Method for manufacturing positive electrode active material for lithium-ion secondary batteries

Abstract

A positive electrode active material for lithium-ion secondary batteries is provided, comprising lithium composite oxide particles. This lithium composite oxide contains Li, Ni, Mn, Zr, and an additive element M(M). The molar ratio of Li, Ni, Mn, Zr, and the additive element M(M) is Li:Ni:Mn:Zr:M = a:b:c:d:e (0.95≦a≦1.20, 0.10≦b<0.70, 0.01≦c≦0.50, 0.0003≦d≦0). 0.02, 0.01≦e≦0.50, the added element M is one or more elements selected from Co, W, Mo, V, Mg, Ca, Al, Ti and Ta), wherein the full width at half maximum (FWHM) of the peak of the (003) plane and the full width at half maximum (FWHM) of the peak of the (104) plane, calculated according to the X-ray diffraction pattern of the lithium composite oxide, satisfy the relationship FWHM(104)≧FWHM(003)×2.90-0.10.

Description

[Technical Field] This invention relates to positive electrode active materials for lithium-ion secondary batteries, a method for manufacturing positive electrode active materials for lithium-ion secondary batteries, and lithium-ion secondary batteries. [Previous Technology] In recent years, with the widespread use of portable electronic devices such as mobile phones and laptops, the demand for small and lightweight rechargeable batteries with high energy density and durability has been increasing. Furthermore, the demand for high-output rechargeable batteries for power tools and electric vehicles, primarily hybrid vehicles, is also growing. Additionally, there is a need for rechargeable batteries that, in addition to the characteristics required above, are resistant to degradation even with repeated use and possess high durability. Lithium-ion secondary batteries exist as rechargeable batteries that meet these requirements. A lithium-ion secondary battery consists of a negative electrode, a positive electrode, and an electrolyte. The active materials used in the negative and positive electrodes are materials that allow lithium to be detached and inserted. As described above, lithium-ion secondary batteries possess high energy density, high output characteristics, and high durability. Currently, we are focusing on the research and development of lithium-ion secondary batteries. Among them, lithium-ion secondary batteries that use layered or spinel-type lithium metal composite oxides as positive electrode materials can achieve a high voltage of 4V, and are therefore being put into practical use as batteries with high energy density. As cathode materials for such lithium-ion secondary batteries, lithium composite oxides that are relatively easy to synthesize, such as lithium cobalt composite oxide (LiCoO2), lithium nickel composite oxide (LiNiO2) which uses nickel, which is cheaper than cobalt, lithium nickel cobalt manganese composite oxide (LiNi1 / 3Co1 / 3Mn1 / 3O2), lithium manganese composite oxide (LiMn2O4) which uses manganese, and lithium nickel manganese composite oxide (LiNi0.5Mn0.5O2) have been proposed. In addition, lithium-ion secondary batteries can generate gases due to electrolyte decomposition during battery use. Therefore, research has been conducted on battery modules that can expel the gases generated inside the battery to the outside of the system. For example, Patent Document 1 discloses a battery module comprising a battery having battery elements such as electrodes, active materials, and electrolytes on its inner side, sealed by a coating film, and a case for storing the battery. The case is characterized by having a structure that supports the front or a portion of the battery, and having a protrusion with a through hole extending from the front end to the outside of the case. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2003-168410 [Summary of the Invention] [The problem that the invention aims to solve] Although methods have been studied to remove gases generated inside the battery from the system by adding components to the battery module, from the viewpoint of reducing costs and improving battery stability, there is a need for a positive electrode active material for lithium-ion secondary batteries that can suppress the generation of such gases when applied to lithium-ion secondary batteries. Furthermore, from the perspective of improving the performance of lithium-ion secondary batteries, there is a need for a positive electrode active material for lithium-ion secondary batteries that can improve cycle characteristics when applied to lithium-ion secondary batteries. Therefore, there is a need for a positive electrode active material for lithium-ion secondary batteries that can not only suppress gas generation but also improve cycle characteristics when applied to lithium-ion secondary batteries. Therefore, in view of the problems of the prior art, the present invention aims to provide a positive electrode active material for lithium-ion secondary batteries that, when applied to lithium-ion secondary batteries, not only improves cycle characteristics but also suppresses gas generation. [Means for Solving the Problem] To address the aforementioned issues, according to one aspect of the present invention, a positive electrode active material for lithium-ion secondary batteries containing lithium composite oxide particles is provided. The lithium composite oxide particles are lithium composite oxide particles containing lithium (Li), nickel (Ni), manganese (Mn), zirconium (Zr), and an additive element M (M). The mass ratio of these substances is Li:Ni:Mn:Zr:M = a:b:c:d:e (wherein, 0.95≦a≦1.20, 0.10≦b<0.70, 0.01≦c≦0.50, 0.0003≦d≦0.02, 0.01≦e≦0.50, and the additive element M is one or more elements selected from Co, W, Mo, V, Mg, Ca, Al, Ti, and Ta). The full width at half maximum (FWHM) of the (003) plane peak and the full width at half maximum (FWHM) of the (104) plane peak, calculated based on the X-ray diffraction pattern of the above-mentioned lithium composite oxide, satisfy the relationship FWHM(104) ≥ FWHM(003) × 2.90 - 0.10. [Effects of the Invention] According to one aspect of the present invention, a positive electrode active material for lithium-ion secondary batteries can be provided that not only improves cycle characteristics but also suppresses gas generation when applied to lithium-ion secondary batteries.

Implementation Method

Claims

1. A method for manufacturing a positive electrode active material for lithium-ion secondary batteries, comprising: a mixing step, wherein a nickel-manganese composite compound containing nickel, manganese, and additive element M, a lithium compound, and a zirconium compound with an average particle size of 0.5 μm or more and 5.0 μm or less are mixed to prepare a raw material mixture containing lithium (Li), nickel (Ni), manganese (Mn), zirconium (Zr), and the aforementioned additive element M (M), wherein, The proportions of the above-mentioned lithium (Li), nickel (Ni), manganese (Mn), zirconium (Zr), and added element M (M) by weight are Li:Ni:Mn:Zr:M=a:b:c:d:e, wherein 0.95≦a≦1.20, 0.10≦b<0.70, 0.01≦c≦0.50, 0.0003≦d≦0.02, 0.01≦e≦0.50, and the added element M is one or more elements selected from Co, W, Mo, V, Mg, Ca, Al, Ti, and Ta; and the firing step involves firing the above-mentioned raw material mixture in an oxygen-containing environment with an oxygen concentration of 80% or more and 97% or less, and at a temperature of 780°C or more and 950°C or less.

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