Nickel Hydrogen Battery Positive Electrode Magnesium Solid Solution

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Solution Overview

Problem

Conventional nickel hydrogen secondary batteries exhibit a flat discharge characteristic curve, making it difficult to accurately detect residual capacity due to a small voltage difference between the discharge early and last periods, which complicates the determination of State of Charge (SOC) and timely switching between discharge and charge.

Innovation Solution

The nickel hydrogen secondary battery incorporates a positive electrode active substance with varying amounts of magnesium solid-dissolved, along with zinc and cobalt, to create a discharge characteristic curve with a varying gradient, enhancing the accuracy of SOC detection by increasing the voltage difference between the discharge early and last periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional nickel hydrogen secondary batteries are used, then high capacity is achieved, but the discharge characteristic curve is flat making residual capacity detection difficult

Engineering Contradiction:
Improvebattery capacityVSAvoidresidual capacity detection accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The invention changes the chemical composition parameters of the positive electrode active substance by solid-dissolving magnesium, zinc, and cobalt in nickel hydroxide. This parameter change modifies the discharge characteristic curve to have a larger voltage difference between early and last periods, enabling accurate residual capacity detection while maintaining high battery capacity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite positive electrode active substance by combining nickel hydroxide with magnesium, zinc, and cobalt elements. This composite material structure produces a discharge characteristic curve with varying gradient that facilitates SOC detection, while the nickel hydroxide base maintains the high capacity characteristics

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If the voltage difference between discharge early and last periods is increased, then residual capacity detection accuracy is improved, but the discharge characteristic curve becomes less stable

Engineering Contradiction:
ImproveSOC detection accuracyVSAvoidvoltage stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The invention carefully controls the amounts of magnesium, zinc, and cobalt solid-dissolved in the nickel hydroxide to optimize the discharge characteristic. By adjusting these compositional parameters, the patent achieves a balance where the voltage difference between discharge periods is sufficiently large for accurate SOC detection, while the overall voltage stability is maintained through the nickel hydroxide matrix

Inventive Principle:
Principle #35Parameter changes

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 approach allows for easier and more accurate detection of residual capacity, improving the ability to determine the State of Charge and ensuring timely switching between discharge and charge, while maintaining a high capacity and cycle life.

Implementation Method 1

a positive electrode active substance, in which magnesium, zinc, and cobalt are solid-dissolved

Methodology Applied
Scientific EffectSolid solution strengthening: Solid Solution Strengthening

Data Source

PatentEP3499613B1Nickel hydrogen secondary battery
Publication Date: 2021.05.19 FDK CORP
  • EP3499613B1 patent drawingFigure 1
  • EP3499613B1 patent drawingFigure 2

AI summary

A nickel hydrogen secondary battery (2) has an outer can (10), and an electrode group (22) accommodated together with an alkali electrolyte solution in the outer can (10), wherein the electrode group (22) includes a positive electrode (24) and a negative electrode (26) stacked through a separator (28); the positive electrode (24) includes a first positive electrode active substance and a second positive electrode active substance; these first and second positive electrode active substances each contain nickel hydroxide as a main component; and the first positive electrode active substance and the second positive electrode active substance differ in the amount of magnesium solid-dissolved.