Negative electrode material, making method, lithium ion secondary battery, and electrochemical capacitor

Abstract

The invention relates to a negative electrode material, a making method, a lithium ion secondary battery and an electrochemical capacitor. A conductive powder is provided in which particles having silicon crystallites dispersed in a silicon compound are coated on their surface with carbon. The conductive powder develops a diffraction peak assigned to Si(111) around 2theta=28.4 DEG on x-ray diffractometry (Cu-Kalpha) using copper as the counter cathode, the peak having a half width of at least 1.0 DEG, and has a specific resistance of up to 50 mOmega. The powder is used as a negative electrode material to construct a non-aqueous electrolyte secondary battery, which has a high charge / discharge capacity and improved cycle performance.

Description

technical field

[0001] The present invention relates to a nonaqueous electrolyte secondary battery, typically a lithium ion secondary battery, and an electrochemical capacitor. In particular, the present invention relates to an anode material suitable for such a battery, which provides high charge / discharge capacity and good cycle performance to a lithium ion secondary battery, and to a preparation method thereof. Background technique

[0002] With the recent rapid development of portable electronic devices and communication devices, secondary batteries having high energy density are highly demanded from the viewpoint of economy and reduction in size and weight. Prior art known attempts for increasing the capacity of such secondary batteries include the use of the following as negative electrode materials: oxides of V, Si, B, Zr, or Sn, etc., and their composite oxides (JP-A 5-174818, JP-A 6-60867), melt-quenched metal oxides (JP-A 10-294112), silicon oxide (Japanese Patent...