batteries that suppress side reactions that reduce the reversibility of the lithium dissolution and deposition reaction is ongoing. Although conventional electrolytic solutions for anodeless batteries can improve the efficiency of lithium dissolution and deposition, they have problems such as poor compatibility with positive electrodes, excessively high specific gravity leading to a decrease in energy density, and excessively high viscosity making them difficult to use in battery manufacturing processes.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] The present invention aims to provide an electrolyte for anodeless batteries that is based on an electrolyte for lithium-ion batteries and exhibits excellent reversibility in the lithium elution reaction, and an anodeless battery using this electrolyte. [Means for solving the problem]

[0006] The electrolyte for the anodeless battery of this application contains a solvent, a lithium salt, and an additive, wherein the additive includes a compound represented by the following general formula (1) and one or more compounds 1 to 2 represented by the following chemical formulas, where n is an integer between 1 and 10.

[0007] [ka]

[0008] [ka]

[0009] The anodeless battery of the present invention comprises a positive electrode having a positive electrode current collector and a positive electrode active material, a negative electrode current collector, a separator provided between the positive electrode and the negative electrode current collector, and the electrolyte for the anodeless battery of the present invention. [Effects of the Invention]

[0010] The electrolyte for anodeless batteries of this invention is based on an electrolyte for lithium-ion batteries that contains a solvent and a lithium salt. Therefore, with the electrolyte for anodeless batteries of this invention, the positive electrode used in lithium-ion batteries can be used as is in anodeless batteries. Furthermore, since the specific gravity of the electrolyte does not become excessively high, the high energy density due to the absence of negative electrode active material can be utilized in anodeless batteries. In addition, the electrolyte for anodeless batteries of this invention contains predetermined additives. Therefore, the electrolyte for anodeless batteries of this invention exhibits excellent reversibility in the lithium dissolution reaction. As a result, the anodeless battery of this invention, which has the electrolyte for anodeless batteries of this invention, has a high capacity retention rate during discharge. [Brief explanation of the drawing]

[0011] [Figure 1] Schematic diagram of an anodeless battery after disassembly. [Figure 2] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1 and Examples 1-1 to 1-5. [Figure 3] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of coin cells in Comparative Example 1 and Examples 1-1 to 1-5. [Figure 4] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Examples 1-3, and Examples 2-1 to 2-3. [Figure 5] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Examples 1-3, and Examples 2-1 to 2-3. [Figure 6] Graphs showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Examples 3a to 3c and Examples 3a-1 to 3c-1. [Figure 7] Graphs showing the relationship between the number of charge / discharge cycles and Coulomb efficiency of coin cells in Comparative Examples 3a to 3c and Examples 3a-1 to 3c-1. [Figure 8] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Comparative Example 4a, Examples 1-3, and Example 4a-1. [Figure 9] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Comparative Example 4a, Examples 1-3, and Example 4a-1. [Figure 10] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Comparative Example 4b, Examples 1-3, and Example 4b-1. [Figure 11] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Comparative Example 4b, Examples 1-3, and Example 4b-1. [Figure 12] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Comparative Example 4c, Examples 1-3, and Example 4c-1. [Figure 13] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Comparative Example 4c, Examples 1-3, and Example 4c-1. [Figure 14] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Comparative Example 4d, Examples 1-3, and Example 4d-1. [Figure 15] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Comparative Example 4d, Examples 1-3, and Example 4d-1. [Figure 16] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of coin cells in Comparative Example 1, Comparative Example 4e, Examples 1-3, and Example 4e-1. [Figure 17] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cells in Comparative Example 1, Comparative Example 4e, Examples 1-3, and Example 4e-1. [Figure 18] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell in Comparative Example 5a and Example 5a-1. [Figure 19] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell in Comparative Example 5a and Example 5a-1. [Figure 20] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell in Comparative Example 5b and Example 5b-1. [Figure 21] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell in Comparative Example 5b and Example 5b-1. [Figure 22] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell in Comparative Example 5c and Example 5c-1. [Figure 23] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell in Comparative Example 5c and Example 5c-1. [Figure 24] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell in Comparative Example 5d and Example 5d-1. [Figure 25] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell in Comparative Example 5d and Example 5d-1. [Figure 26] A graph showing the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell in Comparative Example 5e and Example 5e-1. [Figure 27] A graph showing the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell in Comparative Example 5e and Example 5e-1. [Modes for carrying out the invention]

[0012] The electrolyte for anodeless batteries and the anodeless batteries of this application will be described based on embodiments and examples. The electrolyte for anodeless batteries (hereinafter sometimes simply referred to as "electrolyte") will be described as a component of the anodeless battery. When two numerical ranges are indicated using "~", these two numbers are also included in this range. Repetitive explanations will be omitted as appropriate. Figure 1 schematically shows the components of a coin-type anodeless battery 10 according to an embodiment of this application.

