Impact of the Cu Current Collector Grade and Ink Solid Fraction on the Electrochemical Performance of Silicon-Based Electrodes for Li-Ion Batteries

The influence of the Cu current collector grade (cold-rolled, annealed, or textured) and the ink solid fraction (SF) on the performance of Si-based electrodes for Li-ion batteries is investigated. Two binders are considered for this study: one of carboxymethyl cellulose and citric acid and the other which consists of the same organic components with added Zn(II) cations. These ones cross-link the carboxylate moieties through coordination bonds. The fracture behavior and cyclability of the Zn-free electrodes show a strong dependence on the Cu current collector grade. For this formulation, which has lower cohesion, the increase in electrode adhesion from the roughening of the surface of the current collector and/or the decrease of the current collector yield strength contribute to mitigate the electrode mechanical damage, therefore improving its cyclability. Such a dependence is not observed for the Zn cross-linked electrodes which have a higher cohesion. Regarding the impact of the ink solid fraction, when a higher SF is used, the capacity retention and coulombic efficiency are enhanced for both formulations, though much more significantly for the Zn-free formulation. The underlying mechanism causing this improvement may be partially related to the enhanced adsorption of binder on silicon particles with increasing SF.