A bioinspired high-modulus mineral hydrogel binder for improving the cycling stability of microsized silicon particle-based lithium-ion battery

Silicon with high specific capacity is deemed an ideal anode material for lithium ion batteries,which,however suffers from low cycling life due to its dramatic volume changes.Water-soluble polymer binders recently gain increasing attention by providing an eco-friendly and low-cost way in improving the cycling stability of Si-based anodes.Herein,a novel bioinspired supramolecular mineral hydrogel binder consisting of polyacrylic acid (PAA) physically crosslinked with amorphous calcium carbonate (ACC) nanoparticles is designed for high-performance anodes made from low-cost microsized Si particles.Owing to its organic-inorganic hydrophilic nature,ACC-PAA hybrid binder exhibits the reported highest modulus (~22 GPa) for polymer binders in electrolyte,even higher than lithiated Si species (Li15Si4,~12 GPa).Together with its excellent adhesion and electrochemical stability,ACC-PAA binder can effectively suppress the pulverization of Si particles and maintain the mechanical integrity of electrodes during cycling.Therefore,even with a low binder content,the anode still shows an initial discharge capacity of 2,973 mAh·g^-1 and Coulombic efficiency of 81.5%,and retains 75% at a current density of 600 mA·g^-1 after 100 cycles.The present organic-inorganic hybrid mineral binder may open a new approach for designing more effective polymer binders for Si-based lithium-ion batteries.