Bio-inspired lotus root-like 3D multichannel carbon hosts for stable lithium metal anodes

Abstract

Lithium metal batteries (LMBs) are generally regarded as one of the alternatives for high energy density devices. However, the commercial application of LMBs is seriously restricted by volume changes and dendrite behavior of lithium metal, which cause low efficiency and poor safety. In the present study, and inspired by the structure of the lotus root (which has many interior parallel channels that significantly enlarges the contact area), we have designed lotus root-like 3D multichannel carbon fibers (MCNFs) that are decorated with lithiophilic Ag nanoparticles (Ag NPs). These adhered lithiophilic Ag nanoparticles will facilitate molten Li infusion into the carbon channels, forming stable lithium metal anodes. The ion concentration gradient near the surface Ag protrusions will become reduced, thereby inducing homogeneous nucleation and deposition of Li. The produced multi-channels will provide enough space for volume expansion of Li metal during cycling. As a result, when coupled with a LiFePO4 (LFP) cathode, the MCNF/Ag-Li composite anode maintained 94.7% of its capacity, and 99.1% of the Coulombic efficiency after 600 cycles at 1 C. Moreover, the MCNF/Ag-Li|Li symmetrical cell could be cycled for more than 600 h, with a low hysteresis of 20 mV (at 1 mA cm−1), and with the capacity of 1 mAh cm−1 during the whole cycle (without any short-circuit). These results suggest that anodes, made of a lotus root-like 3D multichannel lithium metal composite material, will have the potential to promote the practical applications of lithium metal batteries.