Electrolyte and battery

Abstract

The present invention belongs to the field of batteries, and specifically relates to an electrolyte and a battery. The electrolyte includes a lithium salt, a solvent, and a lithium salt additive; the lithium salt additive is one of LiF, Li2O, Li2CO3, Li3N, Li i NO3, or a mixture thereof. The lithium salt additive contained in the electrolyte has the following characteristics: 1. It can reduce the amount of Li in the electrolyte. + 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 SE I s on the negative electrode surface; 3. It can promote Li + The transmission of lithium in SE is inhibited, thereby improving the charge and discharge efficiency, cycle stability and safety performance of the battery.

Description

Technical Field

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

[0002] Lithium-ion batteries, with their high energy density, long cycle life, and fast charging rates, have become one of the most promising battery technologies in the current new energy market. With increasing demand for electronic products requiring fast charging speeds and extended battery life, improving lithium-ion batteries' fast-charging performance, cycle stability, and safety while maintaining their environmental friendliness and low cost is crucial.

[0003] As one of the key components of lithium-ion batteries, the electrolyte's formulation and performance largely determine the battery's working mechanism and performance. During the charge and discharge process, the conventional electrolyte currently used consumes some solvent molecules to form an organic-rich solid-electrolyte interface (SEIS) on the negative electrode surface. This reaction is irreversible, which leads to the formation of Li + The 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 is directly related to the beneficial SE I s inorganic compounds by changing the Li + -Solvent molecule coordination and / or Li + - Anion coordination creates Li + A 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 charge and discharge efficiency, cycle stability and safety performance. + High-performance electrolytes in a weakly solvated environment on the surface of SEs 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 comprises a lithium salt, a solvent and a lithium salt additive; the lithium salt additive is one of LiF, Li2O, Li2CO3, Li3N, LiNO3 or a mixture thereof.

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

[0008] The lithium salt is LiPF6, and 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 lithium salt and solvent, and ultrasonically dispersing the mixture 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 charge and discharge 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, 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 transport of lithium in SEIs 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 solutions 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 at 20-25°C and below 1% humidity, we injected 1.3 mol / L of LiPF6 into our company's 3.45Ah, 4.4V battery using an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte. The resulting battery was then subjected to a series of tests.

[0021] Example 1

[0022] In a dry room at 20-25°C and humidity below 1%, 0.5% by mass of inorganic lithium salt LiF particles was added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed under ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0023] Example 2

[0024] In a dry room at 20-25°C and humidity below 1%, 1% by mass of inorganic lithium salt LiF particles was added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed under ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0025] Example 3

[0026] In a dry room at 20-25°C and humidity below 1%, 3% by mass of inorganic lithium salt LiF particles were added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed under ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, and a series of tests were performed.

[0027] Example 4

[0028] In a dry room at 20-25°C and humidity below 1%, 5% by mass of inorganic lithium salt LiF particles were added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) solution. Ultrasonication was then applied for 15 minutes to fully disperse the electrolyte, yielding the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to produce a battery containing this electrolyte, which was then subjected to a series of tests.

[0029] Example 5

[0030] In a dry room at 20-25°C and below 1% humidity, 0.5% by mass of inorganic lithium salt Li₂O particles was added to our company's 1.3 mol / L LiPF₂ electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0031] Example 6

[0032] In a dry room at 20-25°C and humidity below 1%, 1% by mass of inorganic lithium salt Li₂O particles was added to our company's 1.3 mol / L LiPF₂ electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0033] Example 7

[0034] In a dry room at 20-25°C and humidity below 1%, 3% by mass of inorganic lithium salt Li₂O particles were added to our company's 1.3 mol / L LiPF₂ electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 3.45Ah, 4.4V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0035] Control group 2

[0036] In a dry room at 20-25°C and below 1% humidity, we injected 1.3 mol / L of Li PF6 in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte into our company's 5.35Ah, 4.45V laminated batteries. The resulting batteries, containing this electrolyte, were then subjected to a series of tests.

[0037] Example 8

[0038] In a dry room at 20-25°C and humidity below 1%, 1% by mass of inorganic lithium salt LiF particles was added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 5.35Ah, 4.45V laminated battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0039] Example 9

[0040] In a dry room at 20-25°C and below 1% humidity, 2% by mass of inorganic lithium salt LiF particles were added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 5.35Ah, 4.45V laminated battery to produce a battery containing this electrolyte, which was then subjected to a series of tests.

[0041] Control group 3

[0042] In a dry room at 20-25°C and below 1% humidity, we injected 1.3 mol / L of LiPF6 in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) electrolyte into our 4.35Ah, 4.48V battery. The resulting battery was then subjected to a series of tests.

[0043] Example 10

[0044] In a dry room at 20-25°C and humidity below 1%, 1% by mass of inorganic lithium salt LiF particles was added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate, 25:70:5:10) solution. Ultrasonication was performed for 15 minutes to fully disperse the electrolyte to obtain the electrolyte of this example. This electrolyte was then injected into our company's 4.35Ah, 4.48V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0045] Example 11

[0046] In a dry room at 20-25°C and humidity below 1%, 2% by mass of inorganic lithium salt LiF particles were added to our company's 1.3 mol / L LiPF6 electrolyte in an EC / DEC / PC / PP (ethylene carbonate / diethyl carbonate / propylene carbonate / propyl propionate = 25:70:5:10) and thoroughly dispersed by ultrasonication for 15 minutes to obtain the electrolyte of this example. This electrolyte was then injected into our company's 4.35Ah, 4.48V battery to obtain a battery containing this electrolyte, which was then subjected to a series of tests.

[0047] Conventional electrochemical performance tests and cycle performance tests were performed on the batteries of the embodiment and the control group. 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 groups 1-3 and 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 examples 1-7, it can be seen that different inorganic lithium salts can be seen. The effect of different lithium sources on improving the battery capacity retention rate Li F>Li2O.

[0054] In summary, the technical solution of this application aims to improve the charge and discharge 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, 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 transport of lithium in SEIs 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An electrolyte, characterized in that: Including a lithium salt, a solvent and a lithium salt additive; the lithium salt additive is one of LiF, Li2O, Li2CO3, Li3N, LiNO3 or a mixture thereof; the mass concentration of the lithium salt additive is 0.5-5%; The lithium salt is LiPF 6; The concentration of the lithium salt is 1.3 mol / L; 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 25:70:5:

10.

2. A method for preparing the electrolyte according to claim 1, characterized in that: The method comprises the following steps: adding a lithium salt additive into a mixture of lithium salt and a solvent, and performing ultrasonic dispersion to obtain the electrolyte.

3. A battery comprising the electrolyte according to claim 1.

4. The battery according to claim 3, characterized in that The battery is a lithium-ion battery; the electrode group structure of the lithium-ion battery is winding or lamination.

5. The battery according to claim 3, characterized in that The charging cut-off voltage of the battery is 4.2V-4.7V.

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