Multiple hydrogel alginate binders for Si anodes of lithium-ion battery

Abstract

A series of hydrogel alginate binders (M-alg, M = Al, Ba, Mn, Zn) for Si anode of lithium ion battery are synthesized by coordinating alginate molecule chains with different cations respectively. Among these binders, Al-alg and Ba-alg both present their Vickers hardness higher than 32.0 HV while other M-alg binders show Vickers hardness less than 25.5 HV. The Ba-alg binder exhibits a viscosity of 30270 mPa s while other M-alg binders only show their viscosities less than 1700 mPa s. The Si anodes with Al-alg or Ba-alg both deliver their capacities near 2100 mAh g−1 after 300 cycles at 420 mA g−1, while the electrodes with other M-alg binders show capacities less than 1500 mAh g−1. When the current density is increased to 2100 mA g−1 or the Si loading mass is increased to 1.0–1.2 mg cm−2, the electrodes with Al-alg or Ba-alg still have remarkable advantages. Moreover, the ultrahigh viscosity makes Ba-alg strongly adhere with both Si and current collector, so when the electrodes are fabricated with a material mass ratio of 8:1:1 (Si: acetylene black: binder), the electrode with Ba-alg still delivers an outstanding capacity retention of 49.1% after 200 cycles at 840 mA g−1.