Lithium Manganate Cathode Coating for Manganese Dissolution Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries using lithium manganate as a positive electrode active material face challenges with cycling performance and rate performance due to lattice distortion and corrosion by hydrofluoric acid in the electrolyte solution, leading to poor retention of battery capacity and increased impedance.
Innovation Solution
A lithium manganate positive electrode active material is developed with a cladding layer comprising an inner layer of oxyacid salts or fluorides of aluminum, calcium, and magnesium, an organic bonding material interlayer, and an outer oxalate or silicate layer, which acts as a barrier to prevent manganese ion dissolution and enhance chemical reactions to reduce manganese precipitation.
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 and rate performance worsens due to lattice distortion and manganese dissolution
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where lithium manganate particles are coated with a protective layer containing aluminum oxide, aluminum hydroxide, and calcium aluminate. This composite structure combines the cost and safety advantages of lithium manganate with the stability benefits of the protective coating, resolving the contradiction between low cost and good cycling performance
Solution Approach 2:
The patent uses a thin film protective coating composed of aluminum oxide, aluminum hydroxide, and calcium aluminate that forms a flexible barrier around the lithium manganate particles. This thin film prevents manganese dissolution and lattice distortion while maintaining the electrochemical activity of the core material, thus improving cycling performance without significantly increasing cost
2Quantity of substance
If lithium manganate undergoes deep charging and discharging, then battery capacity is increased, but lattice distortion increases and corrosion by hydrofluoric acid worsens, leading to poor capacity retention
Solution Approach 1:
The patent applies preliminary action by pre-forming a protective coating of aluminum oxide, aluminum hydroxide, and calcium aluminate on the lithium manganate particles before electrochemical cycling. This pre-established protective layer prevents corrosion by hydrofluoric acid and suppresses lattice distortion during deep charging and discharging, enabling high capacity retention rates even when operating at high capacity
3Ease of manufacture
If conventional single-layer coating is applied, then manufacturing process is simple, but effectiveness in preventing manganese dissolution is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the protective coating into multiple functional layers with different compositions and roles. The coating includes aluminum oxide for structural stability, aluminum hydroxide for acid neutralization, and calcium aluminate for enhanced protection. This segmented approach improves protection effectiveness while maintaining manufacturing simplicity through a systematic multi-component coating process
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 layer significantly improves battery capacity retention and rate performance by preventing manganese ion migration and corrosion, while maintaining a low cost for large-scale industrialization.
Implementation Method 1
the cladding layer comprises an inner layer provided on the surface of the lithium manganate matrix... which acts as a barrier to prevent manganese ion dissolution
Implementation Method 2
the interlayer is an organic bonding material layer
Implementation Method 3
the outer layer is an oxalate and/or silicate layer... chemical reactions to reduce manganese precipitation
Data Source
AI summary
A lithium manganate positive electrode active material, comprising a lithium manganate matrix and a cladding layer as a “barrier layer” and a “functional layer” are described. 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 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.