LDH Functional Layer Porosity Control to Prevent Separator Cracking
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Solution Overview
Problem
Layered double hydroxide (LDH) functional layers used as separators in alkaline secondary batteries face challenges with cracking during drying shrinkage and maintaining high density, which affects their strength and performance.
Innovation Solution
The development of an LDH functional layer with an average porosity of 1 to 40% and an average pore diameter of 100 nm or less, which enhances strength and reduces cracking, while maintaining high density and alkaline resistance, by optimizing the composition and structure of the LDH with Ni, Ti, and OH groups, and embedding or coating it on a porous substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LDH functional layer is densified to achieve high density and prevent dendritic zinc deposition, then the gas and water impermeability is improved, but the layer becomes prone to cracking during drying shrinkage and loses strength
Solution Approach 1:
The patent applies porous materials by controlling the porosity of the LDH functional layer to be 1-40% with pore diameters of 100 nm or less. This porous structure allows the layer to maintain high density and gas/water impermeability while the controlled pores accommodate drying shrinkage, preventing crack formation and maintaining layer strength.
Solution Approach 2:
The patent applies parameter changes by optimizing specific parameters of the LDH functional layer: porosity (1-40%), pore diameter (≤100 nm), and composition ratios (0.1 < x < 0.4 in the formula M2+1-xM3+x(OH)2An−x/n·mH2O). These parameter optimizations enable the layer to achieve both high density for impermeability and sufficient strength to resist cracking during drying.
2Reliability
If the LDH functional layer is made with high density to prevent penetration of carbon dioxide and dendritic zinc, then the separator performance is improved, but the layer is more susceptible to cracking during drying shrinkage
Solution Approach 1:
The patent utilizes porous materials with controlled porosity (1-40%) and small pore diameters (≤100 nm) in the LDH functional layer. This porous structure provides high density for preventing CO2 and dendritic zinc penetration while the pores accommodate volume changes during drying, reducing crack susceptibility and maintaining separator reliability.
Solution Approach 2:
The patent employs composite materials by combining LDH with specific anions (CO32−, OH−) and controlling the composition ratio (0.1 < x < 0.4) to create a composite functional layer. This composite structure enhances both the density for preventing harmful factor penetration and the mechanical properties to resist cracking during drying shrinkage.
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 optimized LDH functional layer effectively suppresses cracking during drying, retains high density, and exhibits high alkaline resistance and ionic conductivity, making it suitable for use as a solid electrolyte separator in alkaline secondary batteries.
Implementation Method 1
reduce generation of cracks during drying shrinkage
Implementation Method 2
the LDH has also been attractive as a material that conducts hydroxide ions
Implementation Method 3
exhibits high alkaline resistance and ionic conductivity
Data Source
AI summary
There is provided a functional layer including layered double hydroxide. The functional has an average porosity of 1 to 40% and an average pore diameter of 100 nm or less.