Secondary battery and electronic apparatus

An electronic apparatus comprises a secondary battery, the secondary battery comprises a negative electrode, wherein the negative electrode comprises a current collector and a negative electrode active material layer provided on the current collector, the negative electrode active material layer comprises a first active material layer and a second active material layer, and the first active material layer is provided between the current collector and the second active material layer;

• the first active material layer comprises a first active material;
• a first button battery using lithium plate as a negative electrode and the first active material as a positive active material of a positive electrode experiences a charge and discharge test, and a terminal potential slope of a lithium deintercalation curve of the first button battery is denoted as Sa;
• and
• the second active material layer comprises a second active material;
• a second button battery using lithium plate as a negative electrode and the second active material as a positive active material of a positive electrode experiences a charge and discharge test, a terminal potential slope of a lithium deintercalation curve of the second button battery is denoted as Sb, and Sa<Sb;
• wherein 2 mAh·g−1/V≤Sa≤7 mAh·g−1/V, and 5 mAh·g−1/V≤Sb≤14 mAh·g−1/V.

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

• and the method comprises:
• preparation of the first active material:
• mixing artificial graphite and/or natural graphite with a coating agent to prepare a first mixture, wherein a mass percentage of the coating agent is 1% to 5% based on a mass of the first mixture,
• performing a first thermal treatment on the first mixture in an inert atmosphere to prepare a first thermal treatment product, and
• performing a second thermal treatment on the first thermal treatment product in a mixed gas of CO2 and N2 to prepare the first active material;
• and
• preparation of the second active material:
• mixing artificial graphite with the coating agent to prepare a second mixture, wherein a mass percentage of the coating agent is 3% to 8% based on a mass of the second mixture, and
• performing a third thermal treatment on the second mixture in an inert atmosphere to prepare the second active material;
• wherein
• the first thermal treatment is performed at 950° C. to 1200° C. for 1 h to 5 h;
• the second thermal treatment is performed at 750° C. to 1100° C. for 2 h to 8 h;
• the third thermal treatment is performed at 700° C. to 1150° C. for 4 h to 10 h;
• and
• the coating agent is asphalt.