Modification method of lithium ion battery silicon negative electrode material

Abstract

The invention discloses a modification method of a lithium ion battery silicon negative electrode material and relates to design and development of new energy materials. The method comprises the steps: taking a p-type silicon (100) sheet as a substrate, carrying out the electrochemical corrosion by adopting an electrochemical micromachining process, corroding the surface of the substrate into circular holes, gradually enlarging the circular holes and finally performing extruding into a square; forming a depletion layer at an interface of corrosive liquid and a hole wall; under the action of anelectric field, enabling hole carriers to migrate to the hole wall from the substrate along the longitudinal hole wall to participate in reaction with a corrosive liquid interface, wherein the hole wall is gradually thinned in the reaction process; when the wall thickness between two adjacent holes is close to the thickness of a depletion layer, stopping the electrochemical reaction automaticallyto obtain a silicon nanobelt, wherein the surface crystal orientation of the silicon nanobelt is (110), the silicon nanobelt only expands along the crystal orientation (110) after lithium intercalation, and the silicon nanobelt has a recrystallization special behavior after lithium removal, has a high ionic conductance, high-stability interface SEI and high-stability material structure, and can realize high-power and long-life circulation under the condition of keeping high specific capacity of the silicon negative electrode battery.

Description

technical field [0001] The invention relates to the design and development of new energy materials, in particular to a method for modifying silicon negative electrode materials of lithium ion batteries. Background technique [0002] As a new power source, lithium-ion batteries are widely used in 3C, transportation, energy storage, military industry, artificial intelligence and other fields [1 , 2] . With the upgrading of my country's consumption, the adjustment of energy structure and the vigorous development of the industry, terminal products have put forward higher requirements for high energy density, high specific power, safety and environmental protection of batteries. The traditional graphite negative lithium-ion battery system is approaching its theoretical specific energy limit. (~300Wh / kg) [3] . The development of lithium-ion batteries with high specific energy and high specific power has become a key scientific and technological problem that needs to be solved ...

AI Technical Summary

Problems solved by technology

[0015] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art, and provide a method for modifying the silicon negative electrode material of lithium-ion batteries, which utilizes the anisotropic characteristics of silicon intercalated lithium to limit the expansion of silicon, and significantly improves the stability of the silicon negative electrode material. It solves the problem of interface deterioration during cycling, and achieves high power and long-life cycle while maintaining high specific capacity of silicon anode batteries

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