Gradient lithiophilic structure for the homogenized electric field strength to achieve dendrite-free lithium metal anode

Abstract

Uncontrolled dendrite growth restricts the application of lithium metal battery as next-generation batteries. Herein, a 3D gradient lithiophilic framework (CuxO-Ag@CNFs) was constructed by multi-step electrochemical deposition. The symmetric cell can work steadily for 1000 h under low voltage hysteresis conditions at high current and large capacity (10 mA cm−2, 10 mAh cm−2). DFT calculation confirms the difference of lithiophilicity between CuxO, Ag and CuxO-Ag. The gradient structure of CuxO-Ag@CNFs was demonstrated by multiple structural characterization. COMSOL was used to simulate the distribution trend of Li+ concentration and electric field strength on the surface of the framework and verify the role of the composite material in homogenizing the electric field strength. The excellent performance of Li metal composite anode was attributed to the gradient distribution of CuxO and Ag on the CNFs with good lithiophilic property, which can achieve uniform local current density, form a stable SEI layer of Li2O and confine volume expansion ability of Li. Finally, LiFePO4 and CuxO-Ag@CNFs-Li were used as cathode and anode respectively, in full cell, which exhibited the potential for practical applications with superior cycling stability and good rate performance.