CNT/LDH-Stabilized Biomass-Derived Nanocellulose as a Low-Cost Alternative for Asymmetric Supercapacitors: Impact of Sources of Nanocellulose

The current study deals with the problem of waste processing and the need for cheaper and more efficient energy storage devices. In this regard, nanocellulose was extracted from waste parts of examination answer scripts, laboratory tissue paper, grass, rice straw, jute fiber, and then modified with CNT in three different ratios for supercapacitor electrodes. To bind the nanocellulose and CNT together and to add pseudocapacitance, Ni-Al LDH was combined with them. The formation of the composite was evaluated through FESEM, PXRD, and XPS analyses. The composites were used as cathodes and carbon black as the anode to fabricate asymmetric supercapacitors. The optimization of the different devices through electrochemical analysis revealed that cellulose/CNT ratios were 7:1, 7:1, 7:1, 5:1, and 10:1 for waste paper, grass, jute fiber, rice straw, and waste laboratory tissue paper celluloses, respectively. Among all of the devices, the waste examination paper based device with a cellulose/CNT ratio of 7:1 had the highest specific capacitance of 72.4 F g-1 with an energy density of 32.6 Wh kg-1 at 1 A g-1, and a maximum power density of 18 kW kg-1 at an energy density of 17.3 Wh kg-1. This device had 99% stability after 9000 charge-discharge cycles. This study not only used nanocellulose extracted from waste materials but also established the right concentration of CNT needed for each cellulose source to obtain the best electrochemical performance. Thus, this study walks in the path of the motto "Waste to Energy".