Towards High-performance Lithium-Sulfur Batteries: the Modification of Polypropylene Separator by 3D Porous Carbon Structure Embedded with Fe3C/Fe Nanoparticles

Biomass-Derived Carbon Materials for Electrochemical Energy Storage

The environmental impact from the waste disposal has been widely concerned around the world. The conversion of wastes to useful resources is important for the sustainable society. As a typical family of wastes, biomass materials basically composed of collagen, protein and lignin are considered as useful resources for recycle and reuse. In recent years, the development of carbon material derived from biomasses, such as plants, crops, animals and their application in electrochemical energy storage have attracted extensive attention. Through the selection of the appropriate biomass, the optimization of the activation method and the control of the pyrolysis temperatures, carbon materials with desired features, such as high-specific surface area, variable porous framework, and controllable heteroatom-doping have been fabricated. Herein, this review summarized the preparation methods, morphologies, heteroatoms doping in the plant/animal-derived carbonaceous materials, and their application as electrode materials for secondary batteries and supercapacitors, and as electrode support for lithium-sulfur batteries. The challenges and prospects for the controllable synthesis and large-scale application of biomass-derived carbonaceous materials have also been outlooked.

Synergistic catalytic conversion and chemisorption of polysulfides from Fe/Fe3C/FeN0.0324 nanocubes modified separator for advanced Li-S batteries

Lithium sulfur batteries (LSBs) have been considered as one of the most promising options for next generation high-performance batteries. However, the heavy shuttle effect and inferior redox conversion during the charge/discharge processes of the batteries have greatly hindered their further applications. In this study, to address these disadvantages of LSBs, Fe/Fe3C/FeN0.0324 heterostructured nanocubes were designed and prepared through high temperature carbonization process using Prussian blue precursor. Then the Fe/Fe3C/FeN0.0324 nanocubes were used to modify the commercial polypropylene (PP) separator, which can greatly catalyze the redox transformation of polysulfides and provide sufficient active sites for chemisorption. As result, the modified separator endowed LSBs with excellent rate capacity and cycle stability, delivering a high-capacity of 1025 mAh/g at 0.5 C with nearly 100% coulombic efficiency. It also displayed a superb cycling performance with a per-cycle capacity attenuation rate of 0.09% after 300 cycles. When the current density increased to 1 C with the S loading of 1.73 mg cm-2, Fe/Fe3C/FeN0.0324-PP separator presented a satisfactory capacity decay rate of 0.05% per cycle after 1000 cycles. Besides, it also presented outstanding electrochemical performance even at high sulfur loading of 4.5 mg cm-2. This work has provided a new avenue for the design of nanomaterials with synergistic effect of catalytic conversion and chemisorption of polysulfides for the promotion of high-performance Li-S batteries.

Tailoring the growth route of lithium peroxide through the rational design of a sodium-doped nickel phosphate catalyst for lithium-oxygen batteries

Tailoring the morphology and structure of Li2O2, the discharge product of lithium-oxygen batteries (LOBs), through the rational design of cathode catalysts is an efficient strategy to promote the electrochemical performance of LOBs. In this work, sodium-doped nickel phosphate nanorods (Na-NiPO NRs) grown on Ni foam (NF) were prepared by the hydrothermal method and subsequent calcination. For the Na-NiPO NRs, the electronic structure could be optimized and abundant void space among the nanorods would provide abundant transport channels. Adopted as the cathodes, the Na-NiPO NRs could facilitate the uniform growth of sea cucumber-like Li2O2 with sufficient Li2O2-electrolyte and Li2O2-catalyst interfaces, significantly promoting the charge process. Therefore, LOBs could deliver a high discharge capacity of 10365.0 mA h g-1 at 100 mA g-1. And a low potential gap of 1.16 V can be achieved at 200 mA g-1 with a capacity of 500 mA h g-1. The proposed strategy demonstrates the role of the morphology and electronic structure of the cathode catalysts in tuning the Li2O2 morphology and provides a novel approach for achieving high-performance LOBs.