Low-Cobalt NCM Cathode Material for Stable Cycle Life
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Solution Overview
Problem
The reduction of cobalt content in nickel-cobalt-manganese ternary positive electrode active materials for lithium-ion secondary batteries leads to deteriorated structural stability, electronic conductivity, and cycle performance, resulting in low energy density and cycle life.
Innovation Solution
A positive electrode active material with a chemical formula Li1+x(NiaCobMnc)1−dMdO2−yAy, where M is selected from Zr, Sr, B, Ti, Mg, Sn, and Al, and A from S, N, F, Cl, Br, and I, with specific element ratios and particle size distribution, enhancing structural stability and electronic conductivity while reducing cobalt usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt content is reduced in nickel-cobalt-manganese ternary material, then cost is reduced and resource scarcity is mitigated, but structural stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio parameters b/c and b×c/a2 in the chemical formula Li1+x(NiaCobMnc)1−dMdO2−yAy. By adjusting these ratio parameters within specific ranges while reducing cobalt content, the material maintains structural stability despite lower cobalt concentration. This resolves the contradiction by changing the compositional parameters to compensate for reduced cobalt.
Solution Approach 2:
The patent uses composite materials by combining nickel-cobalt-manganese ternary material with additional elements M and A to create a multi-element composite structure. This composite approach allows reduced cobalt content while maintaining structural stability through the synergistic effects of multiple elements working together in the layered structure.
2Quantity of substance
If cobalt content is reduced, then cost is reduced, but electronic conductivity deteriorates
Solution Approach 1:
The patent changes physical and chemical parameters by controlling the b/c ratio and b×c/a2 product within specific ranges. These parameter adjustments optimize the electronic structure and band gap of the material, maintaining electronic conductivity even with reduced cobalt content. The parameter optimization compensates for the loss of cobalt's conductive contribution.
Solution Approach 2:
The patent applies local quality by creating non-uniform element distribution and local structural variations within the material. The specific ratio constraints on b/c and b×c/a2 create localized regions with optimized electronic properties, ensuring adequate electronic conductivity throughout the material despite overall cobalt reduction.
3Quantity of substance
If cobalt content is reduced, then cost is reduced, but cycle performance deteriorates
Solution Approach 1:
The patent uses parameter changes by establishing specific ranges for b/c (0.12 to 0.9) and b×c/a2 (0.002 to 0.23). These parameter constraints ensure that the material maintains structural integrity and electrochemical stability over repeated charge-discharge cycles, compensating for reduced cobalt content and preserving cycle performance.
Solution Approach 2:
The patent employs composite materials by integrating multiple elements (Ni, Co, Mn, M, A) in a layered structure with controlled stoichiometry. This composite structure provides enhanced structural stability and electrochemical performance that maintains cycle life despite lower cobalt content, as the multiple elements work synergistically to prevent degradation.
4Quantity of substance
If cobalt content is reduced, then cost is reduced, but powder compaction density deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the b/c ratio and b×c/a2 product, which influence particle morphology and packing characteristics. By optimizing these compositional parameters, the material achieves improved powder flow and packing behavior, maintaining adequate compaction density even with reduced cobalt content.
Data Source
AI summary
The present application discloses a positive electrode active material, a positive electrode plate, a lithium-ion secondary battery, and an apparatus. The positive electrode active material satisfies a chemical formula Li1+x(NiaCobMnc)1−dMdO2−yAy, wherein M is one or more selected from Zr, Sr, B, Ti, Mg, Sn and Al, A is one or more selected from S, N, F, Cl, Br and I, −0.01≤x≤0.2, 0.12≤b/c≤0.9, 0.002≤b×c/a2≤0.23, a+b+c=1, 0≤d≤0.1, and 0≤y≤0.2; and an interval particle size distribution curve of the positive electrode active material has a full width at half maximum DFW of from 4 μm to 8 μm. The positive electrode active material provided in the present application has relatively low cobalt content and relatively high cycle life and capacity performance.