Synergy of binders and electrolytes in enabling microsized alloy anodes for high performance potassium-ion batteries

Abstract High-capacity alloy anodes are promising for increasing the energy density of emerging potassium-ion batteries (PIBs), although their practical application is hindered by their fast capacity fading due to the universal limitation of their severe volume changes. Herein, without costly nanostructure design, a simple and yet effect approach of coupling the binder and the electrolyte is introduced to maintain the electrode/interface stability of alloy anodes against large volume changes. Thanks to the physically mechanical strength of cross-linked carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) binder and the chemically stable solid-electrolyte interphase (SEI) layer derived from 3 M potassium bis(fluorosulfonyl)imide (KFSI) in dimethyl ether (DME), a microsized SnSb/C anode, prepared by a scalable ball milling process, delivered a high capacity of ~419 mAh/g with capacity retention of 84.3% for 600 cycles at 50 mA/g, and 340 mAh/g with 80.7% capacity retention for 800 cycles at 1000 mA/g. These encouraging results achieved with simple electrode and electrolyte engineering can unlock the enormous potential of high capacity alloy anodes for practical application in PIBs, and can be applicable to other anode materials and other metal-ion batteries.