Lithium-Ion Cathode Particle Mix for High-Density Crack-Resistant Electrodes
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Solution Overview
Problem
Existing lithium-ion battery positive electrode plates face a challenge in achieving high compacted density without excessive elongation, which can lead to brittle fracture during manufacturing processes.
Innovation Solution
A lithium-ion battery positive electrode plate design that combines polycrystalline particles of different sizes with monocrystalline particles in a specific ratio, along with controlled pore volume and shear stress, to achieve high compacted density with low elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional positive electrode plate is used, then the battery has basic charge-discharge function, but the battery exhibits significant expansion and poor cycle stability after long-term use
Solution Approach 1:
The patent applies local quality by creating a gradient structure in the positive electrode plate where the density and composition vary across different regions. The electrode plate has a front side and a back side with different characteristics, allowing differential expansion control. This gradient structure enables the battery to accommodate expansion stresses locally rather than uniformly, improving cycle stability while controlling overall expansion.
Solution Approach 2:
The patent uses composite materials by combining lithium iron phosphate particles with a specific matrix material that has controlled porosity and mechanical properties. This composite structure provides both the electrochemical performance needed for charge-discharge cycles and the mechanical flexibility to accommodate expansion without structural failure, thereby improving reliability and reducing expansion.
2Quantity of substance
If the positive electrode plate density is increased to improve energy density, then the battery capacity increases, but the battery expansion and cycle stability worsen
Solution Approach 1:
The patent implements local quality through a density gradient where the front side of the electrode plate has higher density for maximum capacity utilization, while the back side has lower density to accommodate expansion. This spatial variation in density allows the battery to achieve high capacity while maintaining cycle stability through controlled differential expansion.
Solution Approach 2:
The patent employs porous materials with controlled pore size and distribution to create a matrix that can accommodate lithium iron phosphate particles at high density while providing void spaces for expansion. The porous structure allows the electrode to maintain high active material content for capacity while having the mechanical compliance needed for long-term cycle stability.
3Productivity
If lithium iron phosphate particles are densely packed to maximize capacity, then the energy density improves, but the electrode plate cannot accommodate expansion stresses
Solution Approach 1:
The patent applies local quality by creating regions of different packing densities within the electrode plate. The front side has dense packing for maximum capacity, while the back side has looser packing that provides expansion accommodation. This spatial differentiation allows the electrode to achieve high overall capacity while maintaining structural integrity through localized compliance zones.
Solution Approach 2:
The patent uses a composite material system where lithium iron phosphate particles are embedded in a matrix material with different mechanical properties. This composite structure allows dense packing of active material for high capacity while the matrix provides a compliant framework that can deform to accommodate expansion stresses, preserving overall structural integrity.
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 design ensures high compacted density and toughness, reducing the risk of brittle fracture while maintaining high active material load, thereby enhancing battery performance.
Implementation Method 1
the organic-inorganic composite coating layer has good porosity
Implementation Method 2
the organic-inorganic composite coating layer is formed by sequentially performing a sol-gel process and a sintering process
Implementation Method 3
sequentially performing a sol-gel process and a sintering process
Implementation Method 4
sequentially performing a sol-gel process and a sintering process
Data Source
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AI summary
The present application provides a lithium-ion battery positive electrode plate, comprising a positive electrode current collector and 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. The present application further provides a lithium-ion battery with the positive electrode plate, a battery module, a battery pack and an electrical apparatus.