Lithium ion battery pre-lithiation electrolyte and lithium ion battery

Abstract

The invention discloses a lithium ion battery pre-lithiation electrolyte and a lithium ion battery, and relates to the technical field of lithium ion batteries, the lithium ion battery pre-lithiation electrolyte comprises the following components by weight: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, 0.5-10 parts of a cosolvent, and 0.5-10 parts of a lithium supplement agent; wherein the lithium supplement agent comprises at least one of 1, 2-dihydroxy benzene lithium and derivatives thereof; the lithium supplement agent is used for providing effective lithium ions for the lithium ion battery and making up lithium consumption in the charging and discharging process, and the cosolvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, dimethyl sulfoxide and ethylene glycol diacetate; the pre-lithiation electrolyte is simple in preparation process, lithium ions and electrons can be effectively released in the charging and discharging process of the battery, so that initial irreversible capacity loss caused by active lithium loss is compensated, the actual energy density of the lithium ion battery is improved, and the cycle life of the lithium ion battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a lithium ion battery pre-lithiation electrolyte and a lithium ion battery. Background Art

[0002] As electric vehicles and portable electronic devices have higher requirements for battery life, the development of high-energy-density lithium-ion batteries has become a hot topic of research. During the first charging process of lithium-ion batteries, the electrolyte is reduced and decomposed on the surface of the negative electrode to form a solid electrolyte membrane. The negative electrode material particles fall off and become inactivated, and the irreversible deposition of lithium metal will consume the active lithium of the positive electrode, resulting in the first cycle capacity loss of lithium-ion batteries. The first coulomb efficiency is low, which reduces the capacity and energy density. Pre-lithiation is to introduce lithium-containing substances into the battery material system and make the substances effectively release lithium ions and electrons to make up for the initial irreversible capacity loss caused by the loss of active lithium, thereby improving the capacity and cycle life of the battery.

[0003] In the prior art, the main lithium replenishment methods are positive electrode lithium replenishment and negative electrode lithium replenishment. Among them, positive electrode lithium replenishment includes adding positive electrode lithium replenishing agents, using lithium-rich positive electrodes and other methods, and negative electrode lithium replenishment includes adding negative electrode lithium replenishing agents, chemical pre-lithium treatment of the negative electrode, electrochemical pre-lithium treatment of the negative electrode and other methods.

[0004] However, lithium replenishment of positive and negative electrodes has strict requirements on the environment, and excessive lithium replenishment will cause lithium plating on the surface of the negative electrode, thereby forming lithium dendrites, posing a safety hazard; at the same time, in terms of production costs, the complexity of the lithium replenishment process, the time consumed and the price of raw materials will affect its commercial application. Summary of the invention

[0005] The purpose of the present invention is to provide a lithium ion battery pre-lithiation electrolyte and a lithium ion battery to solve the following technical problems:

[0006] How to simplify the lithium replenishment process of lithium-ion batteries and reduce process costs?

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] In a first aspect, the present invention discloses a lithium-ion battery pre-lithiation electrolyte, comprising the following components in parts by weight: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, 0.5-10 parts of a co-solvent, and 0.5-10 parts of a lithium supplement;

[0009] The lithium supplement comprises at least one of 1,2-dihydroxyphenyllithium and its derivatives; the lithium supplement is used to provide effective lithium ions for the lithium ion battery to compensate for the lithium consumption during the discharge process.

[0010] In a further embodiment of the present invention, the structural formula of the 1,2-dihydroxyphenyllithium is:

[0011]

[0012] The general structural formula of the derivative of 1,2-dihydroxyphenyllithium is as follows:

[0013]

[0014] Wherein, R is selected from any one of a hydrogen atom, a halogen atom, a C1-12 hydrocarbon group or hydrocarbon oxygen substituent, a C1-12 carbonyl group, a sulfonic acid group, and a sulfate ester group.

[0015] In a further embodiment of the present invention, the derivatives of 1,2-dihydroxybenzene lithium include 3,4-dihydroxybenzonitrile dilithium, 4-fluoro-1,2-dihydroxybenzene lithium, and 4-methylsulfonic acid-1,2-dihydroxybenzene lithium, and the chemical formula thereof is as follows:

[0016] 3,4-Dihydroxybenzonitrile dilithium:

[0017] 4-Fluoro-1,2-dihydroxyphenyllithium:

[0018] 4-Methanesulfonic acid-1,2-dihydroxyphenyllithium:

[0019] In a further embodiment of the present invention: the organic solvent is one or more of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC); the organic solvent is mainly used to dissolve lithium salts and provide an environment for the transmission of lithium ions.

