Fine-Grained Si Alloy Prepared By Melt Spinning and Its Electrochemical Performance for Li Ion Battery Anode

Silicon is candidate as an anode material for high energy Li ion batteries. Among Si materials, Si alloys attract great interests from a viewpoint of high durability and high coulombic efficiency. We found that sputter-deposited some of amorphous Si alloys (ex. Si-Sn-Ti ternary alloy) showed high electrochemical performance from the combinatorial study. In the present study, we synthesized amorphous Si alloys by using a Melt Spinning process and investigated the potential toward volume production as well as the electrochemical performance.To obtain amorphous Si alloys, the ease of mixing between Si and added metals or the chemical mixing enthalpy is an important factor. In the case of Si-Sn-Ti alloy, the mixing enthalpy decreases by increasing Ti/(Ti+Sn) ratio and it is expected for easier preparation of the amorphous alloys at higher Ti/(Ti+Sn) ratios (Fig. 1).  The SEM/EPMA elemental mapping of several Si-Sn-Ti alloy indicated that the Si atoms in Ti rich composition alloy (Si/Sn/Ti=60/10/30 wt%) is more uniformly and finely dispersed than Sn rich composition alloy (Fig. 2). The electrochemical performance will be reported in the presentation. This work was partially supported by the project “Research and Development of Lithium ion Battery Application / Research and Development of High Capacity Si-based Alloy Anode” of the New Energy and Industrial Technology (NEDO).