High-voltage electrolyte containing novel additive

Abstract

The invention discloses high-voltage electrolyte containing a novel additive. The high-voltage electrolyte is prepared from the following raw materials in percentage by mass: lithium salt, 85 to 95 percent of organic solvents, 2 to 8 percent of additives A and 5 to 8 percent of additives B. The high-voltage electrolyte containing the novel additive has the advantages that dibenzothiophene sulfonecontaining sulfur elements is used as a high-voltage additive of the lithium-ion electrolyte; the battery interface resistance is improved; the high-voltage performance of a lithium-ion battery is improved; the negative element material can be effectively coated by ethyl ester sulfate; the room temperature cycle performance under high voltage is greatly improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a high-voltage electrolyte solution containing novel additives. Background technique [0002] Lithium-ion batteries have the advantages of high working voltage, large specific capacity, long cycle life, no memory effect, and environmental friendliness, and have been widely used in electronic products such as communication tools and notebook computers. With the application of lithium-ion batteries in electric vehicles and hybrid electric vehicles, people have put forward higher requirements for the energy density of lithium batteries, especially the mass energy density; currently there are many ways to improve the energy density of batteries and improve the performance of positive electrode materials. Gram capacity is an effective way. Among them, the most conventional method is to use NCM with high Ni content as the positive electrode material, but at present, the s...

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Problems solved by technology

With the application of lithium-ion batteries in electric vehicles and hybrid electric vehicles, people have put forward higher requirements for the energy density of lithium batteries, especially the mass energy density; currently there are many ways to improve the energy density of batteries and improve the performance of positive electrode materials. Gram capacity is an effective way. Among them, the most conventional method is to use NCM with high Ni content as the positive electrode material, but at present, the synthesis process of high-nickel ternary materials, especially NCM811 and NCA, is not mature enough. , and the higher the nickel content, the worse the thermal stability, which affects the safety performance of the battery. In addition, increasing the electrochemical window of the positive electrode material can also effectively increase the gram capacity of the positive electrode material. For example, the electrochemical performance of NCM523 material at 2.7-4.2V Within the window, the capacity can reach about 155mAh / g at a charge-discharge current of 1C. When the electrochemical window increases to 4.2-4.4V, the gram capacity can increase to about 175mAh / g under the same conditions; current constraints that limit the development of high-voltage materials There are two main ones. The first is the positive electrode material itself. Under high voltage conditions, a large number of lithium ions in the positive electrode material will come out, causing the structure of the electrode material to collapse, affecting the safety performance and cycle stability of the battery. However, as the positive electrode material is coated and doped With the improvement of miscellaneous technologies, material manufacturers can solve this problem well

The second is the limitation of the electrolyte. The electrolyte will be oxidized and decomposed under high pressure, especially above 4.5V, to produce a large amount of gas. On the one hand, it will corrode the positive electrode material and cause the material capacity to decrease. On the other hand, the battery bulge seriously threatens the safety performance of the battery cell. , which restricts the further development of high-voltage lithium-ion batteries, so a high-voltage electrolyte containing new additives is required

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