Nonaqueous Battery Tungsten Coating Output

Solution Overview

Problem

Nonaqueous electrolyte secondary batteries fail to sufficiently enhance output characteristics for applications in electric vehicles and other power supplies.

Innovation Solution

A nonaqueous electrolyte secondary battery design featuring a positive electrode with lithium transition metal oxide containing tungsten and a phosphate compound, and a negative electrode with graphitic carbon and amorphous/noncrystalline carbon materials, where the amorphous/noncrystalline carbon is surface-coated with tungsten or a tungsten compound, reducing reaction overvoltage and battery resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional positive electrode coating and negative electrode conductive agent methods are used, then basic battery function is maintained, but output characteristics cannot be sufficiently improved

Engineering Contradiction:

Improveoutput characteristicsVSAvoidcharge acceptance

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The invention applies local quality by creating a tungsten-containing surface coating specifically on the amorphous/noncrystalline carbon material particles in the negative electrode. This localized modification concentrates the beneficial effects (lower reaction overvoltage, improved Li intercalation) at the particle surfaces where electrochemical reactions occur, while maintaining the overall electrode structure. The coating is formed preferentially on amorphous carbon due to its nobler reaction potential, creating locally optimized reaction sites that enhance overall battery output characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention employs composite materials by combining graphitic carbon material with amorphous/noncrystalline carbon material in the negative electrode, and further coating the amorphous carbon with tungsten or tungsten compound. This multi-component composite structure leverages the high electrical conductivity of graphitic carbon while utilizing the superior Li intercalation properties of amorphous carbon enhanced by the tungsten coating, achieving synergistic improvement in output characteristics and charge acceptance.

Inventive Principle:

Principle #40Composite materials

2Power

If amorphous/noncrystalline carbon material is added to negative electrode, then reaction overvoltage is reduced and Li intercalation is improved, but electronic conductivity may be compromised

Engineering Contradiction:

Improvereaction overvoltageVSAvoidelectronic conductivity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The invention applies local quality by creating a tungsten-containing surface coating specifically on the amorphous/noncrystalline carbon material particles in the negative electrode. This localized modification concentrates the beneficial effects (lower reaction overvoltage, improved Li intercalation) at the particle surfaces where electrochemical reactions occur, while maintaining the overall electrode structure. The coating is formed preferentially on amorphous carbon due to its nobler reaction potential, creating locally optimized reaction sites that enhance overall battery output characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention employs composite materials by combining graphitic carbon material with amorphous/noncrystalline carbon material in the negative electrode, and further coating the amorphous carbon with tungsten or tungsten compound. This multi-component composite structure leverages the high electrical conductivity of graphitic carbon while utilizing the superior Li intercalation properties of amorphous carbon enhanced by the tungsten coating, achieving synergistic improvement in output characteristics and charge acceptance.

Inventive Principle:

Principle #40Composite materials

3Power

If tungsten is dissolved from positive electrode during charge, then surface coating is formed on negative electrode improving performance, but tungsten loss from positive electrode occurs

Engineering Contradiction:

Improveoutput characteristicsVSAvoidtungsten dissolution

Core Design Contradiction:

PowerVSLoss of substance

Solution Approach 1:

The invention converts the potentially harmful effect of tungsten dissolution from the positive electrode into a beneficial process. The tungsten that dissolves during charge is not lost but rather migrates and precipitates as a surface coating on the amorphous carbon material in the negative electrode. This self-organizing redistribution transforms material loss from one electrode into a performance-enhancing coating on the other electrode, improving Li intercalation and reducing reaction overvoltage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The nonaqueous electrolyte serves as an intermediary medium that facilitates the controlled dissolution of tungsten from the positive electrode and its subsequent precipitation on the negative electrode. The electrolyte enables this material transfer while the phosphate compound in the positive electrode catalyzes the decomposition reaction, ensuring controlled tungsten release and preferential deposition on amorphous carbon due to its nobler reaction potential.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The battery resistance is reduced, and output characteristics are enhanced, allowing for improved performance in electric vehicles and other power supply applications.

Implementation Method 1

During charge, W contained in a positive electrode active material dissolves, migrates to the negative electrode, and precipitates on the negative electrode

Methodology Applied

Scientific EffectDissolution:

Implementation Method 2

W contained in a positive electrode active material dissolves, migrates to the negative electrode

Methodology Applied

Scientific EffectMigration: Diffusion

Implementation Method 3

W contained in a positive electrode active material dissolves, migrates to the negative electrode, and precipitates on the negative electrode

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Implementation Method 4

the decomposition reaction rate of W and a tungsten oxide in the positive electrode is varied by the catalysis of the phosphate compound

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 5

the reaction overvoltage of the intercalation of Li during charge can be reduced

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS10297826B2Nonaqueous electrolyte secondary battery

Publication Date: 2019.05.21 PANASONIC ENERGY CO LTD

AI summary

It is an object of the present invention to provide a nonaqueous electrolyte secondary battery with improved output characteristics. An example of an embodiment of the present invention provides a nonaqueous electrolyte secondary battery comprising an electrode assembly having a structure in which a positive electrode plate and a negative electrode plate are stacked with a separator therebetween. The positive electrode plate contains a lithium transition metal oxide containing tungsten as a positive electrode active material and also contains a phosphate compound. The negative electrode plate contains a graphitic carbon material and an amorphous/noncrystalline carbon material as negative electrode active materials and includes a coating of tungsten or a tungsten compound on the surface of the amorphous/noncrystalline carbon material.