Lysine pre-intercalation modification of δ-MnO2: Expanded interlayer spacing and enhanced Zn2+ kinetics for aqueous zinc-ion batteries

With the growing demand for sustainable energy, aqueous zinc-ion batteries (AZIBs) have attracted considerable attention as an emerging energy-storage technology owing to their low cost and high safety. However, one of the most widely used cathode materials of manganese dioxide (MnO 2 ) for AZIBs suffers from unstable electrochemical performance of sluggish zinc-ion diffusion and gradual structural degradation. To solve these problems, we propose a simple in-situ pre-intercalation strategy to construct lysine-functionalized δ-MnO 2 (Lys-MnO 2 ), thereby reinforcing the structural stability and boosting the electrochemical performance of MnO 2 . XRD and HRTEM characterizations, combined with GITT and EIS analyses, demonstrate that lysine molecules effectively increase the interlayer spacing of MnO 2 and facilitate zinc-ion diffusion. Electrochemical tests show that the Lys-MnO 2 cathode exhibits the markedly enhanced cycling performance. It maintains a reversible capacity of over 274 mAh g −1 after 100 cycles at 0.2 A g −1 and retains 92.7% of its capacity even after 900 cycles at 1 A g −1 , superior to those of the pristine MnO 2 cathode. This work provides an innovative route for the development of high-performance and long-lifespan manganese-based cathode materials for AZIBs.