Electrolyte and battery

Abstract

The invention belongs to the field of batteries, and particularly relates to an electrolyte and a battery. The electrolyte comprises a lithium salt, a solvent and a lithium salt additive; and the lithium salt additive is one or a mixture of Li F, Li2O, Li2CO3, Li3N and L i NO3. The lithium salt additive contained in the electrolyte has the following characteristics: 1, an L < i + > weak solvation environment can be created by reducing Li < + >-solvent molecule coordination and increasing Li < + >-anion coordination in the electrolyte; 2, the decomposition of solvent molecules in the electrolyte can be inhibited, and inorganic-rich and organic-poor SEIs are formed on the surface of the negative electrode; and 3, the transmission of Li < + > in SE I s can be promoted, and the growth of lithium dendrites is inhibited. And thus, the charge-discharge efficiency, the cycle stability and the safety performance of the battery are improved.

Description

Technical Field

[0001] The invention belongs to the field of batteries, and in particular relates to an electrolyte and a battery. Background Art

[0002] Lithium-ion batteries have become one of the most promising battery technologies in the current new energy market due to their high energy density, long cycle life, and fast charging rate. As people's demand for fast charging speed and long standby time of electronic products continues to increase, it is of great significance to improve the fast charging performance, cycle stability and safety performance of lithium-ion batteries while maintaining their environmental protection and low cost.

[0003] As one of the key components of lithium-ion batteries, the formulation and performance of the electrolyte largely determine the working mechanism and performance of the battery. The conventional electrolyte currently used consumes some solvent molecules during the charge and discharge process to form an organic-rich solid-electrolyte interface (SE I s) on the negative electrode surface. This reaction is irreversible, which leads to Li + Irreversible loss of the negative electrode surface leads to problems such as reduced battery charge and discharge efficiency, short cycle life and low energy density. Studies have shown that the evolution of SE I s on the negative electrode surface is related to the Li + The solvation structure of the SE I s is directly related to that of the inorganic compounds, and the beneficial SE I s can be obtained by changing the Li + -Solvent molecule coordination and / or Li + - Anion coordination creates Li + The weak solvation environment inhibits the decomposition of solvent molecules in the electrolyte, forming inorganic-rich and organic-poor SE I s on the negative electrode surface, promoting Li + The transmission in SE I s effectively inhibits the growth of lithium dendrites and improves the battery charging and discharging efficiency, cycle stability and safety performance. + High-performance electrolytes in a weakly solvated environment on the surface of SE Is are one of the current trends in electrolyte research. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an electrolyte and a battery.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] An electrolyte comprising a lithium salt, a solvent and a lithium salt additive; the lithium salt additive is LiF, Li 2 O. Li 2 CO 3 , Li 3 N、L i NO 3 One or a mixture of.

[0007] The mass concentration of the lithium salt additive is 0.1-10%, preferably 0.5-5%.

[0008] The lithium salt is LiPF 6 The concentration of the lithium salt is 1-1.5 mol / L, preferably 1.3 mol / L.

[0009] The solvent is one of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate and propyl propionate, or a mixture thereof.

[0010] The solvent is a mixture of ethylene carbonate, diethyl carbonate, propylene carbonate and propyl propionate, and the mass ratio of ethylene carbonate, diethyl carbonate, propylene carbonate and propyl propionate is (10-30):

[0011] (60-80):(10-30):(5-15); preferably 25:70:5:10.

[0012] The present invention also includes a method for preparing the electrolyte, comprising the following steps: adding a lithium salt additive to a mixture of a lithium salt and a solvent, and performing ultrasonic dispersion to obtain the electrolyte.

[0013] The present invention also includes a battery, comprising the electrolyte.

[0014] The battery is a lithium-ion battery; the electrode group structure of the lithium-ion battery is winding or lamination.

[0015] The charging cut-off voltage of the battery is 4.2V-4.7V.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The technical solution of this application aims to improve the charging and discharging efficiency, cycle life and energy density of conventional electrolytes. + Weak solvation environment promotes Li + transmission and other problems, an electrolyte and a battery containing the electrolyte are provided, wherein the lithium salt additive contained in the electrolyte has the following characteristics: 1. It can reduce the Li + -Solvent molecules coordinate and increase Li + - Anion coordination to create Li + Weak solvent environment; 2. It can inhibit the decomposition of solvent molecules in the electrolyte and form inorganic-rich and organic-poor SEIs on the negative electrode surface; 3. It can promote Li + The transmission in SEI s inhibits the growth of lithium dendrites, thereby improving the charge and discharge efficiency, cycle stability and safety performance of the battery. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the examples and control groups.

[0019] Control group 1

[0020] In a dry room with a temperature of 20-25°C and a humidity of less than 1%, 1.3 mol / L LiPF was injected into our 3.45Ah, 4.4V battery. 6 EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte was prepared to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0021] Example 1

[0022] In a dry room with a temperature of 20-25°C and a humidity of less than 1%, 1.3 mol / L LiPF 6 0.5% inorganic lithium salt LiF particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 3.45Ah, 4.4V battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0023] Example 2

[0024] In a dry room with a temperature of 20-25°C and a humidity of less than 1%, 1.3 mol / L LiPF 6 1% inorganic lithium salt LiF particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse the particles. The electrolyte was injected into the company's 3.45Ah, 4.4V battery to obtain a battery containing the electrolyte, and a series of tests were performed.