[0013] The anodeless battery 10 comprises a positive electrode container 12, a negative electrode container 14, a gasket 16, a positive electrode 18, a negative electrode current collector foil 20, a separator 22, an electrolyte (not shown) provided between the positive electrode 18 and the current collector foil 20 by being contained in the separator 22, a spacer 24, and a spring 26. The anodeless battery 10 does not have a negative electrode active material. When the anodeless battery 10 is charged, lithium ions released from the positive electrode 18 are deposited as lithium metal on the surface of the current collector foil 20, and this lithium metal is dissolved by discharge to supply lithium ions to the positive electrode 18.

[0014] The positive electrode can 12 houses the positive electrode 18. The positive electrode can 12 is made of metal and has a circular disc shape with a peripheral wall. The negative electrode can 14 houses the current collector foil 20. The negative electrode can 14 is made of metal and has a circular disc shape with a peripheral wall that is housed inside the positive electrode can 12. The gasket 16 is filled into the gap formed by the peripheral wall of the positive electrode can 12 and the peripheral wall of the negative electrode can 14, sealing the inside of the anodeless battery 10. The gasket 16 is made of resin, for example polypropylene, and has a ring shape.

[0015] The positive electrode 18 comprises a positive electrode current collector and a positive electrode active material. The positive electrode current collector is made of a metal other than lithium, such as aluminum. Examples of positive electrode active materials include lithium composite oxides and lithium composite phosphate compounds containing Li and one or more of Ni, Co, Mn, Fe, Al, Ti, V, Nb, Mo, and W. The positive electrode 18 may also contain a conductive additive or binder. The current collector foil 20 is a disc-shaped metal foil, such as copper foil.

[0016] The separator 22 is located between the positive electrode 18 and the current collector foil 20, separating the area of ​​the positive electrode 18 from the area of ​​the current collector foil 20. The spring 26 is a metal leaf spring located between the metal spacer 24 and the negative electrode can 14. The spring 26 presses the spacer 24 toward the positive electrode 18, causing the current collector foil 20, the separator 22, the electrolyte in the separator 22, and the positive electrode 18 to come into close contact. The electrolyte may be present not only between the positive electrode 18 and the current collector foil 20, but also in other spaces within the anodeless battery 10.

[0017] The electrolyte contains a solvent, a lithium salt, and additives. The solvent and lithium salt can be those commonly used in electrolytes for lithium-ion batteries. Examples of solvents include carbonates, ethers, and esters. Examples of carbonates include ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. The solvent may be a mixture of two or more. Examples of lithium salts include LiPF6, LiClO4, LiBF4, Lithium bis(trifluoromethanesulfonyl)imide, Lithium bis(fluorosulfonyl)imide, and Lithium bis(pentafluoroethanesulfonyl)imide.

[0018] The additive contains one or more compounds represented by the following general formula (1) and one or more compounds 1 to 2 represented by the following chemical formulas. In other words, the additive contains one or more compounds selected from the compound represented by general formula (1), compound 1, and compound 2, where n is an integer between 1 and 10. Compound 1 is Tetrakis(trimethylsiloxy)titanium, and compound 2 is Tetrakis(trimethylsilyloxy)silane.

[0019] [ka]

[0020] [ka]

[0021] Compounds represented by general formula (1) include compound 3 (n=3) or compound 4 (n=4), which are represented by the following chemical formulas. Compound 3 is Dodecamethylpentasiloxane, and compound 4 is Tetradecamethylhexasiloxane.

[0022] [ka]

[0023] The electrolyte may further contain lithium-ion battery additives. That is, even if the electrolyte contains common lithium-ion battery additives, the capacity retention rate during discharge of anodeless batteries is high. Examples of lithium-ion battery additives include one or more of compounds 5 to 9, represented by the following chemical formulas. Compound 5 is Fluoroetylene carbonate (FEC), compound 6 is Vinylene carbonate (VC), compound 7 is Lithium bis(fluorosulfonyl)amide (LiFSA), compound 8 is Potassium Bis(fluorosulfonyl)imide (KFSA), and compound 9 is Potassium Hexafluorophosphate (KPF6).

