Wang Xu-Ri, Wang Xiao, Xu Xu-Peng, Wu Ya-Qin, Lei Wei-Xin, Zou You-Lan, Ma Zeng-Sheng, Pan Yong
National-Provincial Laboratory of Special Function Thin Film Materials, School of Materials Science and Engineering, Xiangtan University, 411105, Xiangtan, Hunan, P. R. China.
Chemistry. 2021 Jul 21;27(41):10628-10636. doi: 10.1002/chem.202100484. Epub 2021 Jun 10.
Quick capacity loss due to the polysulfide shuttle effects and poor rate performance caused by low conductivity of sulfur have always been obstacles to the commercial application of lithium sulfur batteries. Herein, an in-situ doped hierarchical porous biochar materials with high electron-ion conductivity and adjustable three-dimensional (3D) macro-meso-micropore is prepared successfully. Due to its unique physical structure, the resulting material has a specific surface area of 2124.9 m g and a cumulative pore volume of 1.19 cm g . The presence of micropores can effectively physically adsorb polysulfides and mesopores ensure the accessibility of lithium ions and active sites and give the porous carbon material a high specific surface area. The large pores provide channels for the storage of electrolyte and the transmission of ions on the surface of the substrate. The combined effect of these three kinds of pores and the N doping formed in-situ can effectively promote the cycle and rate performance of the battery. Therefore, prepared cathode can still reach a reversible discharge capacity of 616 mAh g at a rate of 5 C. After 400 charge-discharge cycles at 1 C, the reversible capacity is maintained at 510.0 mAh g . This new strategy has provided a new approach to the research and industrial-scale production of adjustable hierarchical porous biochar materials.
由于多硫化物穿梭效应导致的快速容量损失以及硫的低电导率所引起的差倍率性能，一直是锂硫电池商业应用的障碍。在此，成功制备了一种具有高电子 - 离子传导率且三维（3D）宏观 - 介观 - 微观孔结构可调的原位掺杂分级多孔生物炭材料。由于其独特的物理结构，所得材料的比表面积为2124.9 m²/g，累积孔体积为1.19 cm³/g。微孔的存在可有效物理吸附多硫化物，介孔确保锂离子和活性位点的可及性，并赋予多孔碳材料高比表面积。大孔为电解质的存储和离子在基底表面的传输提供通道。这三种孔与原位形成的N掺杂的协同作用可有效提升电池的循环和倍率性能。因此，制备的正极在5 C倍率下仍可达到616 mAh/g的可逆放电容量。在1 C下进行400次充放电循环后，可逆容量保持在510.0 mAh/g。这种新策略为可调分级多孔生物炭材料的研究和工业规模生产提供了一种新方法。
