柔性锂硫电池材料:综述

In recent years, demand for flexible electronic devices has been constantly growing with the rapid emergence of wearable and portable devices. Flexible batteries as the key components have attracted great research interests. It is most critical to develop batteries with higher energy-density for the future development of flexible electronic devices. Lithium-sulfur (Li-S) batteries are considered to be important frontier of energy storage in the future due to their high theoretical capacity, high energy density and low cost. Thus, the development of high-performance flexible lithium-sulfur batteries can meet better the increasing needs of future flexible wearable electronic devices. However, traditional lithium-sulfur batteries are difficult to achieve high flexibility: the rigid electrode material cannot be bended easily; the liquid electrolytes raise the risk of electrolyte leakage under bending state; poor interfacial contact owing to the assembly method based on physical joining. Once subjected to bending or stretching, traditional lithium-sulfur batteries will lose its function or undergo fast performance decline. Therefore, considerable efforts have been made in these years focusing on developing electrode materials and solid-state electrolytes which are adaptable for flexible batteries, as well as on creating special battery structures. Currently, flexible electrode materials are mainly based on carbon or its modified materials, such as carbon nanotubes, graphene, carbon cloth and carbon paper, as well as polymer materials. These materials not only can meet the flexible requirements, but also are beneficial for the overall battery performance through strengthening Li⁺/electrons transportation and reducing interface impedance due to the porous structure and the large specific surface. Solid-state electrolytes which contains gel polymer electrolytes, polymer electrolytes and inorganic electrolytes, has good chemical stability, high safety, high flexibility and plasticity. At the same time, the novel battery structure design, such as linear structure, paper folding structure and braided structure have been realized according to the topology principle, through which can the stress change of the battery internal structure during deformation process be reduced. This review gives a summary of relevant achievements in the flexibilization of lithium-sulfur batteries from the perspectives of electrode mate-rials, solid-state electrolytes, and battery structure design. It also includes a prospective discussion upon the challenges and future development trends.