A hydrophilic poly(methyl vinyl ether-alt-maleic acid) polymer as a green, universal, and dual-functional binder for high-performance silicon anode and sulfur cathode

Binders could play crucial or even decisive roles in the fabrication of low-cost, stable and high-capacity electrodes. This is especially the case for the silicon (Si) anodes and sulfur (S) cathodes that undergo large volume change and active material loss in lithium-ion batteries during prolonged cycles. Herein, a hydrophilic polymer poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was explored as a dual-functional aqueous binder for the preparation of high-performance silicon anode and sulfur cathode. Benefiting from the dual functions of PMVEMA, i.e., the excellent dispersion ability and strong binding forces, the as-prepared electrodes exhibit improved capacity, rate capability and long-term cycling performance. In particular, the as-prepared Si electrode delivers a high initial discharge capacity of 1346.5 mAh g−1 at a high rate of 8.4 A/g and maintains 834.5 mAh g−1 after 300 cycles at 4.2 A/g, while the as-prepared S cathode exhibits enhanced cycling performance with high remaining discharge capacities of 663.4 mAh g−1 after 100 cycles at 0.2 C and 487.07 mAh g−1 after 300 cycles at 1 C, respectively. These encouraging results suggest that PMVEMA could be a universal binder to facilitate the green manufacture of both anode and cathode for high-capacity energy storage systems.