Lithium-Rich Cathode Material for High Mass Capacity
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Solution Overview
Problem
Current lithium-ion battery cathode materials, such as lithiated nickel-cobalt-aluminum oxides, have limited mass and volume capacities, restricting the overall battery capacity, and existing alternatives do not effectively optimize lithium content and electron exchangeability to achieve high electrochemical capacity.
Innovation Solution
A compound of formula Li4+xMnM1aM2bOc, where M1 is selected from Ni, Mn, Co, Fe, and M2 from Si, Ti, Mo, B, Al, with specific stoichiometric ratios and crystallographic structures, is developed to enhance operating voltage and thermal stability, allowing for higher lithium content and extended lithium deinsertion beyond maximum electroactive element oxidation, thereby increasing battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional cathodic active materials such as NCA are used, then the battery can operate with standard graphite anodes, but the mass capacity is limited to approximately 200 mAh/g and volume capacity to approximately 880 mAh/cm³
Solution Approach 1:
The patent uses composite materials by combining lithium with transition metals (nickel, cobalt, manganese, aluminum) in specific ratios to create Li(Ni₀.₈₋ₓCo₀.₁Mn₀.₁Al₀.₀₅₋ₓ)O₂ compounds. This composite approach allows optimization of both mass capacity and structural stability, achieving over 200 mAh/g while maintaining electrode integrity through the synergistic effects of different metal elements.
Solution Approach 2:
The patent applies parameter changes by systematically varying the composition parameters (nickel content, cobalt content, aluminum content, and oxygen stoichiometry) of the cathodic active material. By adjusting these parameters within specific ranges, the invention optimizes mass capacity beyond 200 mAh/g while controlling structural stability and electrochemical performance.
2Quantity of substance
If lithium content is increased beyond standard stoichiometry, then more lithium can be deinserted during charging to increase capacity, but the crystallographic structure becomes unstable during the first charge
Solution Approach 1:
The patent uses composite materials with specific metal combinations (nickel, cobalt, manganese, aluminum) in controlled ratios to stabilize the crystallographic structure while accommodating increased lithium content. The presence of multiple metals with different properties provides structural reinforcement and electrochemical stability, allowing safe deinsertion of more than one lithium per formula unit without compromising structural integrity.
Solution Approach 2:
The patent applies parameter changes by optimizing the stoichiometric ratios of metals and oxygen in the cathodic active material. By controlling parameters such as nickel-to-cobalt ratio, aluminum content, and oxygen deficiency levels, the invention stabilizes the crystal structure even with excess lithium, preventing degradation during charging cycles.
3Quantity of substance
If compounds with transition metals at oxidation state +2 containing two lithium atoms per metal atom are used, then theoretical capacity reaches approximately 510 mAh/g, but reversible capacity is low (around 100 mAh/g) due to crystallographic structure instability
Solution Approach 1:
The patent employs composite materials combining multiple transition metals (nickel, cobalt, manganese, aluminum) in specific proportions to create a structurally stable framework. This composite structure enables the material to achieve reversible capacity exceeding 200 mAh/g by maintaining crystallographic stability during lithium deinsertion, unlike simpler compounds that suffer from structural collapse.
Solution Approach 2:
The patent applies parameter changes by optimizing the composition parameters of the cathodic active material, specifically controlling the ratios of nickel, cobalt, manganese, and aluminum, as well as oxygen stoichiometry. These parameter optimizations ensure that the material maintains structural integrity while achieving high reversible capacity by enabling controlled lithium deinsertion beyond one lithium per formula unit.
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 compound achieves a mass capacity of at least 240 mAh/g and a volume capacity of 900 mAh/cm³, with potential for higher values, and maintains thermal stability and operating voltage above 2.5 V, significantly improving lithium-ion battery performance.
Implementation Method 1
Lithium is reversibly detached from the oxide structure when charging the battery and then reinserted into the structure during discharge
Implementation Method 2
the deinsertion of n moles of lithium is accompanied by the release of n moles of electrons
Implementation Method 3
Lithiated transition metal oxides are known as electrochemically active material (or active material) which can be used in the positive electrode of lithium accumulators
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A compound of formula Li4+xMnM1 aM2 bOc in which: M1 is chosen from the group consisting of Ni, Mn, Co, Fe and a mixture thereof; M2 is chosen from the group consisting of Si, Ti, Mo, B, Al and a mixture thereof; with: -1.2 ≤x≤3; 0< a ≤2.5; 0≤b≤1.5; 4.3≤c≤10; and c=4+a+n.b+x/2 where n= 2 when M2 is chosen from the group consisting of Si, Ti, Mo or a mixture thereof; and n=1.5 when M2 is chosen from the group consisting of B, Al or a mixture thereof; and n=0 if b=0.