High-Nickel Cathode Material With Boron for Heat-Stable Capacity
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Solution Overview
Problem
Current positive electrode active materials for non-aqueous electrolyte secondary batteries, such as lithium nickel composite oxide, face challenges in achieving high capacity and heat stability, with lithium cobalt composite oxide being expensive and lithium nickelate experiencing low heat stability and excessive heat generation.
Innovation Solution
A positive electrode active material with a layered rock salt structure composed of lithium metal composite oxide, containing 60-90 atomic percent nickel and 1.0-6.0 atomic percent boron, is developed, along with a production process involving a crystallization, drying, and calcining step to enhance both capacity and heat stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel composite oxide is used as positive electrode active material, then high capacity is achieved, but heat stability deteriorates and excessive heat generation occurs
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high-nickel content (60-90 atomic percent) for high capacity, while the outer shell region contains lower nickel content and higher additive element content for heat stability. This spatial differentiation of composition allows simultaneous optimization of capacity and thermal properties in different regions of the same particle.
Solution Approach 2:
The patent uses composite materials by combining multiple elements (nickel, cobalt, manganese, aluminum, boron) in a layered rock salt structure. The composite nature allows the high-nickel core to provide capacity while the multi-element shell provides structural stability and heat resistance, resolving the contradiction between capacity and thermal stability.
2Temperature
If lithium cobalt composite oxide is used as positive electrode active material, then heat stability is improved, but cost increases due to expensive cobalt content
Solution Approach 1:
The patent replaces expensive cobalt with cheaper nickel as the primary metal element, using nickel content of 60-90 atomic percent. Although pure high-nickel materials have poor heat stability, the patent compensates through the layered rock salt structure and additive elements, achieving acceptable thermal properties at lower cost.
Solution Approach 2:
The patent changes the compositional parameters by using additive elements (boron, aluminum, magnesium, calcium, strontium, barium) at controlled concentrations (0.1-10 atomic percent) to modify the properties of high-nickel material, improving heat stability without relying on expensive cobalt.
3Quantity of substance
If high nickel content is used in positive electrode active material, then capacity is improved, but crystal structure stability deteriorates
Solution Approach 1:
The patent segments the material into distinct compositional regions: a core region with high nickel content (60-90 atomic percent) for capacity, and a shell region with lower nickel and higher additive element content for stability. This segmentation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The patent performs preliminary stabilization by incorporating additive elements and forming the layered rock salt structure before the material is subjected to high-nickel composition challenges. The pre-formed stable structure prevents crystal degradation that would otherwise occur with high nickel content.
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 material achieves high capacity and heat stability, with initial discharge capacity exceeding 195 mAh/g and improved safety due to reduced heat generation, making it suitable for high-energy density batteries.
Implementation Method 1
lithium metal composite oxide... comprising lithium, a metal element, and an additive element... initial discharge capacity exceeding 195 mAh/g
Implementation Method 2
a production process involving a crystallization, drying, and calcining step
Implementation Method 3
a production process involving a crystallization, drying, and calcining step
Data Source
AI summary
A positive electrode active material containing a lithium metal composite oxide composed of secondary particles formed by aggregated primary particles, comprising lithium, at least one metal element and at least one additive element, the lithium metal composite oxide having a crystal structure of layered rock salt structure and the metal element including nickel in a content of 60 to 90 atomic percent and the additive element including boron in content of more than 1.0 atomic percent and 6.0 atomic percent or less, the nickel content and the boron content each with respect to the sum of the metal element and the additive element, the porosity of the secondary particles being 8% or more and 20% or less; a non-aqueous electrolyte secondary battery containing the positive electrode active material; and a process for producing the positive electrode active material.