Composite Battery Separator With MOF Pores for Dendrite Suppression
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Solution Overview
Problem
Lithium metal batteries face issues with nonuniform current density and lithium ion concentration during cycling, leading to lithium dendrite formation, which reduces deposition density and impairs cycle life.
Innovation Solution
A separator with nanoscale and sub-nanoscale pore structures, comprising a polymer layer and a porous material layer with metal-organic framework, covalent organic framework, or molecular sieve materials, that confines solvent molecules and enhances lithium ion mobility, reducing side reactions and dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the structure is simple and easy to manufacture, but lithium dendrites form due to nonuniform current density and lithium ion concentration, reducing cycle life
Solution Approach 1:
The patent uses a composite separator structure combining a polymer base layer with a porous coating layer containing metal-organic frameworks (MOFs), covalent organic frameworks (COFs), or molecular sieves. This composite structure addresses the contradiction by providing both mechanical integrity (from the polymer) and controlled ion transport properties (from the porous coating), thereby preventing lithium dendrite formation and extending cycle life while maintaining manufacturability through conventional coating techniques.
Solution Approach 2:
The patent employs porous materials with specifically controlled pore sizes (0.1-10 nm) in the coating layer to regulate lithium ion transport. The porous structure enables uniform current density distribution and prevents lithium dendrite growth by physically constraining ion flow paths, thus improving reliability and cycle life without requiring complete structural redesign of the separator.
2Productivity
If the porous material layer thickness is increased to improve lithium ion mobility, then electrochemical performance increases, but the separator becomes more complex and harder to manufacture
Solution Approach 1:
The patent optimizes the thickness of the porous material layer within a specific range (1-8 μm) to achieve the desired balance between lithium ion mobility and manufacturability. This parameter optimization ensures sufficient ion transport channels while maintaining compatibility with existing coating and fabrication processes, avoiding the need for complex multi-step manufacturing procedures.
3Reliability
If the pore channel diameter is reduced to confine solvent molecules and reduce side reactions, then cycle performance improves, but lithium ion transport may be hindered
Solution Approach 1:
The patent creates local quality variations within the separator structure by implementing a layered architecture where the polymer base layer provides bulk mechanical support and the thin porous coating layer (1-8 μm) with controlled pore sizes (0.1-10 nm) provides selective ion transport functionality. This local differentiation allows the porous layer to confine solvent molecules and reduce side reactions at the critical electrode interface while maintaining adequate lithium ion mobility through the optimized pore structure and thin thickness, thus improving cycle performance without significantly hindering overall ion transport.
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 separator improves cycle performance by reducing side reactions, increasing lithium deposition density and uniformity, and prolonging the cycle life of lithium metal batteries by confining electrolyte solution and homogenizing lithium ion flow.
Implementation Method 1
the separator with the above features is capable of confining solvent molecules in the electrolyte solution within the pore channels of the separator
Implementation Method 2
this application increases the mobility of lithium ions and improves the electrochemical performance of the electrochemical device
Implementation Method 3
this application can increase the density and uniformity of lithium metal deposited on the surface of the negative electrode plate, slow down growth of lithium dendrites
Data Source
Figure 1~4
Figure 5~7A
Figure 7B~8
AI summary
A separator includes a polymer layer and a porous material layer. The porous material layer includes a porous material. The porous material includes a metal-organic framework material, a covalent organic framework material, a molecular sieve material, or a microporous polymer. The separator contains micropores and sub-nanopores. By applying the separator to an electrochemical device, solvent molecules in an electrolyte solution can be confined within pore channels of the separator while the electrolyte solution penetrates the separator, thereby not only reducing side reactions between lithium metal and the electrolyte solution during cycling of the electrochemical device and improving the cycle performance of the electrochemical device, but also increasing the mobility of lithium ions and improving the electrochemical performance of the electrochemical device.