A lithium ion secondary battery

A secondary battery and lithium ion technology, applied in secondary batteries, battery electrodes, battery components, etc., can solve the problems of high cost, low cost, poor discharge safety performance, etc., and achieve improved safety performance and stable discharge voltage , The effect of improving the discharge safety performance

Active Publication Date: 2014-10-08
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the shortcomings of poor discharge safety performance and relatively high cost of lithium-ion secondary batteries in the prior art, and provide a lithium-ion secondary battery, which can effectively improve the discharge safety performance of lithium-ion secondary batteries , and lower cost

Method used

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  • A lithium ion secondary battery
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  • A lithium ion secondary battery

Examples

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preparation example Construction

[0030] The preparation of the lithium-ion secondary battery includes preparing the positive electrode, the negative electrode and the electrolyte of the battery, and winding the positive electrode and the negative electrode through a separator to form an electrode group, placing the electrode group into the battery case, adding the electrolyte, and then sealing A battery case, wherein the negative pole is the negative pole provided by the present invention.

[0031] The positive electrode and electrolyte can be prepared by existing methods. For example, a conventional positive electrode preparation method includes coating or filling a slurry containing positive electrode active materials and a binder on a wide-width electrode sheet, drying, rolling and slitting to obtain a positive electrode. Wherein, the solvent used to form the slurry containing the positive electrode active material and binder can be selected from various conventional solvents, such as N-methylpyrrolidone (...

Embodiment 1

[0037] This example is used to illustrate the preparation of the lithium ion secondary battery of the present invention.

[0038] (1) Preparation of positive electrode:

[0039] Lithium iron phosphate, binder polyvinylidene fluoride (PVDF), conductive agent (Supper-p), dispersant polyvinylpyrrolidone (PVP), N-methylpyrrolidone in mass ratio 100:4:5:0.5:90 Stir in a vacuum mixer to form a uniform positive electrode slurry. The positive electrode slurry was evenly coated on both sides of an aluminum foil with a thickness of 20 μm, and then dried at 150° C. After rolling and cutting, a positive electrode sheet with a size of 453×40 mm was obtained.

[0040] (2) Preparation of negative electrode:

[0041] Natural graphite, binder styrene-butadiene rubber emulsion (SBR), binder carboxymethyl cellulose (CMC), deionized water are stirred in a vacuum mixer in a mass ratio of 100:2:2:130 to form a uniform Negative slurry. The negative electrode slurry was evenly coated on both sid...

Embodiment 2

[0047] (1) Preparation of positive electrode:

[0048] Lithium iron phosphate, binder polyvinylidene fluoride (PVDF), conductive agent (Supper-p), dispersant polyvinylpyrrolidone (PVP), N-methylpyrrolidone in mass ratio 100:4:5:0.5:90 Stir in a vacuum mixer to form a uniform positive electrode slurry. The positive electrode slurry was evenly coated on both sides of an aluminum foil with a thickness of 20 μm, and then dried at 150° C. After rolling and cutting, a positive electrode sheet with a size of 453×40 mm was obtained.

[0049] (2) Preparation of negative electrode:

[0050] Natural graphite, binder styrene-butadiene rubber emulsion (SBR), binder carboxymethyl cellulose (CMC), deionized water are stirred in a vacuum mixer in a mass ratio of 100:2:2:130 to form a uniform Negative slurry. The negative electrode slurry was evenly coated on both sides of a copper foil with a thickness of 12 microns, and then dried at 90°C. After rolling, cutting. Add 0.025 g of lithium...

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Abstract

The invention discloses a lithium ion secondary battery comprising an electrode set and electrolyte. The electrode set comprises an anode, a cathode, and a separating film between the anode and the cathode. The cathode comprises a current collector and a cathode material coated on the current collector. The cathode material comprises cathode active substances and a bonding agent. The cathode material is characterized in that: the cathode material comprises metal lithium and / or lithium alloy. The content of the metal lithium and / or lithium alloy satisfy a condition that k / L<x<(n-m) / L, wherein x is the mass of lithium, L is the theoretical specific capacity of lithium, m is the initial charging volume of the anode, n is the initial charging volume of the cathode, and k is the initial charge / discharge inreversible volume of the cathode. When the battery is discharged to a preset voltage, if discharging is continued, certain volume can still be discharged. Therefore, discharging voltage is stabilized, such that a safety problem caused by over discharging is avoided.

Description

technical field [0001] The invention relates to a lithium ion secondary battery. Background technique [0002] Lithium-ion secondary battery is a brand-new green chemical energy source, which has the advantages of high voltage, long life and high energy density compared with traditional secondary batteries such as nickel separator and nickel hydrogen. In recent years, with the needs of energy and environment, lithium-ion batteries have been used more and more widely due to their advantages such as high voltage, light weight, no memory effect, long cycle life and no environmental pollution. It has been developed rapidly and widely used in various portable devices. [0003] At present, whether it is the power battery market or the energy storage battery market, there is an urgent need for the "consistency" of the combined battery, especially the discharge safety performance of the battery is the top priority. Previously, the discharge safety protection of the battery pack ma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/0525H01M4/505H01M4/525H01M4/66H01M2/16
CPCY02E60/122Y02E60/10
Inventor 田野陆月颖
Owner BYD CO LTD
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