Theoretical Progress of 2D Six-Membered-Ring Inorganic Materials as Anodes for Non-Lithium-Ion Batteries.

The use and storage of renewable and clean energy has become an important trend due to resource depletion, environmental pollution, and the rising price of refined fossil fuels. Confined by the limited resource and uneven distribution of lithium, non-lithium-ion batteries have become a new focus for energy storage. The six-membered-ring (SMR) is a common structural unit for numerous material systems. 2D SMR inorganic materials have unique advantages in the field of non-lithium energy storage, such as fast electrochemical reactions, abundant active sites and adjustable band gap. First-principles calculations based on density functional theory (DFT) can provide a basic understanding of materials at the atomic-level and establish the relationship between SMR structural units and electrochemical energy storage. In this review, the theoretical progress of 2D SMR inorganic materials in the field of non-lithium-ion batteries in recent years is discussed to summarize the common relationship among 2D SMR non-lithium energy storage anodes. Finally, the existing challenges are analyzed and potential solutions are proposed.