[0020] In a further embodiment of the present invention: the lithium salt includes one or more of lithium hexafluorophosphate (Li PF6), lithium bis(fluorosulfonyl)imide (Li FS I), and lithium bis(trifluoromethylsulfonyl)imide (Li TFS I); the lithium salt mainly provides lithium ions that can migrate for lithium-ion batteries.

[0021] In a further embodiment of the present invention: the co-solvent includes one or more of ethylene glycol dimethyl ether (DME), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and ethylene glycol diacetate (EGDA); the co-solvent is mainly used to increase the solubility of the lithium supplement in the electrolyte.

[0022] In a second aspect, the present invention further discloses a lithium-ion battery, wherein the lithium-ion battery contains the lithium-ion battery pre-lithiation electrolyte as described above.

[0023] In a further embodiment of the present invention, the injection amount of the pre-lithiation electrolyte of the lithium-ion battery is 3.35 g / Ah, the charging current is 1C, and the charging voltage is 3.0V-4.3V.

[0024] Beneficial effects of the present invention:

[0025] The lithium ion battery pre-lithiation electrolyte of the present invention comprises an organic solvent, a lithium salt, a co-solvent and a lithium supplement agent, wherein the lithium supplement agent is selected from 1,2-dihydroxyphenyl lithium and its derivatives, and the co-solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, dimethyl sulfoxide, and ethylene glycol diacetate. The preparation process of the pre-lithiation electrolyte is simple, and during the charge and discharge process of the battery, lithium ions and electrons can be effectively released to compensate for the initial irreversible capacity loss caused by the loss of active lithium, thereby improving the actual energy density and cycle life of the lithium ion battery. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0028] Example 1

[0029] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0030] Ethylene carbonate (EC) 30 g, diethyl carbonate (DEC) 30 g, ethylene glycol dimethyl ether (DME) 0.5 g, lithium hexafluorophosphate (LiPF6) 10 g, 1,2-dihydroxyphenyllithium 0.5 g.

[0031] In an argon atmosphere glove box with a moisture content of less than 0.1 ppm, ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed evenly, and then dry lithium hexafluorophosphate (LiPF6) is added to dissolve and mix thoroughly; ethylene glycol dimethyl ether (DME) and 1,2-dihydroxyphenyllithium are added to the above electrolyte, and the pre-lithiation electrolyte is obtained after mixing evenly.

[0032] Example 2

[0033] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0034] Ethylene carbonate (EC) 35 g, diethyl carbonate (DEC) 40 g, ethylene glycol dimethyl ether (DME) 5 g, lithium hexafluorophosphate (Li PF6) 12.5 g, 1,2-dihydroxyphenyllithium 5 g.

[0035] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0036] Example 3

[0037] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0038] Ethylene carbonate (EC) 45 g, diethyl carbonate (DEC) 45 g, ethylene glycol dimethyl ether (DME) 10 g, lithium hexafluorophosphate (LiPF6) 15 g, 1,2-dihydroxyphenyllithium 10 g.

[0039] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0040] Example 4

[0041] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0042] Ethylene carbonate (EC) 35 g, diethyl carbonate (DEC) 40 g, tetrahydrofuran (THF) 5 g, lithium hexafluorophosphate (LiPF6) 12.5 g, 1,2-dihydroxyphenyllithium 5 g.

[0043] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0044] Example 5

[0045] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0046] Ethylene carbonate (EC) 30 g, dimethyl carbonate (DMC) 30 g, tetrahydrofuran (THF) 0.5 g, lithium bis(fluorosulfonyl)imide (LiFSI) 10 g, and dilithium 3,4-dihydroxybenzonitrile 0.5 g.

[0047] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0048] Example 6

[0049] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0050] Ethylene carbonate (EC) 35 g, dimethyl carbonate (DMC) 40 g, tetrahydrofuran (THF) 5 g, lithium bis(fluorosulfonyl)imide (LiFSI) 12.5 g, and dilithium 3,4-dihydroxybenzonitrile 5 g.

[0051] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0052] Example 7

[0053] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0054] Ethylene carbonate (EC) 45 g, dimethyl carbonate (DMC) 45 g, tetrahydrofuran (THF) 10 g, lithium bis(fluorosulfonyl)imide (LiFSI) 15 g, and dilithium 3,4-dihydroxybenzonitrile 10 g.

