MXenes for metal-ion and metal-sulfur batteries: Synthesis, properties, and electrochemistry

In 2011, a new class of 2D materials was discovered; after 2012, they began to be concerned; in 2017, the “gold rush” of the materials was triggered, and they are exactly MXenes. 2D MXenes, a new class of transition metal carbides, carbonitrides and nitrides, have become the star and cutting-edge research materials in the field of emerging batteries systems due to their unique 2D structure, abundant surface chemistry, and excellent physical and electrochemical properties. This review focuses on the MXene materials and summarizes the recent advancements in the synthesis techniques and properties, in addition to a detailed discussion on the electrochemical energy storage applications, including alkali-ion (Li⁺, Na⁺, K⁺) storage, lithium-sulfur (Li–S) batteries, sodium-sulfur (Na–S) batteries, and metal anode protection. Special attentions are given to the elaborate design of nano-micro structures of MXenes for the various roles as electrodes, multifunctional components, S hosts, modified separators, and metal anode protective layers. The paper ends with a prospective summary of the promising research directions in terms of synthesis, structure, properties, analysis, and production on MXene materials.