Nonlinear current stimulation unlocks high-performance Zn–Mn batteries via reversible phase transformation

Abstract

The intrinsic complexity of reactions in Zn–Mn batteries constrains their practical deployment, necessitating precise control over dissolution and deposition processes. Here, we employ a stepwise evolution of current signals—from steady-state constant current through symmetric and asymmetric sine waves to chaotic regimes—to systematically investigate the coupling between nonlinear electrical signals and electrode reactions. Remarkably, chaotic currents enhance the reversible transformation between Zn₄SO₄(OH)₆·nH₂O (ZSH) and Zn_xMnO(OH)₂ (ZMO), revealing for the first time a direct correlation between waveform nonlinearity and electrochemical modulation. This ZSH/ZMO interconversion, alongside Zn²⁺/H⁺ insertion and extraction, underpins the cathodic reaction mechanism. Accumulation of inactive ZSH/ZMO phases emerges as the primary factor driving kinetic decay. Following seven cycles of chaotic activation, Zn–Mn batteries exhibit improved capacity, rate performance and cycling stability. The approach translates to flexible cells, delivering 92.23 mAh g⁻¹ with 76.37% retention after 1550 cycles at 1 A g⁻¹. In situ visualization, SEM imaging, and comprehensive thermodynamic and dynamic analyses reveal that nonlinear current stimulation reconstructs fractal mass transport pathways within the electrode, thereby optimizing ion pathways and structural stability. This study bridges nonlinear circuit dynamics and Zn–Mn electrochemistry, presenting a promising strategy to high-performance aqueous Zn–Mn batteries.