Abstract
Silicon nanoparticles based composite electrodes for Li-ion batteries reach high specific capacities and enhance cyclability compared with larger silicon particles. Such electrodes are foreseen for the next generation Li-ion batteries (LiB). Playing on binder and conductive additives in the formulation of the Si based electrodes is a well-known strategy to to enhance performance. Aqueous electrode formulations using the carboxymethyl cellulose as environmentally friendly binder has already showed great cyclability enhancements, especially when employed in acidic conditions. In this study, pH = 1, 3 and 7 buffered solutions were studied as solvent to prepare the Si/C/CMC composite electrodes. The influence of the formulation pH on the electrode components interactions were followed through a combined ATR-FTIR / XPS experiment and discussed in relation with the electrode electrochemical performance. Interestingly, the pH=7 buffered solution show increased capacity retention and coulombic efficiency during 100 cycles compared with the electrode obtained in acidic conditions. Post mortem analysis and EIS study highlighted differences of electrode/current collector (CC) adhesion and SEI deposition.