Electrode Materials for Rechargeable Sodium‐Ion Batteries: Potential Alternatives to Current Lithium‐Ion Batteries

TLDR

Lithium‑ion batteries dominate the global rechargeable market, powering electric vehicles and portable electronics, but sodium, a more abundant element with similar chemistry, has recently attracted renewed interest as a potential alternative. The article reviews negative and positive electrode materials for sodium‑ion batteries. The authors survey recent studies on these materials, summarizing their structural and electrochemical characteristics. The review finds that sodium‑ion electrodes exhibit lower voltage and larger volume changes than lithium equivalents, that power performance varies with crystal structure, and that cost‑effective sodium‑ion batteries could partially replace lithium‑ion batteries with further improvement.

Abstract

Abstract Lithium (Li)‐ion batteries (LIB) have governed the current worldwide rechargeable battery market due to their outstanding energy and power capability. In particular, the LIB's role in enabling electric vehicles (EVs) has been highlighted to replace the current oil‐driven vehicles in order to reduce the usage of oil resources and generation of CO 2 gases. Unlike Li, sodium is one of the more abundant elements on Earth and exhibits similar chemical properties to Li, indicating that Na chemistry could be applied to a similar battery system. In the 1970s‐80s, both Na‐ion and Li‐ion electrodes were investigated, but the higher energy density of Li‐ion cells made them more applicable to small, portable electronic devices, and research efforts for rechargeable batteries have been mainly concentrated on LIB since then. Recently, research interest in Na‐ion batteries (NIB) has been resurrected, driven by new applications with requirements different from those in portable electronics, and to address the concern on Li abundance. In this article, both negative and positive electrode materials in NIB are briefly reviewed. While the voltage is generally lower and the volume change upon Na removal or insertion is larger for Na‐intercalation electrodes, compared to their Li equivalents, the power capability can vary depending on the crystal structures. It is concluded that cost‐effective NIB can partially replace LIB, but requires further investigation and improvement.