EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Alloying anode materials are promising candidates for developing high energy density Li-ion batteries (LIBs) to meet future electric vehicles' demands. Amorphous silicon (a-Si) is an attractive material due to its advantage of delivering a higher specific capacity of up to 3579 mAh/g (compared to graphite at 372 mAh/g). Despite this benefit, low electrical conductivity and massive volume expansion of silicon during cycling typically lead to pulverization and unstable solid-electrolyte interface (SEI) formation, presenting a hurdle in achieving stable cycling capacity. Current collector modification is a feasible approach to stabilize the electrochemical performance of the anode. Here we describe the use of ultralight and robust one-dimensional copper-rich silicide (Cu15Si4) nanowire (NW) scaffolds as potential current collectors. The NWs support the high-capacity active material while ensuring good electrical conductivity. The a-Si deposition onto the Cu15Si4 NW host forms a core-shell (inactive-active), binder-free architecture to effectively accommodate the stress exerted by lithiation−delithiation processes, resulting in better cycling stability. High-density vertically aligned Cu15Si4 NWs were formed by solvent vapor growth (SVG) technique. The subsequent coating with a high loading a-Si shell via a plasma-enhanced chemical vapor deposition (CVD) technique. The electrochemical performance of these core-shell NW architecture electrodes with active material loading up to 1mg/cm2 was evaluated in half-cell LIB configuration using conventional carbonate and ionic liquid electrolytes. Further, the influence of carbonate-based additives on the SEI layer formation of core-shell NW anodes cycled in a best performed ionic liquid electrolyte was investigated using XPS & NMR techniques.