Promoting Proton Transport in Si-Doped α-MoO₃ via Bond-Weakening Engineering for High-Rate and Long-Life Aqueous...

Aqueous proton batteries (APBs) hold promise for high-rate energy storage, but their development is hindered by the instability of α-MoO₃ electrodes, which suffer from dissolution and hydrogen evolution reactions. Herein, we report a bond-weakening engineering strategy via Si doping to boost proton transport in α-MoO₃. The introduced Si(IV) forms Mo-O─Si linkages, reducing electron density around oxygen and weakening O─H bonds, thereby facilitating proton desorption and migration. The optimized Mo_0.8Si_0.2O_3-x electrode achieves a high specific capacity of 223.03 mAh g^-1 at 1 A g^-1 and retains 63.57% capacity at 20 A g^-1, vastly outperforming pristine α-MoO₃. In a full cell with a vanadium hexacyanoferrate (VHCF) cathode, the Mo_0.8Si_0.2O_3-x anode exhibits exceptional cycling durability (91.87% capacity retention after 4000 cycles at 8 A g^-1). Density functional theory calculations confirm a reduced bandgap and lower proton diffusion barrier, underscoring the potential of non-metal doping for high-rate proton batteries.