Ultra-Thin Polyolefin Battery Separators for Dendrite Shutdown
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Solution Overview
Problem
Current battery separators for lithium batteries face challenges in preventing dendrite growth and internal shorts, which can reduce cycle life and battery safety, particularly in rechargeable lithium-ion batteries.
Innovation Solution
Development of ultra-thin or super-thin, monolayer or multilayer microporous polyolefin battery separators with a thickness of less than 12 μm, featuring a tri-layer configuration with a diaphanous polypropylene layer and controlled polyethylene density at the polypropylene/polyethylene interface, which enables effective thermal shutdown and oxidative protection while maintaining high ion and air transport rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thickness battery separators are used, then mechanical strength and safety are improved, but ion transport resistance increases and energy density decreases
Solution Approach 1:
The patent employs microporous polyolefin materials with controlled pore structures to create ultra-thin separators that maintain mechanical integrity while facilitating ion transport. The porous architecture allows ions to pass through efficiently even at reduced thickness, resolving the contradiction between safety and ion transport resistance.
Solution Approach 2:
The invention uses composite structures combining different polyolefin layers with distinct functions - a polyethylene shutdown layer for safety, a polypropylene structural layer for mechanical strength, and potentially ceramic coatings for enhanced performance. This composite approach enables ultra-thin design while maintaining both safety and ion transport properties.
2Quantity of substance
If separator thickness is reduced to increase energy density, then battery capacity is improved, but dendrite penetration risk increases
Solution Approach 1:
The patent applies local quality by creating a polyethylene shutdown layer specifically positioned to intercept dendrites, while the polypropylene layer provides overall structural support. This localized functional differentiation allows ultra-thin design without compromising dendrite resistance, as the shutdown layer activates when dendrites attempt to penetrate.
Solution Approach 2:
The polyethylene shutdown layer is pre-positioned to provide thermal shutdown functionality before dendrite penetration can occur. When temperature rises or dendrites attempt to grow through, the shutdown layer melts and closes pores in advance, preventing catastrophic failure even in ultra-thin configurations.
3Quantity of substance
If ultra-thin separators are used to increase energy density, then battery capacity is improved, but mechanical strength decreases
Solution Approach 1:
The patent segments the separator into distinct functional layers - a thin polyethylene shutdown layer and a polypropylene structural layer. This segmentation allows each layer to be optimized for its specific function, with the polypropylene layer providing the necessary mechanical strength to support the ultra-thin overall design.
Solution Approach 2:
By combining polyethylene and polypropylene layers in a composite structure, the patent achieves ultra-thin thickness while maintaining mechanical integrity. The polypropylene layer specifically contributes tensile strength and dimensional stability, enabling the separator to function safely at thicknesses below 12 micrometers.
4Reliability
If polyethylene layer thickness is increased to improve shutdown function, then thermal safety is improved, but ion transport resistance increases
Solution Approach 1:
The patent optimizes the polyethylene layer thickness to a specific range (1-5 micrometers) that provides sufficient shutdown function while minimizing ion transport resistance. This parameter optimization ensures the shutdown layer is thin enough for efficient ion transport but thick enough to provide reliable thermal shutdown when needed.
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 prevents dendrite growth and internal shorts, enhancing the cycle life and safety of lithium-ion batteries by providing a high-tortuosity network that inhibits lithium dendrite penetration, thus improving battery performance and longevity.
Implementation Method 1
thermal shutdown
Implementation Method 2
ion transport rates
Data Source
AI summary
In accordance with at least selected aspects, objects or embodiments, optimized, novel or improved membranes, battery separators, batteries, and/or systems and/or related methods of manufacture, use and/or optimization are provided. In accordance with at least selected embodiments, the present invention is related to novel or improved battery separators that prevent dendrite growth, prevent internal shorts due to dendrite growth, or both, batteries incorporating such separators, systems incorporating such batteries, and/or related methods of manufacture, use and/or optimization thereof. In accordance with at least certain embodiments, the present invention is related to novel or improved ultra thin or super thin membranes or battery separators, and/or lithium primary batteries, cells or packs incorporating such separators, and/or systems incorporating such batteries, cells or packs. In accordance with at least particular certain embodiments, the present invention is related to shutdown membranes or battery separators, and/or lithium primary batteries, cells or packs incorporating such separators, and/or systems incorporating such batteries, cells or packs.