Multilayer Graphene Battery Anodes on Plastic Sheets for Flexible Electronics

Anode structures on plastic sheets are essential for next-generation flexible rechargeable batteries. Graphite films, i.e., thick multilayer graphene (MLG), are promising anode materials; however, they typically have a high synthesis temperature. Metal-induced layer exchange is a unique method fabricating uniform MLG directly on arbitrary substrates at low temperatures. Here, we achieved the anode electrode structure at 350 °C, consisting of MLG/metal/polyimide, using a layer exchange with a Ni catalyst. The anode operation of the low-temperature MLG was demonstrated by using a coin-type Li-ion battery. After 100 cycles at a current density of 6.7 μA cm–2, the capacity stabilized at 6.2 μAh cm–2 and a Coulombic efficiency of 99%. The capacity per mass was higher than that of bulk graphite, likely because of the capacitive contribution and reduced diffusion distance of Li ions in local short-range ordered structures. The MLG deterioration owing to the charge/discharge cycles was not significant, which is advantageous for carbon anodes. Thus, we demonstrated the anode operation of MLG formed at low temperature. The results suggest the possibility of integrating reliable batteries into flexible devices, including mobile terminals and sensors.