Transparent film of carbon nanotubes/Ni(OH)2 nanocomposite for application in alkaline batteries

A nanocomposite composed of multi-walled carbon nanotubes (MWCNTs) and Ni(OH)₂ nanoparticles was synthesized, characterized, and processed into thin films for application as cathodes in alkaline batteries. The synthesis was carried out using a modified polyol method, and the thin film was prepared by the liquid-liquid interfacial route (LLIR), enabling uniform film deposition. Structural analysis revealed the formation of α-phase Ni(OH)₂ nanoparticles, which is particularly advantageous for electrochemical applications due to the larger interlayer distances. The presence of MWCNT during synthesis led to significant reduction in Ni(OH)₂ particle size (10–20 nm) compared to the neat Ni(OH)₂ prepared as control (50–80 nm), indicating a nucleating effect induced by MWCNT. The resulting nanocomposite thin film showed high homogeneity, an optical transmittance of 86.3 % at a wavelength of 550 nm, and a thickness of 111 ± 28 nm. Electrochemical measurements in 1 mol L⁻¹ NaOH solution revealed battery-like charge-discharge behavior in both MWCNT/Ni(OH)₂ and Ni(OH)₂ films. The nanocomposite achieved higher specific capacities, reaching ∼105 mA h g⁻¹ at 2.8 A g⁻¹ and ∼ 40 mA h g⁻¹ at 56 A g⁻¹, due to improved conductivity and reduced particle size. In addition, the MWCNT/Ni(OH)₂ exhibited a superior charge-discharge cycling stability, retaining 74 % of its capacity over 2000 cycles at 14 A g⁻¹, compared to 65 % for the Ni(OH)₂ control film at 8.2 A g⁻¹. This stability at high current rates highlights the MWCNT/Ni(OH)₂ nanocomposite thin film as a promising candidate for high-power energy storage and fast charge delivery applications.