Ultrafast lithium-ion capacitors for efficient storage of energy generated by triboelectric nanogenerators

Lithium-ion capacitors (LICs) are assembled with lithium titanate nanoparticles embedded in mesoporous carbon spheres (n-LTO@MC) as anodes and activated carbon (AC) as cathodes. The resulting AC//n-LTO@MC capacitors exhibit excellent high-rate capacities of 155 and 79 mAh g(-1) at current rates of 100 and 1000 C, respectively. Charging the ultrafast LICs by rotating triboelectric nanogenerator (R-TENG) with pulsed output at high frequencies is investigated and compared with LICs based on low-rate LTO nanoparticles (AC//n-LTO) and commercial LTO (AC//c-LTO). Shorter charging times by R-TENG rotating at various revolutions and larger discharging specific capacities are demonstrated for AC//n-LTO@MC than AC//n-LTO and AC//c-LTO LICs. The improved efficiency of AC//n-LTO@MC for storing energy generated by R-TENG indicates that ultrafast LICs are promising energy storage devices that may be combined with TENGs as self-charging power unit for harvesting ambient mechanical energy and powering portable electronic devices and remote sensors.