Secondary battery and electronic apparatus

A method for preparing a negative electrode, wherein the negative electrode comprises a current collector and a negative electrode active material layer disposed on a surface of the current collector, and the negative electrode active material layer comprises a first negative electrode active material layer and a second negative electrode active material layer;

• the first negative electrode active material layer is disposed between the current collector and the second negative electrode active material layer, the first negative electrode active material layer comprises a first negative electrode active material, and the second negative electrode active material layer comprises a second negative electrode active material;
• wherein the method comprises:
• preparing the first negative electrode active material:
• mixing artificial graphite and/or natural graphite with a coating agent to obtain a first mixture, wherein based on a mass of the first mixture, the coating agent has a mass percentage of 1% to 5%;
• performing, in an inert atmosphere, a first heat treatment on the first mixture to obtain a first heat treatment product;
• and
• performing, in a mixed gas of CO2 and N2, a second heat treatment on the first heat treatment product to obtain the first negative electrode active material;
• and
• preparing the second negative electrode active material:
• mixing artificial graphite with a coating agent to obtain a second mixture;
• and
• performing, in an inert atmosphere, a third heat treatment on the second mixture to obtain the second negative electrode active material;
• wherein
• the first heat treatment is performed at 950° C. to 1200° C., and the first heat treatment lasts for 1 h to 5 h;
• the second heat treatment is performed at 500° C. to 900° C., and the second heat treatment lasts for 5 h to 15 h;
• the third heat treatment is performed at 700° C. to 1100° C., and the third heat treatment lasts for 4 h to 10 h;
• and
• the coating agent is asphalt.