Liquid-Phase Exfoliated Few-Layer Iodine Nanosheets for High-Rate Lithium-Iodine Batteries

Rechargeable lithium-iodine (Li-iodine) batteries attract significant attention owning to their high energy density, wide abundance and low cost of iodine resources. However, iodine suffers from low electrical conductivity and high solubility in aprotic electrolyte, leading to fast capacity degradation, low columbic efficiency, as well as poor rate capability. Herein, we propose a simple method for the large-scale production of two-dimensional (2D) few-layer iodine nanosheets (FLINs) via liquid-phase exfoliation of iodine in deionized water. 2D FLINs could effectively improve rate capability by providing sufficient active sites and shortening the Li ion diffusion path. Meanwhile, graphene oxide (GO)@carbon nanotubes (CNT) hosts are designed to suppress the dissolution of iodine and enhance the electrical conductivity. GO@CNT@FLINs film exhibits excellent rate capability (220 mAh g^-1 at 0.2 A g^-1 and 96 mAh g^-1 at 8 A g^-1 ) and outstanding cycle stability (93.2 mAh g^-1 at 2 A g^-1 after 1000 cycles) for lithium storage due to the synergistic effects of GO@CNT hosts and 2D structure of FLINs. The controllable synthesis of FLINs provides a bright prospect for achieving high rate capability of Li-iodine batteries and is of utmost importance to potential large-scale applications.