Elimination of Concentration Polarization Under Ultra-High Current Density Zinc Deposition by Nanofluid Self-Driven Ion Enrichment

Abstract

The commercialization of zinc metal batteries aims at high-rate capability and lightweight, which requires zinc anodes working at high current density, high areal capacity, and high depth of discharge. However, frequent zinc anode fades drastically under extreme conditions. Herein, it is revealed that the primary reason for the anode instability is the severe concentration polarization caused by the imbalanced consumption rate and transfer rate of Zn²⁺ under extreme conditions. Based on this finding, a nanofluid layer is constructed to rapidly absorb Zn²⁺ and mitigate the polarization induced by the nonlinear transport of interfacial ions. The modified zinc anode sustains at extreme conditions for over 1573 h (40 mA cm⁻², 40 mAh cm⁻², DOD = 75.97%) and 490 h (100 mA cm⁻², 100 mAh cm⁻², DOD = 90.91%), and achieving an unprecedented cumulative capacity of 62.92 Ah cm⁻². This work offers both fundamental and practical insights for the interface design in energy storage devices.