Lithium secondary battery and cathode plate thereof

A lithium secondary battery and negative electrode technology, which is applied in secondary batteries, battery electrodes, circuits, etc., can solve problems such as poor high temperature performance, increased negative electrode resistance, and increased irreversible capacity of the battery, achieving good high temperature cycle performance and improving The effect of high temperature performance

Active Publication Date: 2012-07-18
NINGDE AMPEREX TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is well known that the manganese element in spinel lithium manganate is prone to dissolution problems during the use of the battery. The manganese dissolved in the electrolyte will diffuse to the negative electrode and precipitate on the surface of the negative electrode, causing damage to the solid electrolyte film on the negative electrode. (SEI film) damage, leading to an increase in the irreversible capacity of the battery, and a sharp increase in the resistance of the negative electrode, resulting in

Method used

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  • Lithium secondary battery and cathode plate thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Preparation of the positive electrode sheet: spinel lithium manganese oxide (LiMnO 2 ), the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) are added to the solvent nitrogen-methylpyrrolidone (NMP) according to the mass ratio of 94:3:3, and stirred and dispersed using a high-speed mixer to form a uniform positive electrode slurry. This slurry is coated on the aluminum foil current collector, and the solvent is dried. After drying, the positive electrode coating weight per unit area is 20.13mg / cm 2 , and then compact the pole piece, the density of the coating after compaction is about 3.0g / cm 3 .

[0023] Preparation of the negative electrode sheet: the elemental sulfur and acetylene black are placed in a high-speed planetary ball mill at a mass ratio of 0.5:1 to fully disperse and evenly obtain the acetylene black / elemental sulfur mixture. Negative electrode active material artificial graphite, conductive agent acetylene black, binder s...

Embodiment 2

[0027] The difference from Example 1 is the selection of the positive electrode active material and the preparation of the negative electrode sheet.

[0028] Among them, the positive active material is layered lithium manganate (LiMnO 2 ).

[0029] The preparation of the negative electrode sheet is as follows: take the negative electrode sheet prepared in the comparative example, put it into a glove box, and control the humidity in the glove box so that the dew point is lower than -40°C. Anhydrous nano-lithium sulfide (Li 2 S) Ultrasonic dispersion in n-hexane forms a suspension, which is sprayed on the surface of the negative electrode, and the sprayed Li 2 The weight of S is 0.5% of the total mass of the negative electrode active material layer. After the solvent is volatilized, the production of the negative electrode sheet is completed. Thanks to Li 2 S is relatively easy to hydrolyze, so the operating environment and solvent must be kept dry.

[0030] The rest are t...

Embodiment 3

[0032] The difference from Example 1 is the selection of positive electrode active material and the content of elemental sulfur in the negative electrode sheet.

[0033] Among them, the positive electrode active material is lithium nickel cobalt manganate (LiNi 0.3 co 0 4 mn 0.3 o 2 ).

[0034] The elemental sulfur in the negative electrode sheet accounts for 2% of the total mass of the negative electrode active material layer.

[0035] The rest are the same as in Embodiment 1, and will not be repeated here.

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Abstract

The invention belongs to the technical field of lithium secondary batteries and particularly relates to a cathode which can improve the high-temperature cycling property of a battery using a manganese-contained material as an anode. The cathode comprises a cathode current collector and a cathode active material layer coated on the cathode current collector, wherein the cathode active material layer contains an additive; the additive refers to at least one of elemental sulfur, alkali-metal sulfide and alkali-metal polysulfide; and the additive accounts for 0.1wt%-2wt% of the total mass of the cathode active material layer. Compared with the prior art, the elemental sulfur and the sodium polysulfide added in the cathode plate provided by the invention are easily reduced to S2-, sulfur in the elemental sulfur refers to S2-, and the interaction between S2- and manganese ions is strong, therefore the manganese ions dissolved out of electrolyte can be precipitated; and the cathode contains the sulfur, the sulfide or the polysulfide, so that the damage caused by precipitation, on the surface of the cathode, of the manganese dissolved out of the anode can be avoided and consequently the high temperature performance of the battery can be enhanced.

Description

technical field [0001] The invention belongs to the technical field of lithium secondary batteries, and in particular relates to a lithium secondary battery capable of improving the high-temperature cycle performance of batteries using manganese-containing materials as positive electrodes and a negative electrode thereof. Background technique [0002] Lithium secondary batteries have the advantages of high energy density, high rate performance, and long cycle life. They have been widely used in consumer electronics, electric tools, electric vehicles, and power grid peak-shaving energy storage. They are currently the most widely used secondary batteries. . [0003] At present, the cathode materials widely used in lithium secondary batteries mainly include lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate. Among them, spinel lithium manganese oxide has a significant cost advantage due to its rich raw material reso...

Claims

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Application Information

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IPC IPC(8): H01M4/131H01M4/62H01M10/0525
CPCY02E60/122Y02E60/10
Inventor 李萍
Owner NINGDE AMPEREX TECH
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