[0024] [ka] [Examples]

[0025] <Fabrication of an anodeless battery> (Fabrication of the positive electrode) Li, the positive electrode active material 1+x A positive electrode mixture 1 was prepared containing 96% by mass of CoO2 (particle size 2-10 μm), 1.5% by mass of acetylene black (AB) as a conductive additive, and 2.5% by mass of polyvinylidene difluoride (PVdF) as a binder. The positive electrode mixture 1 was applied to aluminum foil, which served as the positive electrode current collector, and dried to produce a positive electrode component 1. The positive electrode component 1 was punched out into a disc shape with a diameter of 12 mm to produce a positive electrode 1.

[0026] Similarly, cathode electrodes 2 to 6 were prepared from cathode mixtures of the following compositions (% represents mass%). The basis weight of the active material for cathode electrodes 1 to 6 is approximately 2 mAhcm², assuming a reversible capacity of 100% for the dissolution and extraction efficiency of metallic lithium. -2 I made it so that it would be like that. Positive electrode 2: Li 1+x96% of CoO₂ (particle diameter 1 to 5 μm), 1.5% of AB, 2.5% of PVdF Positive electrode 3: 93.5% of LiFePO₄, 4% of AB, 2.5% of PVdF Positive electrode 4: LiMn 0.6 Fe 0.4 93.5% of PO₄, 4% of AB, 2.5% of PVdF Positive electrode 5: LiNi 0.5 Co 0.2 Mn 0.3 96% of O₂, 2% of AB, 2% of PVdF Positive electrode 6: LiNi 0.83 Co 0.12 Mn 0.05 96% of O₂, 2% of AB, 2% of PVdF

[0027] (Preparation of Negative Electrode Current Collector) A rolled copper foil having a thickness of 20 μm was punched into a disc shape with a diameter of 16 mm, to prepare a current collector foil serving as a negative electrode current collector.

[0028] (Preparation of Electrolyte Solution) 30 volume% of ethylene carbonate (EC) and 70 volume% of dimethyl carbonate (DMC) were mixed, LiPF₆ was dissolved to obtain various concentrations to prepare a reference electrolyte solution, and then various additives of any one of the aforementioned Compound 1 to Compound 6 were added to prepare various electrolyte solutions. Further, various additives and any one of the aforementioned Compound 5 to Compound 9, which is a common lithium-ion battery additive (hereinafter may be referred to as "combination additive"), were further added to the reference electrolyte solution to prepare various electrolyte solutions.

[0029] (Preparation of Coin Cell) Various positive electrodes were placed in a positive electrode container, various electrolytes were dropped onto the positive electrodes, and a separator, which is a polypropylene microporous membrane with a thickness of 20 μm and a diameter of 19 mm, was placed on the positive electrodes and impregnated with the electrolyte. A gasket was attached to the inner circumference of the positive electrode container, and a current collector foil was placed on the separator. After sequentially placing a spacer, a spring, and a negative electrode container on the current collector foil, the positive electrode container and the negative electrode container were crimped together to produce various 2032 type coin cells (hereinafter sometimes simply referred to as "coin cells") of the examples, which are anodeless batteries. In addition, a comparative example coin cell was produced in the same manner as the coin cell of the examples, using a standard electrolyte without additives.

[0030] <Evaluation of anodeless batteries> The charging and discharging capacities of the coin cells of the example and comparative example were measured under the following conditions when charging and discharging using a charge / discharge device (Electrofield, ABE-1024-5V 0.1A-4).

[0031] Coin cell with positive electrode 1 or positive electrode 2 (Comparative Example 1, Comparative Examples 3a-3c, Comparative Examples 4a-4e, Comparative Example 5a, Examples 1-1-1-1-5, Examples 2-1-2-3, Examples 3a-1-3c-1, Examples 4a-1-4e-1, Example 5a-1) • Charging: 0.2mAcm up to 4.2V -2 (0.2262mA) constant current • Discharge: 0.2mAcm up to 3.0V -2 (0.2262mA) constant current

[0032] Coin cell equipped with positive electrode 3 (Comparative Example 5b, Example 5b-1) • Charging: 0.2mAcm up to 3.8V -2 (0.2262mA) constant current • Discharge: 0.2mAcm up to 2.5V -2 (0.2262mA) constant current

