Vanadium dioxide–zinc oxide stacked photocathodes for photo-rechargeable zinc-ion batteries

Abstract

The development of batteries that can be recharged directly by light, without the need for external solar cells or external power supplies, have recently gained interest for powering off-grid devices....

Light-induced Li extraction from LiMn2O4/TiO2 in a water-in-salt electrolyte for photo-rechargeable batteries

“…Photocharging and electric-discharging proceeded simultaneously, resulting in prolonged discharge capacities according to previous studies on PRBs. 1,4,[7][8][9][10] The potential increased even while discharging at 10 mA g À1 , indicating that the efficiency of photocharging is higher than the current supplied by the galvanostat. In contrast, the potential decreased just after the start of electric discharge at 30 mA g À1 (inset of Fig.…”

“…Recently, a new battery system that can be directly charged by light, called photorechargeable batteries (PRBs), has been proposed. [1][2][3][4][5][6][7][8][9][10] This type of battery offers more compact and simple designs than the combination of solar cells and conventional batteries. PRBs are therefore applicable to internet of things (IoT) devices, which are becoming increasingly common.…”

“…Previous studies have reported various combinations of materials, for example, LiFePO 4 /N719-dye, 3 Cu 2 S/dye-sensitized TiO 2 , 4 polyaniline/TiO 2 , 5 V 2 O 5 /poly(3-hexylthiophene-2,5-diyl), 8,9 and VO 2 / ZnO. 10 It is, however, still challenging to use high-potential cathodes (i.e., 4 V class in LIBs) because the materials that allow for their photocharging are limited (Table S1, ESI †). Among high-potential cathode materials, spinel oxides are one of the most promising candidates because they are highly designable by modifying the crystal structures depending on the battery system, which is a great advantage for improving battery performance.…”

“…A difference from conventional batteries is that PRBs use photoactive materials. Photocatalysts, 1,2,5,6 dyes, 3,4 and cathode materials themselves 8–10 can be employed as them. It is energetically possible to charge electrode materials with the holes and excited electrons generated by illumination in the photoactive materials if the relationship between the energy levels is adequate (Fig.…”

Integrated Photovoltaic Charging and Energy Storage Systems: Mechanism, Optimization, and Future

“…[ 121 ] 2) When two semiconductors such as p‐type VO 2 ( E g = 2.3 EV) and n‐type ZnO ( E g = 3.37 EV) form a p‐n junction, a stronger electric field is generated at the interface, resulting in more significant charge separation effect and lower charge recombination rate. [ 122 ] 3) Another kind of heterojunction is formed by wide‐bandgap semiconductors (such as TiO 2 and ZnO) and narrow‐bandgap semiconductors (such as organic dyes and CH 3 NH 3 PBI 3 ), in which quantum dots with high absorption coefficient act as photosensitizers. Smaller quantum dots have larger bandgap and higher conduction band level, resulting in faster electron transfer to TiO 2 .…”