Secondary Zinc-Air Cell Layout to Limit Electrolyte Evaporation
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Solution Overview
Problem
Secondary zinc-air batteries face challenges with cell drying due to their open system design, leading to reduced reversibility and electrochemical performance, as the electrolyte is susceptible to evaporation when in close proximity to the air electrode.
Innovation Solution
The electrolyte reservoir is placed optimally close to the zinc anode and separated by separators, preventing direct contact with the bifunctional air electrode, thus delaying evaporation and maintaining electrolyte supply to the zinc paste, which enhances cell durability and reversibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrolyte reservoir is placed close to the air electrode to ensure electrolyte supply, then the electrolyte flow to the air electrode is improved, but the electrolyte evaporation and cell drying is accelerated
Solution Approach 1:
The patent introduces a separator as an intermediary component between the electrolyte reservoir and the air electrode. This separator prevents direct contact and evaporation of electrolyte from the reservoir while still allowing ionic transport to the air electrode, thus resolving the contradiction between ensuring electrolyte supply and preventing electrolyte loss through evaporation
Solution Approach 2:
The patent positions the electrolyte reservoir in a different spatial dimension - placing it adjacent to the zinc anode rather than directly between the air electrode and zinc anode. This dimensional repositioning allows the reservoir to be close enough to supply electrolyte through the separator while being far enough from the air electrode to minimize evaporation
2Productivity
If the electrolyte volume is reduced to minimize non-active materials, then the battery energy density is improved, but the cell drying problem is exacerbated
Solution Approach 1:
The patent segments the electrolyte system into two distinct parts: a minimal electrolyte incorporated in the zinc paste (active electrolyte) and a separate electrolyte reservoir (backup electrolyte). This segmentation allows the battery to achieve high energy density with minimal electrolyte while the reservoir provides additional electrolyte supply to prevent cell drying during cycling
Solution Approach 2:
The electrolyte reservoir is pre-filled with additional electrolyte before battery assembly, serving as a preliminary supply that will be gradually consumed during cycling. This preliminary action ensures that even with reduced overall electrolyte volume, the cell has sufficient electrolyte to prevent drying and maintain reliability throughout the battery's operational life
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 configuration significantly increases the durability and reversibility of the secondary zinc-air battery by preventing electrolyte flooding and evaporation, achieving long-term performance exceeding 1800 hours compared to conventional designs.
Implementation Method 1
the electrolyte is susceptible to evaporation when in close proximity to the air electrode
Implementation Method 2
electrolyte reservoir placed next to the zinc-containing anode (both separated by a separator) and away from the BAE supplies electrolyte to the zinc paste as the electrolyte evaporates
Data Source
AI summary
It is provided a secondary zinc-air electrochemical cell comprising an air cathode that is a bifunctional air electrode (BAE); a zinc-containing anode; a free electrolyte contained in a reservoir; and a first and a second separators; wherein the zinc-containing anode is disposed between the BAE and the free electrolyte, and is separated from the BAE by the first separator and separated from the free electrolyte by the second separator. It is also provided a process for the preparation of the secondary zinc-air cell, and a battery comprising at least one cell, and wherein no free electrolyte contained in a reservoir is disposed between the BAE and the zinc-containing anode.