Hybrid superlattice cathodes unlocking diffusion-barrier-free proton storage for high-rate Zn–MnO2 batteries

Abstract

Diffusion-controlled Zn²⁺ intercalation often suffers from strong lattice repulsion when using a MnO₂ cathode in Zn-ion batteries, leading to slow reaction kinetics and irreversible phase transitions. Boosting intercalation-barrier-free Grotthuss proton storage in competition with Zn²⁺ in the MnO₂ host provides a highly promising path to develop high-kinetics and stable Zn-ion batteries, but this remains challenging. Here we incorporate tetraamino-benzoquinone (TABQ) into a nickel-doped δ-MnO₂ host to design a two-dimensional hybrid superlattice cathode (Ni–TABQ@δ-MnO₂), which triggers ultrafast proton transfer via Grotthuss topochemistry. Conductive Ni–TABQ effectively modulates the electronic properties of δ-MnO₂ through π–d electron coupling, enabling a transition from semiconducting to metallic behavior and markedly increasing the current response from 205 to 305 pA. Furthermore, the intermolecular H-bonding network between the coordination water of Ni–TABQ and lattice oxygen of δ-MnO₂ allows H₃O⁺ to transfer protons through the continuous breaking and reformation of O–H bonds. Accordingly, dynamic proton hopping within the Ni–TABQ@δ-MnO₂ cathode shows an ultralow energy barrier (0.124 eV) compared to Zn²⁺ intercalation (0.741 eV), leading to superior rate capacities (453 mA h g⁻¹ at 0.2 A g⁻¹; 151 mA h g⁻¹ at 10 A g⁻¹) and a long lifespan (8000 cycles). This study gives new insights into the design of diffusion-barrier-free proton-conductive hybrid superlattice cathodes for advanced energy storage.