Holey graphene modified LiFePO4 hollow microsphere as an efficient binary sulfur host for high-performance lithium-sulfur batteries
2019 Elsevier B.V. Among various kinds of rising electrochemical energy storage systems, lithium-sulfur batteries (LSBs) are considered as one of the most promising candidates because of their high theoretical energy density and low material cost. However, the poor electronic conductivity and "shuttle effect" as well as large volume change during charge and discharge process of sulfur-based cathodes hinder their further practical applications. Here, LiFePO4 (LFP) hollow microspheres are compounded with holey graphene (HG) through an electrostatic attraction strategy coupled with high temperature treatment, and denoted as HG/LFP binary host, in which, LFP microspheres with relatively high redox potential play the key roles for chemically adsorption of soluble lithium polysulfide intermediates (LiPSs) and facilitating the transition process between long-chain LiPSs and short-chain Li2S2/Li2S, and thus effectively suppressing the "shuttle effect" during charge and discharge process. Moreover, the HG component could guarantee a good electronic conductivity and fast mass transport of the sulfur cathode, which further improves the kinetic process for electrochemical reactions. Therefore, HG/LFP/S cathode composite exhibits high specific capacity, outstanding rate performance and cycling stability under large sulfur loading condition (4.3 and 8.4 mg cm-2), which presents a great potential for practical application in LSBs cathodes.