Porosity-controlled MXene anodes for enhanced rate and long cycle life performance in aqueous proton batteries

Abstract

Proton-based energy storage devices attract attention as a sustainable alternative, and MXene-Ti3C2Tx is a promising anode due to its high conductivity and tunable layer structure. Previously, introducing porosity to MXene films is explored to improve proton diffusion and electrochemical performance. In this study, porosity-controlled MXene (P-MX) films have been developed by sacrificial template method with polylactide (PLA) spheres. The pore density is systematically tuned by controlling the PLA:MXene ratio in a 1:x to synthesize 1:xP-MX (x = 4, 8 and 16). Adequately increased PLA contents lead to larger surface area and superior electrochemical capacity, confirming effectiveness of pore engineering. Notably, 1:8P-MX exhibits 104.8 mAh g−1 capacity at 1 A g−1 and 96.7 % capacity retention over 2000 cycles, making it the highest-performing MXene anode. Furthermore, a full-cell proton battery using 1:8P-MX (anode) and copper iron Prussian blue analogue (cathode) in 1 mol L−1 H2SO4 electrolyte demonstrates 57.9 mAh g−1 at 1 A g−1 (17C) and 53.3 mAh g−1 at 10 A g−1 (188C), surpassing previous reports, as well as 97 % Coulombic efficiency over 200 cycles. These findings highlight the benefits of optimized pore density in MXene anodes, enabling the development of high-performance, fast-charging proton batteries without highly concentrated acidic electrolytes. © 2025 The Authors