A multi-layer film structure negative plate and its mixed solid-liquid electrolyte lithium battery

Abstract

The invention belongs to the technical field of new energy lithium secondary batteries, and in particular relates to a multi-layer film structure negative plate and a mixed solid-liquid electrolyte lithium battery, which have high energy density, long cycle life, excellent rate performance and high safety performance. features. The negative electrode sheet includes a current collector and several negative electrode composite layers arranged on the current collector. The negative electrode composite layer includes a silicon layer, a lithium titanate layer and a graphite layer compounded in sequence, and the silicon layer is fixed on the current collector. The lithium storage battery includes a positive electrode sheet, the above-mentioned negative electrode sheet, a mixed solid-liquid electrolyte membrane, an outer packaging film, a positive electrode tab and a negative electrode tab; the mixed solid-liquid electrolyte membrane is arranged between the graphite layers of the positive electrode sheet and the negative electrode sheet; the outer packaging film Coated on the outside of the positive electrode and the negative electrode; one end of the positive electrode tab is connected to the positive electrode sheet, and the other end protrudes from the outer packaging film; one end of the negative electrode tab is connected to the negative electrode sheet, and the other end protrudes from the outer packaging film. outside of the wrapping film. The negative electrode sheet and the lithium storage battery of the present invention.

Description

technical field [0001] The invention belongs to the technical field of new energy lithium secondary batteries, and in particular relates to a multi-layer film structure negative plate and a mixed solid-liquid electrolyte lithium storage battery. Background technique [0002] As a high-performance secondary battery, lithium battery has the advantages of high voltage, large specific energy, long cycle life, small self-discharge, good safety performance, no pollution, fast charge and discharge, etc. It has been widely used and used since its inception. In the fields of electronic products and electric vehicles, in recent years, with the vigorous development of industries such as electric vehicles and wearable devices, higher requirements have been put forward for the charging speed, energy density and service life of lithium-ion batteries. [0003] At present, the negative electrodes used by most lithium secondary batteries on the market are graphite negative electrodes, silico...

AI Technical Summary

Problems solved by technology

[0003] At present, the negative electrodes used by most lithium secondary batteries on the market are graphite negative electrodes, silicon negative electrodes and lithium titanate negative electrodes. The electrolyte is a liquid electrolyte. The theoretical specific capacity of graphite negative electrodes is 372mAh / g, and the actual mass ratio The capacity is already very close to this value, and it is difficult to increase it

The theoretical capacity of Si is 4200mAh / g, which is much higher than that of graphite, but silicon will produce severe volume expansion and huge stress during the process of deintercalating lithium, resulting in the separation between the electrode and the current collector, and the multiple formation and consumption of the SEI film. , and the conductivity of silicon is poor

When lithium titanate with a spinel structure is used as the battery negative electrode material, because it is a "zero strain" material, the change in battery volume during lithium ion insertion and extraction is almost negligible. However, lithium titanate also has poor electrical conductivity. shortcoming

Liquid electrolytes are volatile and flammable at high temperatures, leading to safety issues such as swelling and even explosion of the battery during use. The above problems limit the development and application of lithium batteries

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