Simultaneous Prelithiation and Compatible Modification toward Ultrafast and Ultrastable Lithium-Ion Capacitors

Lithium-ion capacitors (LICs), which consist of capacitive cathodes from supercapacitors and battery-type anodes from lithium-ion batteries, have been regarded as promising energy storage devices with high energy density, high power density, and long cycle life. Prelithiation plays a crucial role in the manufacturing of LICs due to the low initial Coulombic efficiency of the anode. In this work, a simultaneous prelithiation and compatible modification strategy via the introduction of Li2S as a cathode prelithiation additive and lithium difluoro(oxalato)borate (LiDFOB) as an electrolyte additive has been demonstrated. With the help of the LiDFOB additive, the incompatibility between Li2S and the ester electrolyte can be greatly alleviated, which significantly lowers the delithiation potential of Li2S to 3.15 V vs Li/Li+ with an impressively high irreversible specific capacity of 997 mA h g(-1). Furthermore, the LICs employing Li2S as a cathode prelithiation additive can easily realize anode prelithiation without gas release during the initial charging process, enabled by the decomposition of Li2S. This breakthrough is believed to shed light on the simplified fabrication of LICs via the cathode prelithiation method and hold great promise for largescale commercial applications.