Photoassisted Li-ion de-intercalation and Niδ+ valence conversion win-win boost energy storage performance in Ni/CdS@Ni3S2-based Li-ion battery.

[Display omitted] • A new class of portable photoassisted Lithium-ion battery (PA-LIB) is constructed. • Transition metal sulfide heterojunction is used as a photoelectrode in PA-LIB. • Photoassisted charging/discharging processes are more energy-saving. • Photoinduced Li-ion de-intercalation and Ni valence conversion are revealed. • PA-LIB shows excellent stability and enhanced charge-discharg capacity. The development of bifunctional electrode with photoactivity and lithium storage properties is critical for manufacturing high-efficiency solar energy conversion/storage integrated devices. Herein, for the first time, Ni foam supported Ni 3 S 2 nanosheets covered CdS photocatalyst, a core-shell heterojunction nanorods array (Ni/CdS@Ni 3 S 2), is employed as photoelectrode for photo-assisted lithium-ion batteries (PA-LIBs). The assembled PA-LIBs can be off-grid charged by net solar light and on-grid photoassisted charged/discharged, respectively. Without external bias voltage, the overall solar-to-electrical energy conversion efficiency reaches 0.11 %. In addition, during the photo-assisted charging/discharging processes, the solar to electricity energy conversion efficiency is increased to 3.5 % and 2.1 %, respectively, and the total special capacity of such photocell is significantly improved by 13.7 % and 15.9 % compared with its conventional electric energy charging/discharging battery. Impressively, the PA-LIB maintains good photo-responsive activity even after about 250 charge/discharge cycles. Mechanism investigation reveals that photo-assisted Li-ion de-intercalation and Niδ+ valence conversion together boosts the lithium-ion storage reaction more completely, thus improving the energy storage performance of Ni/CdS@Ni 3 S 2 -based Li-ion battery. [ABSTRACT FROM AUTHOR]