As high-performance power sources for renewable applications such as electric vehicles and consumer electronics, lithium-ion batteries (LIBs) require electrodes that can deliver high energy density without compromising battery lifespan. According to foreign media reports, researchers from Northwestern University and other institutions have investigated the root causes of degradation in high-energy-density LIB cathode materials and developed strategies to mitigate degradation mechanisms, so as to enhance LIB performance. This research is likely to be valuable for many emerging applications, especially grid-scale energy storage applications for electric vehicles and renewable energy sources (such as wind and solar energy). Researcher Mark Hersam said, "Most of the degradation mechanisms of LIBs occur on the electrode surfaces in contact with the electrolyte. We have tried to understand the chemical reactions taking place on these surfaces and then formulate strategies to minimize the degree of degradation." The researchers used surface chemical characterization to identify and reduce hydroxide and carbonate impurities remaining during the synthesis of nickel-cobalt-aluminum (NCA) nanoparticles. They found that when preparing the surface of LIB cathodes, it is first necessary to subject them to proper annealing, heating the cathode nanoparticles to remove surface impurities, and then lock them into the ideal structure via an atomically thin graphene coating. In LIBs, cathodes made from graphene-coated NCA nanoparticles exhibit excellent electrochemical performance, including low impedance, high-rate capability, high volumetric energy and power density, as well as long-lasting cycle life. The graphene coating also acts as a barrier between the electrode surface and the electrolyte, thereby further extending battery lifespan. The researchers believe that the use of graphene coating alone is sufficient to improve performance. However, the results show that pre-annealing the cathode materials to optimize their surface chemical properties before applying the graphene coating is of great significance. At present, this work has mainly focused on nickel-rich LIB cathodes. The method can also be extended to other types of energy storage electrodes, such as sodium-ion or magnesium-ion batteries that contain nanostructured materials with high specific surface areas, which will pave the way for the development of high-performance nanoparticle-based energy storage devices.