Multilayer nano-composite electrode for lithium ion battery and preparation method thereof

Abstract

The invention discloses a multilayer nano-composite electrode for a lithium ion battery and preparation method thereof. The multilayer nano-composite electrode is mainly composed of a copper current collector and multilayer active substances; the copper current collector is provided with a porous structure and a nano-needle structure; the multilayer active substances comprise a silicon layer and a carbon layer. The preparation method of the multilayer nano-composite electrode is as follows: (1) sintering of copper powder; (2) growing and reducing of copper oxide nanoneedle structure; (3) depositing of a silicon nanometer layer; and (4) cladding of the carbon nanometer layer. The multilayer nano-composite electrode disclosed by the invention can effectively limit the sharp change of the volume of silicon active substance in the charging / discharging process of the battery, thereby prolonging the cycle life of the battery; and meanwhile, the porous structure and the nano-needle structure of the current collector are directly and tightly contacted with the active substances, the use of each of the adhesive and the conductive additive is reduced, thereby facilitating the improvement of the reversible capacity, the coulombic efficiency, the cycle stability and other electrochemical properties of the battery.

Description

Technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a multilayer nano composite electrode for lithium ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries have only been in existence for less than thirty years. Compared with valve-regulated lead-acid batteries, rechargeable nickel-cadmium batteries or nickel-hydrogen batteries, lithium-ion batteries have a high unit energy density and a wide range of applications, as well as excellent high current Discharge and other advantages have become the best among these secondary batteries. At the beginning of the new century, with the development and development of new energy power vehicles, energy reforms are being promoted for the purpose of reducing environmental pollution caused by energy consumption and replacing the old energy structure based on fossil fuels. The energy structure with lithium-ion batteries as the core is being p...

AI Technical Summary

Problems solved by technology

Graphite is currently used as the negative electrode active material for lithium-ion batteries. However, the theoretical specific capacity of graphite is not high enough to meet the growing energy demand.

As an active material, silicon has a high theoretical specific capacity, but the volume expansion is greater than 300%, which will cause the active material to pulverize and fall off, increase the irreversible capacity, and shorten the battery life

Many researchers use carbon-silicon core-shell nanostructures as the active material, which can well limit the expansion of silicon volume, but the resistance of the active material is large and the battery performance is low.

Some researchers have also developed electrodes containing copper-silicon core-shell nanostructures, but the expansion and contraction of silicon leads to the shedding of silicon nanomaterials.

Traditional active material coatings contain conductive agents, binders and other materials that have no effect on battery capacity, which not only reduces the effective use volume of the battery, but also increases the resistance of the active material

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