Synthesis and Electrochemical Properties of Carbon Foam/SnS/C Composite for Flexible Lithium Ion Batteries

With the rapid development of flexible mobile electronics and wearable devices, the demand for flexible power sources continues to rise. Among various power sources, Li ion batteries (LIBs) have attracted a lot of interest as the power source of flexible devices due to their high energy density, reasonable cost, and long cycle life. However, conventional electrode fabrication process of LIBs is insufficient to satisfy flexibility of the flexible devices. Besides flexibility, there is still a challenge to increase energy density for long-lasting batteries. Currently, carbonaceous materials are used as commercial anode materials because of their good cycle performance. However, commercial graphite anode has limited capacity (372mAh·g–1), which cannot meet the requirements of high-performance LIBs. Therefore, development of high-capacity anode materials is critical. To increase the reversible capacity of an anode, Li-alloy type or conversion type materials have been intensively studied. Tin sulfide (SnS), which exhibits conversion reaction with Li ions, is one of the attractive anode materials because of its high theoretical specific capacity and large interlayer spacing. Despite these many advantages of SnS, SnS anodes cannot be commercially used due to some drawbacks. The poor electric conductivity of SnS and the fatal volume change during the discharge/charge cycles cause the poor electrochemical performance. To resolve these issues, there are many efforts such as introduction of carbon-based materials and use of SnS nanostructure. This study proposes a flexible carbon foam/SnS nano sheets/C composite as anode materials for flexible LIBs. An elastic carbon foam can be simply obtained by carbonization of commercially available and low-cost melamine foam. Carbon foam/SnS nano sheets structure was prepared by a simple solvothermal method. Then, a carbon coating on the composite was performed to further improve the cyclic performance. The prepared materials were investigated by various materials and electrochemical analysis tools. The obtained composite electrode exhibited excellent lithium storage performance.