Graphene for flexible lithium-ion batteries: Applications and prospects

Abstract

With the advent of flexible electronics, flexible lithium-ion batteries (LIBs) have attracted great attention as a promising power source in the emerging field of flexible and wearable electronic devices. Flexible LIBs are generally LIBs that can operate within the normal elastic range. When the external force is unloaded, it can completely restore its original state without any remaining plastic deformation. According to the different types of deformation, most of the as-reported flexible LIBs are referred to as bendable LIBs. This review summarizes the recent developments in the application of graphene in bendable LIBs. Graphene has superior electronic conductivity. Thus, graphene can act as a type of conductive phase to form composite films containing polymers, paper and cloth. In this structure, graphene has a conductive network and the substrates provide a flexible support. Because of its unique two dimensional structure and rich functional groups, graphene can form composites with other active materials. Graphene-based materials can work as flexible electrodes and can effectively improve the overall energy density of LIBs, making them highly anticipated in the near future. This review also introduces methods to characterize the mechanical and electrochemical properties of flexible LIBs. In this review, the trends of flexible LIBs are also included. Future flexible LIBs will be stretchable, enabling them to work under different conditions. Newly developed flexible LIBs should also have self-healing abilities and should be able to be charged at high rates. Although there are still many problems to overcome, the ubiquitous applications of flexible LIBs with superior electrochemical and mechanical properties in flexible electronic devices are highly anticipated in the near future.