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Secondary cell

A secondary battery and electrolyte technology, applied in the direction of secondary batteries, battery electrodes, lithium batteries, etc., can solve the problems of capacity reduction, electrolyte deterioration, etc., and achieve the effect of excellent performance

Inactive Publication Date: 2005-11-23
NEC CORP
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Problems solved by technology

[0004] However, after adding LiNi 0.5 mn 1.5 o 4 In batteries such as 5V-level positive electrode materials used as active materials, with LiCoO 2 , LiMn 2 o 4 Compared with batteries with 4V-class active materials, since the positive electrode potential is higher, the decomposition reaction of the electrolyte will occur, and in the case of charging and discharging cycles or leaving it in a charged state, significant electrolysis will occur with a decrease in capacity. fluid deterioration problem
In addition, when operating in a high-temperature environment such as 50°C, the above-mentioned phenomenon tends to be more prominent.
[0005] In addition, especially in batteries that use 5V-grade spinel-type lithium-manganese composite oxide for the positive electrode and amorphous carbon for the negative electrode, there may be a decrease in capacity caused by the accumulation of decomposition products of the electrolyte on the surface of the negative electrode. question

Method used

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Embodiment

[0067] Hereinafter, the present invention will be described in detail by showing examples. In this example, it is expressed as figure 1 A coin-type battery is shown.

[0068] The 22 types of batteries shown in Tables 1 to 4 were produced in the following procedure.

[0069] (Preparation of positive electrode) As the supply source of Mn, Ni, Li, Ti, Si, Al, F, MnO 2 , NiO, Li 2 CO 3 、TiO 2 , SiO 2 、Al 2 o 3 , LiF is weighed according to the method of achieving the target metal composition ratio, pulverized and mixed. Furthermore, LiF also serves as a Li supply source. Then, the powder obtained by mixing the raw materials was fired at 750° C. for 8 hours. All the crystal structures thus obtained were confirmed to have a substantially single-phase spinel structure. In addition, as shown in Table 1, all the prepared active materials had an average discharge potential of 4.5 V or more with respect to Li metal.

[0070] The produced positive electrode active material and...

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Abstract

A positive electrode active material having an average discharge potential of 4.5V or more to Li is used. A solvent of the electrolyte is a combination of a high-dielectric solvent such as ethylene carbonate and at least one of dimethyl carbonate or ethyl methyl carbonate. The decrease of the capacity due to cycle and the degradation of the reliability due to high temperature are prevented. The operating voltage is high.

Description

technical field [0001] The present invention relates to a secondary battery, in particular to a secondary battery including a positive electrode active material having an average discharge potential of 4.5 V or higher relative to Li metal. Background technique [0002] Lithium-ion secondary batteries are widely used in portable electronic devices, personal computers, and the like. In addition, it is also expected to be applied to automobiles in the future. In these applications, although miniaturization and weight reduction of batteries have been pursued, on the other hand, improving the energy density of batteries has also become an important technical issue. [0003] Several methods are considered to increase the energy density of lithium ion secondary batteries, but among them, increasing the action potential of the battery is very effective. In the past, lithium cobalt oxide (LiCoO 2 ) or lithium manganate (LiMn 2 o 4 ) in the lithium ion secondary battery used as t...

Claims

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Application Information

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IPC IPC(8): H01M10/05H01M4/505H01M4/525H01M6/16H01M10/052H01M10/0525H01M10/0569
CPCH01M2300/0037Y02E60/122H01M2004/028H01M10/0569H01M4/587H01M4/505H01M10/052H01M4/525H01M10/0525Y02E60/10
Inventor 野口健宏山崎伊纪子川崎大辅沼田达治
Owner NEC CORP
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