Regulating lithium nucleation and deposition on carbon cloth decorated with vertically aligned Ag-doped MnO2 nanosheet arrays for dendrite-free lithium metal anode

Abstract

Metallic Li with high specific capacity and low electrode potential is considered as the most promising anode material. The main obstacles to its application are uncontrollable Li dendrites growth and infinite volume changes. Herein, we design a modified carbon cloth (CC) by vertically aligned MnO2 nanosheet arrays embedded with tiny Ag (Ag/MnO2@CC) through hydrothermal approach. Density functional theory (DFT) calculations indicate that MnO2 and Ag show a more negative adsorption energy (−4.31 and −2.34 eV) than C (−1.65 eV), implying their better lithiophilicity. Finite element simulations demonstrate that the Ag-doped MnO2 nanosheet arrays reduce local current density and redistribute Li-ion flux. Moreover, the channels assembled by vertical-aligned MnO2 nanosheets and 3D CC can offer sufficient spaces to buffer volume fluctuation during cycling. Accordingly, the Ag/MnO2@CC is employed as a lithiophilic host to supervise homogenous Li nucleation and deposition. The Ag/MnO2@CC electrodeposited with Li exhibits dendrite-free feature and a high Coulombic efficiency of 99.9% during 300 cycles. The symmetric cell shows an ultra-low polarization voltage of 14 mV over 1300 h at 1 mA cm−2 with the capacity of 1 mAh cm−1. The full cell paired with LiFePO4 exhibits excellent capacity of 105.5 mAh g−1 after 400 cycles at 1 C.