This presentation reports Si alloy anode materials developed for commercial application for lithium ion batteries(LIBs). This Si alloy material consists of amorphous Si embedded metal-silicide anode materials. It’s synthesized by using mechanical milling. Our alloy have attained a high capacity(energy), high initial efficiency, excellent power property, high coulombic efficiency during cycling. However, sudden failure problem have happened with less FEC contained electrolyte sometimes before 200 or 300 cycles. In an attempt to overcome this major issue, we prepared amorphous C-coated Si alloy, and optimized C-coating process conditions like temperature, carbon contents. As a result, we could improve sudden failure problem with our new amorphous C-coated Si alloy. This new Si alloy’s performance suggests a promising approach to commercial Si anode materials with high capacity.