Lithium Manganate Cathode Cladding for Manganese Dissolution Control
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Solution Overview
Problem
Current lithium-ion batteries with lithium manganate positive electrode active materials face challenges in maintaining cycling performance and rate performance due to lattice distortion and corrosion by hydrofluoric acid in the electrolyte solution, leading to poor capacity retention and impedance issues.
Innovation Solution
A lithium manganate positive electrode active material with a cladding structure comprising an inner layer of oxyacid salts or fluorides, an interlayer of organic bonding materials, and an outer layer of oxalates and silicates, which acts as a barrier to prevent manganese ion migration and electrolyte corrosion, enhancing cycling capacity retention and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium manganate is used as positive electrode active material, then cost is reduced and safety is improved, but cycling performance deteriorates due to lattice distortion and transition metal dissolution
Solution Approach 1:
A cladding layer comprising calcium aluminate, magnesium aluminate, aluminum fluoride, calcium fluoride, or magnesium fluoride is formed on the surface of the lithium manganate particles. This intermediary layer prevents direct contact between the lithium manganate and the electrolyte solution, thereby preventing transition metal dissolution and lattice distortion while maintaining the cost advantage of lithium manganate.
Solution Approach 2:
A thin film cladding layer is formed on the surface of lithium manganate particles to protect the underlying material from degradation. The cladding layer acts as a protective shell that prevents electrolyte penetration and maintains structural integrity during cycling.
2Quantity of substance
If lithium manganate undergoes deep charging and discharging, then battery capacity is increased, but lattice distortion occurs and transition metal dissolution increases, worsening cycling performance
Solution Approach 1:
The cladding layer serves as a protective barrier that allows deep charging and discharging to proceed while preventing lattice distortion and transition metal dissolution. The intermediary layer withstands the mechanical and chemical stresses of deep cycling without compromising the underlying lithium manganate structure.
3Reliability
If lithium manganate is used, then safety is improved and raw materials are abundant, but hydrofluoric acid corrosion occurs, worsening rate performance
Solution Approach 1:
The cladding layer comprising calcium aluminate, magnesium aluminate, aluminum fluoride, calcium fluoride, or magnesium fluoride acts as a protective barrier that prevents hydrofluoric acid from the electrolyte from corroding the lithium manganate. This intermediary layer maintains safety while enabling faster charging and discharging rates by preventing performance-degrading corrosion.
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 cladding structure significantly improves battery capacity retention and rate performance by reducing manganese ion migration and electrolyte consumption, thereby extending battery life and enhancing energy storage efficiency.
Implementation Method 1
the cladding layer clads the lithium manganate matrix... during charging and discharging, the cladding layer can not only 'prevent' the transition metal manganese ions which have been produced by the lithium manganate matrix from directly 'running' into the electrolyte solution
Implementation Method 2
the cladding layer... 'prevent' the hydrofluoric acid in the electrolyte solution from directly contacting with the lithium manganate substrate, and then prevent the lithium manganate matrix from dissolving out more transition metal manganese ions due to corrosion by the hydrofluoric acid
Data Source
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AI summary
The present application provides a lithium manganate positive electrode active material, comprising a lithium manganate matrix and a cladding layer as a "barrier layer" and a "functional layer". The cladding layer can not only "prevent" the transition metal ions which have been produced by the lithium manganate matrix from directly "running" into the electrolyte solution, but also "prevent" the hydrofluoric acid in the electrolyte solution from directly contacting with the lithium manganate substrate, and then prevent the lithium manganate matrix from dissolving out more transition metal manganese ions; as a "functional layer", the cladding layer contains various effective ingredients (oxyacid salts of aluminum, calcium and/or magnesium; organic bonding materials; oxalates and/or silicates) inside, which can reduce the transition metal manganese ions already present inside the battery through chemical reactions or adsorption effects, thus slowing down the generation of transition metal manganese and the decomposition of the SEI film (solid electrolyte interphase film) catalyzed by the transition metal manganese, thereby improving the cycling capacity retention rate of the battery.