Polyacid Additive Suppresses Gas in Lithium Batteries

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Solution Overview

Problem

Lithium transition metal complex oxide-based secondary batteries experience gas generation and swelling due to internal pressure increases, leading to safety concerns, particularly when using a laminate film exterior, and existing technologies do not adequately address safety improvements.

Innovation Solution

Incorporating a polyacid and/or polyacid compound as an additive in the positive and negative electrode active material layers and separator of non-aqueous electrolyte batteries, which helps suppress gas generation and maintains separator integrity, preventing direct contact between electrodes and reducing thermal runaway risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If lithium transition metal complex oxide is used as positive electrode active material, then high capacity and high voltage are achieved, but gas generation occurs and internal pressure increases causing battery swelling

Engineering Contradiction:

Improvebattery capacityVSAvoidgas generation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A heteropoly acid compound is introduced as an intermediary substance between the lithium transition metal complex oxide and the electrolyte. This compound acts as a mediator that suppresses gas generation from the positive electrode while maintaining high capacity and voltage characteristics, thereby resolving the contradiction between high performance and gas generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameters of the positive electrode by incorporating heteropoly acid compounds with specific molecular structures (such as phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid). This parameter change suppresses the gas-generating reactions while preserving the high capacity and voltage output of the lithium transition metal complex oxide.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If lithium metal is used for negative electrode, then high energy density is achieved, but dendrite precipitation occurs causing internal short-circuiting and thermal runaway

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The heteropoly acid compound serves as an intermediary layer on the negative electrode surface, preventing direct contact between lithium dendrites and the separator. This mediator suppresses dendrite growth and penetration, thereby maintaining high energy density while improving safety and preventing thermal runaway.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The heteropoly acid compound provides beforehand cushioning by forming a protective layer on the negative electrode before dendrites can grow and penetrate the separator. This prior protection prevents internal short-circuiting and thermal runaway while allowing the battery to maintain its high energy density characteristics.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of moving object

If separator thickness is reduced to prevent battery swelling, then battery size is minimized, but separator integrity is compromised leading to electrode contact

Engineering Contradiction:

Improvebattery sizeVSAvoidseparator integrity

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The invention uses composite materials by combining the separator with heteropoly acid compounds that form a reinforcing layer. This composite structure maintains separator integrity even at reduced thickness, preventing electrode contact while minimizing battery size and swelling.

Inventive Principle:

Principle #40Composite materials

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 use of polyacids and polyacid compounds effectively reduces gas generation and battery swelling, enhancing safety by maintaining separator resistance and preventing internal short-circuits, thus ensuring high safety and performance in lithium transition metal complex oxide-based batteries.

Implementation Method 1

The use of polyacids and polyacid compounds effectively reduces gas generation and battery swelling

Methodology Applied

Scientific EffectGas absorption: Absorption (physical)

Implementation Method 2

maintaining separator resistance and preventing internal short-circuits

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentUS9825337B2Non-aqueous electrolyte battery including an amorphous material

Publication Date: 2017.11.21 MURATA MFG CO LTD

AI summary

A battery is composed of a positive electrode in which a positive electrode active material layer including a positive electrode active material is formed on a positive electrode collector, a negative electrode in which a negative electrode active material layer including a negative electrode active material is formed on a negative electrode collector, a separator provided between the positive electrode and the negative electrode, and an electrolyte impregnated in the separator. The battery further includes at least one of a heteropoly acid and a heteropoly acid compound as an additive at least in one of the positive electrode, the negative electrode, the separator, and the electrolyte.