Hierarchical cellulose-derived CNF/​CNT composites for electrostatic energy storage

Today many appli­ca­tions require new effec­tive approach­es for ener­gy deliv­ery on demand. Super­ca­pac­i­tors are viewed as essen­tial ener­gy stor­age devices that can con­tin­u­ous­ly pro­vide quick ener­gy. The per­for­mance of super­ca­pac­i­tors is most­ly deter­mined by elec­trode mate­ri­als that can store ener­gy via elec­tro­sta­t­ic charge accu­mu­la­tion. This study presents new sus­tain­able cel­lu­lose-derived com­pos­ite elec­trodes which con­sist of car­bon nanofi­brous (CNF) mats cov­ered with vapor-grown car­bon nan­otubes (CNTs). The CNF/​CNT elec­trodes have high elec­tri­cal con­duc­tiv­i­ty and sur­face area: the two most impor­tant fea­tures that are respon­si­ble for good elec­tro­chem­i­cal per­for­mance of super­ca­pac­i­tor elec­trodes. The results show that the com­pos­ite elec­trodes have fair­ly high val­ues of spe­cif­ic capac­i­tance (101 F/​g at 5 mV s−1), ener­gy and pow­er den­si­ty (10.28 Wh/​kg and 1.99 kW/​kg, respec­tive­ly, at 1 A/​g) and can retain excel­lent per­for­mance over at least 2000 cycles (96.6 % reten­tion). These results indi­cate that sus­tain­able cel­lu­lose-derived com­pos­ites can be exten­sive­ly used in the future as super­ca­pac­i­tor electrodes.