Alkaline Cell Anode with Dehydrated Molecular Sieves
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Solution Overview
Problem
Conventional alkaline electrochemical cells face challenges in enhancing discharge capacity and service life due to zinc corrosion and polarization issues, particularly in maintaining adequate conductivity and preventing zinc oxide buildup, while adhering to environmental regulations that limit the use of mercury.
Innovation Solution
Incorporating dehydrated molecular sieves, such as dehydrated alkali metal aluminosilicates, into the anode mixture of zinc or zinc alloy particles to retard zinc oxide deposition and improve the cell's discharge capacity and service life, without adding mercury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of zinc or other active material in the anode is increased by decreasing the amount of electrolyte, then the discharge capacity is improved, but the utilization of the anode active material begins to decrease
Solution Approach 1:
The patent changes the chemical composition parameters of the anode by introducing zinc oxide and zinc chloride additives. This modifies the electrochemical environment to improve zinc utilization efficiency while maintaining high discharge capacity, resolving the contradiction between quantity of active material and utilization rate
Solution Approach 2:
The patent creates a composite anode system by combining zinc particles with zinc oxide and zinc chloride additives. This composite structure enhances the overall performance by improving zinc dissolution and utilization while preventing polarization, allowing both high capacity and high utilization
2Quantity of substance
If the amount of manganese dioxide or other active material in the cathode is increased by decreasing the amount of non-electrochemically active materials, then the discharge capacity is improved, but the bulk conductivity of the cathode decreases
Solution Approach 1:
The patent modifies the cathode composition by adding zinc oxide and zinc chloride, which change the electrochemical parameters and improve ion transport. This allows increased manganese dioxide content while maintaining adequate conductivity through enhanced electrochemical activity
3Quantity of substance
If electrode active material is packed too densely in the cell, then the discharge capacity is improved, but the rates of electrochemical reactions during cell discharge are reduced
Solution Approach 1:
The patent changes the chemical environment parameters by introducing zinc oxide and zinc chloride additives. This modifies the reaction kinetics and electrochemical activity, enabling faster reaction rates even at high packing densities by improving ion transport and reducing polarization effects
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 addition of molecular sieves effectively delays zinc oxide buildup, enhancing zinc utilization and extending the service life of alkaline cells, thereby improving discharge capacity and maintaining reliable performance without the need for mercury.
Implementation Method 1
The molecular sieve additive comprises dehydrated aluminosilicate, preferably a dehydrated alkali metal aluminosilicate... The addition of small amounts of molecular sieves to the anode mixture comprising zinc or zinc alloy particles has been determined to increase the service life of the cell during normal usage
Data Source
AI summary
An alkaline cell having an anode mixture comprising zinc particles, aqueous alkaline electrolyte, and molecular sieve additive. The cathode preferably comprises manganese dioxide. The cell may be cylindrical or any other shape or size. The molecular sieve additive preferably comprises a crystalline aluminosilicate material which is in at least a partially dehydrated state before admixture with the aqueous electrolyte, preferably potassium hydroxide. The aluminosilicate crystalline structure has average pore size between about 3 and 25 Angstrom. The addition of the molecular sieves to the zinc anode improves the cell's discharge capacity and service life. The molecular sieves preferably comprises between about 0.07 and 0.7 percent by weight of the anode mixture.