Lithium-Ion Cathode Particle Blend for High Density Without Fracture
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Solution Overview
Problem
Lithium-ion battery positive electrode plates face challenges in achieving high compacted density without excessive elongation, which can lead to brittle fracture during winding or hot pressing under high active material loads.
Innovation Solution
A lithium-ion battery positive electrode plate comprising a mixture of polycrystalline particles of different sizes, including a first positive electrode active material with a particle size of 11.0-20.0 μm, a second with 6.0-10.5 μm, and monocrystalline particles of 1.1-5.2 μm, in specific ratios, to achieve high compacted density at low elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the roller pressure is increased to increase the compacted density of the positive electrode plate, then the compacted density is improved, but the elongation of the electrode plate becomes excessive
Solution Approach 1:
The patent changes the particle size parameters of the positive electrode active material to resolve the contradiction between compacted density and elongation. By using particles with specific size ranges (11.0-20.0 μm for first material, 6.0-10.5 μm for second material, and 1.1-5.2 μm for third material) and controlling their size distribution span within 1.60-2.20, the patent achieves high compacted density without excessive elongation during rolling. This parameter optimization allows the electrode plate to maintain structural integrity while achieving the desired density.
2Volume of stationary object
If the compacted density is increased under high active material load, then the energy density is improved, but the electrode plate becomes prone to brittle fracture
Solution Approach 1:
The patent optimizes particle size parameters and size distribution to prevent brittle fracture while achieving high compacted density. By controlling the span of particle sizes (Dv90-Dv10)/Dv50 within 1.60-2.20 and using specific particle size ranges, the patent creates a more uniform stress distribution during rolling, reducing the likelihood of particle breakage and electrode plate fracture even under high active material load conditions.
Solution Approach 2:
The patent uses a composite mixture of three different positive electrode active materials with distinct particle size ranges. This composite approach allows the larger particles (11.0-20.0 μm) to provide structural framework while smaller particles (1.1-5.2 μm) fill interstitial spaces, creating a more robust composite structure that resists brittle fracture while achieving high compacted density under rolling pressure.
3Volume of stationary object
If the particle size of the positive electrode active material is reduced to increase compacted density, then the density is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent defines specific particle size ranges for three different active materials (11.0-20.0 μm, 6.0-10.5 μm, and 1.1-5.2 μm) and controls the overall span parameter (Dv90-Dv10)/Dv50 within 1.60-2.20. These clearly defined parameters provide straightforward manufacturing guidance, making it easier to control particle size distribution during production while achieving high compacted density, thereby reducing manufacturing complexity.
Data Source
AI summary
Provided are a lithium-ion battery positive electrode plate, comprising a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material mixture composed of the following materials: polycrystalline particles of a first positive electrode active material with a particle size of 11.0-20.0 μm; polycrystalline particles of a second positive electrode active material with a particle size of 6.0-10.5 μm; and monocrystalline particles of a third positive electrode active material with a particle size of 1.1-5.2 μm; wherein the number of the polycrystalline particles of the first positive electrode active material is a, the number of the polycrystalline particles of the second positive electrode active material is b, the number of the monocrystalline particles of the third positive electrode active material is c, and (a+b):c is in the range of 5.7:4.3 to 7.7:2.3.