AA Alkaline Battery Zinc Electrode Tin Coating Overdischarge Protection
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Solution Overview
Problem
AA alkaline batteries with increased capacity and power, fabricated at low cost, are prone to alkaline electrolyte leakage during overdischarge due to accelerated hydrogen gas generation, which increases internal pressure and poses safety hazards.
Innovation Solution
The AA alkaline battery design includes a negative electrode with zinc, indium, and bismuth, a copper and iron-based negative electrode current collector, and a tin coating on the current collector surface, which suppresses hydrogen gas generation by precipitating copper and tin on zinc particles, thereby reducing electrolyte leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the content of indium and bismuth in the negative electrode is reduced to increase power and reduce cost, then the reaction efficiency of zinc is enhanced and cost is reduced, but hydrogen gas generation is accelerated during overdischarge
Solution Approach 1:
Tin is introduced as an intermediary substance on the current collector surface. During overdischarge, tin precipitates along with copper to form a protective layer on zinc particles, suppressing hydrogen gas generation. This intermediary mechanism allows the battery to achieve high power with reduced indium and bismuth content while preventing the harmful effect of accelerated hydrogen generation.
2Object-generated harmful factors
If tin is provided on the surface of the negative electrode current collector to suppress hydrogen gas generation, then hydrogen gas generation is suppressed, but manufacturing complexity increases
Solution Approach 1:
The invention specifies precise parameter ranges for tin content (5-100 ppm relative to current collector weight) and iron content (100 ppm or less relative to current collector weight). By controlling these compositional parameters, the patent achieves hydrogen gas suppression through a standardized manufacturing process rather than complex structural modifications, thus minimizing manufacturing complexity while maintaining effectiveness.
3Quantity of substance
If the weight of zinc in the negative electrode is increased to enhance capacity, then capacity is increased, but the battery becomes more prone to electrolyte leakage during overdischarge
Solution Approach 1:
The tin coating on the current collector performs a preliminary protective action before overdischarge occurs. During normal operation and the onset of overdischarge, tin precipitates to form a protective layer on zinc particles, preventing the conditions that would lead to electrolyte leakage. This preliminary protection allows the battery to safely accommodate higher zinc content for enhanced capacity.
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 enhances the reaction efficiency of zinc, increases battery capacity and power, reduces costs, and effectively prevents electrolyte leakage by suppressing hydrogen gas generation during overdischarge, ensuring safer operation.
Implementation Method 1
bismuth or indium, for example, is added to the negative electrode in the alkaline battery in order to suppress corrosion of zinc by the alkaline electrolyte
Implementation Method 2
when the AA alkaline battery is overdischarged so that copper is eluted from the negative electrode current collector, not only copper but also tin is eluted. This causes copper and tin to be precipitated, as metals, on the surface of zinc particles near the negative electrode current collector
Implementation Method 3
In case of an increase in internal pressure of the alkaline battery, a safety valve opens to reduce the pressure inside the alkaline battery
Data Source
AI summary
An AA alkaline battery according to the present invention includes: a positive electrode; a negative electrode; a separator; an alkaline electrolyte; and a negative electrode current collector. The negative electrode contains zinc, indium, and bismuth. The weight of zinc is 4.0 g or more, and the total weight of indium and bismuth is 450 ppm or less with respect to the weight of zinc. The negative electrode current collector contains copper. Tin is provided on at least part of the surface of the negative electrode current collector.