Separator-Integrated Electrode with Composite Porous Layer
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges with internal short circuits due to dendrite precipitation on the surface of active material layers, particularly when using porous layers with particles or fibers less than 1 μm in diameter, leading to uneven resistance distribution and increased lithium ion concentration.
Innovation Solution
A separator-integrated electrode with a porous layer composed of inorganic particles and resin fibers, where the first layer contains inorganic particles and the second layer is formed by electrospinning resin fibers, providing a more even texture and reducing the risk of dendrite precipitation through controlled resistance distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a porous layer made of solid particles or fibers with diameters less than 1 μm is used to reduce separator thickness and cost, then manufacturing cost is reduced and separator thickness is decreased, but internal short circuit occurs due to dendrite precipitation and uneven resistance distribution
Solution Approach 1:
The patent uses a composite porous layer combining organic fibers (from electrospinning) and inorganic particles. This composite structure provides both mechanical strength and controlled porosity, preventing dendrite formation while maintaining low cost and thin thickness. The organic-inorganic combination resolves the contradiction by achieving reliability without sacrificing manufacturing ease.
Solution Approach 2:
The patent creates a porous layer with locally optimized properties: organic fibers provide a mesh structure for mechanical strength and uniform lithium ion distribution, while inorganic particles fill spaces to control porosity and prevent dendrite precipitation. This local quality differentiation resolves the contradiction between thin separator design and short circuit prevention.
2Length of stationary object
If a porous layer with particles or fibers less than 1 μm in diameter is used, then separator thickness is reduced, but uneven resistance distribution occurs leading to increased lithium ion concentration and dendrite formation
Solution Approach 1:
The composite of organic fibers and inorganic particles creates a dual-function porous layer that is thin yet provides uniform resistance distribution. The organic fiber mesh ensures uniform lithium ion flux, while inorganic particles maintain structural integrity, resolving the contradiction between reduced thickness and improved manufacturing precision.
Solution Approach 2:
The patent changes the physical and chemical parameters of the porous layer by combining materials with different properties. The organic-inorganic composite alters porosity, mechanical strength, and electrical resistance parameters simultaneously, achieving thin thickness while maintaining uniform resistance distribution to prevent dendrite formation.
3Reliability
If conventional polyolefin fine porous film is used as separator, then battery reliability is maintained, but manufacturing process becomes complicated and lead time is extended due to stacking and rolling steps
Solution Approach 1:
The patent merges the separator function with the electrode structure by forming a porous layer directly on the electrode. This integration eliminates the need for separate separator stacking and rolling steps, reducing manufacturing complexity while maintaining reliability through the composite porous layer design that prevents short circuits.
Solution Approach 2:
The porous layer serves multiple functions: it acts as both the electrode structure component and the separator, providing mechanical support, controlling lithium ion transport, and preventing short circuits. This multi-functionality resolves the contradiction by eliminating separate separator manufacturing steps while maintaining battery reliability.
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 reduces the risk of internal short circuits and enhances the reliability and electrochemical characteristics of nonaqueous electrolyte secondary batteries by maintaining even lithium ion passage and preventing dendrite formation.
Implementation Method 1
the second layer is formed by electrospinning resin fibers
Data Source
AI summary
Provided are a separator-integrated electrode and a nonaqueous electrolyte secondary battery with a reduced risk of a short circuit between electrodes due to precipitation of metallic lithium on a surface of an electrode mixture layer. A positive electrode (12) configured as a separator-integrated electrode includes a positive current collector (22), a positive active material layer (24) formed on a surface thereof, a first porous layer (26) formed on a surface of the positive active material layer (24) and containing inorganic particles, and a second porous layer (28) formed on a surface of the first porous layer (26) and made of resin fibers.