High Capacity, Rate-Capability, and Power Delivery at High-Temperature by an Oxygen-Deficient Perovskite Oxide as Proton Insertion Anodes for Energy Storage Devices
Aman Bhardwaj, Hohan Bae, Inho Kim, Lakshya Mathur, Jun‐Young Park, Sun‐Ju Song
Abstract
Ni/MH batteries have undergone constant development over time to fulfill emerging demands; however, poor high-temperature performance limits their widespread applicability as a cheap and robust energy storage system. Herein, Sm 1-x Sr x CoO 3− δ (x = 0, 0.5, 1) perovskite oxides are investigated as proton insertion anodes for batteries. The oxygen-deficient Sm 0.5 Sr 0.5 CoO 3‒ δ (SSC) unveils maximum reversible discharge capacity of 182 mAh g −1 at 25 °C, the highest for oxide materials investigated so far. It also increases with temperature to 240 mAh g −1 at 60 °C. Partial substitution of samarium for acceptor dopant strontium is found to induce lattice expansion and improve cobalt-ion reducibility to facilitate higher hydrogen storage. The kinetic properties viz. exchange current density, hydrogen diffusivity, the activation energies of the charge-transfer process, and hydrogen diffusion are scrutinized. The complex impedance analysis indicates a gradual reduction of bulk ( R b ) and charge-transfer ( R ct ) polarization with temperature. Moreover, the SSC exhibits good cyclability, low self-discharge rates, satisfactory rate-capability, good power delivery, and a high coulombic efficiency even at elevated temperatures to be a potentially suitable anode for Ni/Oxide or proton rechargeable batteries.