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

Abstract

Photocharging of spinel LiMn2O4 has been demonstrated by utilizing a water-in-salt electrolyte with an electron acceptor and TiO2 nanoparticles, which paves the way for developing high-potential cathode materials for photo-rechargeable batteries.

Optimizing LiMn1.5M0.5O4 cathode materials for aqueous photo-rechargeable batteries

“…The discharge capacities from around 1.0 V vs. Ag/AgCl clearly indicate the redox reactions of the Mn-based spinel-oxide cathode materials. 17 As demonstrated here, spinel oxides modified from LiMn 2 O 4 were successfully photocharged, for what we believe is the first time.…”

“…The water-in-salt electrolyte enables the charging/discharging of Mn-based spinel oxides due to its high oxidative stability. 17,21 Note that Mn-based spinel cathode materials exhibit multiple redox potentials, 18,25 i.e. , so-called 3, 4, and 5 V regions.…”

“…[13][14][15][16] Our group recently reported the photocharging of LiMn 2 O 4 , in which we employed a half-cell with an electron acceptor to demonstrate Li extraction from the spinel structure induced by the holes generated in TiO 2 nanoparticles. 17 Spinel LiMn 2 O 4 is promising for a high-potential cathode; however, a problem is its low stability during charge/discharge. For instance, it is well known that Mn 2+ formed by the disproportionation of Mn 3+ in LiMn 2 O 4 easily dissolves into electrolytes, 18 resulting in capacity fading.…”

Mg–Zn–Mn Oxide Systems for a Rechargeable Mg-Battery Cathode

“…Thus, modifying the crystal structure of ZnMnO 3 with these elements would be a promising way to improve its cathode performance. In addition, spinel-oxide cathode materials have been employed in many kinds of advanced rechargeable battery systems such as Zn-ion batteries, − Li–Mg dual-cation batteries, , and Li-ion photorechargeable batteries . We therefore hope this work provides basic guidelines for understanding the relationship between the phase stability and electrochemical properties of spinel oxides and helps develop future advanced materials.…”

A perspective on photoelectrochemical storage materials for coupled solar batteries

“…To explore a high-potential PSC, Kohei Shimokawa et al reported the preparation of TiO 2 /LiMn 2 O 4 , where TiO 2 nanoparticles were the photoactive material responsible for photovoltaic conversion, and LiMn 2 O 4 was for energy storage. 63 Once illuminated by UV-visible light, the photo-generated electrons within TiO 2 were transferred from HOMO to LUMO. The HOMO energy level for TiO 2 was high enough to extract Li + cations from LiMn 2 O 4 .…”