High-capacity rapid charge-discharge graphene lithium ion battery and synthesis process thereof

Abstract

The invention relates to a high-capacity rapid charge-discharge graphene lithium ion battery and a synthesis process thereof. The synthesis process comprises the following steps: preparing a graphenecoated hard carbon / tin microsphere composite material, preparing negative electrode slurry, preparing a negative electrode sheet, and assembling the lithium ion battery. According to the synthesis process provided by the invention, loofah sponge is used as a load, a tin source precursor is embedded into the activated loofah sponge gaps, the activated loofah sponge is carbonized to tin-loaded hardcarbon sphere through spray calcination, the graphite in the gas is coated on the hard carbon sphere in the air in the spray process to form the graphene coated hard carbon / tin microsphere composite material, the tin is embedded in the gaps of the hard carbon, the hard carbon provides an expansion space for the tin, the conductivity is improved by the coated graphene, the tin is coated in the hardcarbon to prevent the desorption of the tin and to form a tight connection, thereby improving the capacity of the lithium ion battery, enhancing the rate performance and the cycle stability, and maintaining the deactivation of active materials.

Description

technical field [0001] The invention relates to the field of lithium-ion battery preparation, in particular to a large-capacity fast charge-discharge graphene lithium-ion battery and a synthesis process thereof. Background technique [0002] Compared with secondary batteries such as nickel-cadmium, nickel-metal hydride, and lead-acid, lithium-ion batteries have unique advantages. First, the open circuit voltage of lithium-ion batteries is as high as 3.6V, which is much higher than the 1.2V of nickel-metal hydride and nickel-cadmium, which can effectively reduce The number of batteries in the battery pack is conducive to the lightweight and miniaturization of the battery. Lithium-ion batteries with lithium cobalt oxide as the positive electrode have a service life of up to 1,000 times under deep and complete discharge. Charging without fully discharging does not affect its capacity. The self-discharge rate is low. After the first charge and discharge, an electrolyte film can ...

AI Technical Summary

Problems solved by technology

[0004] However, due to the characteristics of elemental tin, there are still some problems to be solved urgently as an anode material for lithium-ion batteries.

During the alloying reaction between tin and lithium ions, the intercalation and extraction of lithium ions will lead to serious volume expansion of simple tin, with an expansion rate as high as 300%, which will cause the electrode material itself to be pulverized and separated from the current collector. Form tight connections, thereby reducing the capacity of lithium-ion batteries, affecting their rate performance and cycle stability, and may eventually lead to the deactivation of active materials

At the same time, after tin and lithium form an alloy phase, the conductivity is poor, and the internal resistance increases, which hinders the complete delithiation and produces irreversible capacity.

In addition, during the first discharge of the battery, a layer of SEI film will be formed on the surface of the tin material in contact with the electrolyte, which will affect the movement of lithium ions, resulting in the irreversible capacity of the electrode material for the first discharge.