Positive Electrode Plate Coating for Lower Battery Internal Resistance
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Solution Overview
Problem
The safety coating on lithium-ion battery positive electrode current collectors increases internal resistance, leading to rapid temperature rises during charging, which affects the rate performance of secondary batteries.
Innovation Solution
A positive electrode plate design featuring a conductive layer with a conductivity of 0.02 S/cm to 1 S/cm, composed of materials like carbon nanotubes, conductive carbon black, and ceramic materials, is applied to reduce contact impedance between the coating and the active substance layer, thereby alleviating high internal resistance and enhancing safety and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety coating is applied onto the positive electrode current collector to improve safety, then safety performance is improved, but internal resistance increases leading to rapid temperature rise during charging
Solution Approach 1:
The patent applies a composite coating structure consisting of a safety coating layer and a conductive layer. The safety coating layer (containing metal oxide or ceramic material) provides safety performance, while the conductive layer (containing conductive material with conductivity 0.01-10 S/cm) reduces internal resistance and prevents rapid temperature rise during charging.
2Reliability
If a safety coating is applied to improve safety performance, then safety is enhanced, but rate performance deteriorates due to high internal resistance
Solution Approach 1:
The composite coating structure combines safety coating material (metal oxide or ceramic) with conductive material. The conductive layer with controlled conductivity (0.01-10 S/cm) reduces contact impedance at the junction between the safety coating and active substance layer, thereby improving rate performance while maintaining safety performance.
3Productivity
If the conductivity of the conductive layer is increased to reduce internal resistance, then rate performance improves, but contact impedance at the junction increases
Solution Approach 1:
The patent optimizes the conductivity parameter of the conductive layer within a specific range (0.01-10 S/cm). This parameter optimization balances the reduction of internal resistance with the maintenance of appropriate contact impedance at the junction between the safety coating and active substance layer, achieving both improved rate performance and reliable electrical contact.
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 design significantly reduces internal resistance, improves rate performance, and ensures good safety performance by effectively dispersing current and maintaining structural stability while reducing side reactions.
Implementation Method 1
a conductivity of the conductive layer in this application is 0.02 S/cm to 1 S/cm... contact impedance at a junction between the first coating and the positive electrode active substance layer is reduced
Data Source
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AI summary
A positive electrode plate (20) includes a positive electrode current collector (21), a first coating (22), a conductive layer (23) and a positive electrode active substance layer (24). The first coating (22) is disposed on at least one surface of the positive electrode current collector (21), the conductive layer (23) is disposed on a surface of the first coating (22), and the positive electrode active substance layer (24) is disposed on a surface of the conductive layer (23); and the first coating (22) is controlled to include a first material, where the first material comprises one or more selected from the group consisting of a layer-structured metal oxide, a spinel-structured metal oxide, a phosphate metal oxide and a ceramic material, and a conductivity of the conductive layer (23) is 0.02 S/cm to 1 S/cm.