Are Halide‐Perovskites Suitable Materials for Battery and Solar‐Battery Applications–Fundamental Reconsiderations on Solubility, Lithium Intercalation, and Photo‐Corrosion

In recent years the development of autonomous photo-rechargeable batteries has received growing attention. Especially highly integrated photobatteries based on multifunctional materials able to harvest sunlight and store charge carriers are the holy grail amongst such devices. Recently 2-(1-cyclohexenyl)ethyl ammonium lead iodide (CHPI) has been reported as multifunctional photoelectrode material for the design of highly integrated Li-ion photobatteries. CHPI is thereby believed to be able to reversibly intercalate Li-ions from polar carbonate-based electrolytes, typically used in Li-ion batteries (LIBs). Herein, CHPI is examined closer to investigate its stability against dissolution, the possibility of Li-intercalation and photo-assisted deintercalation, and its general behavior under illumination in standard carbonate-based electrolytes as well as in a newly developed low polarity electrolyte based on ortho-difluorobenzene (o-DFB). This study demonstrates that CHPI dissolves in contact with carbonate-based electrolytes while being stable in o-DFB-based electrolyte and that no Li-intercalation takes place in the latter. Furthermore, CHPI irreversibly photo-corrodes during illumination and photo-assisted deintercalation of lithium ions is not detected. These results lead to the conclusion, that CHPI is neither a suitable nor a stable material for the design of Li-ion-based photo-rechargeable batteries and similar behavior for other organic-inorganic lead halide perovskite materials is expected.