A proton-selective coating enables fast-kinetics high-mass-loading cathodes for sustainable zinc batteries. This study introduces a two-dimensional polyimine membrane (2DPM) with dual ion-transport nanochannels and proton-conduction groups, which facilitates rapid and selective proton transport. This coating enables a transition from sluggish Zn²⁺-dominated to fast-kinetics H⁺-dominated Faradic reactions in high-mass-loading cathodes. The NaV3O8·1.5H2O cathode with this coating exhibits an ultrahigh areal capacity of 4.5 mAh cm⁻² and a state-of-the-art energy density of 33.8 Wh m⁻², along with enhanced cycling stability. The 2DPM coating is shown to be applicable to different cathodes and aqueous electrolytes, validating its universality for developing reliable aqueous batteries. The 2DPM membrane has dual ion-transport nanochannels and proton-conduction sites, enabling high H⁺ flux and selectivity over Zn²⁺. The membrane's high crystallinity and face-on orientation are confirmed by HR-TEM and SAED. The 2DPM-80 membrane shows a high H⁺ permeation rate of 0.91–0.95 mol m⁻² h⁻¹ and an excellent H⁺ transport selectivity of 140.7 over Zn²⁺. The 2DPM coating significantly improves the specific capacity, areal capacity, and energy density of the NVO electrode. The coating also enhances the cycling stability of NVO, maintaining 87.8% of its original capacity after 1000 cycles. The 2DPM coating is shown to be effective for other cathodes, such as ε-MnO2 and α-MoO3, in different electrolytes. The study demonstrates that the 2DPM coating strategy can enhance the charge-storage kinetics and durability of AZB cathodes by promoting H⁺ transport and mitigating Zn²⁺ diffusion. The 2DPM coating also improves the cycling stability of NVO by inhibiting the loss of active material due to intermediate dissolution. The study highlights the potential of the 2DPM coating for developing sustainable and high-performance aqueous batteries. The 2DPM coating strategy is promising for addressing the challenges of Zn metal anodes, with high Zn²⁺ conductivity/selectivity and hydrophobicity as key criteria. The study provides fundamental insights into interfacial ion regulation, offering essential guidelines for designing sustainable and high-performance aqueous batteries. The 2DPM coating is shown to be effective for different cathodes and aqueous electrolytes, validating its universality for developing reliable aqueous batteries. The study demonstrates that the 2DPM coating can enhance the charge-storage kinetics and durability of AZB cathodes by promoting H⁺ transportA proton-selective coating enables fast-kinetics high-mass-loading cathodes for sustainable zinc batteries. This study introduces a two-dimensional polyimine membrane (2DPM) with dual ion-transport nanochannels and proton-conduction groups, which facilitates rapid and selective proton transport. This coating enables a transition from sluggish Zn²⁺-dominated to fast-kinetics H⁺-dominated Faradic reactions in high-mass-loading cathodes. The NaV3O8·1.5H2O cathode with this coating exhibits an ultrahigh areal capacity of 4.5 mAh cm⁻² and a state-of-the-art energy density of 33.8 Wh m⁻², along with enhanced cycling stability. The 2DPM coating is shown to be applicable to different cathodes and aqueous electrolytes, validating its universality for developing reliable aqueous batteries. The 2DPM membrane has dual ion-transport nanochannels and proton-conduction sites, enabling high H⁺ flux and selectivity over Zn²⁺. The membrane's high crystallinity and face-on orientation are confirmed by HR-TEM and SAED. The 2DPM-80 membrane shows a high H⁺ permeation rate of 0.91–0.95 mol m⁻² h⁻¹ and an excellent H⁺ transport selectivity of 140.7 over Zn²⁺. The 2DPM coating significantly improves the specific capacity, areal capacity, and energy density of the NVO electrode. The coating also enhances the cycling stability of NVO, maintaining 87.8% of its original capacity after 1000 cycles. The 2DPM coating is shown to be effective for other cathodes, such as ε-MnO2 and α-MoO3, in different electrolytes. The study demonstrates that the 2DPM coating strategy can enhance the charge-storage kinetics and durability of AZB cathodes by promoting H⁺ transport and mitigating Zn²⁺ diffusion. The 2DPM coating also improves the cycling stability of NVO by inhibiting the loss of active material due to intermediate dissolution. The study highlights the potential of the 2DPM coating for developing sustainable and high-performance aqueous batteries. The 2DPM coating strategy is promising for addressing the challenges of Zn metal anodes, with high Zn²⁺ conductivity/selectivity and hydrophobicity as key criteria. The study provides fundamental insights into interfacial ion regulation, offering essential guidelines for designing sustainable and high-performance aqueous batteries. The 2DPM coating is shown to be effective for different cathodes and aqueous electrolytes, validating its universality for developing reliable aqueous batteries. The study demonstrates that the 2DPM coating can enhance the charge-storage kinetics and durability of AZB cathodes by promoting H⁺ transport