The state-of-the-art lithium ion batteries (LIBs) do not have sufficient specific energy for emerging applications such as electrical vehicles. One route to increase the energy density of LIBs is the use of a silicon-based anode. Unlike conventional graphite anodes, which only have capacity of one lithium ion per six carbon atoms (372 mA-h/g), silicon-based anodes have a theoretical capacity of 4.4 lithium ions per silicon atom (4,200 mA-h/g). These results indicate that the Si anode offers great promising for achieving high specific energy LIBs. However, silicon-based anodes have yet to achieve widespread adoption or commercialization due to the large volume change that occurs upon lithiation/delithiation, resulting in severe electrode pulverization and degradation. In this work, novel polymer binder materials mitigating the volume expansion of the Si particles were developed. These binder materials were applied in half-cell and the batteries exhibited excellent cyclability. The battery exhibited area capacity over 1.5 mAh/cm² and negligible degradation in the first 100 cycles. The first cycle coulombic efficiency is over 80%.

Figure 1 LIBs with commercial binder and UA binder. UA binder provides better cyclability at higher mass loading.