Calcium-Coated Cathode Particles to Suppress Oxygen Release
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with high cobalt content leading to high costs, oxygen release, and cation mixing issues, which affect their capacity and reliability.
Innovation Solution
A positive electrode active material structure is developed with a primary particle containing lithium, nickel, cobalt, and manganese, where calcium is added as a secondary particle coating to inhibit oxygen release and improve reliability, using a manufacturing method that includes heat treatment with calcium compounds to form a coating film on the surface of primary particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt content is increased to improve battery reliability and reduce deterioration, then battery reliability is improved, but manufacturing cost increases due to high cobalt prices
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central region contains high cobalt content (0.5-0.8 atomic ratio) for reliability, while the outer region contains low cobalt content (0.1-0.3 atomic ratio) to reduce cost. This spatial differentiation of composition allows simultaneous optimization of both reliability and manufacturing cost.
Solution Approach 2:
The patent uses composite materials by combining nickel-cobalt-manganese oxide with aluminum oxide coating. The composite structure integrates the high capacity of nickel-rich regions with the stability of manganese-rich regions and the protective properties of aluminum oxide, achieving both reliability and cost-effectiveness.
2Quantity of substance
If nickel content is increased to improve charge and discharge capacity, then battery capacity is improved, but oxygen release occurs leading to deterioration
Solution Approach 1:
The patent applies local quality by concentrating high nickel content (0.7-0.95 atomic ratio) in the central region to maximize capacity, while the outer region has reduced nickel content (0.05-0.5 atomic ratio) to minimize oxygen release. This spatial distribution allows the battery to achieve high capacity while maintaining stability.
Solution Approach 2:
The patent uses beforehand cushioning by applying an aluminum oxide coating layer (5-50 nm thickness) on the particle surface before battery operation. This coating acts as a protective barrier that prevents oxygen release from the nickel-rich core during charging and discharging, cushioning against deterioration before it occurs.
3Ease of manufacture
If cobalt content is reduced to lower manufacturing cost, then manufacturing cost is reduced, but battery reliability and resistance to deterioration decrease
Solution Approach 1:
The patent applies local quality by creating a gradient structure where the outer region has low cobalt content (0.1-0.3 atomic ratio) to reduce manufacturing cost, while the central region maintains high cobalt content (0.5-0.8 atomic ratio) to ensure reliability and resistance to deterioration. This allows cost reduction without sacrificing overall battery performance.
Solution Approach 2:
The patent uses beforehand cushioning by applying an aluminum oxide coating layer that prevents deterioration of the low-cobalt outer region. This coating protects the structure from degradation during cycling, maintaining reliability even with reduced cobalt content in the overall composition.
4Reliability
If aluminum oxide coating is applied to prevent oxygen release, then battery reliability is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the composition control and coating formation into a single heat treatment process. By controlling heating temperature (400-1000°C) and atmosphere, the aluminum oxide coating is formed in-situ during the sintering process, rather than requiring a separate coating step. This integration reduces manufacturing process complexity while achieving the desired protective coating.
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 enhances the charge and discharge capacity, maintains the layered structure of the primary particle, reduces deterioration, and achieves high initial discharge capacity, ensuring a long-life and safe secondary battery.
Implementation Method 1
heating a first mixture of the compound containing at least nickel, cobalt, and manganese, a lithium compound, and a calcium compound at a first heating temperature and crushing or grinding the first mixture; heating the first mixture at a second heating temperature
Implementation Method 2
calcium is contained between adjacent primary particles of the secondary particle... calcium inhibits oxygen release from the primary particle in charging and discharging
Data Source
AI summary
A secondary battery includes a positive electrode active material layer including a primary particle containing lithium, nickel, cobalt, and manganese and a secondary particle formed by aggregation of the primary particles, and calcium is contained between adjacent primary particles of the secondary particle. With such a structure, calcium inhibits oxygen release from the primary particle in charging and discharging, whereby the reliability of the secondary battery is improved.