Silver Positive Electrode for Alkaline Batteries
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Solution Overview
Problem
Silver-zinc (AgZn) storage batteries have a limited service life due to the rapid degradation of zinc anodes and silver cathodes, leading to short cycling capabilities and high internal resistance, which restricts their commercial application beyond military uses.
Innovation Solution
A silver positive electrode with a three-dimensional collector and cathodic additives like zinc oxide and titanium dioxide is used, enhancing the surface area and ionic diffusion, allowing for more homogeneous silver deposition and improved cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional silver electrodes are used in AgZn storage batteries, then high power specific to the system is achieved, but the service life remains limited to approximately tens of cycles
Solution Approach 1:
The patent employs a porous substrate as the support for the silver electrode, which increases the surface area available for electrochemical reactions. This porous structure allows for better distribution of the active material and improved electrolyte penetration, thereby enhancing both power delivery and cycling stability without compromising the high power characteristics of the AgZn system.
Solution Approach 2:
The invention uses composite material structures combining silver with other materials to form the electrode. This composite approach allows optimization of both electrical conductivity and mechanical stability, enabling the electrode to maintain high power output while resisting degradation over extended cycling periods, thus extending service life beyond tens of cycles.
2Use of energy by moving object
If zinc anodes are used in alkaline environment, then electrochemical reactions occur, but dendritic and spongy deposits form leading to short-circuiting
Solution Approach 1:
The patent applies local quality modifications to the zinc anode surface, creating regions with different properties that control zinc deposition. By modifying specific areas of the electrode surface with catalysts or structural features, the invention promotes uniform zinc plating in certain zones while preventing dendritic growth in others, thereby maintaining reliable operation.
Solution Approach 2:
The invention introduces intermediary substances or layers between the zinc anode and electrolyte that mediate the electrochemical reactions. These intermediaries control the deposition process, preventing direct formation of dendritic structures while maintaining efficient electrochemical activity, thus eliminating short-circuiting risks.
3Stability of the object's composition
If zinc is redistributed non-uniformly during formation, then anodic active mass densifies at surface, but porosity is reduced accelerating preferential zinc formation
Solution Approach 1:
The patent addresses the dimensional issue of zinc redistribution by transitioning from a two-dimensional surface problem to a three-dimensional solution. The porous three-dimensional substrate provides depth and volume for zinc deposition, distributing the active mass throughout the bulk structure rather than concentrating it at the surface, thereby maintaining porosity and preventing accelerated degradation.
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 new silver electrode design significantly increases the cycling capacity and service life of AgZn storage batteries, enabling them to operate efficiently in both open and tight configurations with reduced internal resistance and prolonged cycle life.
Implementation Method 1
A silver positive electrode with a three-dimensional collector and cathodic additives like zinc oxide and titanium dioxide is used, enhancing the surface area and ionic diffusion
Implementation Method 2
A silver positive electrode with a three-dimensional collector and cathodic additives like zinc oxide and titanium dioxide is used, enhancing the surface area and ionic diffusion
Implementation Method 3
allowing for more homogeneous silver deposition and improved cycling stability
Data Source
AI summary
Silver positive electrode for alkali secondary batteries having an enhanced cycling capability, and consequently a longer lifetime in cycling of the storage batteries incorporating it, by optimizing, in recharge mode, the conditions for electrochemically reducing the oxidized silver species. The silver electrode according to the invention is of the plasticized type, and a high-porosity collector, such as a woven fabric, a felt or a reticulated cellular metal foam, is used. The active compound introduced into the collector is prepared in paste form, in which the active material consists of metallic silver particles and/or silver monoxide particles, and may advantageously include a metal oxide acting as pore-forming and wetting agent for the electrode. Such an electrode is particularly intended for mounting in silver-zinc storage batteries operating in open mode or sealed mode.