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Current work presents a high-performance asymmetric supercapacitor (ASC) using nanostructured cobalt nickel sulfide (CoNi2S4) derived via African marigold flower-like layered double hydroxide (CoNi-LDH) as a cathode and Manihot esculenta-derived activated carbon (MAC) synthesized from oxygen-rich hydrochar as an anode. Optimization for LDH precursors with different times of synthesis was carried out, and best performed CoNi-LDH-12 displayed a specific capacitance of 928 F/g at 1 A/g in a three-electrode system, which was further sulfurized with two different sulfur ratios to obtain CoNi2S4. As-prepared spinel CoNi2S4-800 achieved a remarkable specific capacitance of 1637 F/g at 2 A/g, and the specific capacity was found to be 184 mAh/g, whereas the capacitance for synthesized MAC was found to be 315 F/g at 0.5 A/g in a three-electrode system. The ASC device CoNi2S4//MAC fabricated offered remarkable energy densities of 55.37 and 10.66 Wh/kg at power densities of 3200 W/kg and 10.66 kW/kg, respectively. The prolonged cycle life studies of the ASC device for 5000 cycles achieved a coulombic efficiency of 95.90% with a capacitance retention of ∼90.03%, proving the electrode materials to be promising for energy storage application.

The demand for the development of electrochemical energy storage systems from abundant, renewable, eco-friendly, and cost-effective materials has been the focal and driving point in the advancement of electronic devices. This task and demand can be addressed with a resource that is abundant and possesses the attributes of being developed into efficient electrochemical energy storage systems. Lignin and cellulose, which are collectively known as lignocellulose, are the two most abundant biopolymers available, and they possess the attributes and the qualities to meet this demand. Lignocellulose biopolymers possess unique characteristics such as mechanical flexibility, porosity, and tunability because of their abundant and diverse functional groups. These qualities enable suitable pairing with electronically conducting polymers as enhanced materials for the development of sustainable energy storage devices. This Review highlights the challenges and the utilization of lignocellulose with electronically conducting polymers in supercapacitors applications and battery applications in various capacities as electrodes, separators, binders, and electrolytes.

Advancements to tackle the 21st-century energy crisis are being made focusing majorly on sustainability. Lignin and cellulose comprise major parts of biomass and have plenty of advantages such as abundance, eco-friendliness, cost effectiveness, sustainability, and renewability. Utilizing them as precursors for electrode materials for supercapacitors and batteries is promising. The present review discusses extensively the exploitation of tunable features of different special structures of carbons derived from components of lignin, cellulose, and lignocellulose, and their transformations as electrode materials for supercapacitors and battery applications. The structures have been categorized into carbon nanosheets, carbon nanofibers, hierarchically porous carbon, and heteroatom-doped carbon. Their performance studies with various electrochemical optimizations for energy storage have been discussed comprehensively with a significant emphasis on the structural morphologies of the discussed materials. As the materials also have some limitations, the review highlights a few gaps and challenges to be encountered for further developments with a future perspective in energy storage.

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