Dual mechanism of ion (de)intercalation and iodine redox towards advanced zinc batteries

Materials with layered structures have been widely adopted as ion-(de)intercalated-type cathodes for zinc ion batteries but suffer from the limited operating voltage of the restricted redox couple, while the I − /I 2 transition at high potential is limited by poor reversibility. Herein, a dual-active ion solution of Zn(CF 3 SO 3 ) 2 and ZnI 2 in ethylene-glycol-substituted solvent is proposed, with a bifunctional cathode of NH 4 V 4 O 10 and porous activated carbon to realize the integration of Zn 2+ (de)intercalation and I − /I 2 redox. The solvation structure of Zn 2+ with fewer H 2 O molecules, formed by monodentate and bidentate coordination with ethylene glycol, ensures stability and reversibility of the interfacial reaction, thus providing enhanced discharge medium voltage (0.96 V) and capacity retention (0.032% per cycle) at 0.2 A g −1 . The compatibility of halogen redox and ion-(de)intercalation is deeply explored, offering a direction for mechanistic synergy in constructing advanced zinc-based batteries. We propose a dual-storage ion solution of Zn 2+ and I − with a cathode containing a mixture of NH 4 V 4 O 10 and porous activated carbon, exhibiting a dual mechanism of Zn 2+ (de)intercalation and iodine redox with adsorption-desorption.