Hollow Particle Coated Separator for High-Power Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high power output and durability due to heat shrinkage of separators, which can lead to localized shorting and reduced adhesive strength of porous heat-resistant layers with increased porosity.
Innovation Solution
Incorporating hollow particles made of inorganic materials with a binder in the porous heat-resistant layer, which increases ionic permeability without compromising adhesion, allowing for higher porosity and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the porosity of the porous heat-resistant layer is increased to achieve high power output, then ionic permeability is improved, but adhesive strength between the porous heat-resistant layer and the separator or electrode deteriorates
Solution Approach 1:
The patent applies porous materials by forming a porous heat-resistant layer with controlled porosity (40-60%) on the separator surface. The porous structure provides ion-conducting paths while the heat-resistant properties prevent thermal shrinkage. The porosity is optimized to balance ionic permeability for high power output with sufficient adhesive strength to prevent peeling.
Solution Approach 2:
The patent uses composite materials by combining the porous heat-resistant layer (made from heat-resistant resin particles) with the separator and electrode materials. This composite structure integrates the thermal stability of the heat-resistant layer with the functional properties of the separator and electrode, achieving both high power output through ionic permeability and durability through strong adhesion.
2Productivity
If the porosity of the porous heat-resistant layer is increased to improve ionic permeability, then high-rate characteristics are enhanced, but the surface area of contact between the porous heat-resistant layer and the separator or electrode decreases
Solution Approach 1:
The porous heat-resistant layer with optimized porosity (40-60%) provides extensive internal surface area for ion conduction while maintaining adequate external contact area with the separator. The porous structure allows high ionic permeability for improved high-rate characteristics without compromising the adhesive bonding area.
Solution Approach 2:
The patent optimizes the porosity parameter within the range of 40-60% to achieve the desired balance. This parameter optimization ensures sufficient ionic permeability for high-rate discharge performance while maintaining adequate surface area for adhesive bonding between the porous heat-resistant layer and the separator or electrode.
3Reliability
If the separator undergoes heat shrinkage to actuate shutdown function, then safety is improved, but localized shorting due to film breakage may arise
Solution Approach 1:
The porous heat-resistant layer serves as a cushioning layer between the separator and the electrode. When the separator undergoes heat shrinkage, this layer absorbs the mechanical stress and prevents direct contact between the separator and electrode, thereby preventing localized shorting while allowing the shutdown function to operate.
Solution Approach 2:
The porous heat-resistant layer acts as an intermediary between the separator and the electrode. It mediates the interaction during thermal events by providing a physical barrier that prevents film breakage and localized shorting, while still allowing ion transport to maintain battery 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 use of hollow particles enhances high-rate characteristics and durability by maintaining adhesion and suppressing heat shrinkage, leading to stable high-performance lithium secondary batteries suitable for vehicle applications.
Implementation Method 1
the porous heat-resistant layer includes hollow particles made of an inorganic material and also includes a binder... the porous heat-resistant layer having a large porosity
Implementation Method 2
Because such separators are porous, heat shrinkage arises at elevated temperatures... to prevent heat shrinkage of the separator, the formation of a porous heat-resistant layer on the separator surface has been disclosed
Data Source
AI summary
A nonaqueous electrolyte secondary battery 100 according to this invention includes a positive electrode 10, a negative electrode 20, a separator 40 interposed between the positive electrode 10 and the negative electrode 20, and a nonaqueous electrolyte solution. A porous heat-resistant layer 42 is additionally provided between the separator 40 and at least one electrode from among the positive electrode 10 and the negative electrode 20. The porous heat-resistant layer 42 includes hollow particles 44 made of an inorganic material, and a binder 46.