Lithium ion battery electrolyte and lithium ion battery

Abstract

The invention discloses a lithium ion battery electrolyte and a lithium ion battery. The electrolyte comprises the following components in parts by weight: 60-90 parts of an organic solvent, 10-15 parts of lithium salt and 0.5-10 parts of a lithium supplement agent, wherein the lithium supplement agent is at least one of lithium 1, 2-benzene disulfide, lithium 1, 3-benzene disulfide and lithium 1, 4-benzene disulfide. The lithium ion battery 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 the 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 electrolyte and a lithium ion battery. Background Art

[0002] With the booming development of consumer electronic devices and electric vehicles, people have put forward higher requirements for the energy density of energy storage devices. Among them, lithium-ion batteries have greatly facilitated the supply and use of energy with their advantages such as long life, high output voltage and no memory effect, and have become the most commonly used energy storage device. One of the problems currently faced by lithium-ion batteries is the low initial coulomb efficiency, which leads to low energy density of the battery. This is mainly due to the formation of SEI film on the negative electrode surface during the initial charge and discharge process of lithium-ion batteries, which consumes some active lithium ions, volume expansion effect, irreversible side reactions and irreversible decomposition of oxides. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a lithium-ion battery electrolyte based on lithium supplementation, and directly adds a lithium supplement agent into the electrolyte to simplify the lithium supplementation operation process of the lithium battery. The lithium supplement agent effectively releases lithium ions in the electrolyte to compensate for the lithium consumption of the battery during the charge / discharge reaction process, effectively improving the actual energy density and cycle stability of the lithium-ion battery.

[0004] A further technical problem to be solved by the present invention is to provide a lithium ion battery.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A lithium ion battery electrolyte, comprising the following components by weight: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, and 0.5-10 parts of a lithium supplement;

[0007] Wherein, the lithium supplement is at least one of 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium.

[0008] Wherein, the structural formula of the 1,2-phenylenedisulfide lithium is:

[0009] ;

[0010] The structural formula of the 1,3-phenylenedisulfide lithium is:

[0011] ;

[0012] The structural formula of the 1,4-phenylenedisulfide lithium is:

[0013] .

[0014] Wherein, the organic solvent is one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0015] Wherein, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate.

[0016] A lithium ion battery comprises the above-mentioned lithium ion battery electrolyte.

[0017] Wherein, in the lithium-ion battery, the injection amount of the lithium-ion battery electrolyte is 3~3.5 g / Ah.

[0018] The beneficial effects of the present invention are as follows:

[0019] The lithium-ion battery lithium supplement electrolyte of the present invention comprises an organic solvent, a lithium salt and a lithium supplement agent, wherein the lithium supplement agent is selected from at least one of 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium. The lithium-ion battery electrolyte has a simple preparation process, and can effectively release lithium ions and electrons during the charge and discharge process of the battery 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the electrochemical performance test of Examples 1 to 7 of the present invention and a comparative example. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] A lithium ion battery electrolyte, the electrolyte comprising the following components in weight proportion: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, and 0.5-10 parts of a lithium supplement;

[0023] Wherein, the lithium supplement is at least one of 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium.

[0024] The main principle of the present invention is to directly add a lithium replenisher into the electrolyte to simplify the lithium replenishment operation process of the lithium battery. Lithium replenishment refers to adding a lithium source to the inside of the lithium-ion battery before the battery works to replenish lithium ions, compensate for irreversible lithium loss, and improve battery performance. The lithium replenisher of the present invention is selected from 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium. During the battery charging process, 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium can release lithium ions and are converted into cyclic dimers, trimers and tetramers respectively, without affecting other components in the electrolyte.

[0025] Wherein, the structural formula of the 1,2-phenylenedisulfide lithium is:

[0026] ;

[0027] The structural formula of the 1,3-phenylenedisulfide lithium is:

[0028] ;

[0029] The structural formula of the 1,4-phenylenedisulfide lithium is:

[0030] .

[0031] Furthermore, the organic solvent is one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0032] Furthermore, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate.

[0033] The present invention also provides a lithium ion battery, which comprises the above-mentioned lithium ion battery electrolyte.

[0034] In the lithium ion battery, the injection amount of the lithium ion battery electrolyte is 3-3.5 g / Ah.

