Free-standing SiOC/nitrogen-doped carbon fibers with highly capacitive Li storage

Silicon oxycarbide (SiOC) as a prospective electrode material for next-generation lithium ion batteries (LIBs) was restricted by the unsatisfactory discharge capacity and inflexibility used in flexible and wearable electronics. Herein, freestanding flexible SiOC/nitrogen-doped carbon fiber films are constructed through electrospinning process followed by carbonizing in NH₃ atmosphere. In this way, SiOC particles are tightly embedded in N-doped carbon fibers, forming a 3D conductive network to promote electron transport and faster reaction kinetics. The nitrogen dopants create more defects in carbon fibers matrix, which improve the electronic conductivity and electrochemical active sites of the electrodes. Owing to the above synergistic effect, SiOC/nitrogen-doped carbon fiber electrodes exhibit a high initial Coulombic efficiency of 73 % and a reversible remaining capacity of 595 mA h g⁻¹ at 200 mA g⁻¹ even after 200 cycles. The electrodes with good flexibility can successfully drive a light-emitting diode even when the package battery is bended to 180°.