Active material for nonaqueous electrolyte secondary battery, method for production of the active material, electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

Abstract

The invention provides an active material for a nonaqueous electrolyte secondary battery, a method for production of the active material and the nonaqueous electrolyte secondary battery using the active material, the active material excellent high-rate discharge characteristics. The active material for a nonaqueous electrolyte secondary battery includes a lithium-transition metal composite oxide which has an alpha-NaFeO2 -type crystal structure and of which the average composition is represented by the composition formula of Li1+[alpha]Me1-[alpha]O2 (Me is a transition metal containing Co, Ni and Mn; and alpha > 0), wherein the lithium-transition metal composite oxide is a particle having a core and a coated part, the cobalt concentration of the coated part is higher than the cobalt concentration of the core, the manganese concentration of the coated part is lower than the manganese concentration of the core, and the ratio of cobalt present in the coated part is 3 to 10% in terms of a molar ratio based on the amount of the transition metal present in the core. In addition, the method for production of the active material of the nonaqueous electrolyte secondary battery is characterized by enabling cobalt-containing compounds, cobalt-nickel-containing compounds and cobalt-nickel-manganese-containing compounds with more cobalt than manganese in a molar ratio to coat co-precipitated precursor core particles of transition metal compounds containing cobalt, nickel and manganese and being with more manganese than cobalt in the molar ratio, mixing the co-precipitated precursor core particles and lithium compounds, and then firing.

Description

technical field

[0001] The present invention relates to an active material for a nonaqueous electrolyte secondary battery, a method for producing the active material, and a nonaqueous electrolyte secondary battery using the active material. Background technique

[0002] So far, non-aqueous electrolyte secondary batteries mainly use LiCoO 2 as a positive electrode active material. However, the discharge capacity is around 120-130mAh / g.

[0003] As a positive electrode active material material for non-aqueous electrolyte secondary batteries, LiCoO is known 2 and solid solutions of other compounds. With α-NaFeO 2 type crystal structure, LiCoO 2 , LiNiO 2 and LiMnO 2 The Li[Co 1-2x Ni x mn x ]O 2 (0<x≤1 / 2) was published in 2001. As an example of the aforementioned solid solution, LiNi 1 / 2 mn 1 / 2 o 2 、LiCo 1 / 3 Ni 1 / 3 mn 1 / 3 o 2 It has a discharge capacity of 150 to 180 mAh / g, and is excellent in charge and discharge cycle performance.

[0004] Compared with...

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