Aqueous Lithium Battery Cathode Oxide for Wider Stable Voltage Range
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Solution Overview
Problem
Secondary batteries using aqueous solutions face challenges in maintaining stability and preventing deterioration during charge and storage due to water electrolysis, which limits the potential range and durability of the battery.
Innovation Solution
A positive electrode active material with a complex oxide structure represented by LiaNixCoyMnzMbO2, where 0.9≤a<1.1, 0.4≤x<1.0, 0≤y<0.4, 0≤z<0.4, 0≤b<0.2, and 0.9<(x+y+z+b)<1.1, and M includes Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Ga, and In, is used, along with a specific aqueous electrolytic solution containing a lithium salt and additives to suppress water decomposition and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional positive electrode active material is used in an aqueous electrolytic solution, then the battery can operate, but water electrolysis occurs at potentials above 3.85 V (pH=7), limiting the potential range and causing battery deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by incorporating multiple transition metals (Ni, Co, Mn, Al) in specific ratios, and adjusting the oxygen content to create a complex oxide structure that remains stable at higher potentials in aqueous solutions, thereby expanding the usable potential range while preventing water electrolysis
Solution Approach 2:
The patent uses a composite positive electrode active material composed of multiple transition metals (Ni, Co, Mn, Al) in a complex oxide structure with formula Li1-aNixCoyMnzAlbO2, where each metal contributes different properties: Ni provides high capacity, Co provides stability, Mn provides structural integrity, and Al enhances chemical stability in aqueous environments, collectively preventing water electrolysis while expanding the potential range
2Quantity of substance
If the potential range is expanded to extract more Li, then the battery capacity increases, but water electrolysis occurs more readily, causing battery deterioration
Solution Approach 1:
The patent adjusts the chemical composition parameters of the positive electrode active material, specifically controlling the ratios of Ni, Co, Mn, and Al, and optimizing the oxygen content to create a material that can extract more lithium while maintaining stability at higher potentials, thereby increasing capacity without triggering water electrolysis
Solution Approach 2:
The patent converts the potential harm of water electrolysis into a benefit by designing a positive electrode active material with enhanced chemical stability that raises the potential threshold for water decomposition, allowing the battery to operate at higher potentials where more lithium can be extracted without causing water electrolysis, thus turning the limitation of aqueous solutions into an opportunity for higher capacity
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 suppresses battery deterioration during charge and storage by expanding the potential region where electrolysis does not occur, thereby improving the battery's stability and durability.
Implementation Method 1
an active material which is stable in an aqueous solution, and reversibly enables occluding and releasing a large amount of lithium in a potential range in which oxygen or hydrogen is not generated by water electrolysis
Implementation Method 2
the hydrogen generating potential is 2.62 V and the oxygen generating potential is 3.85 V for the water decomposition voltage
Data Source
AI summary
A positive electrode active material that is a composite oxide that is represented by the general formula LiaNixCoyMnzMbO2, wherein 0.9<a<1.1, 0.4≤x<1.0, 0≤y<0.4, 0≤z<0.4, 0≤b<0.2, 0.9<(x+y+z+b)<1.1, and the element M includes at least one element from the group that consists of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Ga, and In. The ratio (B/A) of BET specific surface area (A) before particle compression testing and BET specific surface area (B) after particle compression testing of the composite oxide particles is 1.0-3.0.