Effect of temperature on behavior of perovskite-type oxide LaGaO₃ used as a novel anode material for Ni-MH secondary batteries

Abstract

Summary To obtain a novel negative electrode for nickel‐metal hydride rechargeable batteries, perovskite‐type oxide LaGaO3 was synthesized by the sol‐gel method. The electrochemical properties of the oxide were systematically investigated at different temperatures by using galvanostatic, chronoamperometric, and potentiodynamic polarization methods. We have selected 298, 313, and 328 K as room, intermediate, and high temperatures, respectively. The galvanostatic results showed that the discharge capacity of the oxide LaGaO3 increased with the temperature elevating during the first 3 cycles. This oxide has the highest discharge capacity of about 220 mAh g−1at high temperature. For room and intermediate temperatures, we observed that the discharge capacity maintains a constant about of 5 and 13 mAh g−1 for 298 and 313 K, respectively, when the number of cycles is increased. The electrochemical kinetic analysis indicates that the exchange current density and the hydrogen diffusion coefficient of the oxide LaGaO3 increase with the rise in temperature. The apparent activation energy (Ea) for hydrogen diffusion process and the activation energy (ΔrH*) for charge‐transfer reaction of the investigated oxide electrode LaGaO3 are estimated. The calculated values of the Ea and ΔrH* are 117.46 and 105 kJ mol−1, respectively. The above experimental results indicated that the kinetic properties of the working electrode have been significantly improved by the elevating of the temperature. The best electrochemical performance (faster activation and highest maximum capacity) of the oxide electrode is obtained at high temperature (328 K).

The impacts of nitrogen doping on the electrochemical hydrogen storage in a carbon

“…There are several types of hydrogen storage alloys have been developed, such as AB 5 -type, AB 2 -type, Mg-based alloys, Ti-V-based alloys and rare-earth-Mg-Ni-based alloys, and significant improvements have been made to promote their electrochemical performances. [64][65][66][67][68][69][70][71][72][73][74][75] Many of them are made of heavy elements, and still suffer from high cost and poor cycle life. Carbonaceous materials, however, with merits of high electronic conductivity, low mass density, tunable porous nanostructure with high special surface area, become the alternative and effective candidates for storing hydrogen electrochemically.…”

“…Obviously, the hydrogen storage capacity of carbon materials studied here is quite low with respect to those commercial metal‐hydride alloys, which have been widely used as negative electrodes in Ni/MH batteries. There are several types of hydrogen storage alloys have been developed, such as AB 5 ‐type, AB 2 ‐type, Mg‐based alloys, Ti‐V‐based alloys and rare‐earth‐Mg‐Ni‐based alloys, and significant improvements have been made to promote their electrochemical performances 64‐75 . Many of them are made of heavy elements, and still suffer from high cost and poor cycle life.…”

High Capacity, Rate-Capability, and Power Delivery at High-Temperature by an Oxygen-Deficient Perovskite Oxide as Proton Insertion Anodes for Energy Storage Devices

“…5c) yields a value of Δ * H r to be 44.79 KJ mol −1 , which seems relatively higher than MH electrodes 34 but much lower than earlier reported oxide electrodes. 35 In addition to the charge-transfer process, hydrogen diffusion in the oxide material could be rate-determining step for battery's charge-discharge process. Therefore, it is undoubtedly a critical factor in the evaluation of electrode material.…”