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Non-aqeous electrolyte secondary battery

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Non-aqeous electrolyte secondary battery


A non-aqueous electrolyte secondary battery has a positive electrode containing a positive electrode active material containing a lithium-containing oxide active material, a negative electrode, and a non-aqueous electrolyte. The lithium-containing oxide active material is represented by the general formula LiaMgbMO2±α where 0.65≦a≦1.05, 0<b≦0.3, 0≦α≦0.3, and M is at least one of manganese and cobalt.
Related Terms: Cobalt Electrode Electrolyte Lithium Manganese

Browse recent Sanyo Electric Co., Ltd. patents - Osaka, JP
Inventors: Motoharu Saito, Sho Tsuruta, Masahisa Fujimoto
USPTO Applicaton #: #20130011741 - Class: 429224 (USPTO) - 01/10/13 - Class 429 
Chemistry: Electrical Current Producing Apparatus, Product, And Process > Current Producing Cell, Elements, Subcombinations And Compositions For Use Therewith And Adjuncts >Electrode >Chemically Specified Inorganic Electrochemically Active Material Containing >Manganese Component Is Active Material

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The Patent Description & Claims data below is from USPTO Patent Application 20130011741, Non-aqeous electrolyte secondary battery.

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CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 12/728,718, filed on Mar. 22, 2010, which claims benefit of priority from the prior Japanese Patent Application No. 2009-069497, filed on Mar. 23, 2009, the entire contents of both of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a non-aqueous electrolyte secondary battery that achieves high capacity and to a method of manufacturing the battery.

2. Description of Related Art

Mobile information terminal devices such as mobile telephones, notebook computers, and PDAs have become smaller and lighter at a rapid pace in recent years. This has led to a demand for higher capacity batteries as the drive power source for the mobile information terminal devices. With their high energy density and high capacity, non-aqueous electrolyte secondary batteries, which perform charge and discharge by transferring lithium ions between the positive and negative electrodes, have been widely used as a driving power source for the mobile information terminal devices.

As the mobile information terminal devices tend towards having greater numbers of functions, such as moving picture playing functions and gaming functions, the power consumption of the devices tends to increase. It is therefore strongly desired that the non-aqueous electrolyte secondary batteries used for the power sources of such devices have further higher capacities and higher performance to achieve longer battery life and improved output power. In addition, applications of the non-aqueous electrolyte secondary batteries are expected to expand from just the above-described applications but to power tools, power assisted bicycles, and moreover hybrid electric vehicles (HEVs) and electric vehicles (EVs). In order to meet such expectations, it is strongly desired that the capacity and the performance of the battery be improved further.

In order to increase the capacity of the non-aqueous electrolyte secondary battery, it is necessary to increase the capacity of the positive electrode. In particular, layered compounds are viewed as promising materials for positive electrode active materials. To date, many lithium-containing layered compounds have been studied. Among the materials that have been developed are LiCoO2, LiNiO2, LiNi1/3Co1/3Mn1/3O2, and NaxCoyMn1-yO2 where 0.6≦x≦0.8 and 0.4≦y≦0.6 (see Japanese Published Unexamined Patent Application No. 2002-220231).

In addition, a technique for synthesizing a lithium compound from a sodium compound has been studied as a method for synthesizing a novel lithium compound (see Japanese Published Unexamined Patent Application No. 2007-220650). According to this method a layered compound, which is difficult to synthesize with lithium, can be easily obtained. In particular, Na0.7CoO2 and NaCo1/2Mn1/2O2 can be used as positive electrode active materials for lithium-ion batteries by ion-exchanging sodium for lithium. Therefore, much research has been conducted on synthesis methods and ion-exchange methods by chemical techniques using Na0.7CoO2 and NaCo1/2Mn1/2O2.

The positive electrode active materials using sodium-based oxides are promising materials that are expected to yield high capacity, and by adding lithium thereto, further high capacity can be obtained. However, the addition of lithium causes the average discharge potential to decrease. Moreover, it causes formation of an impurity similar to Li2MnO3, resulting in the problem of side reactions during charge and discharge.

BRIEF

SUMMARY

OF THE INVENTION

Accordingly, it is an object of the present invention to provide a non-aqueous electrolyte secondary battery and a manufacturing method of the battery that can inhibit side reactions during charge and discharge by suppressing formation of an impurity similar to Li2MnO3 and that can preventing the discharge potential from decreasing even when lithium is added.

The present inventors studied various materials that may suppress formation of Li2MnO3 impurity and prevent the discharge voltage from decreasing, and as a result found that the foregoing object can be accomplished by using magnesium as an additive metal.

Accordingly, the present invention provides a non-aqueous electrolyte secondary battery comprising: a positive electrode containing a positive electrode active material comprising a lithium-containing oxide active material; a negative electrode; and a non-aqueous electrolyte, wherein: the lithium-containing oxide active material is represented by the general formula LiaMgbMO2±α where 0.65≦a≦1.05, 0<b≦0.3, 0≦α≦0.3, and M is at least one of manganese and cobalt; and the lithium-containing oxide active material has a main peak at 2θ=17.95° to 18.15°, as determined by an X-ray powder crystal diffraction measurement (Cukα).

According to the present invention, formation of a lithium-containing impurity that is caused when adding lithium is suppressed so that side reactions are inhibited during charge and discharge, and at the same time, the discharge potential is prevented from decreasing, because magnesium is added to the positive electrode active material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a test cell used for the embodiments of the present invention;

FIG. 2 is a graph showing the result of an XRD analysis for a present invention oxide a1;

FIG. 3 is a graph showing the result of an XRD analysis for a present invention oxide a2;

FIG. 4 is a graph showing the result of an XRD analysis for a present invention oxide a3;

FIG. 5 is a graph showing the result of an XRD analysis for a comparative reference oxide x;

FIG. 6 is a graph showing the result of an XRD analysis for a comparative oxide z1;



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Previous Patent Application:
Lithium secondary battery
Next Patent Application:
Current collector for flexible electrode, method of manufacturing same, and negative electrode including same
Industry Class:
Chemistry: electrical current producing apparatus, product, and process
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stats Patent Info
Application #
US 20130011741 A1
Publish Date
01/10/2013
Document #
13614425
File Date
09/13/2012
USPTO Class
429224
Other USPTO Classes
4292316
International Class
01M4/131
Drawings
17


Cobalt
Electrode
Electrolyte
Lithium
Manganese


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