Zirconium-Graded Cathode Material for High-Voltage Cycle Life
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Solution Overview
Problem
The challenge in the battery industry is to enhance the energy density of ternary materials while maintaining their cycle life, especially under high voltage and temperature conditions.
Innovation Solution
A positive active material comprising a combination of first and second lithium-nickel transition metal oxides, both containing zirconium, where the first oxide is monocrystalline or quasi-monocrystalline and the second oxide is a secondary particle formed by aggregation of primary particles, optimizing their zirconium content ratio and particle structure to improve strength and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the working voltage of ternary materials is increased to obtain higher capacity, then the energy density is improved, but the lifespan decreases significantly, especially under high temperature conditions
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region has different zirconium content (0.01-0.05 mol) compared to the outer shell region (0.05-0.1 mol). This gradient distribution allows the inner core to maintain structural stability at high voltage while the outer shell provides enhanced protection and crack resistance, thereby improving lifespan without sacrificing the high capacity achieved through increased working voltage
Solution Approach 2:
The patent uses composite materials by combining lithium-nickel transition metal oxide with zirconium doping to create a composite structure. The zirconium-containing phases form a composite with the ternary material, where the zirconium-rich outer shell creates a protective composite layer that enhances mechanical strength and crack resistance, allowing the material to maintain both high capacity and extended lifespan under high voltage conditions
2Reliability
If the zirconium content is increased to improve particle strength and cracking resistance, then the cycle life is improved, but the discharge specific capacity may be reduced
Solution Approach 1:
The patent applies local quality by implementing a gradient zirconium distribution where the inner core has lower zirconium content (0.01-0.05 mol) to preserve capacity, while the outer shell has higher zirconium content (0.05-0.1 mol) to provide strength and crack resistance. This localized differentiation allows the material to achieve both high cycle life and high discharge specific capacity by optimizing zirconium content in different regions according to their functional requirements
3Reliability
If the particle strength is increased to reduce cracking in the cycle process, then the cycle performance is improved, but the lithium ion diffusion may be hindered
Solution Approach 1:
The patent applies local quality by creating a zirconium concentration gradient where the inner core has lower zirconium content to maintain open crystal structure and fast lithium ion diffusion pathways, while the outer shell has higher zirconium content to provide mechanical strength and crack resistance. This spatial differentiation of zirconium content allows the material to simultaneously achieve high cycle performance and rapid lithium ion diffusion by optimizing each region's properties for its specific function
Data Source
AI summary
A positive active material includes a first lithium-nickel transition metal oxide and a second lithium-nickel transition metal oxide. Both the first lithium-nickel transition metal oxide and the second lithium-nickel transition metal oxide contain zirconium, and a molar content of zirconium element in the first lithium-nickel transition metal oxide is less than a molar content of zirconium element in the second lithium-nickel transition metal oxide, the first lithium-nickel transition metal oxide is of one or more structures of a monocrystalline particle or a quasi-monocrystalline particle, and the second lithium-nickel transition metal oxide is a secondary particle formed by aggregation of a plurality of primary particles.