Composite Separator with Active Material Coating for Thermal Stability
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Solution Overview
Problem
Lithium-ion batteries face issues with thermal stability and complex manufacturing processes, leading to safety concerns such as ignition and explosion, and have lower capacity and insufficient discharging in low temperatures.
Innovation Solution
An electrochemical device with a composite separator featuring porous coating layers made of cathode and anode active material particles and binder polymers on both surfaces of a porous substrate, eliminating the need for additional electrode active material coatings and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin porous substrate is used as a separator, then it provides basic separation function, but it shows extreme thermal shrinking behavior at 100°C or above causing electric short circuit
Solution Approach 1:
The patent applies composite materials by forming a porous coating layer comprising inorganic particles and binder polymer on the polyolefin porous substrate. This composite structure combines the porous substrate's separation function with the coating layer's thermal stability, preventing thermal shrinkage at high temperatures while maintaining the separator's basic functions.
Solution Approach 2:
The patent uses porous materials by creating a porous coating layer with controlled porosity (30-70%) on the porous substrate. The porous structure allows electrolyte penetration and ion transport while the inorganic particles provide thermal stability, preventing the harmful thermal shrinkage effect.
2Ease of manufacture
If conventional separate electrode and separator manufacturing processes are used, then each component can be optimized independently, but the overall manufacturing process becomes complicated
Solution Approach 1:
The patent merges the separator manufacturing process with electrode active material coating by forming a porous coating layer that simultaneously serves as the separator coating and electrode active material layer. This integration eliminates separate coating steps and reduces manufacturing complexity while maintaining independent optimization capabilities.
Solution Approach 2:
The porous coating layer is designed to perform multiple functions: it acts as the separator coating providing thermal stability, serves as the electrode active material layer, and maintains ion transport pathways. This multi-functionality reduces the number of separate manufacturing steps required.
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 enhances thermal stability and reduces manufacturing complexity, improving the safety and performance of lithium-ion batteries by integrating active material functions into the separator layers, while maintaining capacity comparable to conventional cells.
Implementation Method 1
a polyolefin porous substrate commonly used as a separator of an electrochemical device shows extreme thermal shrinking behavior at a temperature of 100 C or above due to the features of its material and its manufacturing process such as elongation
Implementation Method 2
the inorganic particles in the porous coating layer formed on the porous substrate act as a kind of spacer that keeps a physical shape of the porous coating layer, so the inorganic particles restrain thermal shrinkage of the porous substrate when the electrochemical device is overheated
Implementation Method 3
In addition, interstitial volumes exist among the inorganic particles, thereby forming fine pores
Data Source
AI summary
An electrochemical device includes an electrode structure provided with a composite separator having a porous substrate with a plurality of pores and a porous coating layer formed on at least one surface of the porous substrate and made of a mixture of electrode active material particles and a binder polymer. The porous coating layer of the composite separator improves thermal stability of the porous substrate and plays a function of electrode active material layer of the electrochemical device. Accordingly, this electrochemical device has excellent stability and good economical efficiency since the electrode structure does not need coating of an electrode active material layer on a surface of a current collector.