Nitrogen-sulfur co-doped ZIF-8-derived carbon materials for supercapacitors with low self-discharge

Supercapacitors (SCs) have attracted extensive attention due to the properties of high power density, long cycle life, and high rate performance. However, the high self-discharge is one giant challenge for long-term energy storage applications of SC. Herein, we prepared a high-performance SC with low self-discharge based on nitrogen-sulfur co-doped ZIF-8-derived (NS-PC) materials. The synergistic effects of high-temperature carbonization and nitrogen-sulfur (N-S) doping are systematically investigated. With a carbonization temperature of 900 degrees C, assisted with N-S doping, the maximum specific capacitance of the NS-PC-900//NS-PC-900 symmetrical SC is 42.7 F g- 1, while the power densities range from 650 to 13,000 W kg-1 at the energy densities of 10.04-7.5 Wh kg- 1. The specific capacitance remains 95.7 % even after 20,000 charge-discharge cycles. More importantly, the as-prepared NS-PC-900//NS-PC-900 SC exhibits an ultra-low self-discharge rate of solely 0.025 V h-1 within 24 h. This work provides a universal strategy to fabricate high-performance SCs with low self-discharge.