Lithium Ion Battery Positive Electrode Moisture Suppression

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Solution Overview

Problem

Lithium nickelate-based positive electrodes in lithium ion secondary batteries are prone to surface deterioration due to moisture absorption, leading to gas generation and performance degradation during charging, discharging, and storage at high temperatures, and conventional coating methods fail to effectively suppress moisture absorption.

Innovation Solution

A positive electrode with a mixture layer containing a transition metal-containing complex oxide on a current collector, having a surface roughness of 0.1 μm to 0.5 μm Ra value, treated with a coupling agent to enhance water repellency and prevent surface deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the active material powder is coated with a coupling agent and then processed by applying pressure, then the irreversible capacity is decreased, but the active material particles easily cause cracks or deformation, making it difficult to obtain sufficient moisture absorption suppression effect

Engineering Contradiction:

Improvecycle characteristicsVSAvoidparticle integrity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The coupling agent is applied to the active material particles before they are formed into the electrode plate. This preliminary coating protects the particles from moisture absorption and prevents cracks or deformation during subsequent pressing operations, resolving the contradiction between improving cycle characteristics and maintaining particle integrity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coupling agent acts as an intermediary substance between the active material particles and the external environment. It forms a protective layer that prevents direct contact between moisture and the active material surface, thereby suppressing moisture absorption without affecting particle structural integrity during processing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the electrode plate is subjected to rolling treatment to improve density, then the manufacturing efficiency is improved, but the active material particles cause cracks or deformation, reducing the coating effectiveness

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidmoisture absorption suppression

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The coupling agent coating is applied to the active material particles before the electrode plate is subjected to rolling treatment. This preliminary protective coating prevents cracks or deformation of the particles during rolling, maintaining the coating's moisture absorption suppression effectiveness while enabling efficient manufacturing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coupling agent layer serves as a cushioning protective layer that absorbs and distributes the mechanical stress during rolling treatment. This prevents direct transmission of rolling forces to the active material particles, avoiding cracks or deformation that would compromise the coating's moisture barrier function

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively suppresses moisture absorption, preventing gas generation and performance degradation, while maintaining battery thickness and cycle characteristics.

Implementation Method 1

the mixture layer has a surface treated layer treated with a coupling agent on the surface... effectively suppresses moisture absorption

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Data Source

PatentUS8187749B2Positive electrode for lithium ion secondary battery and lithium ion secondary battery using the same

Publication Date: 2012.05.29 PANASONIC HOLDINGS CORP

AI summary

According to a positive electrode for a lithium ion secondary battery comprising a current collector and a mixture layer containing a transition metal-containing complex oxide as a positive electrode active material formed on the current collector, wherein the mixture layer has surface roughness of 0.1 μm or more and 0.5 μm or less in terms of a Ra value and the mixture layer has a surface treated layer treated with a coupling agent on the surface, it is possible to obtain a positive electrode which is excellent in suppression of moisture absorption. By using the positive electrode, it is possible to obtain a lithium ion secondary battery which is excellent in storage characteristics and causes less battery swelling since the amount of a gas generated upon charging and discharging decreases.