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Positive electrode active substance for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery

a technology of active substances and positive electrodes, which is applied in the direction of cell components, electrochemical generators, and nickel compounds, etc., can solve the problems of li concentration variation the literature 1 to 3 fails to specifically describe the variation of li concentration in grain boundary and crystal variation, etc., to improve the output characteristics and durability of active substances, reduce conductive path or deterioration, and good effects

Inactive Publication Date: 2018-01-25
TODA IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a problem faced by active substances used in batteries, which is the degradation of the aggregated form during charging and discharging cycles and the occurrence of cracks in the particles, which causes reduction in conductive path and deterioration in electrode density, and further indu individuals with reduced performance. The conventional method of controlling the interface reaction between the electrode active substance and electrolyte solution by surface treatments has limitations in improving the output characteristics and durability of the active substance. Therefore, the present invention aims to overcome this problem by designing a new composition of the grain boundary, which prevents the formation and growth of resistive components and improves the performance and service life of the battery.

Problems solved by technology

That is, by utilizing only technologies of the aforementioned Patent Literatures 1 to 3, it may be difficult to obtain an electrode that is capable of conducting stable charging and discharging operations without significant deterioration in characteristics thereof when subjected to repeated charging and discharging cycles.
In addition, the Patent Literatures 1 to 3 fail to specifically describe the variation of a concentration of Li in the grain boundary and crystals.

Method used

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  • Positive electrode active substance for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery
  • Positive electrode active substance for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery
  • Positive electrode active substance for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery

Examples

Experimental program
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Effect test

example 1

[0067]In a reaction vessel equipped with a blade-type stirrer, a sodium hydroxide aqueous solution having a pH value of 12.0 was prepared, and an ammonia aqueous solution was added dropwise into the sodium hydroxide aqueous solution such that the obtained reaction solution had an ammonia concentration of 0.80 mol / L. Furthermore, a mixed solution comprising cobalt sulfate, nickel sulfate and manganese sulfate was continuously fed to the reaction vessel. During the aforementioned procedure, a sodium hydroxide aqueous solution and an ammonia aqueous solution were continuously fed to the reaction vessel so as to control a pH value of the resulting reaction solution to 12 and an ammonia concentration thereof to 0.8 mol / L, so that the particles in the reaction solution were grown to those having an average secondary particle diameter as aimed, and further by applying a mechanical shear force to the resulting suspension, a precipitate comprising a spherical composite transition metal was o...

example 2

[0073]The same procedure as in Example 1 was conducted except that the ratio of Ni / Co / Mn was changed to 1.0 / 1.0 / 1.0, and a mixture comprising the Li raw material and the transition metal mixed spherical oxide was calcined in an oxygen atmosphere at 750° C. for 10 hours, and then the resulting calcined product was deaggregated to produce positive electrode active substance particles, thereby obtaining a positive electrode active substance.

[0074]The section of the thus obtained particles was subjected to Nano-SIMS element distribution analysis, so that it was confirmed that a coefficient of variation of Li / Me in the composition including the crystals and grain boundaries was 18.7%.

[0075]As a supplemental measurement, using high resolution TEM, multi-wave interference images and selected area electron diffraction patterns as well as STEM-EELS analysis were conducted from the grain boundaries to an inside of the crystals at intervals of 20 nm. As a result, it was confirmed that the crys...

example 3

[0077]The same procedure as in Example 2 was conducted except that the ratio of Ni / Co / Mn was changed to 1.0 / 1.0 / 1.0, and the ratio of Li / Me was changed to 1.00 (Li / Me=1.00), thereby obtaining a positive electrode active substance.

[0078]The section of the thus obtained particles was subjected to Nano-SIMS element distribution analysis, so that it was confirmed that a coefficient of variation of Li / Me in the composition including the crystals and grain boundaries was 7.1%.

[0079]As a supplemental measurement, using high resolution TEM, multi-wave interference images and selected area electron diffraction patterns as well as STEM-EELS analysis were conducted from the grain boundaries to an inside of the crystals at intervals of 20 nm. As a result, it was confirmed that the crystal structure in the vicinity of the grain boundaries was the same R-3m structure as that of a bulk thereof, and no reduction of the transition metals was caused.

[0080]The resulting positive electrode active subst...

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Abstract

In accordance with the present invention, there are provided positive electrode active substance particles for non-aqueous electrolyte secondary batteries which is excellent in life characteristics of a battery with respect to a repeated charging and discharging performance thereof, as well as a non-aqueous electrolyte secondary battery. The present invention relates to a positive electrode active substance for non-aqueous electrolyte secondary batteries comprising lithium transition metal layered oxide having a composition represented by the formula: Lia(NixCoyMn1-x-y)O2 wherein a is 1.0≦a≦1.15; x is 0<x<1; and y is 0<y<1, in which the positive electrode active substance is in the form of secondary particles formed by aggregating primary particles thereof, and a coefficient of variation of a compositional ratio: Li / Me wherein Me is a sum of Ni, Co and Mn (Me=Ni+Co+Mn) as measured on a section of the secondary particle is not more than 25%.

Description

TECHNICAL FIELD[0001]The present invention relates to a positive electrode (cathode) active substance for non-aqueous electrolyte secondary batteries, and more particularly, to a positive electrode active substance that is capable of conducting stable charging and discharging operations without significant deterioration in characteristics thereof even when subjected to repeated charging and discharging cycles.BACKGROUND ART[0002]With the recent rapid development of portable and cordless electronic devices such as audio-visual (AV) devices and personal computers, there is an increasing demand for secondary batteries having a small size, a light weight and a high energy density as a power source for driving these electronic devices. Also, in consideration of global environments, electric cars and hybrid cars have been recently developed and put into practice, so that there is an increasing demand for lithium ion secondary batteries for large size applications which exhibit excellent d...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01M4/505H01M4/04H01M10/0525H01M4/525
CPCH01M4/505H01M4/525H01M4/0471H01M10/0525H01M2004/028C01G53/006C01G53/50C01P2004/61Y02E60/10H01M10/052C01P2006/40C01G45/1228C01G51/44
Inventor KAJIYAMA, AKIHISAMASAKI, RYUTAWAKIYAMA, TSUYOSHIKASHIMA, TETSUYAFUJINO, SHOICHISASAKI, OSAMUMATSUMOTO, KAZUTOSHI
Owner TODA IND
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