Interlayer Engineering of α-MoO Modulates Selective Hydronium Intercalation in Neutral Aqueous Electrolyte.

Among various charge-carrier ions for aqueous batteries, non-metal hydronium (H O ) with small ionic size and fast diffusion kinetics empowers H O -intercalation electrodes with high rate performance and fast-charging capability. However, pure H O charge carriers for inorganic electrode materials have only been observed in corrosive acidic electrolytes, rather than in mild neutral electrolytes. Herein, we report how selective H O intercalation in a neutral ZnCl electrolyte can be achieved for water-proton co-intercalated α-MoO (denoted WP-MoO ). H O molecules located between MoO interlayers block Zn intercalation pathways while allowing smooth H O intercalation/diffusion through a Grotthuss proton-conduction mechanism. Compared to α-MoO with a Zn -intercalation mechanism, WP-MoO delivers the substantially enhanced specific capacity (356.8 vs. 184.0 mA h g ), rate capability (77.5 % vs. 42.2 % from 0.4 to 4.8 A g ), and cycling stability (83 % vs. 13 % over 1000 cycles). This work demonstrates the possibility of modulating electrochemical intercalating ions by interlayer engineering, to construct high-rate and long-life electrodes for aqueous batteries.