[0055] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0056] Example 8

[0057] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0058] Ethylene carbonate (EC) 30 g, diethyl carbonate (DEC) 20 g, ethyl methyl carbonate (EMC) 10 g, dimethyl sulfoxide (DMSO) 0.5 g, lithium hexafluorophosphate (LiPF6) 10 g, 4-fluoro-1,2-dihydroxyphenyllithium 0.5 g.

[0059] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0060] Example 9

[0061] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0062] Ethylene carbonate (EC) 30 g, diethyl carbonate (DEC) 30 g, ethyl methyl carbonate (EMC) 15 g, dimethyl sulfoxide (DMSO) 5 g, lithium hexafluorophosphate (LiPF6) 12.5 g, 4-fluoro-1,2-dihydroxyphenyllithium 5 g.

[0063] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0064] Example 10

[0065] The pre-lithiation electrolyte of the lithium-ion battery of this embodiment includes the following substances:

[0066] Ethylene carbonate (EC) 35 g, diethyl carbonate (DEC) 35 g, ethyl methyl carbonate (EMC) 20 g, dimethyl sulfoxide (DMSO) 10 g, lithium hexafluorophosphate (LiPF6) 15 g, 4-fluoro-1,2-dihydroxybenzene lithium salt 10 g.

[0067] The preparation method of the pre-lithiation electrolyte is the same as that in Example 1.

[0068] Comparative Example 1

[0069] The only difference from Example 2 is that ethylene glycol dimethyl ether (DME) and 1,2-dihydroxyphenyllithium are not added to the pre-lithiation electrolyte.

[0070] Comparative Example 2

[0071] The only difference from Example 2 is that no 1,2-dihydroxyphenyllithium is added to the pre-lithiation electrolyte.

[0072] The pre-lithiation electrolytes prepared in Examples 1-10 and Comparative Examples 1-2 were used to make lithium-ion batteries at 3.35 g / Ah, and electrochemical performance tests were performed under the conditions of a charging current of 1C and a charging voltage of 3.0 V to 4.3 V. The test results are listed in Table 1. Table 1 is as follows:

[0073] Table 1

[0074] serial number First coulombic efficiency (%) Capacity retention after 200 cycles (%) Example 1 87.4 88.1 Example 2 89.8 90.4 Example 3 88.8 89.5 Example 4 89.9 89.8 Example 5 88.5 88.6 Example 6 90.3 91.5 Example 7 89.2 89.4 Example 8 88.6 89.7 Example 9 90.1 92.1 Example 10 89.4 89.6 Comparative Example 1 84.3 85.2 Comparative Example 2 85.2 86.7

[0075] By analyzing the data in Table 1, it can be seen that the lithium-ion batteries formed by the pre-lithiation electrolytes prepared in Examples 1-10 have stronger electrochemical properties than those in Comparative Examples 1-2.

[0077] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A lithium ion battery pre-lithiation electrolyte, characterized in that: The invention comprises the following components in parts by weight: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, 0.5-10 parts of a co-solvent, and 0.5-10 parts of a lithium supplement; Wherein, the lithium supplement comprises at least one of 1,2-dihydroxyphenyllithium and its derivatives.

2. The lithium-ion battery pre-lithiation electrolyte according to claim 1, characterized in that: The structural formula of the 1,2-dihydroxyphenyllithium is: The general structural formula of the derivative of 1,2-dihydroxyphenyllithium is as follows: Wherein, R is selected from any one of a hydrogen atom, a halogen atom, a C1-12 hydrocarbon group or hydrocarbon oxygen substituent, a C1-12 carbonyl group, a sulfonic acid group, and a sulfate ester group.

3. The lithium ion battery pre-lithiation electrolyte according to claim 2, characterized in that: The derivatives of 1,2-dihydroxyphenyllithium include the following compounds:

4. The lithium-ion battery pre-lithiation electrolyte according to claim 1, characterized in that: The organic solvent is one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

5. The lithium-ion battery pre-lithiation electrolyte according to claim 1, characterized in that: The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.

6. The lithium-ion battery pre-lithiation electrolyte according to claim 1, characterized in that: The co-solvent includes one or more of ethylene glycol dimethyl ether, tetrahydrofuran, dimethyl sulfoxide, and ethylene glycol diacetate.

7. A lithium ion battery, characterized in that: The lithium-ion battery contains the lithium-ion battery pre-lithiation electrolyte according to any one of claims 1 to 6.

8. The lithium-ion battery according to claim 7, characterized in that: The injection amount of the pre-lithiation electrolyte of the lithium-ion battery is 3.35g / Ah, the charging current is 1C, and the charging voltage is 3.0V-4.3V.

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