Mn-Substituted Tunnel-Type Polyantimonic Acid Confined in a Multidimensional Integrated Architecture Enabling Superfast-Charging Lithium-Ion Battery Anodes

Abstract

Given the inherent features of open tunnel-like pyrochlore crystal frameworks and pentavalent antimony species, polyantimonic acid (PAA) is an appealing conversion/alloying-type anode material with fast solid-phase ionic diffusion and multielectron reactions for lithium-ion batteries. Yet, enhancing the electronic conductivity and structural stability are two key issues in exploiting high-rate and long-life PAA-based electrodes. Herein, these challenges are addressed by engineering a novel multidimensional integrated architecture, which consists of 0D Mn-substituted PAA nanocrystals embedded in 1D tubular graphene scrolls that are co-assembled with 2D N-doped graphene sheets. The integrated advantages of each subunit synergistically establish a robust and conductive 3D electrode framework with omnidirectional electron/ion transport network. Computational simulations combined with experiments reveal that the partial-substitution of H3O+ by Mn2+ into the tunnel sites of PAA can regulate its electronic structure to narrow the bandgap with increased intrinsic electronic conductivity and reduce the Li+ diffusion barrier. All above merits enable improved reaction kinetics, adaptive volume expansion, and relieved dissolution of active Mn2+/Sb5+ species in the electrode materials, thus exhibiting ultrahigh rate capacity (238 mAh g−1 at 30.0 A g−1), superfast-charging capability (fully charged with 56% initial capacity for ≈17 s at 80.0 A g−1) and durable cycling performance (over 1000 cycles).