Recent Advances in the Rational Design and Synthesis of Two-Dimensional Materials for Multivalent Ion Batteries.

With the increase of device requirements, rechargeable lithium-ion batteries are facing tremendous challenges in large-scale applications due to the high price and gradual shortage of lithium sources. In contrast, multivalent ion batteries, such as aluminum, magnesium, and zinc, are promising candidates for the next-generation energy-storage systems because of their high volumetric energy density, safe operation, and abundant reserves. The strong intercalation between multivalent ions and the host materials, however, will cause lower ion-diffusion kinetics and a poor discharge capacity. One of the main challenges is to search for a suitable cathode material with a high capacity and good structural stability to overcome the abovementioned problems. Two-dimensional layered materials, with characteristic unique structural features, good conductivity, and high electrochemically active surface, have attracted attention from researchers during the past decade. In this review, the design approach and synthetic procedures for the preparation of two-dimensional materials as cathodes for multivalent ion batteries, including interlayer engineering, two-dimensional heterostructures, pore/hole engineering, and heteroatom doping, are summarized. Meanwhile, the relationship between the design configuration and optimized electrochemical performance is rationally and systematically presented. Additionally, perspectives for the sustainable synthesis of cathode materials are proposed for multivalent metal-ion chemistry.