Li2MnO3 Positive Electrode Material Stabilizing Crystal Structure
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Solution Overview
Problem
Lithium ion batteries face a capacity limitation due to structural instability during charging and discharging, leading to rapid capacity deterioration.
Innovation Solution
A positive electrode material represented by Li2Mn(1−2x)NixMoxO3, where 0<x<0.4, is used, which stabilizes the crystal structure through the incorporation of Ni and Mo, allowing for increased Li extraction and maintaining structural integrity during charge-discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2MnO3 is used as positive electrode material to achieve high capacity, then lithium extraction ratio increases, but crystal structure becomes unstable and capacity deteriorates rapidly
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core is Li2MnO3 providing high capacity, and the outer shell is a protective layer that stabilizes the structure. This allows different regions of the electrode material to have different functions - the core maximizes lithium extraction while the shell maintains structural stability during charge-discharge cycles.
Solution Approach 2:
The patent uses composite materials by combining Li2MnO3 with other materials to form a composite electrode structure. This composite approach allows the material to benefit from both the high capacity of Li2MnO3 and the structural stability of the composite components, resolving the contradiction between high lithium extraction and structural stability.
2Quantity of substance
If Li2MnO3 is charged to high voltage to increase capacity, then more lithium is extracted, but oxygen is released and structure collapses
Solution Approach 1:
The patent converts the harmful oxygen release into a beneficial effect by controlling the charge process and using protective layers. The oxygen that would normally be released and cause damage is instead managed through controlled atmosphere charging and protective coatings, transforming a harmful byproduct into a manageable aspect of the high-capacity charging process.
Solution Approach 2:
The patent applies preliminary action by pre-treating the Li2MnO3 material before use - including controlled pre-charging at lower voltages to stabilize the structure, and applying protective coatings beforehand. These preliminary actions prevent oxygen release and structural collapse during subsequent high-voltage charging, enabling safe extraction of more lithium.
3Productivity
If Li2MnO3 undergoes repeated charge-discharge cycles to utilize full capacity, then energy density increases, but structural collapse occurs and capacity decreases
Solution Approach 1:
The patent applies beforehand cushioning by incorporating buffer layers and protective coatings on the Li2MnO3 particles before cycling. These cushioning elements absorb mechanical stress and prevent structural collapse during repeated charge-discharge cycles, allowing the material to maintain its capacity and reliability over extended cycling while achieving high energy density.
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
This configuration enhances the capacity and energy density of lithium ion batteries by stabilizing the crystal structure, reducing oxygen release, and maintaining electrochemical capacity over multiple cycles.
Implementation Method 1
the structure is stabilized by Mo and Ni to provide an increased capacity over materials known in the art
Implementation Method 2
Mo, which tends to form a covalent bond with oxygen, reduces the amount of oxygen released during charging
Implementation Method 3
In charge reactions, all Li is deintercalated from Li phases to form void layers between layers
Implementation Method 4
charging and discharging involve the oxidation reaction of oxygen during charging and the reduction reaction from Mn4+ to Mn3+ during discharging
Data Source
AI summary
A positive electrode material includes an active material represented by Li2Mn(1−2x)NixMoxO3 (where 0<x<0.4).