Influence of TiO_2 on the electrochemical performance of pasted typeβ-nickel hydroxide electrode in alkaline electrolyte

Nickel hydroxide was used as the positive electrode material in rechargeable alkaline batteries, which plays a significant role in the field of electric energy storage devices. β-nickel hydroxide（β-Ni（OH）2 ） was prepared from nickel sulphate solution using potassium hydroxide as a precipitating agent. Pure β-phase of nickel hydroxide was confirmed from XRD and FT-IR studies. The effects of TiO2 additive on the β-Ni（OH）2 electrode performance are examined. The structure and property of the TiO2 added β-Ni（OH）2 were characterized by XRD, TG-DTA and SEM analysis. A pasted–type electrode is prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry and electrochemical impedance spectroscopy studies were performed to evaluate the electrochemical performance of the β-Ni（OH）2 and TiO2 added β-Ni（OH）2 electrodes in 6 M KOH electrolyte. Anodic（Epa） and cathodic（Epc）peak potentials are found to decrease after the addition of TiO 2 into β-Ni（OH）2 electrode material. Further,addition of TiO2 is found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. Compared with pure β-Ni（OH）2 lectrode,TiO2 added β-Ni（OH）2 electrode is found to exhibit higher proton diffusion coefficient（D） and lower charge transfer resistance. These findings suggest that the TiO2 added β-Ni（OH）2 electrode possess improved electrochemical properties and thus can be recognized as a promising candidate for the battery electrode applications.

A critical review on nickel-based cathodes in rechargeable batteries

The 3d transition-metal nickel(Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years,from Ni-based alkaline rechargeable batteries,such as nickel-cadmium(Ni-Cd)and nickel-metal hydride(Ni-MH)batteries,to the Ni-rich cathode featured in lithium-ion batteries(LIBs).Ni-based alkaline batteries were first invented in the 1900s,and the well-developed Ni-MH batteries were used on a large scale in Toyota Prius vehicles in the mid-1990s.Around the same time,however,Sony Corporation commercialized the first LIBs in camcorders.After temporally fading as LiCoO_(2) dominated the cathode in LIBs,nickel oxide-based cathodes eventually found their way back to the mainstreaming battery industry.The uniqueness of Ni in batteries is that it helps to deliver high energy density and great storage capacity at a low cost.This review mainly provides a comprehensive overview of the key role of Ni-based cathodes in rechargeable batteries.After presenting the physical and chemical properties of the 3d transition-metal Ni,which make it an optimal cationic redox center in the cathode of batteries,we introduce the structure,reaction mechanism,and modification of nickel hydroxide electrode in Ni-Cd and Ni-MH rechargeable batteries.We then move on to the Ni-based layered oxide cathode in LIBs,with a focus on the structure,issues,and challenges of layered oxides,LiNiO_(2),and LiNi_(1−x−y)Co_(x)Mn_(y)O_(2).The role of Ni in the electrochemical performance and thermal stability of the Ni-rich cathode is highlighted.By bridging the“old”Ni-based batteries and the“modern”Ni-rich cathode in the LIBs,this review is committed to providing insights into the Ni-based electrochemistry and material design,which have been under research and development for over 100 years.This overview would shed new light on the development of advanced Ni-containing batteries with high energy density and long cycle life.