Ionic Liquid Electrolytes for Corrosion-Resistant Metal Hydride Batteries
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Solution Overview
Problem
Existing metal hydride batteries face issues with corrosive aqueous KOH electrolytes and limitations due to hydrogen and oxygen evolution potential, which affect electrochemical performance and cycle life.
Innovation Solution
The use of an electrolyte composition comprising an ionic liquid and a protic acid and/or organic solvent, along with a negative electrode active material that is an ABx type alloy capable of reversibly adsorbing and desorbing hydrogen, improves the performance of metal hydride batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If aqueous KOH electrolyte is used, then the battery can operate with simple composition, but the electrolyte becomes corrosive to electrode materials and limited by hydrogen and oxygen evolution potential
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing aqueous KOH with ionic liquids having different chemical properties. This substitution eliminates water-related corrosion and hydrogen/oxygen evolution limitations while maintaining ionic conductivity necessary for battery operation.
Solution Approach 2:
The patent employs composite electrolyte systems combining ionic liquids with other compatible substances to create an electrolyte that simultaneously provides corrosion resistance, appropriate viscosity, and ionic conductivity. This composite approach allows optimization of multiple properties that cannot be achieved with a single component.
2Productivity
If ABx type alloy is used for negative electrode, then hydrogen adsorption and desorption capability is improved, but the electrode material becomes more sensitive to electrolyte corrosion
Solution Approach 1:
The patent converts the potential harm of using reactive ABx alloys by pairing them with ionic liquid electrolytes that provide protective characteristics. The ionic liquid environment reduces corrosive attacks on the alloy surface while maintaining the alloy's hydrogen storage functionality, effectively turning a vulnerable combination into a stable system.
Solution Approach 2:
The ionic liquid electrolyte acts as an intermediary between the ABx alloy negative electrode and the rest of the battery system. It provides a chemically stable interface that enables hydrogen adsorption/desorption reactions while protecting the alloy from direct exposure to corrosive environments.
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 new electrolyte composition enhances the electrochemical performance and cycle life of metal hydride batteries by mitigating corrosion and overcoming hydrogen and oxygen evolution limitations, achieving a nominal open-circuit voltage of >1.2 V and up to 6 V.
Implementation Method 1
The electrolyte composition comprises an ionic liquid and a protic acid and/or an organic solvent... the active material of the negative electrode comprises an ABx type alloy capable of reversibly adsorbing and desorbing hydrogen
Implementation Method 2
the active material of the negative electrode comprises an ABx type alloy capable of reversibly adsorbing and desorbing hydrogen
Data Source
AI summary
Electrolyte compositions comprising a) an ionic liquid and b) a protic acid and/or an organic solvent are suitable for use in electrochemical cells, e.g. metal hydride batteries. The electrolyte compositions may replace the currently employed 30% by weight aqueous KOH. Suitable protic acids include carboxylic acids, mineral acids, sulfonic acids and the like. Suitable organic solvents include organic carbonates, ethers, glymes, ortho esters, polyalkylene glycols, esters, lactones, glycols, formates, sulfones, sulfoxides, amides, alcohols, ketones, nitro solvents, nitrile solvents and combinations thereof. Present batteries may achieve a nominal open-circuit voltage of > 1.2 V (volts) and up to about 6 V. The electrolyte compositions allow enlargement of the electrochemical window, thus allowing the use of further cathode active materials. Further cathode active materials include transition metals and their oxides, hydroxides and fluorides; for example, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, Ta, W, Re, Os, Ir, Pt and Au and their oxides, hydroxides, oxide/hydroxides and fluorides.