Modulating Diffusion Double Layer by In Situ Constructed Ultrathin Dipole Layer Towards Uniform Lithium Deposition

Abstract

The popularization of lithium metal anode has been limited due to uneven deposition processes and lithium dendrites. Guiding homogeneous nucleation during the initial plating stage of lithium is vital to obtain a stable lithium metal anode. Herein, an ultra-thin dipole layer that can be used to regulate the diffusion layer is prepared by anodizing and strong polarization on a titanium foil collector. It is demonstrated that the vertical distributions of ionic concentration and electrostatic potential on the nBTO@Ti electrode are modulated by the ultrathin dipole layer, leading to uniform diffusion of lithium ions and reduction of overpotential. Consequently, a uniform lithium nucleation and plating process are achieved on a polarized BaTiO3 collector, which is verified by microscopy. The average coulombic efficiency of the deposition-dissolution process is as high as 98.3% for 300 cycles at 0.5 mA cm−2. Moreover, the symmetrical cell shows flat potential platforms of 25 mV for 1000 cycles at 0.5 mA cm−2. Full cell with LiFePO4 as cathode also reveals excellent electrochemical performances with a steady discharge capacity of 120 mAh g−1 at 1 C and a high capacity retention of 93.3% after 200 cycles.

Keywords

• lithium metal anode
• diffusion double layer
• lithium dendrites
• dipole
• lithium battery