Direct mask-free fabrication of patterned hierarchical graphene electrode for on-chip micro-supercapacitors

Abstract

• Functionalized membrane with customized pattern is prepared by fast laser carving. • Selective permeable membrane complemented with vacuum filtration is used to develop intact interdigital thin film. • Macroscopic assembly based on size effect rationally guide the structural design and precise fabrication of flexible electrode with expected high performances. • Flexible high-performance on-chip micro-supercapacitors with planar arbitrary shape are fabricated. Graphene-based electrodes with rational structural design have shown extraordinary prospect for enhanced electrical double-layer capacitance of micro-supercapacitors (MSCs). Herein, a facile fabrication method for flexible planar MSCs based on hierarchical graphene was demonstrated by using a laser-treated membrane for electrode patterning, complemented with hierarchical electrode configuration taking full advantages of size-determined functional graphene. The in-plane interdigital shape of MSCs was defined through vacuum filtration with the assistance of the functionalized polypropylene (PP) membrane. The hierarchical graphene films were built by macroscopic assembly based on size effect of different lateral sized graphene sheets (rGO-LSL). The sample of MSCs based on rGO-LSL (MSCs-LSL) exhibited excellent volumetric capacitance of 6.7 F cm −3 and high energy density of 0.37 mWh cm −3 . The MSCs-LSL presented superb flexibility and cycling stability with no capacitance deteroriated after 2000 cycles. This newly developed fabrication strategy is of good scalability and designability to manufacture flexible electrode for MSCs with customized shapes, while the construction of hierarchical graphene can enlighten the structural design of analogous two-dimensional materials for potential advanced electronics. A facile mask-free filtration approach is developed for the fabrication of patterned onchip micro-supercapacitors based on hierarchical graphene. The use of the functionalized membrane complemented with macroscopic assembly based on size effect provides the control over the planar configuration of micro-supercapacitors, and rationally guide the structural design of flexible electrode with expected high performances.