Aluminum-ion batteries (AIBs) are regarded to be one of the most promising alternatives for next-generation batteries thanks to the abundant reserves, low cost, and lightweight of aluminum anode. Like other electrochemical energy storage systems, the electrochemical performances of AIBs intimately depend on the properties of electrolytes and electrode materials. This chapter provides an overview of the advancements and challenges in electrolytes, anodes, and cathodes for AIBs as well as the fundamental understanding of their reaction mechanisms. In addition, from the practical point of view, the development of other components in AIBs such as separators, current collectors, and the cell configurations are also discussed.