Materials for simultaneous energy conversion and storage
- Authors
- Publication Date
- Jan 20, 2022
- Source
- HAL-Descartes
- Keywords
- Language
- English
- License
- Unknown
- External links
Abstract
Our approach to alleviate the solar intermittency is to combine, in a single photo-electrochemical cell, solar energy conversion and storage. Starting from a Li-ion battery configuration, we propose to use Li-ion host photo-electrodes, which could both harvest solar energy and store it. We will be presenting the case of mesoporous TiO2 anatase, as a positive electrode. The illumination of the lithiated electrode (after discharge) induces a lithium-ion extraction reaction (i.e. the recharge of the battery), opening the way to Li-ion photo-rechargeable batteries. Photo-extraction of lithium ions at open circuit voltage and during electrochemical cycling was demonstrated. The holes’ photo-generated seems to oxidize the Ti3+ into Ti4+ resulting in the extraction of the lithium ion, however the fate of the photo-electrons was not elucidated. In this thesis, we chose to control and orient the fate of the electrons by adding water as a photo-electron acceptor, thereby choosing a water-based electrolyte (i.e. water-in-salt, WIS) to also be able to access a large storage capacity of lithium ions and produce a storage molecule, the dihydrogen. Depending of the state of charge of the battery, the electrode composition varies a lot: from a single crystalline phase to a two-phase material. The impact of this composition change in the dynamics of, the production of hydrogen and the light-induced processes, both will be discussed in this thesis. This work constitutes a proof of concept that low potential Li-ion batteries could solely be recharged by exposure to light.
