Abstract: Provided are a modified graphite and a preparation method thereof, a carbon-coated negative active material and a preparation method thereof, a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electrical device. The preparation method of a modified graphite includes the following steps: (S10) providing a graphite substrate; and (S20) heat-treating the graphite substrate in a micro-oxidizing atmosphere to obtain the modified graphite, where the micro-oxidizing atmosphere includes a reactive gas, and the reactive gas is one or more selected from CO2, O2, and O3. The preparation method of a carbon-coated negative active material includes the following steps: (S100) providing a negative active material substrate; and (S200) heat-treating the negative active material substrate and a carbonaceous precursor in a micro-oxidizing atmosphere to obtain the carbon-coated negative active material, where the micro-oxidizing atmosphere includes a reactive gas.

Abstract: This application discloses a negative-electrode active material and a preparation method thereof, a secondary battery, and a battery module, a battery pack, and an apparatus that include such secondary battery. The negative-electrode active material includes a core and a coating layer covering at least part of a surface of the core, where the core includes artificial graphite, the coating layer includes amorphous carbon, a volume-based particle size distribution of the negative-electrode active material satisfies Dv99?24 ?m, a volume-based median particle size Dv50 of the negative-electrode active material satisfies 8 ?m?Dv50?15 ?m, Dv99 is a particle size corresponding to a cumulative volume distribution percentage of the negative-electrode active material reaching 99%, and Dv50 is a particle size corresponding to a cumulative volume distribution percentage of the negative-electrode active material reaching 50%.

Abstract: This application provides a negative electrode active material and a preparation method thereof. The negative electrode active material may be self-embedded graphite composed of graphite A and graphite B, where the surface of the graphite A may have a tenon structure, the surface of the graphite B may have a mortise structure, the tenon structure of the graphite A and the mortise structure of the graphite B may be mutually embedded, and a hydrogen bond may be formed between the tenon structure of the graphite A and the mortise structure of the graphite B.

Abstract: A secondary battery, a preparation method thereof, and a battery module, a battery pack, and an apparatus containing such secondary battery are provided. In some embodiments, the secondary battery includes a negative-electrode plate, where the negative-electrode plate includes a negative-electrode current collector and a negative-electrode film layer, the negative-electrode film layer includes a first negative-electrode film layer and a second negative-electrode film layer, and the second negative-electrode film layer is located between the negative-electrode current collector and the first negative-electrode film layer; and the first negative-electrode film layer includes a first negative-electrode active material, the first negative-electrode active material includes a first graphite, the first graphite is artificial graphite, and a distribution of volume-based particle size Dv99 of the first negative-electrode active material is ?23 ?m.

Abstract: A secondary battery, a preparation method thereof, and an apparatus including the secondary battery are described.

Abstract: This application discloses a negative-electrode active material and a preparation method thereof, a secondary battery, and a battery module, a battery pack, and an apparatus that include such secondary battery. The negative-electrode active material includes a core and a coating layer covering at least part of a surface of the core, where the core includes artificial graphite, the coating layer includes amorphous carbon, a volume-based particle size distribution of the negative-electrode active material satisfies Dv99?24 ?m, a volume-based median particle size Dv50 of the negative-electrode active material satisfies 8 ?m?Dv?15 ?m, Dv99 is a particle size corresponding to a cumulative volume distribution percentage of the negative-electrode active material reaching 99%, and WO is a particle size corresponding to a cumulative volume distribution percentage of the negative-electrode active material reaching 50%.

Abstract: A secondary battery, a preparation method thereof, and an apparatus including the secondary battery are described.