Advances in Nanofiber Cathodes for Aluminum-Ion Batteries

Abstract

Rechargeable aluminum-ion batteries (AIBs) possess a higher theoretical volumetric capacity than lithium-ion batteries (LIBs) and offer a sustainable, low-cost alternative. However, the performance of AIBs fails to meet commercial standards due to the challenges experienced including volume changes caused by interfacial issues, side reactions of the electrolyte with electrode, and low cyclic stability. These issues are attributed to the inability of existing cathode materials to perform effectively. To address these challenges, 1-dimensional (1D) structures, especially nanofiber (NF) cathodes offer a promising solution due to their higher aspect ratios, specific surface area, flexibility, and quantum scale effects. To date, there has been no comparative analysis of the electrochemical and structural performances of NF based cathodes in AIBs. Thus, this review focuses on the recent developments in various transition metal oxides and chalcogenides of (Mo, V, Mn, Ni, Cu, W, Se, and Co) along with carbon-based NFs as cathodes for AIBs. Challenges were observed in adopting trivalent Al³⁺ cations as charge carriers and maintaining the structural integrity of the cathode. Several novel approaches have been developed to enhance electrical conductivity, including the incorporation of the metal oxides/chalcogenides with the carbon NF substrates, crystallizing the nanoparticles at high temperatures, and using self-assembly and templating techniques to create multi-dimensional NF films. Other battery components such as separators were replaced with carbonaceous structures in the MnSe based cathodes to increase ion mobility, and Mo current collectors to prevent dendrites. This review includes prospects aimed at improving performance and functionality, based on observations from the discussed work and innovations in AIBs such as compositing, surface functionalization, and defect engineering through ion doping.

Graphical Abstract