[0033] Coin cell equipped with positive electrode 4 (Comparative Example 5c, Example 5c-1) • Charging: 0.2mAcm up to 4.3V -2(0.2262mA) constant current, then 0.04mAcm -2 Constant voltage until it reaches • Discharge: 0.2mAcm up to 2.5V -2 (0.2262mA) constant current

[0034] Coin cell equipped with positive electrode 5 or positive electrode 6 (Comparative Example 5d, Comparative Example 5e, Example 5d-1, Example 5e-1) • Charging: 0.2mAcm up to 4.3V -2 (0.2262mA) constant current • Discharge: 0.2mAcm up to 3.0V -2 (0.2262mA) constant current

[0035] (Comparative Example 1 and Examples 1-1 to 1-5) Table 1 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The additive concentration (mass%) is calculated as follows: Additive mass (g) / (Reference electrolyte mass (g) + Additive mass (g)) × 100, i.e., Additive mass (g) / Electrolyte mass (g) × 100 (the same applies below). Discharge capacity (mAhg) at 30 cycles. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was defined as () × 100. Figure 2 shows the relationship between the number of charge / discharge cycles and the discharge capacity of the coin cell. Figure 3 shows the relationship between the number of charge / discharge cycles and the Coulomb efficiency (charge / discharge capacity efficiency). As shown in Table 1, Figure 2, and Figure 3, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0036] [Table 1]

[0037] (Comparative Example 1, Examples 1-3, and Examples 2-1 to 2-3) Table 2 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity (mAhg) at the 10th cycle was determined to be as follows. -1) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was defined as () × 100. Figure 4 shows the relationship between the number of charge / discharge cycles and the discharge capacity of the coin cell. Figure 5 shows the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell. As shown in Table 2, Figure 4, and Figure 5, the inclusion of compounds 1 to 4 in the electrolyte improved the capacity retention rate and stabilized the Coulomb efficiency of the coin cell.

[0038] [Table 2]

[0039] (Comparative Examples 3a-3c and Examples 3a-1-3c-1) Table 3 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte was 0.8 to 2.0 mol / dm³. 3 (See Table 3). Discharge capacity at 25 cycles (mAhg) -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was defined as ) × 100. Figure 6 shows the relationship between the number of charge / discharge cycles and the discharge capacity of the coin cell. Figure 7 shows the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell. As shown in Table 3, Figure 6, and Figure 7, regardless of the LiPF6 concentration of the electrolyte, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0040] [Table 3]

[0041] (Comparative Example 1, Comparative Example 4a, Examples 1-3, and Example 4a-1) Table 4 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity at the 15th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1The capacity retention rate (%) was defined as ) × 100. Figure 8 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 9 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 4, Figure 8, and Figure 9, by including compound 1, an additive, in the electrolyte, the capacity retention rate of the coin cell improved and the Coulomb efficiency stabilized, even when compound 5 (FEC), a co-additive, was also included in the electrolyte.

[0042] [Table 4]

[0043] (Comparative Example 1, Comparative Example 4b, Examples 1-3, and Example 4b-1) Table 5 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte was 1.0 mol / dm³. 3 The discharge capacity at the 30th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was defined as ) × 100. Figure 10 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 11 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 5, Figure 10, and Figure 11, even when compound 6 (VC), a common lithium-ion battery additive, is included in the electrolyte, the presence of compound 1, an additive in the electrolyte, improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0044] [Table 5]

[0045] (Comparative Example 1, Comparative Example 4c, Examples 1-3, and Example 4c-1) Table 6 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity (mAhg) at the 10th cycle was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1The capacity retention rate (%) was defined as ) × 100. Figure 12 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 13 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 6, Figure 12, and Figure 13, even when compound 7 (LiFSA), a common lithium-ion battery additive, is included in the electrolyte, the presence of compound 1, an additive, in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0046] [Table 6]

[0047] (Comparative Example 1, Comparative Example 4d, Examples 1-3, and Example 4d-1) Table 7 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte was 1.0 mol / dm³. 3 The discharge capacity (mAhg) after the 5th cycle was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was defined as ) × 100. Figure 14 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 15 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 7, Figure 14, and Figure 15, even when compound 8 (KFSA), a common lithium-ion battery additive, is included in the electrolyte, the presence of compound 1, an additive, in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0048] [Table 7]

