Anion doping-induced enhancement of electrochemical catalysis in NiCo2O4 for energy conversion and storage

The advancement of electrode materials exhibiting high catalytic activity is crucial for the application of solid oxide fuel cells (SOFCs) and lithium-ion batteries (LIBs). Herein, the anion substitution strategy is used to enhance the electrochemical catalytic activity of spinel oxide NiCo2O4. For the first time, F-doped NiCo2O3F (NCOF) was synthesized and systematically studied as the electrode for both SOFCs and LIBs. The results demonstrate a noticeable increase in both the content of oxygen vacancies and the unit cell free volume after F doping. Simultaneously, there is a reduction in the band gap width, consequently significantly enhancing the conductivity of NCO. These changes are beneficial to the oxygen reduction reaction (ORR) process. At 750 °C, the Rp of NCOF is 0.05 Ω cm2, exhibiting a reduction of 61.5 % compared to NCO. F doping accelerates the process of charge transfer and the adsorption/dissociation of oxygen. At 800 °C, NCOF exhibits an output performance of 0.85 W cm2, which is 46.6 % higher than that of NCO. Simultaneously, the initial discharge specific capacity of NCOF-based LIB reaches 1395 mAh/g at a current density of 100 mA g−1. F doping demonstrates a noteworthy improvement in both insertion potential and cycling performance. As a result, the NCOF electrode exhibits exceptional rate capability, highlighting its enhanced ability to efficiently handle charging and discharging processes over multiple cycles. These findings suggest that NCOF holds significant potential as an advanced electrode material for both SOFC and LIBs. This study introduces fresh perspectives for designing and developing high catalytic activity multifunctional electrodes for energy conversion and storage devices in the future.