Emerging non-lithium ion batteries

Li-ion batteries have dominated the field of electrochemical energy storage for the last 20 years. It still remains to be one of the most active research fields. However, there are difficult problems still surrounding lithium ion batteries, such as high cost, unsustainable lithium resource and safety issues. Rechargeable batteries base on alternative metal elements (Na, K, Mg, Ca, Zn, Al, etc.) can provide relatively high power density and energy density using abundant, low-cost materials. Therefore, non-lithium ion batteries are regarded as promising candidates to partially replace lithium ion batteries in near future. In recent years, the research on non-lithium rechargeable batteries is progressing rapidly, but many fundamental and technological obstacles remain to be overcome. Here we provide an overview of the current state of non-lithium rechargeable batteries based on monovalent metal ions (Na⁺ and K⁺) and multivalent metal ions (Mg²⁺, Ca²⁺, Zn²⁺ and Al³⁺). The needs and possible choices of superior electrode materials and compatible electrolytes beneficial for ion transport were emphatically discussed in this review.