[0049] (Comparative Example 1, Comparative Example 4e, Examples 1-3, and Example 4e-1) Table 8 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity at the 15th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1The capacity retention rate (%) was defined as ) × 100. Figure 16 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 17 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 8, Figure 16, and Figure 17, even when compound 9 (KPF6), a common lithium-ion battery additive, is included in the electrolyte, the presence of compound 1, an additive, in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0050] [Table 8]

[0051] (Comparative Example 5a and Example 5a-1) Table 9 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity at the 30th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was calculated as () × 100. Figure 18 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 19 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 9, Figure 18, and Figure 19, Li with a particle size of 1 to 5 μm was used as the positive electrode active material. 1+x Even with positive electrode 2 containing CoO2 as the positive electrode, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0052] [Table 9]

[0053] (Comparative Example 5b and Example 5b-1) Table 10 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity (mAhg) at the 10th cycle was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1The capacity retention rate (%) was defined as ) × 100. Figure 20 shows the relationship between the number of charge / discharge cycles and the discharge capacity of the coin cell. Figure 21 shows the relationship between the number of charge / discharge cycles and the Coulomb efficiency of the coin cell. As shown in Table 10, Figure 20, and Figure 21, even when positive electrode 3 containing LiFePO4 as the positive electrode active material is the positive electrode, the capacity retention rate of the coin cell is improved and the Coulomb efficiency is stabilized by including compound 1 in the electrolyte.

[0054] [Table 10]

[0055] (Comparative Example 5c and Example 5c-1) Table 11 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte was 1.0 mol / dm³. 3 The discharge capacity at the 30th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was calculated as ) × 100. Figure 22 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 23 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 11, Figure 22, and Figure 23, LiMn was used as the positive electrode active material. 0.6 Fe 0.4 Even with positive electrode 4 containing PO4 as the positive electrode, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0056] [Table 11]

[0057] (Comparative Example 5d and Example 5d-1) Table 12 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity at the 30th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1The capacity retention rate (%) was calculated as ) × 100. Figure 24 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 25 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 12, Figure 24, and Figure 25, LiNi was used as the positive electrode active material. 0.5 Co 0.2 Mn 0.3 Even with O2-containing positive electrode 5 as the positive electrode, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0058] [Table 12]

[0059] (Comparative Example 5e and Example 5e-1) Table 13 shows the capacity retention rates of various coin cells. The LiPF6 concentration of the reference electrolyte is 1.0 mol / dm³. 3 The discharge capacity at the 25th cycle (mAhg) was determined to be as follows. -1 ) / Maximum discharge capacity (mAhg -1 The capacity retention rate (%) was calculated as ) × 100. Figure 26 shows the relationship between the number of charge / discharge cycles and discharge capacity of the coin cell. Figure 27 shows the relationship between the number of charge / discharge cycles and Coulomb efficiency of the coin cell. As shown in Table 13, Figure 26, and Figure 27, LiNi was used as the positive electrode active material. 0.83 Co 0.12 Mn 0.05 Even with O2-containing positive electrode 6 as the positive electrode, the inclusion of compound 1 in the electrolyte improved the capacity retention rate of the coin cell and stabilized the Coulomb efficiency.

[0060] [Table 13] [Explanation of Symbols]

[0061] 10 Anodeless batteries 12 Positive electrode cans 14 Negative electrode cans 16 Gaskets 18 Positive electrode 20 Current collector foil 22 Separators 24 Spacers 26 Spring

Claims

1. An electrolyte for an anodeless battery containing a solvent, a lithium salt, and an additive, The aforementioned additive is an electrolyte for an anodeless battery comprising a compound represented by the following general formula (1) and one or more compounds 1 to 2 represented by the following chemical formula. 【Chemistry 1】 However, n is an integer between 1 and 10 (inclusive). 【Chemistry 2】

2. In claim 1, An electrolyte for an anodeless battery, wherein the compound represented by the general formula (1) is compound 3 or compound 4 represented by the following chemical formula. 【Transformation 3】

3. In claim 1, An electrolyte for anodeless batteries further containing one or more of compounds 5 to 9 represented by the following chemical formulas. 【Chemistry 4】

4. A positive electrode comprising a positive electrode current collector and a positive electrode active material, Negative electrode current collector and A separator is provided between the positive electrode and the negative electrode current collector, An electrolyte for an anodeless battery according to any one of claims 1 to 3, an anodeless battery having the following characteristics.

Images