Doped NCM Single-Particle Cathode for Cycle-Life and Strength
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Solution Overview
Problem
High-capacity and high-energy-density secondary batteries face challenges due to the large specific surface area of positive electrode materials, leading to gas generation and cycle-life deterioration, as well as weak particle strength causing breakage during the rolling process, resulting in poor particle uniformity and reduced battery performance.
Innovation Solution
A positive electrode active material composed of metal oxide particles with nickel, cobalt, manganese, and doping elements like Zr and Al, featuring a surface film with an amorphous structure and a layered center structure, which enhances particle strength and uniformity, allowing for easier disintegration and improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the specific surface area of positive electrode material is increased to improve capacity, then energy density is improved, but gas generation increases and cycle-life deteriorates
Solution Approach 1:
The patent applies local quality by creating a bimodal particle size distribution where small particles (0.5-2 μm) provide high surface area for capacity while large particles (5-10 μm) provide structural stability. This spatial differentiation of particle sizes allows different regions of the electrode to serve different functions: small particles for high reactivity and energy density, large particles for maintaining structural integrity and reducing gas generation during cycling.
2Quantity of substance
If secondary particles are used to increase electrode density, then energy density is improved, but particle strength decreases causing breakage during rolling
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution parameters within specific ranges: small particles of 0.5-2 μm and large particles of 5-10 μm. This precise control of size parameters allows the electrode to achieve high density while maintaining adequate particle strength, as the larger particles provide structural framework that prevents breakage during rolling while the smaller particles fill interstices to maximize density.
3Strength
If primary particle size is increased to improve particle strength, then particle strength is improved, but particle uniformity deteriorates due to presence of fine and coarse particles
Solution Approach 1:
The patent applies segmentation by dividing the particle population into two distinct size segments: small particles (0.5-2 μm) and large particles (5-10 μm). This segmentation strategy resolves the contradiction by assigning different functional roles to each segment - small particles ensure uniform distribution and fill voids while large particles provide structural strength. The controlled segmentation avoids the formation of unwanted fine and coarse particles through precise process control.
Data Source
AI summary
The present exemplary embodiments relate to positive electrode active materials. The positive electrode active material according to an exemplary embodiment is a metal oxide particle including a center and a surface portion positioned on the surface of the center, where the metal oxide particle includes nickel, cobalt, manganese, and doping elements, and is composed of single particles, and the doping elements include two or more species selected from the group consisting of Zr, Al, B, P, La, Ta, Ti, W, Mo, Si, Ga, Zn, Nb, Ag, Sn, Bi, Au, Y, Ge, V, Cr, and Fe.