Electrolytic Manganese Dioxide for Alkaline Batteries
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Solution Overview
Problem
Alkali-manganese dry cells using manganese dioxide as a cathode active material face challenges with high rate discharge characteristics and middle rate discharge characteristics, leading to impaired discharge capacity and corrosion issues with metal materials.
Innovation Solution
Electrolytic manganese dioxide with an alkali potential of 280-310 mV and a full width at half maximum (FWHM) of 2.2-2.9° in XRD measurements, produced through a method involving varying sulfuric acid concentrations during electrolysis, neutralization, and washing processes to optimize physical properties and reduce corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrolytic manganese dioxide is produced by conventional methods to improve high rate discharge characteristic, then high rate discharge characteristic is improved, but middle rate discharge characteristic becomes insufficient
Solution Approach 1:
The invention controls specific parameters of electrolytic manganese dioxide: alkali potential (280-310 mV), sulfate group content (0.8-1.5 wt%), and JIS-pH (2.0-3.5). By optimizing these parameters simultaneously, the invention achieves both improved high rate discharge characteristic and middle rate discharge characteristic, resolving the contradiction between the two discharge rates
2Speed
If sulfuric acid amount is increased to improve high rate discharge characteristic, then high rate discharge characteristic is improved, but corrosion of metal materials occurs
Solution Approach 1:
The invention optimizes the sulfate group content to a specific range (0.8-1.5 wt%) and controls JIS-pH (2.0-3.5), which balances the high rate discharge characteristic with corrosion resistance. This parameter optimization prevents excessive sulfuric acid from causing corrosion while maintaining good high rate discharge performance
3Speed
If sodium amount is reduced to improve high rate discharge characteristic, then high rate discharge characteristic is improved, but neutralization becomes insufficient causing corrosion
Solution Approach 1:
The invention controls the alkali potential (280-310 mV) and JIS-pH (2.0-3.5) to achieve proper neutralization. This ensures sufficient neutralization to prevent corrosion while maintaining the optimized sodium content for improved high rate discharge characteristic
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 resulting electrolytic manganese dioxide exhibits improved high and middle rate discharge characteristics while minimizing corrosion, enhancing the performance and longevity of alkali-manganese dry cells.
Implementation Method 1
a method for producing electrolytic manganese dioxide by changing the sulfuric acid concentration during the electrolysis period
Implementation Method 2
full width at half maximum (FWHM) of diffraction lines appearing in the vicinity of 2θ＝22±1° in XRD measurement using CuKa radiation as a light source
Data Source
Figure 1~2
AI summary
An object of the present invention is to provide electrolytic manganese dioxide to be used as a cathode active material for an alkali-manganese dry cell, which has a high alkali potential and is provided with a high reactivity and packing efficiency as a cathode for the cell, and which is excellent in the middle rate discharge characteristic, and electrolytic manganese dioxide excellent in the high rate discharge characteristic and the middle rate discharge characteristic, which will not cause corrosion of metal materials, and a method for its production. In the present invention, electrolytic manganese dioxide having an alkali potential of at least 280 mV and less than 310 mV, and FWHM of at least 2.2° and at most 2.9°, is used. It is preferred that of the electrolytic manganese dioxide, the (110)/(021) peak intensity ratio in the X-ray diffraction peaks is at least 0.50 and at most 0.80, and the (110) interplanar spacing is at least 4.00 Å and at most 4.06 Å. Further, electrolytic manganese dioxide wherein the JIS-pH (JIS K1467) is at least 1.5 and less than 2.6, the sodium content is at least 0.02 wt% and less than 0.10 wt%, the sulfate group content is less than 1.30 wt%, the median diameter is at least 30 µm and at most 50 µm, and the BET specific surface area is at least 20 m2/g and at most 50 m2/g, is preferred.