Juglone bonded carbon nanotubes interweaving cellulose nanofibers as self-standing membrane electrodes for flexible high energy supercapacitors

High-performance flexible energy storage is highly desirable for portable electronic devices. We report herein a facile strategy in precisely anchoring redox juglone onto carbon nanotubes (CNTs) and interweaving with bacterial cellulose (BC) nanofibers as stretchable nonwoven porous membrane. The chemical bonding of juglone on CNTs greatly enhanced charge transfer of the composites via smooth electron hopping between pendant organic molecules along the CNTs conductive highway. The optimal composite J(11)-CNT-BC (11:1:5, juglone/CNTs/BC feeding mass ratio) exhibits the highest specific surface area and electric conductivity. The self-standing electrode exhibits a highest specific capacitance of 461.8 F g(-1) at 0.5 A g(-1), over 5-fold higher than that of CNT-BC. A specific capacitance retention of 87.1% is observed after 10,000 cycles of continuous charge/discharge operation at 10 A g(-1). All solid-state asymmetric supercapacitor (ASC) assembled with activated carbon as negative electrode exhibits excellent tolerance to bending (both angles and times) and high specific capacitance retention (82.4% after 10,000 cycles under 10 A g(-1)). The ASC achieves a maximum energy density of 41.9 Wh kg(-1) at a power density of 1.0 kW kg(-1), a performance superior to most CNTs-based devices reported to date. Our work may open a new avenue in the design of redox molecules chemically decorated carbonaceous materials for mass production of self-standing flexible electrodes for high performance energy storage.