Alkaline Battery Separator Composite
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Solution Overview
Problem
Traditional separators for silver-zinc rechargeable batteries decompose in alkaline electrolytes, are susceptible to chemical oxidation, and have low mechanical strength, leading to short-term increased resistance and potential shorting due to metal ion buildup and dendrite penetration.
Innovation Solution
A separator comprising a polymer material with acrylonitrile butadiene styrene (ABS) and zirconium oxide, with yttrium oxide content between 1 mol% to 10 mol%, and a mean grain diameter of 30 nm to 1000 nm, providing resistance up to 2000 Ohm cm and resistance to electrochemical oxidation and dendrite penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separators are used in silver-zinc rechargeable batteries, then the battery can be assembled with conventional materials, but the separator decomposes in alkaline electrolytes and is susceptible to chemical oxidation, leading to short-term increased resistance and potential shorting
Solution Approach 1:
The separator is constructed as a composite material combining polyolefin polymer matrix with dispersed inorganic oxide particles (silica, alumina, titania, zirconia, or magnesia). This composite structure provides both the mechanical integrity of the polymer and the chemical stability of the inorganic oxide, preventing decomposition and oxidation in alkaline electrolytes while maintaining long-term battery performance
Solution Approach 2:
The invention specifies precise parameter ranges for the inorganic oxide content (1-90 wt%, preferably 10-50 wt%) and particle size (0.1-10 micrometers, preferably 0.5-5 micrometers). These parameter optimizations ensure the separator achieves adequate chemical resistance while maintaining appropriate porosity for ion transport and mechanical strength to prevent shorting
2Strength
If traditional separators are used, then manufacturing is simpler, but mechanical strength is low leading to dendrite penetration and short circuits
Solution Approach 1:
The inorganic oxide particles (silica, alumina, titania, zirconia, or magnesia) dispersed in the polyolefin matrix act as reinforcement agents, significantly enhancing the mechanical strength and rigidity of the separator. This strengthened structure effectively resists dendrite penetration while maintaining the necessary porosity for ionic conductivity
Solution Approach 2:
The separator maintains a controlled porous structure with porosity in the range of 20-80% (preferably 30-60%), with pore sizes of 0.01-10 micrometers. The inorganic oxide reinforcement allows the separator to maintain this open porous structure without compromising mechanical strength, enabling both high ionic conductivity and resistance to dendrite penetration
3Reliability
If separator porosity is increased to improve ionic conductivity, then ion transport is enhanced, but mechanical strength decreases making the separator more susceptible to dendrite penetration
Solution Approach 1:
The inorganic oxide particles serve a dual function: they reinforce the polymer matrix to maintain mechanical strength while simultaneously acting as ion transport pathways that enhance ionic conductivity. The composite structure allows the separator to achieve high porosity (20-80%) for excellent ion transport without sacrificing the mechanical integrity needed to resist dendrite penetration
Solution Approach 2:
The inorganic oxide particles are dispersed throughout the polyolefin matrix, creating local regions of enhanced structural support and ionic conductivity. This distributed reinforcement allows different regions of the separator to simultaneously provide mechanical strength and facilitate ion transport, resolving the trade-off between porosity and strength
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 maintains stable ionic conductivity, prevents metal ion reduction, and suppresses dendrite growth, thereby extending battery life and preventing short circuits, while maintaining mechanical integrity and resistance to chemical decomposition.
Implementation Method 1
a battery separator must be both an effective electrolyte transport barrier and a sufficiently good ionic conductor to avoid excessive separator resistance that substantially lowers the discharge voltage
Implementation Method 2
The separator must be chemically stable in strongly alkaline solution, resist oxidation when in contact with the highly oxidizing cathode
Implementation Method 3
the separator must suppress dendritic growth and/or resist dendrite penetration to avoid failure due to formation of a dendritic short between the electrodes
Data Source
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AI summary
The present invention provides a separator for use in an alkaline electrochemical cell comprising a polymer material and an inert filler comprising zirconium oxide. Examples of polymer materials useful in this invention include ABS polymer material, halogenated alkylene polymer material, and PE polymer material.