High Performance Photorechargeable Li‐Ion Batteries Based on Nanoporous Fe2O3 Photocathodes

Abstract In recent years, photorechargeable Li‐ion batteries (Li‐PRBs) are investigated as potential energy devices to supply continuous power to remote IoT or electronic devices. These Li‐PRBs, due to their lightweight and low‐cost, offers various advantages compared to conventional combination of solar cells and a battery. Single active material‐based PRBs have gained attention due to the use of multifunctional materials which perform both solar energy harvesting and storage, however most of the PRBs studied so far are based on ion intercalation. Herein, the use of conversion type active material α ‐Fe 2 O 3 for efficient and stable operation of Li‐PRBs is demonstrated. Cost‐effective solution processing method is used to synthesize α ‐Fe 2 O 3 nanorods (NRs), which form nanoporous morphology when blended with Multi‐walled carbon nanotubes / Phenyl‐C61 butyric acid methyl ester (MWCNT/PCBM) conducting additives to form photocathodes. α ‐Fe 2 O 3 NRs shown simultaneous solar energy harvesting in visible region of spectra, owing to its energy bandgap E g ≈ 2.1 eV, and efficient Li‐ion storage via conversion reaction mechanism. Li‐PRB has shown photoconversion and storage efficiency of ≈1.988% when illuminated with blue LED ( λ ex ≈ 470 nm) for large voltage window (0.8–2.57 V). The use of conversion type material like Fe 2 O 3 in PRBs opens up new pathways to explore new materials and mechanisms for these emerging devices.