Core-Shell Nickel Composite for Battery Stability
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Solution Overview
Problem
Current nickel-based composite oxides used in lithium secondary batteries lack satisfactory capacity and stability, and there is a need for a material that is thermally stable and has high packing density, as well as a method to prepare such a material that minimizes damage during the manufacturing process.
Innovation Solution
A positive active material comprising a core and shell part with a nickel-based composite oxide structure, where the core has a higher nickel content than the shell, and the core part is characterized by needle-like particles and open pores, prepared through a method involving coprecipitation and heat treatment to enhance adhesion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based composite oxide is used as positive active material, then capacity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core region has high nickel content (0.6≤x1<0.8) for high capacity, while the shell region has lower nickel content (0.3≤x2<0.6) for thermal stability. This spatial differentiation of composition allows each region to perform its specific function optimally, resolving the contradiction between capacity and thermal stability.
Solution Approach 2:
The patent uses composite materials by combining nickel-based composite oxide with a coating layer comprising at least one of metal oxide, metal hydroxide, or metal oxyhydroxide. This composite structure integrates the high capacity characteristics of nickel-based materials with the protective properties of the coating layer, achieving both high capacity and improved thermal stability.
2Productivity
If battery is pressed during manufacturing, then productivity is improved, but positive active material is damaged
Solution Approach 1:
The patent applies beforehand cushioning by forming a protective coating layer on the surface of the positive active material particles before assembly. This coating layer acts as a cushion that absorbs mechanical stress during battery pressing, preventing particle breakage while allowing the battery to be assembled with high productivity.
Solution Approach 2:
The patent uses flexible shells and thin films by applying a coating layer of metal oxide, metal hydroxide, or metal oxyhydroxide on the particle surface. This thin film layer provides mechanical protection and flexibility, allowing particles to withstand pressing forces without breaking, thus maintaining particle integrity during high-speed manufacturing.
3Stability of the object's composition
If cobalt material is used for positive active material, then stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by adjusting the nickel content parameter (x) to be in the range of 0.6≤x<0.8, which provides sufficient stability without requiring cobalt. This parameter optimization allows the use of abundant nickel resources while maintaining the structural stability needed for battery performance, thereby reducing manufacturing cost and improving supply stability.
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 proposed material achieves high capacity and stability for lithium secondary batteries, with improved thermal stability and reduced damage during manufacturing, leading to enhanced performance and durability.
Implementation Method 1
a first process for mixing a first precursor solution comprising a nickel salt, a cobalt salt, and a manganese salt, at a molar ratio of x:y:z satisfying 0.05≤x≤0.9, 0.1≤y≤0.8, 0.1≤z≤0.8, and a first base, to prepare a first mixture and inducing a reaction in the first mixture to obtain a precipitate
Implementation Method 2
mixing the composite metal hydroxide with a lithium salt and heat treating the mixed composite metal hydroxide to prepare the positive active material
Data Source
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AI summary
A positive active material for a lithium secondary battery (30), a method of preparing the same, and a lithium secondary battery (30) including the positive active material. The positive active material includes a core part and a shell part that include a nickel-based composite oxide. The content of nickel in the core part is larger than the content of nickel in the shell part.