Negative plate with multilayer film structure and mixed solid-liquid electrolyte lithium storage battery thereof

Abstract

The invention belongs to the technical field of new energy lithium secondary batteries, and particularly relates to a negative plate with a multilayer film structure and a mixed solid-liquid electrolyte lithium storage battery thereof, which have the characteristics of high energy density, long cycle life, excellent rate capability and high safety performance. The negative plate comprises a current collector and a plurality of negative composite layers arranged on the current collector, each negative composite layer comprises a silicon layer, a lithium titanate layer and a graphite layer whichare sequentially compounded, and the silicon layers are fixed on the current collector. The lithium storage battery comprises a positive plate, the negative plate, a mixed solid-liquid electrolyte membrane, an outer packaging membrane, a positive tab and a negative tab, the mixed solid-liquid electrolyte membrane is arranged between the graphite layers of the positive plate and the negative plate; the outer packaging film coats the outer sides of the positive plate and the negative plate; one end of the positive tab is connected to the positive plate, and the other end of the positive tab extends out of the outer packaging film; one end of the negative tab is connected to the negative plate, and the other end of the negative tab extends out of the outer packaging film. The invention discloses the negative plate and the lithium storage battery.

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...

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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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