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Low-temperature lithium ion battery considering both energy density and safety

A lithium-ion battery, energy density technology, applied in the direction of battery electrodes, secondary batteries, non-aqueous electrolyte battery electrodes, etc., can solve the problems of flammability, high activity, low boiling point, etc., to improve oxidation resistance, improve Energy density, effect of improving low-temperature performance

Active Publication Date: 2020-08-11
CHANGSHA STORM ENERGY TTECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there are few patents for low-temperature batteries that take into account both high safety and high energy density. Patent CN109742339A invented a high-energy ultra-low temperature and high-safety polymer lithium-ion battery. limited energy density
In addition, low-temperature batteries use a low-temperature electrolyte system, which has high activity, low boiling point, and is flammable and explosive at high temperatures, resulting in poor safety performance of the battery, especially at high energy densities, where safety performance cannot be guaranteed

Method used

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  • Low-temperature lithium ion battery considering both energy density and safety
  • Low-temperature lithium ion battery considering both energy density and safety
  • Low-temperature lithium ion battery considering both energy density and safety

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] This embodiment provides a kind of soft package lithium ion battery, and its preparation method is as follows:

[0031] (1) Preparation of the positive electrode sheet: The preparation of the positive electrode sheet is obtained through two steps of pulping and coating. The pulping steps are as follows, mix PVDF (polyvinylidene fluoride) and NMP (N-methyl-2-pyrrolidone) evenly to make glue, then add ECP (Ketjen black) and SP (carbon black) to mix Evenly made conductive glue. Add the positive electrode active material high voltage 4.45V lithium cobaltate (LiCoO 2) (purchased from Shanshan New Energy), each time the material was added, it was mixed evenly to prepare the positive electrode slurry. Finally, NMP was used to adjust the viscosity of the positive electrode slurry to 8000±2000cp to obtain positive electrode slurry with good fluidity. Among them, the mass ratio of lithium cobaltate, ECP and PVDF is: 95.4:0.6:2:2. The next step is the coating step. The prepare...

Embodiment 1

[0036] The soft pack lithium-ion battery of embodiment one carries out performance test:

[0037] (1) Energy density test: charge the battery at 0.5C constant current and constant voltage to 4.45V, with a cut-off current of 0.02C, and discharge it at 0.5C constant current to 2.0V after leaving it for 5 minutes. The test results are as figure 2 shown.

[0038] (2) Discharge test at -40°C: First, obtain the capacity at room temperature, charge the battery at 0.5C constant current and constant voltage to 4.45V, with a cut-off current of 0.02C, and then discharge it at 0.5C constant current to 2.0V after standing for 5 minutes. Room temperature capacity. Then, the battery was transferred to a low-temperature box, and after standing at -40°C for 4 hours, it was discharged at a constant current of 0.5C to 2.0V, and the discharge capacity at -40°C was obtained. The test results are as image 3 shown.

[0039] (3) Cycling performance test: 1C constant current and constant voltag...

Embodiment 2

[0042] Embodiment 2 provides a soft-pack lithium-ion battery, wherein the negative electrode active material is a mixture of 3wt% two-dimensional silicon nanosheets and 97wt% graphite, and its specific capacity is 400 mAh / g. Two-dimensional silicon nanosheets were prepared by the following method: CaSi 2 Powder AlCl in vacuum 3 The exfoliation is carried out in a molten salt environment, and two-dimensional silicon nanosheets are obtained after pickling. All the other are identical with embodiment 1. The properties of the resulting product are shown in Table 1.

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Abstract

The invention discloses a low-temperature lithium ion battery with high energy density and high safety. According to the invention, the problem of poor low-temperature performance of a high-capacity lithium ion battery is fundamentally solved by utilizing the rapid electron conduction and ion conduction characteristics of a two-dimensional silicon nano-sheet, the safety of the low-temperature battery is ensured by utilizing a firm crystal structure of a high-voltage 4.45 V lithium cobalt oxide, and the energy density of the battery is further improved, so that the low-temperature lithium ion battery has the energy density of 257 Wh / kg, can still release 80% of capacity at a temperature of-40 DEG C, and can pass severe needling and heavy object impact tests in a full-charge 4.45 V state; and the low-temperature lithium ion battery disclosed by the invention has a wide application space, and particularly has great application potential in the aspect of special equipment.

Description

technical field [0001] The invention relates to the technical field of low-temperature lithium-ion batteries, in particular to a low-temperature lithium-ion battery capable of both high energy density and high safety. Background technique [0002] Lithium-ion batteries are widely used in portable electronic products, power tools, electric vehicles and large-scale energy storage systems due to their high energy density, good cycle performance and rate performance. Low-temperature batteries with high energy density and high safety have a large market, especially in military applications. Due to the decrease of lithium ion migration rate in lithium ion batteries at low temperature, the discharge performance of lithium ion batteries deteriorates sharply at low temperatures. Therefore, improving the reaction kinetics of battery materials at low temperature and reducing battery impedance is the key to solving the problem of low-temperature performance degradation of batteries. H...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/139H01M4/38H01M4/525H01M10/0525
CPCH01M4/13H01M4/139H01M4/386H01M4/525H01M10/0525Y02E60/10
Inventor 张坤
Owner CHANGSHA STORM ENERGY TTECH