High performance binder-free SiO_x/C composite LIB electrode made of SiO_x and lignin

A high performance binder-free SiO_x/C composite electrode was synthesized by mixing SiO_x particles and Kraft lignin in a cryo-mill followed by heat treatment at 600 °C. After the heat treatment, lignin formed a conductive matrix hosting SiO_x particles, ensuring electronic conductivity, connectivity, and accommodation of volume changes during lithiation/delithiation. As the result, no conventional binder or conductive agent was necessary. When electrochemically cycled, the composite electrode delivered excellent performance, maintaining ∼900 mAh g⁻¹ after 250 cycles at a rate of 200 mA g⁻¹, and good rate capability. The robustness of the electrode was also examined by post-cycling SEM images, where few cracks were observed. The excellent electrochemical performance can be attributed to the comparatively small volume change of SiO_x-based electrodes (160%) and the flexibility of the lignin derived carbon matrix to accommodate the volume change. This work should stimulate further interests in using bio-renewable resources in making advanced electrochemical energy storage systems.