Atomic-Layer-Deposition Functionalized Carbonized\nMesoporous Wood Fiber for High Sulfur Loading Lithium Sulfur Batteries

Abstract

Lithium–sulfur\nbattery (LSB) as one of the most promising energy storage devices\nsuffers from poor conductivity of sulfur and fast capacity decay triggered\nby the dissolution of polysulfides. In this work, functionalized carbonized\nmesoporous wood fiber (f-CMWF) is employed as a host to accommodate\nsulfur for the first time. Natural wood microfiber has unique hierarchical\nand mesoporous structure, which is well-maintained after carbonization.\nWith such a hierarchical mesoporous structure, a high sulfur loading\nof 76 wt % is achieved in CMWF electrodes. The pore size of CMWF is\ntunable by atomic layer deposition (ALD) of a 5 nm Al₂O₃ coating to form the f-CMWF. Such a thin layer slightly decreases\nthe sulfur loading to 70%, but it remarkably promotes the cyclic stability\nof sulfur cathode, which delivers an initial capacity of 1115 mAh\ng^–1, and maintains a reversible capacity of 859\nmAh g^–1 for 450 cycles, corresponding to a slow\ncapacity decay rate of 0.046% per cycle. More importantly, natural\nwood microfiber is first used as a raw material for sulfur encapsulating.\nThis work is also critical for using low cost and mesoporous biomass\ncarbon as bifunctional scaffold for LSB.