Achieving ultrastable long-cycling performance of Si/C composites by spontaneous assembling via electrostatic interactions

In the realm of electrochemical energy storage, it is vital to design electrode materials that are both high-performance and stable cycling. Compositing with carbon material is an effective method for addressing the volume expansion of silicon-based negative electrodes, with the uniformity and dependability of the composite material structure design dictating its electrochemical performance. We offer a simple and scalable electrostatic self-assembly approach for constructing cations and anions prone to in situ electrostatic interactions adsorbed onto Si nanoparticles and lignin (Si/C-lignin@C-SE), which is generated by carbon sintering the lignin@C onto Si. Unlike ball milling and hydrothermal methods, Si/C-lignin@C-SE exhibits homogeneous carbon layer (3–6 nm) with high specific surface area and graphitization degree, resulting in abundant binding sites for nano‑silicon particles. This unique structure can offer stability and limit the influence of Si nanoparticle volume expansion, as well as significantly increase electronic conductivity and electrochemical activity. Compared to the traditional mechanical ball milling method, Si/C-lignin@C-SE composite shows excellent specific capacity and ultrastable long-cycling performance: an initial discharge capacity of 2593.19 mAh g −1 with coulombic efficiency of 92.3 %, and stable capacity of 1200 mAh g −1 after 200 cycles. As a result, as-prepared Si/C-lignin@C-SE electrodes are expected to achieve good electrochemical performance and long-term durability.