Abstract
Electrochemical pre-doping of a silicon electrode was investigated to create a new class of rechargeable battery with higher energy density. The electrochemical reaction during pre-doping formed a high-quality solid electrolyte interface (SEI) on the surface of silicon particles, which improved the charge and discharge cycle life with a small irreversible capacity. The surface composition of the pre-doped silicon particles was characterized using transmission electron microscopy (TEM), solid state magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and X-ray diffraction analysis (XRD). Pressurization promoted SEI growth and lithium binding with silicon to form Li15Si4 accompanied by the reductive reaction product of Li2CO3 originated from electrolyte. The Li15Si4 was highly stable when the silicon anode was used in a full cell, thus resulting in a silicon anode with a long cycle life.
Highlights
An increasing number of intelligent devices, electric vehicles, and smart energy management systems are being used in all parts of society, and this growing market, especially in mobility and transportation, requires low-cost rechargeable batteries with high energy density
The large surface area of nanostructured silicon should produce irreversible capacity caused by the formation of a solid electrolyte interface (SEI) passivation layer[8]
This study proposes a pre-doping process for silicon anodes, in which electrochemical pre-doping under pressure produces the SEI on the surface of silicon particles
Summary
An increasing number of intelligent devices, electric vehicles, and smart energy management systems are being used in all parts of society, and this growing market, especially in mobility and transportation, requires low-cost rechargeable batteries with high energy density. Rechargeable lithium-ion batteries (LIBs) are integral to these sophisticated devices; a serious drawback is that their energy density and capacity density have not increased substantially[1] To solve this problem, silicon is an attractive anode material for the generation of LIBs due to its high capacity of 3572 mA h/g2, which is approximately 10 times larger than that of graphite (372 mA h/g). The intercalation causes the expansion and collapse of the silicon particles, continuously exposing new surfaces where the SEI is formed. This study proposes a pre-doping process for silicon anodes, in which electrochemical pre-doping under pressure produces the SEI on the surface of silicon particles. We describe the properties and structure of a silicon anode electrochemically pre-doped under pressure
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