Silicon carbon negative electrode lithium ion battery

Abstract

The invention provides a silicon carbon negative electrode lithium ion battery. The silicon carbon negative electrode lithium ion battery comprises a positive electrode plate, a negative electrode plate, a diaphragm and an electrolyte; the positive electrode plate comprises a positive electrode current collector and positive electrode paste coated on the surface of the positive electrode current collector; the negative electrode plate comprises a negative electrode current collector and negative electrode paste coated on the surface of the negative electrode current collector; the positive electrode paste comprises a lithium nickel cobalt manganate ternary positive electrode material, a conductive agent and a positive electrode binder; the negative electrode paste comprises a silicon carbon negative electrode material, a conductive agent and a negative electrode binder; the electrolyte comprises an organic solvent, a lithium salt, a negative electrode film-forming agent and functionaladditives; the functional additives comprise polysiloxane and LiPC<4>O<4>F<2>, wherein polysiloxane accounts for 2-10mass% of the electrolyte; and LiPC<4>O<4>F<2> accounts for 0.1-2mass% of the electrolyte.

Description

【Technical field】 [0001] The invention belongs to the technical field of batteries, and in particular relates to a silicon-carbon negative electrode lithium-ion battery. 【Background technique】 [0002] At present, in order to increase the energy density of lithium-ion batteries, it is mainly through the selection of positive and negative active materials with high capacity, high voltage and high compaction. The negative electrode active material in the prior art is mostly graphite, but its gram capacity is low, which is an important factor restricting the energy density of lithium-ion batteries. Silicon material has an ultra-high specific capacity and a discharge platform comparable to graphite, so it is regarded as the first choice for the anode active material of the next generation of lithium-ion batteries. However, pure silicon undergoes a huge volume change during charging and discharging, which will lead to irreversible capacity loss, resulting in low initial discharg...

AI Technical Summary

Problems solved by technology

However, pure silicon undergoes a huge volume change during charging and discharging, which will lead to irreversible capacity loss, resulting in low initial discharge efficiency, and at the same time, the SE I film (solid electrolyte interface film) formed for the first time will be continuously damaged, and the exposed The surface of the silicon negative electrode will react with the electrolyte to form an SE I film again, and this cycle will continue to reduce the capacity of the lithium-ion battery, the cycle attenuation is serious, the life is reduced or even pulverized, so the silicon carbon negative electrode material emerges as the times require

[0003] Nanosizing silicon materials and compounding them with carbon materials to produce silicon-carbon anode materials is the most likely technical route for industrialization first. Nanosizing has improved the electrical properties of silicon anodes to a certain extent, but the improved battery performance is still unsatisfactory, especially The long-life cycle performance is poor, and the battery is prone to gas generation under high-temperature storage conditions, because there is no matching electrolyte and binder

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