Porous silicon copper coated electrode for lithium ion battery and preparation method thereof

Abstract

The invention discloses a porous silicon copper coated electrode for a lithium ion battery and a preparation method thereof. The porous silicon copper coated electrode is in a cylindrical shape and consists of copper coated porous silicon particles; each copper coated porous silicon particle consists of an outer case and an inner core; the outer case is a copper particle and is of a porous nanostructure; the inner core is porous silicon. The preparation method comprises the following steps of (1) polycrystalline silicon powder pretreatment; (2) nanometer Ag particle deposition; (3) porous silicon preparation; (4) outer case preparation; (5) electrode formation. The porous silicon copper coated electrode has the advantages that the copper particles and silicon are organically and tightly combined; the contact area is increased; the contact resistance is effectively reduced; the electrode electroconductibility is greatly improved; the volume expansion of the silicon in a lithiation process is limited to the greatest degree by the copper particles; the lithium ion battery failure due to falling and separation of the silicon from the surface of a current collector in the battery cyclic charging and discharging processes can be effectively prevented, so that the service life of the lithium ion battery is prolonged; the cyclic stability of the lithium ion battery is improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a porous silicon copper-plated electrode for lithium ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion battery is a green high-energy rechargeable chemical power source, which has outstanding advantages such as high voltage, high energy density, good cycle performance, small self-discharge, and no memory effect. It has been widely used in defense industry and other fields. At present, in the commercial lithium-ion battery system, graphite-like carbon is generally used as the negative electrode material, but the theoretical capacity of graphite is only 372mAh / g, and the rate performance is not good. The development of new high-capacity negative electrode materials has become a research hotspot. The theoretical specific capacity of silicon is as high as 4200 mAh / g, which is an order of magnitude higher than that of graphite-bas...

AI Technical Summary

Problems solved by technology

However, during the alloying reaction process of silicon and lithium, the silicon material will undergo severe volume expansion (>400%), which will easily lead to the rapid pulverization of the active material during the cycle, so that it will fall off from the copper current collector, and the silicon and copper will be in electrical contact. Weakened, making the battery cycle life rapidly decay

At the same time, due to the volume expansion effect of the silicon material, the silicon material cannot produce a solid surface solid electrolyte film in the electrolyte, the electrode structure is destroyed, and a new electronic insulation (SEI) film will continue to be formed on the newly exposed silicon surface, resulting in The charge and discharge efficiency is reduced and the capacity decay is accelerated

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