[0025] Example 3

[0026] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 63% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 3.45Ah, 4.4V battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0027] Example 4

[0028] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 5% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 3.45Ah, 4.4V battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0029] Example 5

[0030] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 0.5% of inorganic lithium salt Li was added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte. 2 O particles were fully dispersed by ultrasonic treatment for 15 minutes to obtain the electrolyte of this embodiment. The electrolyte was injected into a 3.45Ah, 4.4V battery of our company to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0031] Example 6

[0032] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 1% inorganic lithium salt Li was added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte. 2 O particles were fully dispersed by ultrasonic treatment for 15 minutes to obtain the electrolyte of this embodiment. The electrolyte was injected into a 3.45Ah, 4.4V battery of our company to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0033] Example 7

[0034] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 3% of inorganic lithium salt Li was added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte. 2 O particles were fully dispersed by ultrasonic treatment for 15 minutes to obtain the electrolyte of this embodiment. The electrolyte was injected into a 3.45Ah, 4.4V battery of our company to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0035] Control group 2

[0036] In a dry room with a temperature of 20-25°C and a humidity of less than 1%, 1.3 mol / L Li PF was injected into our 5.35Ah, 4.45V laminated battery. 6 EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte was prepared to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0037] Example 8

[0038] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 1% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 5.35Ah, 4.45V laminated battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0039] Example 9

[0040] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 2% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 5.35Ah, 4.45V laminated battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0041] Control group 3

[0042] In a dry room with a temperature of 20-25°C and a humidity of less than 1%, 1.3 mol / L Li PF was injected into our 4.35Ah, 4.48V battery. 6 EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte was prepared to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0043] Example 10

[0044] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 1% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate - 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 4.35Ah, 4.48V battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0045] Embodiment 11

[0046] In a dry room at a temperature of 20-25°C and a humidity of less than 1%, provide our company with 1.3 mol / L Li PF 6 2% inorganic lithium salt Li F particles were added to the EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte, and the electrolyte of this embodiment was obtained by ultrasonication for 15 minutes to fully disperse them. The electrolyte was injected into the company's 4.35Ah, 4.48V battery to obtain a battery containing the electrolyte, and a series of tests were carried out.

[0047] The batteries of the embodiment and the control group were subjected to conventional electrochemical performance tests and cycle performance tests. The test results are shown in Tables 1 and 2.

[0048] Table 1

[0049]

[0050] Table 2

[0051]

[0052]

[0053] The test results show that: 1. By comparing the control group 1-3 and the examples 1-11, it can be seen that adding different concentrations of inorganic lithium salt particles to the electrolyte can not only improve the initial charge and discharge efficiency, but also have excellent cycle performance, and its K value and AC internal resistance have no disadvantageous effect; 2. By comparing the control group 1 and the examples 1-7, it can be seen that different inorganic lithium salts can be seen. The effect of different lithium sources on the improvement of battery capacity retention rate Li F>Li 2 O.

[0054] In summary, the technical solution of this application aims to improve the charging and discharging efficiency, cycle life and energy density of conventional electrolytes, and + Weak solvation environment promotes Li + transmission and other problems, an electrolyte and a battery containing the electrolyte are provided, wherein the lithium salt additive contained in the electrolyte has the following characteristics: 1. It can reduce the Li + -Solvent molecules coordinate and increase Li + - Anion coordination to create Li + Weak solvent environment; 2. It can inhibit the decomposition of solvent molecules in the electrolyte and form inorganic-rich and organic-poor SEIs on the negative electrode surface; 3. It can promote Li + The transmission in SEI s inhibits the growth of lithium dendrites, thereby improving the charge and discharge efficiency, cycle stability and safety performance of the battery.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An electrolyte, characterized in that: It includes lithium salt, solvent and lithium salt additive; the lithium salt additive is one of LiF, Li2O, Li2CO3, Li3N, LiNO3 or a mixture thereof.

2. The electrolyte according to claim 1, characterized in that The mass concentration of the lithium salt additive is 0.1-10%, preferably 0.5-5%.

3. The electrolyte according to claim 1, characterized in that The lithium salt is LiPF6.

4. The electrolyte according to claim 1, characterized in that The concentration of the lithium salt is 1-1.5 mol / L, preferably 1.3 mol / L.

5. The electrolyte according to claim 1, characterized in that The solvent is one of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate and propyl propionate, or a mixture thereof.

6. The electrolyte according to claim 1, characterized in that The solvent is a mixture of ethylene carbonate EC, diethyl carbonate DEC, propylene carbonate PC and propyl propionate PP, and the mass ratio of ethylene carbonate EC, diethyl carbonate DEC, propylene carbonate PC and propyl propionate PP is (10-30):(60-80):(10-30):(5-15); preferably 25:70:5:

10.

7. A method for preparing the electrolyte according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: adding a lithium salt additive into a mixture of a lithium salt and a solvent, and ultrasonically dispersing the mixture to obtain the electrolyte.

8. A battery comprising the electrolyte according to any one of claims 1 to 6.

9. The battery according to claim 8, characterized in that The battery is a lithium-ion battery; the electrode group structure of the lithium-ion battery is winding or lamination.

10. The battery according to claim 8, characterized in that The charging cut-off voltage of the battery is 4.2V-4.7V.

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