Composite Separator for Electrochemical Cells
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Solution Overview
Problem
Current separator membranes for electrochemical cells are expensive, prone to shrinkage at high temperatures, and inefficient in preventing dendrite bridging, leading to safety concerns and reduced battery performance.
Innovation Solution
A composite separator made of inorganic particles and a polymeric binder with a bimodal pore distribution, providing excellent adhesion to electrodes and maintaining dimensional stability at high temperatures, is developed. This composite is directly coated onto electrodes, ensuring strong adhesion and preventing delamination, even under deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer separator membranes are used to prevent electrode contact, then separation function is achieved, but cost increases significantly and dimensional stability at high temperatures deteriorates
Solution Approach 1:
The patent employs a porous inorganic coating layer with controlled pore structure to achieve separator function. The porous structure allows electrolyte penetration and ionic conduction while maintaining physical separation between electrodes, replacing expensive polymer membranes with cost-effective inorganic porous materials that also provide superior thermal stability.
Solution Approach 2:
The invention creates a composite structure combining inorganic particles (such as氧化铝, 氧化钛) with a polymer binder matrix. This composite approach integrates the low cost and thermal stability of inorganic materials with the flexibility and processability of polymers, achieving both economic and performance advantages over pure polymer separators.
2Reliability
If polymer separator membranes are used for electrode separation, then separation is achieved, but dimensional stability at high temperatures worsens due to shrinkage
Solution Approach 1:
The porous inorganic coating layer maintains its pore structure and dimensions at high temperatures, preventing the shrinkage issues encountered with polymer separators. The inorganic porous framework provides thermal stability while preserving ionic conductivity pathways.
Solution Approach 2:
The inorganic-polymer composite structure leverages the high thermal stability of inorganic particles as a rigid framework that constrains polymer matrix shrinkage at elevated temperatures, thereby maintaining dimensional stability and preventing electrode contact during thermal runaway conditions.
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 results in a low-cost, high-performance separator that enhances safety and efficiency by reducing lithium plating and maintaining ionic conductivity while withstanding temperature changes, thus improving the overall performance and safety of electrochemical cells.
Implementation Method 1
maintaining dimensional stability at high temperatures
Implementation Method 2
permitting electrolyte to pass there through
Implementation Method 3
coating a surface of an electrode with a coating solution
Data Source
AI summary
An electrode/separator assembly for use in an electrochemical cell includes a current collector; a porous composite electrode layer adhered to the current collector, said electrode layer comprising at least electroactive particles and a binder; and a porous composite separator layer comprising inorganic particles substantially uniformly distributed in a polymer matrix to form nanopores and having a pore volume fraction of at least 25%, wherein the separator layer is secured to the electrode layer by a solvent weld at the interface between the two layers, said weld comprising a mixture of the binder and the polymer. Methods of making and using the assembly are also described.