Oriented Carbon Fiber Networks by Design from Renewables for Electrochemical Applications

Abstract

With the explosion of global demands for electrified mobility systems and a surge in rural energy transport mechanisms augmented by the scarcity of key metals, carbon by design has become a transformational pathway to fill the gap as an energy material of choice. The development of functional carbon from renewables with outstanding electrostatic double-layer capacitance is still in its infancy, as there is a significant gap in understanding the relationship between the tunable structure and properties of the bioresources both before and after their controlled carbonization. Herein, we report carbon fiber networks (CFNs) with highly controllable intact structure manufactured from four functional lignins originating from different types of processing residues, demonstrating excellent electrochemical efficacies, which makes them promising self-standing electrodes in supercapacitors. This study also underpins the feasibility and importance of preparing CFNs with highly oriented structure, which endows superior specific capacitance and cycle stability compared to the CFNs with randomly oriented fibers. The randomly oriented CFNs reached a specific capacitance value of 456 F g-1 under current densities of 1 A g-1 and a cycle stability of 73.6%, while the CFNs with an orientation factor of 0.87 exhibited significant improvement of the specific capacitance by approximately 15% (529 F g-1) and the cycle stability reached 95% after 10 »000 charge-discharge cycles. The high specific capacitance and excellent overall electrochemical properties of the highly oriented CFNs make them a cost-effective and greener material of choice for energy storage devices.