Porous Separator Coating in Zinc Secondary Batteries for ZnO Segregation
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Solution Overview
Problem
Zinc secondary batteries experience a reduction in charge-discharge capacity due to zinc oxide segregation at the negative electrode, which is exacerbated by repeated charge-discharge cycles, leading to poor cycle characteristics.
Innovation Solution
A zinc secondary battery design featuring a covering film-attached porous film layer with a porous covering film comprising compounds like Mg(OH)2, Mg2P2O7, or ZrO2 adjacent to the negative electrode, inhibiting the diffusion of Zn(OH)42- and thereby preventing zinc oxide segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in a zinc secondary battery, then the battery can operate, but zinc oxide segregation occurs at the negative electrode during repeated charge-discharge cycles, leading to reduced charge-discharge capacity and poor cycle characteristics
Solution Approach 1:
A porous covering film containing basic compounds (such as metal hydroxides, oxides, or carboxylates) is introduced as an intermediary layer between the separator and the negative electrode. This covering film mediates the interaction between Zn(OH)4 2- ions and the separator, preventing zinc oxide segregation while maintaining ionic conductivity. The basic compounds in the covering film neutralize acidic species and prevent the harmful reactions that lead to capacity loss.
Solution Approach 2:
The covering film is designed with a porous structure that allows ionic transport while providing a large surface area for the basic compounds to interact with Zn(OH)4 2- ions. The porous structure ensures that the covering film does not hinder the charge-discharge process but effectively prevents zinc oxide segregation through the chemical action of the basic compounds distributed throughout the porous matrix.
2Stability of the object's composition
If the concentration of Zn(OH)4 2- near the negative electrode is maintained, then zinc oxide segregation is prevented, but this requires a specific structure that may increase device complexity
Solution Approach 1:
The separator is constructed as a composite structure consisting of a base separator layer and a porous covering film layer. The covering film contains basic compounds dispersed in a porous matrix, creating a composite material that combines the ionic conductivity of the separator with the chemical stability provided by the basic compounds. This composite structure maintains Zn(OH)4 2- concentration stability without requiring complex external control systems.
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
This design significantly improves the cycle characteristic of zinc secondary batteries by maintaining Zn(OH)42- near the negative electrode, reducing zinc oxide segregation, and maintaining charge-discharge capacity over repeated cycles.
Implementation Method 1
the porous covering film comprises at least one compound selected from the group consisting of Mg(OH)2, Mg2P2O7, MgTiO3, MgCO3, Ca(OH)2, CaSO4, Ca2P2O7, SrTiO3, SrF2, TiO2, SnO2, Zr(OH)4 and ZrO2... inhibiting the diffusion of Zn(OH)4 2-
Data Source
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AI summary
The present disclosure provides a zinc secondary battery with an improved cycle characteristic. The zinc secondary battery of the disclosure has a positive electrode layer, a covering film-attached porous film layer and a negative electrode layer in that order, with an electrolyte solution impregnating the positive electrode layer, the covering film-attached porous film layer and the negative electrode layer, wherein the covering film-attached porous film layer has a porous film layer and a porous covering film formed on the porous film layer, the covering film-attached porous film layer is directly adjacent to the negative electrode layer, and the porous covering film comprises at least one compound selected from the group consisting of Mg(OH)2, Mg2P2O7, MgTiO3, MgCO3, Ca(OH)2, CaSO4, Ca2P2O7, SrTiO3, SrF2, TiO2, SnO2, Zr(OH)4 and ZrO2.