Nickel-Zinc Battery Electrode Additives for Hydrogen Evolution
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Solution Overview
Problem
Nickel-zinc secondary batteries face issues with hydrogen evolution and safety risks due to the use of Co2+ ions, which lead to corrosion and potential explosions, while Cd added to improve conductivity causes environmental pollution.
Innovation Solution
A nickel-zinc secondary battery design that replaces Co2+ ions with yttrium oxide and calcium hydroxide, using spherical nickel hydroxide coated with Co3+ as the positive electrode material, and a tilted-mesh negative electrode substrate to reduce hydrogen evolution and enhance safety and environmental friendliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Co2+ ions are added to improve conductivity and reduce oxygen evolution, then charging efficiency is improved, but hydrogen evolution increases and safety risks arise
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Co2+ ions with yttrium oxide and calcium hydroxide in specific weight ratios (0.6-1.0% yttrium oxide, 0.2-0.6% calcium hydroxide). This parameter change maintains the conductivity improvement function while eliminating the harmful hydrogen evolution effect that occurs with Co2+ ions.
Solution Approach 2:
The patent replaces expensive and harmful Co2+ ions with more environmentally friendly and safer alternative materials (yttrium oxide and calcium hydroxide). While the new materials serve the same functional purpose of improving conductivity, they do not produce the harmful side effects of hydrogen evolution and battery corrosion associated with cobalt.
2Reliability
If Co2+ ions are used to form conductive network and improve overpotential, then resistance is reduced, but battery corrosion and explosion risk increase
Solution Approach 1:
The patent replaces harmful Co2+ ions with safer alternative materials (yttrium oxide and calcium hydroxide) that provide the same conductivity improvement function without causing battery corrosion or explosion risks. The new material combination maintains reliability while eliminating harmful effects.
Solution Approach 2:
The patent uses a composite material system combining yttrium oxide and calcium hydroxide together with spherical nickel hydroxide coated with Co3+. This composite approach creates a synergistic effect where the combination of materials provides both the desired conductivity improvement and enhanced safety, avoiding the harmful effects of using Co2+ ions alone.
3Productivity
If Cd is added to improve electrolytic charging overpotential, then charging performance is enhanced, but environmental pollution occurs
Solution Approach 1:
The patent replaces environmentally harmful cadmium (Cd) with non-toxic alternative materials (yttrium oxide and calcium hydroxide). These replacement materials provide the same function of improving charging performance and electrolytic charging overpotential without causing environmental pollution, making the battery more environmentally friendly.
Solution Approach 2:
The patent changes the chemical composition by substituting cadmium with alternative compounds in specific weight ratios. This parameter change maintains the charging performance enhancement function while eliminating the environmental pollution associated with cadmium, resulting in a greener battery system.
4Quantity of substance
If flexible foil electrode with Ni(OH)2 coating is used, then energy storage capacity is sufficient, but conductivity is poor and oxygen evolution occurs early
Solution Approach 1:
The patent changes the chemical composition parameters by adding yttrium oxide (0.6-1.0%) and calcium hydroxide (0.2-0.6%) to the Ni(OH)2 coating. These compositional changes improve the electrical conductivity of the electrode while maintaining sufficient energy storage capacity and delaying oxygen evolution to higher voltages.
Solution Approach 2:
The patent creates a composite electrode material system combining spherical nickel hydroxide coated with Co3+ and the positive electrode additives (yttrium oxide and calcium hydroxide). This composite structure provides both the necessary energy storage capacity of Ni(OH)2 and the improved conductivity and oxygen evolution characteristics provided by the additive combination.
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 solution effectively reduces hydrogen evolution, improves charging/discharging efficiency, and extends the battery's life and safety while maintaining high capacity, addressing the environmental concerns associated with Cd pollution.
Implementation Method 1
the conductivity of this semiconductor not only depends on the motility of the electron defects and the concentration of the electron defects in the lattice, but also on the above defects existed in the lattice
Implementation Method 2
During the preparing and charging/discharging process of Ni(OH)2, there are always some unreduced Ni (III) ions
Implementation Method 3
nickel powder, and the functions of the nickel powder are to improve the discharging depth of the nickel electrode, catalyze the compounding of hydrogen and oxygen, and decrease the amount of hydrogen evolved
Implementation Method 4
so that the reaction product Co3+ can form an excellent conductive net between the particles of nickel hydroxide with the proceeding of charge, so as to improve the 'overpotential for oxygen evolution' of the nickel electrode
Implementation Method 5
A nickel-zinc battery includes a battery case, an electrode assembly, and electrolyte
Implementation Method 6
it is often necessary to add Cd2+ to Ni(OH)2, so as to improve the electrolytically charging overpotential of the battery
Data Source
AI summary
The present invention provides a nickel-zinc secondary battery, including: a battery case; an electrode assembly, disposed in the battery case; and an electrolyte solution, positioned in the battery case, and filled around the electrode assembly, wherein the electrode assembly includes a nickel positive electrode, a zinc negative electrode, and a membrane separator disposed between the nickel positive electrode and the zinc negative electrode; the nickel positive electrode includes: a substrate and positive electrode material coated on the surface of the substrate; the positive electrode material includes: 68 wt %˜69 wt % positive electrode active material, 0.6 wt %˜1 wt % yttrium oxide, 0.2 wt %˜0.6 wt % calcium hydroxide, 3.5 wt %˜4 wt % nickel powder, and a binder in balance; and the positive electrode active material is a spherical nickel hydroxide coated with Co3+. The nickel-zinc secondary battery provided by the present invention can reduce the amount of hydrogen evolved and have good cycling performance while maintaining the battery capacity. The present invention further provides a method for preparing a nickel-zinc secondary battery.