Syntheses, challenges and modifications of single-crystal cathodes for lithium-ion battery

Single-crystal cathodes (SCCs) are promising substitute materials for polycrystal cathodes (PCCs) in lithium-ion batteries (LIBs), because of their unique ordered structure, excellent cycling stability and high safety performance. Cathode materials with layered (LiCoO2, LiNixCoyMnzO2, LiNixCoyAlzO2) and spinel structure (LiMn2O4, LiNi0.5Mn1.5O4) show a relatively stable electrochemical performance, but still lack of sufficient attention in research field. In this review, we begin with the definition, structural features and electrochemical advantages of SCCs. Common SCCs synthesis methods and the thermodynamic growth mechanism of SCCs with oriented facet exposure are summarized in the following part. Then we introduce the problems and challenges of SCCs faced and the corresponding modification strategies. Finally, the industrialization progress of SCCs is brifly outlined. We intend to tease out the difficulties and advances of SCCs to provide insights for future development of high-performance SCCs for practical LIBs.