Lithium ion battery negative electrode material, negative plate and battery

Abstract

The invention discloses a lithium ion battery negative electrode material which comprises the following raw materials: a negative electrode active material, a conductive agent, a thickening agent anda binder, and the thickening agent is nicandra physaloides seed colloid. The invention also discloses a lithium ion battery negative plate which comprises a current collector and a negative electrodematerial layer coating the surface of the current collector, and the negative electrode material layer is formed by the lithium ion battery negative electrode material. The invention further disclosesa lithium ion battery. The lithium ion battery comprises the lithium ion battery negative plate. According to the invention, the nicandra physaloides seed colloid is selected as the thickening agent,so that the infiltration and retention capacity of the negative plate to electrolyte is improved, the impedance of the battery is reduced, the rate capability is obviously improved, and the nicandraphysaloides seed colloid is high in elasticity after crosslinking and can better adapt to volume expansion during the charging and discharging of a negative electrode, thereby effectively improving the retention rate of the cycle capacity.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery negative electrode material, a negative electrode sheet and a battery. Background technique [0002] Due to the advantages of high energy density, excellent rate and power performance, long cycle life, safety and environmental protection, lithium-ion batteries are widely used in our daily life as an important chemical power source. In addition to long-term applications in traditional digital products such as mobile phones and portable computers, the application scope of lithium-ion batteries has gradually expanded to high-tech fields such as electric vehicles, aerospace and energy storage. [0003] Lithium-ion batteries are mainly composed of positive electrode sheets, negative electrode sheets, separators and electrolytes. The positive and negative electrode sheets are mainly composed of active materials, binders, thickeners, conductive agents...

AI Technical Summary

Problems solved by technology

However, when using PVDF as a binder, N-methylpyrrolidone (NMP) needs to be used as an organic solvent. NMP will pollute the environment and cause higher production costs

Therefore, commercial lithium-ion batteries usually use more environmentally friendly and low-cost aqueous systems to prepare negative electrodes. Due to the poor dispersion of common aqueous binders such as styrene-butadiene rubber (SBR), it is necessary to add sodium carboxymethyl cellulose Thickeners such as (CMC) are used to form a more stable slurry system, but the use of CMC / SBR combined system reduces the content of effective active materials in the negative plate on the one hand, and on the other hand, the CMC thickener has greater brittleness. After rolling, the structure will collapse due to excessive pressure, and problems such as powder drop and foil leakage will occur, and the volume expansion of the negative electrode material during the cycle cannot be effectively suppressed, resulting in a short cycle life.

[0004] Researchers have done more in-depth research on lithium-ion battery active materials, conductive agents and binders, but less research on thickeners. Therefore, how to choose a more effective thickener to combine with existing binders It is an important research direction in this field to further improve the electrochemical performance of lithium-ion batteries with better cooperation.

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