Si-based-alloy anode material

Abstract

Disclosed is an Si-based-alloy anode material for a lithium ion secondary battery. The Si-based-alloy anode material comprises an alloy phase configured from an Si primary phase comprising Si, and a compound phase comprising at least two elements. The at least two elements include: at least one first added element (A) selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, and Mg; and at least one low-melting-point second added element (B) selected from the group consisting of S, Se, Te, Sn, In, Ga, Pb, Bi, Zn, Al, and Ag. The compound phase: (i) contains a first compound phase comprising Si and a first added element (A), a second compound phase comprising a first added element (A) and a second added element (B), and a single phase of a second added element (B) and / or a third compound phase comprising at least two second added elements (B); or (ii) a compound phase comprising Si and a first added element (A), and a single phase of a second added element (B) and / or a compound phase comprising at least two second added elements (B). The average minor axis width of the Si primary phase is no greater than 4 [mu]m. By means of the anode material, it is possible to provide a secondary battery having favorable charging / discharging capacity and cycle life.

Description

[0001] Cross-reference of related applications [0002] This application claims priority based on Japanese Patent Application No. 2012-19622 filed on February 1, 2012 and Japanese Patent Application No. 2012-276615 filed on December 19, 2012, the entire disclosure of which is incorporated by reference in this manual. technical field [0003] The present invention relates to a Si-based alloy negative electrode material excellent in electrical conductivity, which is used in electrical storage devices such as lithium ion secondary batteries and hybrid capacitors that are accompanied by migration of lithium ions during charge and discharge. Background technique [0004] In recent years, along with the popularization of portable devices, the development of high-performance secondary batteries centered on lithium-ion batteries has been flourishing. In addition, the development of hybrid capacitors that apply lithium-ion secondary batteries and their reaction mechanisms to the neg...

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Problems solved by technology

[0006] However, when Si is used alone as a negative electrode material, the Si phase is micronized due to the repetition of expansion when it is alloyed with lithium during charging and shrinkage when it is dealloyed with lithium during discharge, and the Si phase is generated during use. There are problems such as detachment from the electrode substrate or inability to obtain electrical conductivity between Si phases, so there is a problem that the life as an electrical storage device is extremely short

[0007] In addition, Si is poor in conductivity compared with carbon materials and metal-based materials, and the effective transfer of electrons accompanying charge and discharge is limited. Therefore, it is used as a negative electrode material in combination with a material that supplements conductivity such as carbon materials. However, in this case, especially It is the initial charge and discharge, and the charge and discharge characteristics at high efficiency are also a problem

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