Negative electrode of secondary battery, manufacturing method of negative electrode, and secondary battery with negative electrode

A manufacturing method of a negative electrode of a secondary battery, comprising:

• preparing a first paste that comprises a first Si-containing particle as a negative electrode active material and comprises a dispersion medium;
• preparing a second paste that comprises a second Si-containing particle as the negative electrode active material and comprises the dispersion medium;
• applying the first paste to coat a negative electrode current collector and to dry so as to form a dry layer of the first paste;
• applying the second paste to coat the dry layer of the first paste and to dry so as to form a dry layer of the second paste;
• and
• pressing the dry layer of the first paste and the dry layer of the second paste, wherein
• an expansion rate S2 of the second Si-containing particle after an electrical charge A with respect to before the electrical charge A, in which a constant current electrical charge is performed under 25° C. environment by a current value being 0.01 C till 4.2 V and then a constant voltage electrical charge is performed till the current value reaches 0.005 C, is more than 0.3 and not more than 0.9 when an expansion rate S1 of the first Si-containing particle after the electrical charge A with respect to before the electrical charge A is treated as 1,
• each of the first Si-containing particle and the second Si-containing particle comprises a LiF coating layer, and
• when, on an XPS spectrum of the first Si-containing particle measured by a X-ray photoelectron spectroscopy, a ratio of a peak intensity of an F of a LiF with respect to the peak intensity of the F of one being other than the LiF is defined as a first peak intensity ratio, and on an XPS spectrum of the second Si-containing particle, the ratio of the peak intensity of the F of the LiF with respect to the peak intensity of the F of one being other than the LiF is defined as a second peak intensity ratio,
• the first peak intensity ratio is larger than the second peak intensity ratio, and a difference between the first peak intensity ratio and the second peak intensity ratio is at least 0.050.