[0035] 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.

[0036] Example 1

[0037] The lithium supplement electrolyte of this embodiment includes the following substances:

[0038] 30 g of ethylene carbonate, 30 g of diethyl carbonate, 10 g of lithium hexafluorophosphate, and 0.5 g of lithium 1,2-phenylenedisulfide.

[0039] In an argon atmosphere glove box with a moisture content of less than 0.1 ppm, ethylene carbonate and diethyl carbonate are mixed evenly, and then dry lithium hexafluorophosphate is added to dissolve and fully mixed; lithium 1,2-phenylenedisulfide is added to the above electrolyte, and after mixing evenly, a lithium-supplemented electrolyte is obtained.

[0040] Example 2

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

[0042] 35 g of ethylene carbonate, 40 g of diethyl carbonate, 12.5 g of lithium bis(fluorosulfonyl)imide, and 5 g of lithium 1,2-phenylenedisulfide.

[0043] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0044] Example 3

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

[0046] 30 g of ethylene carbonate, 60 g of ethyl methyl carbonate, 15 g of lithium hexafluorophosphate, and 10 g of lithium 1,2-phenylenedisulfide.

[0047] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0048] Example 4

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

[0050] 30 g of ethylene carbonate, 30 g of dimethyl carbonate, 10 g of lithium bis(fluorosulfonyl)imide, and 0.5 g of lithium 1,3-phenylenedisulfide.

[0051] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0052] Example 5

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

[0054] 35 g of ethylene carbonate, 40 g of diethyl carbonate, 12.5 g of lithium hexafluorophosphate, and 5 g of lithium 1,3-phenylenedisulfide.

[0055] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0056] Example 6

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

[0058] 35 g of ethylene carbonate, 40 g of dimethyl carbonate, 12.5 g of lithium hexafluorophosphate, and 0.5 g of lithium 1,4-phenylenedisulfide.

[0059] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0060] Example 7

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

[0062] 45 g of ethylene carbonate, 45 g of ethyl methyl carbonate, 15 g of lithium bis(fluorosulfonyl)imide, and 5 g of lithium 1,4-phenylenedisulfide.

[0063] The preparation method of the lithium-supplementing electrolyte is the same as that of Example 1.

[0064] Comparative Example 1

[0065] The only difference from Example 1 is that no 1,2-phenylenedisulfide lithium is added to the electrolyte.

[0066] The lithium-supplemented electrolytes prepared in Examples 1-10 and Comparative Example 1 were used to make lithium-ion batteries at 3.4 g / Ah, and the electrochemical performance tests were carried out under the conditions of a charging current of 1C and a charging voltage of 3.0V-4.3V. The test results are listed in Tables 1 and Figure 1 In Table 1, the following is shown:

[0067]

[0068] Table 1 and Figure 1 By analyzing the data in, it can be seen that the lithium-ion batteries formed by the lithium-supplemented electrolytes prepared in Examples 1-7 have higher first coulombic efficiency and capacity retention rate than those in Comparative Example 1.

[0069] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0070] The parts not elaborated in detail in the description of the present invention belong to the known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A lithium ion battery electrolyte, characterized in that: The lithium-ion battery electrolyte comprises the following components by weight: 60-90 parts of an organic solvent, 10-15 parts of a lithium salt, and 0.5-10 parts of a lithium supplement; Wherein, the lithium supplement is at least one of 1,2-phenylenedisulfide lithium, 1,3-phenylenedisulfide lithium and 1,4-phenylenedisulfide lithium.

2. The lithium ion battery electrolyte according to claim 1, characterized in that: The structural formula of the 1,2-phenylenedisulfide lithium is: ； The structural formula of the 1,3-phenylenedisulfide lithium is: ； The structural formula of the 1,4-phenylenedisulfide lithium is: 。 3. The lithium ion battery 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.

4. The lithium ion battery electrolyte according to claim 1, characterized in that: The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium bis(oxalatoborate), and lithium difluorooxalatoborate.

5. A lithium ion battery, characterized in that: A lithium-ion battery electrolyte comprising the electrolyte of any one of claims 1 to 4.

6. The lithium-ion battery according to claim 5, characterized in that: In the lithium ion battery, the injection amount of the lithium ion battery electrolyte is 3-3.5 g / Ah.

Images