Layered Battery Separator for Dendrite Blocking and Thermal Stability
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Solution Overview
Problem
Current battery separators are prone to puncture by lithium or sodium dendrites, leading to internal short circuits, poor ion conduction, and safety issues due to poor electrolyte infiltration and thermal shrinkage.
Innovation Solution
A separator comprising a first substrate layer, a mixed material layer with an inorganic material and dispersant, and a second substrate layer, which delays dendrite puncture, enhances ion transport, and improves thermal stability, while preventing reaction with the negative electrode to maintain coulombic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the battery structure is simple, but the separator is easily punctured by lithium dendrites or sodium dendrites causing internal short circuit
Solution Approach 1:
The separator uses a composite structure consisting of a substrate layer and a coating layer. The substrate layer provides mechanical strength and basic separation function, while the coating layer containing inorganic materials (such as Al2O3, SiO2, TiO2, ZnO, SnO2, CuO, Fe2O3, Fe3O4, MnO, MnO2, Mn2O3, BaTiO3, CoO, NiO, or their mixtures) provides enhanced puncture resistance by reacting with lithium dendrites or sodium dendrites. This composite structure resolves the contradiction by combining materials with different functions to achieve both reliability and controlled complexity.
Solution Approach 2:
The separator employs porous materials in both the substrate layer and coating layer with controlled pore structures. The substrate layer has pores allowing ion transport, while the coating layer contains pores filled with inorganic materials that can react with dendrites. The porous structure enables the separator to maintain ion conductivity while providing mechanical and chemical resistance to dendrite puncture, thus improving reliability without excessive complexity.
2Reliability
If the separator uses inorganic material coating, then dendrite puncture resistance is improved, but the inorganic material may react with negative electrode consuming lithium or sodium metal
Solution Approach 1:
The coating layer is applied locally on specific surfaces of the substrate layer rather than uniformly throughout the entire separator structure. This localized coating approach ensures that inorganic materials are positioned where they are most needed (facing the negative electrode where dendrites form) while minimizing the total amount of inorganic material in contact with lithium or sodium metal. This resolves the contradiction by providing puncture resistance only where required, reducing unnecessary reactions with the negative electrode.
Solution Approach 2:
The substrate layer acts as an intermediary between the negative electrode and the inorganic material coating. It provides a controlled interface that allows the coating to face the negative electrode for dendrite protection while the substrate itself serves as a buffer layer. This intermediary structure enables the coating to perform its protective function while reducing direct contact between inorganic materials and lithium/sodium metal, thereby maintaining coulombic efficiency.
3Reliability
If the separator uses existing materials, then manufacturing is simple, but electrolyte infiltration is poor resulting in low ion conduction rate
Solution Approach 1:
The invention modifies key parameters of the separator including pore size distribution, porosity, and coating thickness to optimize electrolyte infiltration and ion conduction. The substrate layer is designed with specific pore structures (average pore size and porosity control) to enhance electrolyte penetration, while the coating layer parameters (inorganic material particle size, distribution, and thickness) are optimized to maintain ion conductivity. These parameter changes improve ion conduction rate while using conventional manufacturing techniques, thus resolving the contradiction between performance and manufacturing simplicity.
4Reliability
If the separator uses conventional structure, then manufacturing cost is low, but thermal shrinkage is serious leading to safety problems
Solution Approach 1:
The separator uses a composite structure with the substrate layer providing mechanical framework and the coating layer containing inorganic materials (Al2O3, SiO2, TiO2, ZnO, SnO2, CuO, Fe2O3, Fe3O4, MnO, MnO2, Mn2O3, BaTiO3, CoO, NiO, or their mixtures) that exhibit excellent thermal stability. These inorganic materials resist thermal shrinkage at elevated temperatures, maintaining separator integrity and preventing safety issues. The composite structure achieves thermal shrinkage resistance while keeping the overall design relatively simple and manufacturable.
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 prolongs battery life, increases charge/discharge rates, and enhances safety by reducing internal short circuits and self-discharge, while maintaining high coulombic efficiency.
Implementation Method 1
the inorganic material in the mixed material layer react with the lithium dendrites or sodium dendrites on the negative electrode plate
Implementation Method 2
Under the action of an electric field, holes and electrons in the inorganic material move in a directional manner, making the inorganic material have electronic conductivity
Implementation Method 3
the mixed material layer increases the infiltration of the separator to the electrolyte solution, the transport rate of sodium ions or lithium ions
Data Source
AI summary
Provided a separator, a preparation method therefor, a secondary battery and a power consuming device. The separator comprises a first substrate layer, a mixed material layer and a second substrate layer; the mixed material layer is provided between the first substrate layer and the second substrate layer; the mixed material layer comprises an inorganic material and a dispersant. The separator of the present application can delay the occurrence of lithium dendrites or sodium dendrites puncturing the separator and the occurrence of internal short circuit in the battery, prolong the service life of the battery, increase the infiltration of the separator to the electrolyte solution and the charge and discharge rate of the battery, improve the thermal shrinkage performance of the battery, and increase the safety and the first coulombic efficiency of the battery.