Positive Electrode Safety Coating for High-Temperature Adhesion
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Solution Overview
Problem
Lithium-ion batteries face safety risks due to poor high-temperature resistance in existing positive electrode safety coatings, which can shed powder, deform, or detach, leading to potential fires or explosions from internal short circuits.
Innovation Solution
A safety coating is applied to the positive electrode current collector, formed by dehydrating silica sol and/or alumina sol, creating a siloxane or alumina network structure that withstands high temperatures, enhancing adhesion and preventing detachment during high-temperature events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing positive electrode safety coatings are used, then basic safety function is provided, but high-temperature resistance is poor causing powder shedding, deformation, or detachment
Solution Approach 1:
The patent uses a composite coating structure consisting of an aluminum oxide layer and an aluminum hydroxide layer. This composite material approach combines the high-temperature stability of aluminum oxide with the protective and adhesive properties of aluminum hydroxide, achieving both high-temperature resistance and coating stability that single materials cannot provide alone.
Solution Approach 2:
The patent controls the thickness parameters of each layer (aluminum oxide layer: 1-5 μm, aluminum hydroxide layer: 5-20 μm) and adjusts processing parameters such as drying temperature and coating composition ratios to optimize the coating's high-temperature performance and adhesion, preventing powder shedding and detachment.
2Object-affected harmful factors
If safety coating is applied to protect current collector, then thermal safety is improved, but coating may detach during high-temperature events
Solution Approach 1:
The dual-layer composite structure provides both protection and stability: the aluminum oxide layer offers high-temperature resistance while the aluminum hydroxide layer provides excellent adhesion to the current collector. This combination ensures the coating remains attached during thermal events while maintaining protective function.
Solution Approach 2:
The aluminum hydroxide layer acts as an intermediary between the aluminum oxide layer and the current collector, enhancing interfacial adhesion and preventing coating detachment during high-temperature conditions while allowing the aluminum oxide layer to provide the primary thermal protection.
3Reliability
If coating materials are used to prevent short circuit, then safety function is achieved, but powder shedding occurs at high temperatures
Solution Approach 1:
The composite coating structure prevents powder shedding by creating a stable, bound coating system where aluminum oxide and aluminum hydroxide are chemically and physically integrated. This eliminates loose powder particles that could shed during thermal events while maintaining the short circuit prevention function.
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 safety coating effectively protects the aluminum foil, reducing the risk of fires or explosions by maintaining adhesion and preventing direct contact between electrodes, thus improving thermal safety performance.
Implementation Method 1
the substance I is formed by dehydration of a first substance via a drying process of the positive electrode plate, where the first substance includes silica sol and/or alumina sol. During the drying process, the first substance dehydrates to form a specific siloxane network structure and/or dehydrates and condenses to form a -O-Al-O- three-dimensional network structure.
Implementation Method 2
the first substance dehydrates to form a specific siloxane network structure and/or dehydrates and condenses to form a -O-Al-O- three-dimensional network structure
Implementation Method 3
the safety coating will not detach from the positive electrode current collector, significantly reducing a probability of peeling of the safety coating
Data Source
AI summary
A positive electrode plate includes a positive electrode current collector and a positive electrode active material layer. A safety coating is provided between the positive electrode current collector and the positive electrode active material layer, and the safety coating is disposed on a surface of the positive electrode current collector. The safety coating contains substance I, and the substance I is formed by dehydration of a first substance via a drying process of the positive electrode plate, where the first substance includes silica sol and/or alumina sol. The surface of the current collector of the positive electrode plate is provided with the safety coating, where the safety coating has good high-temperature resistance and can effectively protect the aluminum foil at high temperatures, thereby enhancing the thermal safety performance of the lithium-ion battery.