Effect of ethanol-assisted electrode fabrication on the performance of silicon anodes

The performance of high-silicon-content anodes was tested as a function of silicon particle-size (44 μm, 1.8 μm and 70-100 nm), surface pre-treatment and solvent chosen for anode preparation. Two simple procedures, leading to significant improvements in electrode performance are reported. First, pre-treatment of nano-Si in ethanol which unexpectedly yields functionalised surfaces improving cycling stability. Second, the use of a 30:70 solution of ethanol and water to dissolve the CMC-binder for the electrode preparation boosts specific battery capacity. Ethanol pre-treatment of nano-Si also resulted in improved adhesion of the electrode to the current collector as well as in de-agglomeration of nano-Si powder. All these treatments improved capacity stability during cycling. Changes in surface chemistry of nano-Si before and after ethanol treatment have been analysed by XPS. A stable capacity of about 1630 mAh g⁻¹ was obtained after 25 cycles for an electrode containing 80% silicon using ethanol during electrode coating preparation.