Developments of Silicon-based Anode Materials for Practical Lithium-ion Battery Applications

Abstract

Lithium-ion batteries (LIB) have been considered the most promising energy storage devices for portable electronic devices like smart phones, notebook computer, and wireless electronics because of many advantages such as its high energy density, high operating voltage, and lower self-discharge. However, Li-ion batteries must be developed with even higher energy density, higher specific energy, and cycle life due to expanding use of Li-ion batteries to electric transportation systems such as electric vehicles (EV) and energy storage system (ESS). According to demands of the people used Li-ion batteries for EV, the current choice of cathode and anode materials for Li-ion batteries should be certainly replaced with other materials. At side of anode, the graphite anode use commercial batteries due to its stable reaction with lithium and its long cycle life, but it has the low specific capacity (LiC6, 372 mAh g-1) because of limited number of intercalation sites of Li ions within layers. In constant, alloy anodes are known for their high specific capacity due to 2-10 times higher than graphite due to reaction with Li ion reaction mechanism, which involves breaking bonds between host atoms. Among these materials, Silicon is an attractive material owing to high theoretical specific capacity of 4200 mAh g-1 for Li4.4 Si, low electrochemical potential between 0 – 0.4 V. However, the large number of Li atoms that can be inserted into these materials extreme volume changes (310% for full lithiation of Si). The structural change has usually results in cracking and disintegration of the electrode, giving severe capacity fade and short cycle life. Therefore, several strategies for making highly efficient Si-based anode materials have been developed to reduce detrimental effect of a huge volume change such as multiphase composite, particle size control, and modification of surface. Here, I present various structure change strategies using micro size Si and SiO (silicon monoxide) by metal-assisted chemical etching, which is simple and low-cost method for fabricating 3D structures with the ability to control various parameters. Also, I propose a simple route for synthesizing 3D Si-SiOx-SiO2 particle from bulk particles via a thermal annealing process in the presence of sodium hydroxide (NaOH) for anode of Li-ion batteries. Finally, I present various surface modification methods of Si using metal oxide (SnO2, Lithium titanate), metal silicide (TixSiy) and polymer (polyimide) to stable solid electrolyte interphase layer on the surface. All presented strategies may be extended to make high-performance other anode materials in Li-ion batteries.