Al-Y-W Coated Nickel-Rich Cathode for High-Voltage Stability
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Solution Overview
Problem
The increasing demand for high-capacity and high-energy-density rechargeable lithium batteries is hindered by the scarcity and high cost of cobalt, and existing cobalt-free materials face challenges in maintaining structural stability, efficiency, and cycle-life characteristics under high-voltage and high-temperature conditions.
Innovation Solution
A positive electrode active material comprising lithium nickel-based composite oxide core particles coated with a layer containing aluminium, yttrium, and tungsten, which enhances structural stability and reduces gas generation under high-voltage and high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cobalt-free lithium nickel-based composite oxide is used as positive electrode active material, then production cost is reduced and supply security is improved, but structural stability and cycle-life characteristics deteriorate under high-voltage and high-temperature conditions
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where the core is made of lithium nickel-based composite oxide (cobalt-free) and the shell is a coating layer containing aluminium, yttrium, and tungsten. This composite structure allows the bulk material to be cost-effective cobalt-free composition while the coating layer provides the necessary structural stability and surface protection under high-voltage and high-temperature conditions, thus resolving the contradiction between production cost and structural stability.
Solution Approach 2:
The patent applies local quality by creating a coating layer with specific composition (aluminium, yttrium, and tungsten) only on the surface of the core particles. The coating layer thickness is controlled to be 5-50 nm, providing localized protection where it is most needed (at the particle surface exposed to electrolyte and high voltage) while maintaining the cost-effective cobalt-free bulk composition throughout the interior of the particles.
2Ease of manufacture
If cobalt content is reduced or eliminated, then production cost decreases and supply security improves, but capacity and efficiency characteristics worsen
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters of the lithium nickel-based composite oxide with specific ratios of nickel, manganese, and aluminium in the core, and controlling the thickness and composition of the coating layer. By adjusting these parameters, the material achieves high capacity (4.3V initial charge capacity of 220 mAh/g or more) while maintaining cobalt-free composition, thus resolving the contradiction between production cost and capacity.
3Productivity
If high-voltage operation is implemented to increase energy density, then battery capacity improves, but gas generation increases and cycle-life decreases
Solution Approach 1:
The patent applies the intermediary principle by introducing a coating layer containing aluminium, yttrium, and tungsten as a mediator between the lithium nickel-based composite oxide core and the electrolyte. This coating layer acts as a protective barrier that prevents direct harmful interactions at high voltage (4.3V), suppressing gas generation and improving cycle-life while allowing the high-voltage operation to proceed for increased energy density.
4Power
If high-temperature operation is implemented to increase power output, then battery performance improves, but structural stability deteriorates and gas generation increases
Solution Approach 1:
The patent applies beforehand cushioning by pre-applying a protective coating layer containing aluminium, yttrium, and tungsten on the surface of the core particles before battery operation. This coating layer provides advance protection against thermal degradation and structural collapse during high-temperature operation, cushioning the core material from harmful thermal effects and maintaining structural stability when high power output is required.
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 initial charge/discharge capacity, long cycle-life, and suppresses gas generation, while minimizing production costs and ensuring improved high-voltage and high-temperature characteristics.
Implementation Method 1
a coating layer provided on the surfaces of the core particles, with the coating layer including aluminium, yttrium, and tungsten
Data Source
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AI summary
Provided are a positive electrode active material, and a method of preparing the positive electrode active material, and a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode active material. The positive electrode active material comprises core particles including a lithium nickel-based composite oxide and a coating layer provided on the surfaces of the core particles, with the coating layer including aluminium, yttrium, and tungsten.