(684i) High Capacity Silicon Nitride-Based Composite Anode for Lithium Ion Batteries

One of the busiest areas of research in Li ion batteries is the development of stable high energy anode materials. The main material of choice is Si, due to its high theoretical specific capacity (4,200 mAh/g), which is more than ten times the value of current anode material, graphite (370 mAh/g). One of the main challenges for Si as an anode is its huge volume expansion (~400%) upon the formation of silicon-lithium alloys, resulting in the pulverization of electrodes and performance degradation. In this paper, we report the synthesis and performance of a Si nitride (SiNx) based composite anode material that demonstrates a two-step reaction mechanism during cycling: reversible conversion reaction then alloying reaction. These steps are necessary to divert the full alloying reaction to follow reaction pathways that improve the cycling characteristics of the anode material. Elucidation of the resulting performance was performed using spectroscopy, microscopy and electrochemical techniques. The potential of this material that displays better volume stress management and thus improves the overall electrochemical cycling stability is presented.