Lithium-Ion Cathode Composition With Controlled Magnesium Inclusion
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Solution Overview
Problem
The production of positive electrode active materials for lithium ion batteries is hindered by the high cost and instability of nickel and cobalt supplies, and the difficulty in purifying magnesium, leading to variations in cycle performance and storage stability.
Innovation Solution
A positive electrode active material represented by the formula LiaNi(1-b-c-d)Co b Mn c Mg d O 2 with controlled lithium, nickel, cobalt, manganese, and magnesium compositions, along with specific particle size, density, and lattice constant, is produced through a method involving a crystallization reaction and subsequent baking, allowing for the inclusion of magnesium while maintaining good battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnesium is completely removed to improve purity, then battery characteristics are improved, but production cost increases significantly
Solution Approach 1:
The invention changes the approach from complete removal to controlled inclusion of magnesium, specifying a precise concentration range (0.00005≤d≤0.003) to achieve both good battery characteristics and cost-effective production
Solution Approach 2:
The invention accepts a small amount of magnesium impurity rather than investing in expensive purification processes, treating the magnesium as an acceptable minor component that does not significantly harm performance
2Reliability
If nickel and cobalt are used in high amounts, then battery performance is improved, but supply stability and cost are worsened
Solution Approach 1:
The invention optimizes the composition parameters by limiting nickel to 0.47≤x<0.92 and cobalt to 0.06≤y≤0.21, replacing a significant portion with manganese to reduce dependence on scarce metals while maintaining performance
Solution Approach 2:
The invention creates a composite cathode material (Li1-a-b-c-dNixCoyMn1-x-y-dO2) that combines multiple metal oxides, leveraging the advantages of each component to achieve both performance and supply stability
3Manufacturing precision
If magnesium is completely removed, then purity is improved, but manufacturing complexity increases
Solution Approach 1:
The invention extracts the requirement for complete magnesium removal and replaces it with a simpler controlled inclusion approach, specifying only that 0.00005≤d≤0.003, which is easier to achieve in manufacturing
Solution Approach 2:
Instead of trying to remove magnesium completely (traditional approach), the invention inverts the strategy by intentionally allowing and controlling a small amount of magnesium presence, which simplifies the manufacturing 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 solution results in a positive electrode active material with improved cycle characteristics and reduced production costs by incorporating magnesium, enhancing the battery's performance and stability.
Implementation Method 1
a crystallization reaction is carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound
Implementation Method 2
the precipitate obtained was then filtered by suction, washed with water, and dried at 120° C. for 12 hours using a box dryer
Data Source
AI summary
A positive electrode active material for a lithium ion battery, represented by the formula: LiaNi(1-b-c-d)CobMncMgdO2 (wherein, in the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.00005≤d≤0.003), having a 50% cumulative volumetric particle size D50 of 3.0 to 11.0 µm, a tap density of 2.0 to 2.6 g/cc, and a c-axis lattice constant of 14.184 to 14.240 Å.