Tortuosity modulation on microspherical assembly host of graphene via in-plane nano-perforations for stable Li metal anode

초록

Development of Li metal batteries is hindered by preferential accumulations of Li metal on the upper surface of the 3D host electrode, which blocks ion-transport pathways and causes a loss of host utilization. Decreasing the tortuosity of the host is an effective way to accelerate ion transport, however, no previous studies have modified host particles to decrease their tortuosity. Herein, we report the low-tortuosity modulation of a microspherical graphene assembly host to stabilize Li metal anodes by introducing in-plane nano-perforations into graphene. In the low-tortuosity graphene assembly host, graphene sheets are perforated with -5 nm in-plane nano-perforations evenly spaced and separated by -15 nm. These nano-perforations with lithiophilic edges provide lowtortuosity channels between different layers of graphene that behave as shortcuts for ion diffusion, thereby facilitating ion transport and uniform plating throughout the graphene assembly. The low-tortuosity graphene host maintains a high Coulombic efficiency of 97.9% for 400 cycles, with a low overpotential of 21 mV and stable Li plating/stripping performance at a high current density of 5 mA cm-2. Furthermore, it achieves a high volumetric capacity of 1000 mA h cm-3 for the host electrode. This study provides new insights into lowtortuosity, high-lithiophilicity hosts for 3D Li metal anodes.

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