▎ 摘　　要

NOVELTY - A composite comprises nanoparticles of an active material, and conformal graphene coating on each surface of the nanoparticles. The surface of nanoparticles are refined by a post-synthetic annealing treatment to remove or minimize surface impurities. USE - Composite used for electrode for electrochemical device (all claimed) e.g. lithium-ion battery used for electric vehicles, consumer electronics, and grid-level energy storage applications. ADVANTAGE - The composite provides the electrode having superlative performance such as high rate capability, low impedance, high volumetric energy and power densities, and long cycle life, compared with control electrode that comprises nanoparticles of the active material without surface refining and/or conformal graphene coating. The electrode has high initial capacity and rate capability than that of the control electrode. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) electrode; (2) electrochemical device; and (3) manufacture of the electrode.