Li Hong, Zhao Zirui, Li Yuyun, Xiang Mingwu, Guo Junming, Bai Hongli, Liu Xiaofang, Yang Xinzhou, Su Changwei
National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, Yunnan Minzu University, Kunming, 650500, China.
Institute of Science and Technology, Dehong Teachers college, Dehong, 678400, China.
Dalton Trans. 2022 Jan 25;51(4):1502-1512. doi: 10.1039/d1dt03705f.
Promising applications of lithium-sulfur batteries with high theoretical capacity are still severely limited due to the poor conductivity of sulfur, the polysulfide shuttle effect and volume expansion. Herein, low-cost and carbon/nitrogen-rich waste honeycombs are used to prepare N-doped hierarchical porous carbon (INHPC) and firstly applied as a sulfur host by facile high-temperature carbonization combined with KHCO activation. The influence of mass ratios of the activator to honeycomb on the morphology and pore structure of the as-prepared carbon materials was investigated in detail. Among them, the optimized INHPC with a mass ratio of 4 : 1 presents block-like morphology with interconnected pore structure, while showing a high specific surface area of 1683.6 m g and a large pore volume of 0.974 cm g. Moreover, the N-doped carbon materials not only have good electronic conductivity but also strong chemical adsorption with polysulfide intermediates, hence effectively alleviating the shuttle effect. When used as the sulfur host, the as-obtained INHPC-4/S composite cathode with a sulfur content of 60 wt% delivers a high initial discharge capacity of 913.4 mA h g and retains a reversible capacity of 538.3 mA h g after 200 cycles at 0.2 C. Even at a current rate of 1 C, the first discharge capacity of 623.2 mA h g can be obtained, simultaneously achieving the durable cycle life up to 500 cycles. These good electrochemical performances are ascribed to physicochemical synergistic adsorption of N-doping and hierarchical porous structure as well as high ionic/electronic conductivity.
具有高理论容量的锂硫电池，其应用前景仍受到严重限制，这是由于硫的导电性差、多硫化物穿梭效应以及体积膨胀。在此，采用低成本且富含碳氮的废弃蜂窝制备了氮掺杂分级多孔碳（INHPC），并首次通过简便的高温碳化结合KHCO活化将其用作硫宿主。详细研究了活化剂与蜂窝的质量比对所制备碳材料的形貌和孔结构的影响。其中，质量比为4∶1的优化后的INHPC呈现出具有相互连通孔结构的块状形貌，同时具有1683.6 m²/g的高比表面积和0.974 cm³/g的大孔体积。此外，氮掺杂碳材料不仅具有良好的电子导电性，而且对多硫化物中间体具有很强的化学吸附作用，从而有效减轻了穿梭效应。当用作硫宿主时，所获得的硫含量为60 wt%的INHPC-4/S复合阴极具有913.4 mA h/g的高初始放电容量，在0.2 C下循环200次后仍保留538.3 mA h/g的可逆容量。即使在1 C的电流速率下，也可获得623.2 mA h/g的首次放电容量，同时实现高达500次的持久循环寿命。这些良好的电化学性能归因于氮掺杂和分级多孔结构的物理化学协同吸附以及高离子/电子导电性。
