Utilizing polyaniline to dominate the crystal phase of Ni(OH)2 and its effect on the electrochemical property of polyaniline/Ni(OH)2 composite

Abstract

In this study, three-dimensional (3D) flower-like nickel hydroxide (Ni(OH)2) is decorated on one-dimensional fiber-like polyaniline (PANI) to obtain PANI/Ni(OH)2 composite. Two-step hydrothermal method is used where PANI serves as crystal growth modifier of Ni(OH)2. By reducing the initial concentration of PANI, the polymorph of Ni(OH)2 converts from β-to α-phase and the morphology of Ni(OH)2 correspondingly changes from nanoplate to 3D flower-like, which significantly impacts the electrochemical activity of PANI/Ni(OH)2 composite. Results show that fibrous PANI with high available surface area is expected to have many active sites for the deposition of nanoparticles. Besides, 3D flower-like Ni(OH)2, which can facilitate the transition for charge, contacts closely with PANI. Due to the good electrical conductivity and electrochemical activity of PANI with high proton doping level, the introduction of PANI can enhance the electrical conductivity and electrochemical performance of composite. Consequently, the PANI/Ni(OH)2 electrode exhibits good electrochemical property, including high capacity, good rate capability and long cycle life. In addition, this work will provide a new concept for using polymer in dominating the structure, morphology and electrochemical property of electrode material.