A conductive-dielectric gradient framework for stable lithium metal anode

Lithium (Li) metal is one of the most promising anode materials for future high-energy-density rechargeable batteries. However, the uncontrollable growth of dendrites and the related safety issue hindered its practical application. Involving three-dimensional (3D) frameworks for hosting Li metal can provide large electrochemically active surface area and thus endow more homogeneous deposition and delay dendrite formation. But a more ideal situation for ultimately safe and high-performance Li metal based battery is to enable a gradient Li deposition/dissolution process, with the merit of effective utilization of spatial dimension to stabilize Li metal anode to achieve superior electrochemical performance. Here, we report a conductive-dielectric gradient framework which can guide a “bottom-up” Li deposition and “top-down” Li dissolution within this structure, rendering controllable and stable Li metal deposition/dissolution process. As a result, in a symmetric cell such anode can deliver stable Li metal deposition/dissolution for 780 h with a low overpotential (<20 mV) at 1 mA cm−2, and maintain superior cycle stability with a Coulombic efficiency over 95.6% even at a high current density of 8 mA cm−2. This conductive-dielectric gradient structure design paves a new avenue to stabilize Li metal anode and improve the safety level of metal anode based batteries.