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Powder graphite and non-water electrolyte secondary cell

A non-aqueous electrolyte and secondary battery technology, applied in the direction of non-aqueous electrolyte batteries, secondary batteries, graphite, etc., can solve the problems of non-rechargeable and discharge, and achieve the effect of improving load characteristics and cycle characteristics

Active Publication Date: 2009-02-11
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Under the above conditions, lithium ion intercalation / deintercalation reactions in graphite only occur on the electrode surface, and it is not possible to carry out efficient charging and discharging well

Method used

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  • Powder graphite and non-water electrolyte secondary cell
  • Powder graphite and non-water electrolyte secondary cell
  • Powder graphite and non-water electrolyte secondary cell

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Samples 1, 2, and 3 were used to form negative electrodes, and subsequently, coin-type test cells were formed with and without magnetic field orientation. Next, measure the load characteristics of the battery.

[0054] [Formation of coin-type test battery]

[0055] To each of Samples 1, 2, and 3, styrene-butadiene rubber (SBR) was added as a binder to make the content 2% by weight, and carboxymethyl cellulose was added as a viscosity modifier to the above mixture to form a negative electrode mixture. The negative electrode mixture thus formed was then dispersed in water to obtain a slurry. To form an electrode, a strip-shaped copper foil having a thickness of 15 μm was used as a current collector, and the slurry of the negative electrode mixture was uniformly coated on both sides of the current collector. Immediately after the above coating, the electrodes not to be subjected to magnetic field orientation treatment were dried, followed by compression molding, and the...

Embodiment 2

[0066] Using samples 1, 2 and 3 as the following negative electrode materials to form image 3The shown cylindrical non-aqueous electrolyte secondary battery with a diameter of 1.8 mm and a height of 65 mm was then subjected to a cycle test. As the cycle retention rate, the discharge capacity at initial charge was regarded as 100%, and the discharge capacity (%) obtained after 100 charge-discharge cycles was measured. Using each of the above-mentioned samples, a secondary battery in which the negative electrode was subjected to the magnetic field orientation treatment and a secondary battery in which the negative electrode was not subjected to the magnetic field orientation treatment were formed, and then their cycle retention ratios were measured.

[0067] [Formation of negative electrode]

[0068] In each of Samples 1, 2 and 3, styrene-butadiene rubber (SBR) was added as a binder to make its content 2% by weight, and then carboxymethyl cellulose was added as a viscosity mod...

Embodiment 3

[0083] Specific surface areas of samples 2 and 3 were measured and compared with sample 1 composed of flaky graphite to measure the state of spheroidization. The specific surface area is measured by the BET method. The adsorption material in the measurement was nitrogen, and the degassing temperature and time were set to 120° C. and 30 minutes, respectively.

[0084] In Table 3 below, specific surface area values ​​of Samples 1, 2 and 3 measured by the BET method are shown.

[0085] table 3

[0086] Specific surface area (m 2 / g) sample 1 4.83 sample 2 4.30 sample 3 3.60

[0087] From the above results, it can be seen that the specific surface area decreases as the grinding time using the impact type pulverizer increases, and therefore, it can be understood that the natural graphite particles are indeed spheroidized.

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Abstract

Through grinding and / or impacting, the invention carries out proper spheroidization for natural graphite with large capacity in order to form active material for cathode, and then forms cathode active material layer on metal electrode foil. Afterwards, applying magnetic field on metal electrode foil makes spheroidized natural graphite take orientation. Finally, drying and pressing mold procedure produces cathode. Using the cathode forms non-aqueous electrolyte secondary battery of possessing excellent performances of battery such as cycle performance and skimming resistance.

Description

[0001] Cross References to Related Applications [0002] The present invention contains subject matter related to Japanese Patent Application JP2004-270802 filed in the Japan Patent Office on Sep. 17, 2004, the entire content of which is hereby incorporated by reference. technical field [0003] The present invention relates to powdery graphite and a nonaqueous electrolyte secondary battery, more particularly, the present invention relates to powdery graphite used for the negative electrode of a lithium ion secondary battery and a nonaqueous electrolyte secondary battery using it. Background technique [0004] In recent years, with the development of portable information devices such as notebook personal computers and mobile phones, the demand for batteries has increased rapidly, and the application fields of batteries have also expanded. In this context, in addition to the trend towards miniaturization and weight reduction of batteries, there is also a need to increase the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58H01M4/02H01M10/40C01B31/04H01M4/133H01M4/1393H01M4/587H01M10/05H01M10/0525H01M10/0587
CPCH01M2004/027H01M4/133H01M4/1393Y02E60/122H01M4/0402C01B31/04H01M10/0525H01M2004/021C01B32/21Y02E60/10Y02P70/50C01B32/20
Inventor 德岳棹织小丸笃雄冈江功弥
Owner MURATA MFG CO LTD
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