Carbon Conductive Agent with Metal Compound Coating for High-Voltage Battery

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Solution Overview

Problem

Existing nonaqueous electrolyte secondary battery technologies face challenges in suppressing oxidative decomposition reactions and maintaining cycle characteristics under high temperature and high voltage conditions, as previous methods do not adequately address the catalytic properties of conductive agents and the resulting electrolyte decomposition.

Innovation Solution

A conductive agent composed of carbon with a surface-coated compound containing aluminum, zirconium, magnesium, or rare earth elements, where the average particle size of the compound is smaller than that of the conductive agent, reducing the contact area and catalytic properties, thereby suppressing oxidative decomposition and maintaining electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the end-of-charge voltage is increased to achieve higher capacity, then the battery capacity is improved, but the oxidative decomposition reaction between the positive electrode and electrolyte occurs, resulting in shorter lifetime

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifetime

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A compound containing aluminum, zirconium, magnesium, or rare earth elements is introduced as an intermediary substance between the positive electrode active material and the electrolyte. This intermediary layer suppresses the direct contact and oxidative decomposition reaction between the electrode and electrolyte, enabling high voltage operation (4.2V or higher) without excessive electrolyte decomposition, thus achieving both high capacity and long lifetime

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses composite materials consisting of positive electrode active material particles coated with a compound containing specific metal elements (aluminum, zirconium, magnesium, or rare earth elements). This composite structure combines the high capacity characteristics of the active material with the protective and catalytic suppression properties of the metal compound coating, resolving the contradiction between capacity and lifetime

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If conventional coating materials such as magnesium hydroxide are used on the positive electrode, then some suppression of oxidative decomposition is achieved, but the cycle characteristics under high temperature and high voltage conditions are insufficient

Engineering Contradiction:

Improveoxidative decomposition suppressionVSAvoidcycle characteristics

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention changes the chemical composition parameter of the coating material from conventional magnesium hydroxide to compounds containing aluminum, zirconium, magnesium, or rare earth elements. This parameter change results in compounds with lower catalytic activity for electrolyte decomposition, providing superior suppression of oxidative decomposition and improved cycle characteristics under high temperature and high voltage conditions

Inventive Principle:

Principle #35Parameter changes

3Power

If a conductive agent main body composed of carbon is used, then electrical conductivity is maintained, but the catalytic properties cause oxidative decomposition of the electrolyte

Engineering Contradiction:

Improveelectrical conductivityVSAvoidelectrolyte decomposition

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The invention applies local quality modification by coating only the surface of the carbon conductive agent particles with compounds containing aluminum, zirconium, magnesium, or rare earth elements. The interior carbon structure maintains its electrical conductivity function, while the surface coating locally suppresses catalytic activity and electrolyte decomposition, achieving both conductivity and decomposition suppression

Inventive Principle:

Principle #3Local quality

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

This approach significantly improves cycle characteristics and reduces oxidative decomposition, ensuring better electrical conductivity and capacity retention at high temperatures and voltages.

Implementation Method 1

the catalytic property of the conductive agent main body, which is induced by adhesion to the positive electrode active material, is lowered and the oxidative decomposition reaction of the electrolyte at the surface of the conductive agent main body is suppressed

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS9318745B2Conductive agent for nonaqueous electrolyte secondary battery, positive electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Publication Date: 2016.04.19 PANASONIC ENERGY CO LTD

AI summary

To provide a conductive agent for a nonaqueous electrolyte secondary battery and the like, in which oxidative decomposition reaction of an electrolyte is sufficiently suppressed during charging and discharging under high-temperature, high-voltage conditions and thus the cycle characteristics under these conditions are improved.A conductive agent main body composed of carbon and a compound attached to a surface of the conductive agent main body are contained. The average particle size of primary particles or secondary particles of the conductive agent main body is larger than the average particle size of the compound and the compound contains at least one metal element selected from the group consisting of aluminum, zirconium, magnesium, and a rare earth element.