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Lithium secondary battery

A lithium secondary battery and lithium ion technology, applied in secondary batteries, battery electrodes, circuits, etc., can solve problems such as loss of initial battery capacity, improve charge-discharge cycle characteristics, suppress capacity reduction, and increase discharge termination potential Effect

Inactive Publication Date: 2012-07-11
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, if a battery is constructed using a nickel-based lithium-containing composite oxide as the positive electrode active material, there is also a problem of losing the initial capacity of the battery.

Method used

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Experimental program
Comparison scheme
Effect test

no. 1 Embodiment approach

[0071] Hereinafter, a lithium secondary battery according to a first embodiment of the present invention will be described.

[0072] The lithium secondary battery of this embodiment includes: a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material capable of storing and releasing lithium; a separator arranged between the positive electrode and the negative electrode; and a nonaqueous electrolyte.

[0073] The positive electrode active material in this embodiment is a nickel-based lithium-containing composite oxide capable of occluding and releasing lithium. Examples of nickel-based lithium-containing composite oxides include LiNiO 2 As a basis, a part of Ni is replaced with another element selected from Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B.

[0074] As the negative electrode active material in this embodiment, a graphite-based material having a reversible capacity of 350 mAh...

Embodiment 1～4 and comparative example 1～3

[0246] Cells D to F for evaluation with different irreversible capacity ratios Qc / Qa of the positive and negative electrodes were produced, and the relationship between the irreversible capacity ratio Qc / Qa, the discharge termination potential of the positive electrode, and the charge-discharge cycle characteristics was examined.

[0247] (3-1) Preparation of unit cell D for evaluation

[0248] (3-1-1) Preparation of positive electrode

[0249] Using the same method as that described in (1-1) of (Experiment 1), a 0.815 co 0.15 Al 0.035 o 2 Indicates the composition of the positive active material.

[0250] To get LiNi 0.815 co 0.15 Al 0.035 o 2 100 g of powder was sufficiently mixed with 2 g of acetylene black (conductive agent), 1.25 g of artificial graphite (conductive agent), 1.25 g of polyvinylidene fluoride powder (binder) and 50 ml of organic solvent (NMP) to prepare a mixture paste. This mixture paste was coated on one side of an aluminum foil (positive electrode...

Embodiment 5～7

[0289] Using a negative electrode active material containing a graphite-based material and lithium titanium oxide (LTO), evaluation unit cells H to J having different weight ratios of LTO and graphite-based material were produced. Using these unit cells for evaluation, the relationship between the weight ratio of LTO and the graphite-based material, the irreversible capacity ratio of the positive electrode and the negative electrode, and the charge-discharge cycle characteristics was examined.

[0290] (4-1) Production of cells H to J for evaluation

[0291] (4-1-1) Preparation of positive electrode

[0292] Using the same method as that described in (2-1) of (Experiment 2), a 0.815 co 0.15 Al 0.035 o 2 Indicates the composition of the positive active material.

[0293] (4-1-2) Preparation of negative electrode

[0294] A negative electrode was produced by mixing lithium titanate (LTO) into a graphite material and coating it on a negative electrode current collector.

...

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Abstract

Disclosed is a lithium secondary battery which comprises: a positive electrode which has a positive electrode active material that is capable of adsorbing / desorbing lithium ions; a negative electrode which has a negative electrode active material that is capable of adsorbing / desorbing lithium ions; a separator which is arranged between the positive electrode and the negative electrode; and an electrolyte which has lithium ion conductivity. The positive electrode active material contains a nickel-based lithium-containing complex oxide, and the negative electrode active material contains a graphite material that has a reversible capacity of 350 mAh / g or more and an irreversible capacity of 30 mAh / g or less. The ratio of the irreversible capacity per unit area (Qc) of a portion of the positive electrode facing the negative electrode to the irreversible capacity per unit area (Qa) of a portion of the negative electrode facing the positive electrode, namely Qc / Qa is 0.50 or more but less than 1.13. Consequently, the charge / discharge cycle life can be improved, while maintaining high capacity.

Description

technical field [0001] The present invention relates to a lithium secondary battery including a nickel-based lithium-containing composite oxide in a positive electrode active material. Background technique [0002] Lithium secondary batteries have high capacity and high energy density, and are easy to be miniaturized and lightened, so they are used as portable batteries such as mobile phones, portable information terminals (Personal Digital Assistants; PDA), notebook personal computers, video cameras, and portable game machines. Power supplies for small electronic devices are widely utilized. Portable small electronic devices are required to be multi-functional, and on the other hand, it is desired to eliminate the trouble of battery replacement and improve the design of the device. Therefore, there is an increasing demand for a structure in which a lithium secondary battery is built into a device (lithium battery built-in type). In addition, lithium secondary batteries ar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0525H01M4/525H01M4/587
CPCY02E60/12Y02E60/122H01M4/525Y02T10/7011H01M10/0525H01M2010/4292H01M4/587H01M2004/021H01M4/485Y02E60/10Y02T10/70
Inventor 山本泰右武泽秀治
Owner PANASONIC CORP
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