Zr-based-MOF composite electrode design enabling uniform and dense lithium deposition through tuned conductivity

Abstract

Lithium metal batteries offer high theoretical energy density but face critical challenges such as dendritic growth and surface lithium accumulation. To address these issues, extensive efforts have been devoted to designing lithium host electrodes that regulate lithium deposition behavior. Among these, gradient-layer architectures, typically comprising conductive bottom layers and insulating top layers, have shown promise in guiding lithium deposition. However, their application is limited by interfacial resistance between the layers and challenges associated with scalable fabrication. Herein, we present a single-layer electrode (M808/C-80) composed of liquid-phase-synthesized MOF-808 and its carbonized derivative (C-MOF-808) in an optimized ratio. This design leverages the ionic transport properties of MOF-808 with the conductivity of C-MOF-808 to enable bottom–up lithium plating and suppress surface accumulation. The pre-lithiated M808/C-80, when used as lithium host electrodes, exhibited excellent cycling stability, maintaining a low voltage hysteresis of 18.2 mV over 1250 h in symmetric cells. When combined with a LiFePO₄ cathode in full-cell applications, the electrode demonstrated a high specific capacity of 143.5 mAh g⁻¹ at 2.0C and improved rate capability, attributed to the reduced interfacial resistance of the optimized electrode design.