Solvent-Free Process to Produce Three Dimensional Graphene Network with High Electrochemical Stability

Three-dimensional (3D) graphene has attracted increasing attention in electrochemical devices. However, the existing preparation technologies usually involve a solvent process, which introduces defects and functional groups into the 3D network. Here, we find the defects and functional groups influence the electrochemical stability of graphene. After an electrochemical process, the current decreases by more than 1 order of magnitude, indicating remarkable etching of graphene. To improve the electrochemical stability, we develop a solvent-free preparation process to produce 3D graphene for the first time. After growth on a 3D microporous copper by chemical vapor deposition (CVD), the copper template is removed by a high temperature evaporation process, resulting in 3D graphene network without any solvent process involved. The samples exhibit remarkably improved stability with durable time 2 times, compared with normal CVD samples, and 55 times, compared with reduced graphite oxide, and no obvious etching is observed at 1.6 V versus saturated calomel electrode, showing great potential for application in future 3D graphene-based high stable electrochemical devices.