NCM Cathode Composition to Reduce Metal Dissolution and Microcracks
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Solution Overview
Problem
Existing lithium-ion batteries face issues with transition metal dissolution, interaction between the sliding crack fresh interface and electrolyte, which affect charging capacity, cycle life, and safety performance.
Innovation Solution
A lithium nickel cobalt manganese oxide positive active material is formulated with controlled molar contents of manganese, cobalt, and nickel, along with additional elements like Zr, Al, and others, to stabilize the crystal structure and reduce metal dissolution, enhancing charging capacity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive active material uses conventional composition ratios, then the charging capacity can be maintained, but transition metal dissolution occurs and cycle life deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar content ratios of Mn, Co, and Ni elements in the lithium nickel cobalt manganese oxide, where the Mn content is 20-40%, Co content is 10-30%, and Ni content is 30-60%. This specific parameter range optimizes the crystal structure stability and reduces transition metal dissolution, thereby improving cycle life while maintaining charging capacity.
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Mn, Co, Ni) in specific ratios within the lithium nickel cobalt manganese oxide structure. This composite approach leverages the complementary properties of each element: Mn provides structural stability, Co enhances electrochemical activity, and Ni increases capacity, while the composite structure reduces overall metal dissolution compared to single-element materials.
2Quantity of substance
If the positive active material has high nickel content for high capacity, then charging capacity improves, but structural stability decreases and metal dissolution increases
Solution Approach 1:
The patent applies parameter changes by controlling the Ni content within 30-60% rather than using high Ni content alone. This optimized parameter range, combined with specific Mn (20-40%) and Co (10-30%) content, maintains high charging capacity while the presence of Mn and Co stabilizes the crystal structure and reduces metal dissolution that would occur with higher Ni content.
Solution Approach 2:
The patent uses composite materials by creating a multi-element lithium nickel cobalt manganese oxide where Ni (30-60%) provides high capacity, while Mn (20-40%) and Co (10-30%) contribute to structural stability. This composite structure mitigates the structural degradation and metal dissolution issues that would arise from using high Ni content alone, achieving both high capacity and stability.
3Ease of manufacture
If the positive active material uses conventional element ratios, then manufacturing is simpler, but interaction between sliding crack fresh interface and electrolyte increases
Solution Approach 1:
The patent applies parameter changes by optimizing the molar content ratios of Mn (20-40%), Co (10-30%), and Ni (30-60%) to control crystal growth and reduce sliding crack formation during charging cycles. This specific parameter optimization reduces the creation of fresh interfaces that would otherwise interact harmful with the electrolyte, while maintaining manufacturability through conventional synthesis methods.
Data Source
AI summary
A positive active material and a lithium ion battery are provided. The positive active material includes a lithium nickel cobalt manganese oxide; in lithium nickel cobalt manganese oxide, based on the total molar content of the nickel element, the cobalt element and the manganese element being 100%, molar contents of manganese element being being denoted as m % and n % respectively, satisfying: 20<n+m<50, and 0.1<n/m<0.6; full width at half maximums of (003) peak and (104) peak of the positive active material being denoted as FWHW(003) and FWHW(104) respectively; FWHW(003) and FWHW(104) satisfying: 0.4≤FWHW(003)/FWHW(104)≤2.0. The present invention can inhibit the metal ion dissolution of the positive active material, and improve the charging capacity, cycle life and safety performance of the battery. The invention can reduce microcracks of positive electrode particles in the positive electrode plate processing process, while ensuring the battery has better charging capacity, cycle life and safety performance.