碳纳米材料构建高性能锂离子和锂硫电池研究进展EI北大核心CSCD

碳作为单一元素可形成像零维碳纳米球、一维碳纳米管、二维石墨烯等多种碳纳米结构,它们在锂离子和锂硫电池中的表现也有所不同。需要阐明的是,碳纳米管和石墨烯由于具有以下缺点不适合直接作为锂离子或锂硫电池电极材料:(1)第一次不可逆容量大,首次充放电效率低;(2)在充放电曲线中电压滞后现象严重;(3)缺少稳定的电压平台;(4)容量衰减快。科学家们一直在为获得具有更高能量密度和更广阔应用前景的锂离子电池和锂硫电池而努力,由于可充电电池的性能主要取决于阴极和阳极的性能,因此,设计先进的电极材料以及制备具有特定成分和结构的电极成为近年来的研究热点。本文综述了碳纳米材料在构建高性能锂离子、锂硫电池电极材料和特定电极方面的作用。首先,从促进电子和离子传输、固定多硫化物位置以及缓冲体积膨胀三个方面讨论了碳纳米材料在修饰电活性材料的作用;其次,从作为导电添加剂、电流集流体和导电中间层三个方面讨论了碳纳米材料在最优化非活性组分的作用;然后,从作为非导电基体上的导电相、柔性电流集流体和自支撑复合电极三个方面讨论了碳纳米材料在柔性电池设计的作用。最后,本文对碳纳米材料的未来发展趋势作了概述,兼具多种功能的碳纳米材料被认为是今后的研究重点。

Research progress on carbon nano-materials to construct Li-ion and Li-S batteries of high performance

Carbon solely can form a lot of nanostructures, such as zero-dimensional nanosphere, one-dimensional nanotube and two-dimensional graphene. They perform differently in Li-ion and Li-S batteries. It is worth noting that CNTs and graphene are not appropriate to be used as electroactive materials for Li-ion or Li-S batteries for four reasons. First, when CNTs and graphene are used as an anode, they often exhibit high specific capacities during the first lithiation step, but a large fraction of lithium ions is irreversibly consumed instead of reversibly stored, leading to a low Coulombic efficiency of the cell. Second, a graphene-based anode has a large voltage hysteresis in the charge/discharge curves. Third, it has been reported a CNT-based anode lacks a steady voltage plateau with large change in voltage during discharge. Fourth, despite their high initial capacities, graphene and CNT-based anodes often suffer from fast capacity decay after a few tens of cycles. Continuous efforts have been made to build better lithium batteries with a higher energy density and wider applicability, including both current state-of-the-art Li-ion batteries and near-term Li-S batteries. Because the behavior of a rechargeable battery is mainly based on the performance of its anode and cathode, designing advanced electrode materials as well as electrode with tailored compositions and structures has been the hot topic in recent years. The role of carbon nano-materials to construct electrode materials and tailored electrodes in Li-ion and Li-S batteries in high performance was reviewed in the paper from three aspects. Firstly, the role of carbon nano-materials in modifying the electroactive materials was discussed from three aspects: electron-and ion-transport facilitators, immobilization sites and volume expansion buffering. Secondly, the role of carbon nano-materials in optimizing the inactive components was considered as follows: conducting additives, current collectors and conductive interlayers. Thirdly, the role of carbon nano-materials in designing the bendable and stretchable devices are discussed from three aspects: conductive phases in nonconductive substrates, flexible current collectors and freestanding composite electrode. Finally, perspectives on future development of Li-ion and Li-S batteries were presented. It is considered that multi-functional carbon nano-materials will be main research focus in the future.