Modification from bulk to interphase towards improved performance for aqueous sodium-ion batteries.

Sodium vanadium phosphate in aqueous sodium-ion batteries is limited by vanadium dissolution and unstable interphase. A dual strategy, Fe substitution and saturated Na2SO4, enhances bulk/interphase stability and suppresses dissolution, achieving 62.3 mAh g-1 after 5000 cycles at 5.0 A g-1 in full cell with a sdoium titanium phosphate anode.