Li-Ni Composite Oxide Cathode Particles for Battery
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Solution Overview
Problem
Current Li-Ni composite oxide materials for non-aqueous electrolyte secondary cells face challenges in achieving high packing density, stable crystal structure, and excellent storage performance due to particle breakage during electrode production and high temperature storage, which leads to increased electric resistance and poor cycle characteristics.
Innovation Solution
The development of Li-Ni composite oxide particles with a specific composition (Li x Ni 1-y-z Co y Al z 2) and production process involving Ni-Co hydroxide particles coated with aluminum hydroxide, ensuring low sulfate ion content and controlled particle size, which results in stable particles with minimal surface area change under pressure, enhancing packing density and storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiNiO2 is used as cathode material to achieve large charge/discharge capacity, then the charge/discharge capacity is improved, but thermal stability and charge/discharge cycle durability deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region contains LiNiO2 particles with high charge/discharge capacity, while the outer shell region contains Li-Mn-Ni composite oxide particles with improved thermal stability. This spatial differentiation allows each region to perform its specialized function, resolving the contradiction between capacity and stability.
Solution Approach 2:
The patent uses composite materials by combining LiNiO2 particles with Li-Mn-Ni composite oxide particles to form a secondary particle structure. The composite structure integrates the high capacity advantage of LiNiO2 with the thermal stability advantage of Li-Mn-Ni composite oxide, thereby resolving the contradiction between capacity and reliability.
2Volume of stationary object
If Li-Ni composite oxide particles with small primary particle diameter are used to achieve high packing density, then packing density is improved, but particle breakage during electrode production increases
Solution Approach 1:
The patent merges multiple small primary particles into larger secondary particles through aggregation. The secondary particles have a diameter of 3-20 μm and contain multiple primary particles with diameter of 0.5-2 μm. This hierarchical structure maintains high packing density while the larger secondary particle size reduces breakage during electrode production compared to using only small primary particles.
3Volume of stationary object
If Li-Ni composite oxide particles are compressed to achieve high electrode density, then electrode density is improved, but particle breakage increases leading to increased surface area
Solution Approach 1:
The patent performs preliminary action by pre-forming secondary particles with controlled size distribution (3-20 μm) before electrode compression. This preliminary structuring allows the particles to better withstand subsequent compression forces, reducing breakage and surface area increase during electrode production while still achieving high electrode density.
4Shape
If impurities such as lithium sulfate are present in Li-Ni composite oxide to achieve complete crystal growth, then crystal growth is improved, but decomposition reactions during charge/discharge cycle increase leading to non-conductive film formation
Solution Approach 1:
The patent extracts harmful impurities such as lithium sulfate from the Li-Ni composite oxide system. By removing these impurities, the patent prevents decomposition reactions during charge/discharge cycles that would otherwise form non-conductive films on particle surfaces, thereby maintaining electrical conductivity while still achieving complete crystal growth of the desired phases.
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 effectively reduces particle breakage and reactivity with electrolytes, maintaining high packing density and storage performance under high temperature conditions, thereby improving the safety and efficiency of non-aqueous electrolyte secondary cells.
Implementation Method 1
Ni-Co hydroxide particles coated with aluminum hydroxide
Implementation Method 2
stable particles with minimal surface area change under pressure
Data Source
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AI summary
The present invention relates to Li-Ni composite oxide particles for a non-aqueous electrolyte secondary cell which have a large charge/discharge capacity, an excellent packing density and excellent storage performance. The Li-Ni composite oxide particles for a non-aqueous electrolyte secondary cell which have a composition represented by the formula: LixNi1-y-zCoyAlzO2 in which 0.9 < x < 1.3; 0.1 < y < 0.3; and 0 < z < 0.3, wherein the composite oxide particles have a rate of change in specific surface area of not more than 10% as measured between before and after applying a pressure of 1 t/cm2 thereto, and a sulfate ion content of not more than 1.0%, can be produced by mixing Ni-Co hydroxide particles having a sulfate ion content of not more than 1.0% whose surface is coated with an Al compound having a primary particle diameter of not more than 1 µm, with a lithium compound; and calcining the resulting mixture.