Lithium Ion Battery Current Collector Corrosion Protection

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Solution Overview

Problem

Lithium ion secondary batteries using two-phase positive electrode active materials face performance deterioration during endurance testing, particularly due to corrosion of the positive electrode current collector, which affects their suitability for vehicle applications.

Innovation Solution

Incorporating a compound with a metal element B having a higher ionization tendency than the current collector's main component into the positive electrode composite layer, which inhibits corrosion and increases in internal resistance, thereby enhancing the battery's endurance for harsh usage conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a two-phase compound is used as the positive electrode active material, then battery safety is improved, but corrosion of the positive electrode current collector occurs during endurance testing

Engineering Contradiction:

Improvebattery safetyVSAvoidcurrent collector corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An additive compound containing metal element B is introduced as an intermediary substance between the two-phase compound and the current collector. This additive acts as a mediator that prevents direct harmful interactions, specifically corrosion, while allowing the beneficial safety properties of the two-phase compound to be maintained.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The additive compound containing metal element B provides self-protective functionality to the current collector. By having the protective agent incorporated into the positive electrode composite layer itself, the system achieves self-service corrosion prevention without requiring external protective measures.

Inventive Principle:

Principle #25Self-service

2Reliability

If a two-phase compound is used as the positive electrode active material, then battery safety is improved, but internal resistance increases during endurance testing

Engineering Contradiction:

Improvebattery safetyVSAvoidinternal resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The additive compound containing metal element B serves as an intermediary that prevents direct degradation reactions between the two-phase compound and current collector, thereby preventing increases in internal resistance while maintaining the safety benefits of the two-phase compound.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective additive is incorporated into the positive electrode composite layer before battery assembly and endurance testing. This preliminary inclusion of the protective agent prevents corrosion and internal resistance increases from occurring in the first place, rather than addressing them after they manifest.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If endurance testing for vehicle applications is conducted, then battery performance is evaluated, but charge/discharge cycle characteristics deteriorate considerably

Engineering Contradiction:

Improveendurance testing evaluationVSAvoidcharge/discharge cycle characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The additive compound containing metal element B acts as a protective intermediary that enables the battery to withstand the harsh conditions of vehicle application endurance testing without deteriorating charge/discharge cycle characteristics, thus allowing proper performance evaluation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The introduction of the additive compound changes the chemical and electrochemical parameters of the positive electrode composite layer, creating a more stable environment that maintains charge/discharge cycle characteristics even under the demanding parameters of vehicle application endurance testing.

Inventive Principle:

Principle #35Parameter changes

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 addition of the ionization-tendency-enhanced additive effectively prevents corrosion of the current collector and associated internal resistance increases, enabling lithium ion secondary batteries to maintain superior performance and endurance compatible with vehicle applications and harsh charge/discharge cycling.

Implementation Method 1

contains as an additive a compound having a metal element B in the composition thereof that has a higher ionization tendency than the metal element A

Methodology Applied

Scientific EffectIonization tendency: Oxidation

Data Source

PatentUS9184446B2Non-aqueous electrolyte lithium ion secondary battery

Publication Date: 2015.11.10 TOYOTA JIDOSHA KK

AI summary

A lithium ion secondary battery provided by the present invention has a positive electrode having a current collector and a positive electrode composite layer provided on the current collector. The current collector contains a metal element A as a main component thereof. The positive electrode composite layer contains a two-phase compound containing lithium as a positive electrode active material. The positive electrode composite layer also contains as an additive a compound having a metal element B, in a composition thereof, that has a higher ionization tendency than the metal element A.