Wu Jian, Zhang Qi, Li Mo, Yan Jian, Zhang Yong, Liu Jiaqin, Wu Yucheng
Institute of Industry and Equipment Technology, Hefei University of Technology Hefei 230009 China
School of Materials Science and Engineering, Hefei University of Technology Hefei 230009 China.
RSC Adv. 2019 May 20;9(28):15715-15726. doi: 10.1039/c9ra02037c.
The diverse textures and tunable surface properties of abundant bioresources offer great opportunities to utilize biochar materials as sulfur hosts for naturally boosting the electrochemical performances of Li-S batteries. Herein, a N, S-codoped micro-mesoporous carbon was synthesized from boat-fruited sterculia seed, and used as a sulfur host matrix for Li-S batteries. After sulfur infiltration (≈62% sulfur) and cell assembly, the obtained S/NSBC cathode shows outstanding discharge-charge performance, good rate capability, and especially long cycling stability. A high initial discharge capacity of 1478 mA h g was achieved at 0.1C, and the reversible discharge capacity was still retained at 649 mA h g after 500 cycles at 0.5C with ultralow decay rate of 0.08% per cycle, and especially zero-capacity-decay after 300 cycles. Such superior electrochemical performance of S/NSBC cathode is attributed to the synergy of the unique 3D conductive micro-mesoporous frameworks and huge N, S-codoped polar surface within the carbon matrix, which can physically confine the dissolved polysulfides within the pore structures, and chemically anchor the polysulfides through chemical interaction between lithium polysulfides and N and S sites, thus enabling the favorable reaction kinetics, efficient utilization of sulfur, and effective mitigation of polysulfide diffusion and shuttling within the cathode. This work well manifests the great feasibility and superiority of utilizing bioresources for high performance Li-S batteries.
丰富生物资源多样的质地和可调节的表面性质为利用生物炭材料作为硫宿主以自然提升锂硫电池的电化学性能提供了巨大机遇。在此，由苹婆种子合成了一种氮、硫共掺杂的微介孔碳，并将其用作锂硫电池的硫宿主基质。经过硫浸渍（≈62%硫）和电池组装后，所得的S/NSBC阴极表现出出色的充放电性能、良好的倍率性能，尤其是长循环稳定性。在0.1C下实现了1478 mA h g的高初始放电容量，在0.5C下500次循环后可逆放电容量仍保持在649 mA h g，每循环超低衰减率为0.08%，特别是在300次循环后零容量衰减。S/NSBC阴极如此优异的电化学性能归因于碳基质内独特的三维导电微介孔框架与大量氮、硫共掺杂极性表面的协同作用，这可以将溶解的多硫化物物理限制在孔结构内，并通过多硫化锂与氮和硫位点之间的化学相互作用化学锚定多硫化物，从而实现有利的反应动力学、硫的高效利用以及有效减轻多硫化物在阴极内的扩散和穿梭。这项工作很好地体现了利用生物资源制备高性能锂硫电池的巨大可行性和优越性。
