Positive Electrode Slurry Composition to Prevent Gelling
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Solution Overview
Problem
Existing lithium ion batteries face issues with storage performance and safety due to gelling problems in the positive electrode slurry, affecting the coating process and overall battery performance.
Innovation Solution
A positive electrode slurry composition comprising lithium-containing phosphate, a lithium-supplementing agent, and a binder with specific molecular weight and fluorine substitution, which prevents agglomeration and enhances bonding, improving the processability and safety of the positive electrode plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode slurry is used, then the battery can be manufactured, but the slurry is prone to gelling which compromises storage performance and safety performance
Solution Approach 1:
The patent changes the chemical composition parameters of the slurry by introducing a lithium-supplementing agent with specific properties (particle size D50 of 5-15 μm, specific surface area of 0.5-20 m2/g, and controlled pH). These parameter changes prevent gelling while improving storage and safety performance.
Solution Approach 2:
The patent creates a composite slurry system combining positive electrode active material, binder, conductive agent, and lithium-supplementing agent. This composite approach prevents gelling by distributing multiple functional components that work synergistically to maintain slurry stability.
2Reliability
If lithium-supplementing agent is added to prevent gelling, then storage performance improves, but the complexity of slurry composition increases
Solution Approach 1:
The lithium-supplementing agent serves multiple functions simultaneously: it supplements lithium content, prevents gelling, improves storage performance, and enhances safety. This multi-functionality reduces the need for multiple separate additives, thereby managing composition complexity.
Solution Approach 2:
The patent specifies precise parameter ranges for the lithium-supplementing agent (particle size D50: 5-15 μm, specific surface area: 0.5-20 m2/g) to optimize its effectiveness while maintaining manageable slurry composition. These controlled parameters prevent excessive complexity.
3Strength
If binder with high molecular weight is used to enhance bonding strength, then bonding between active material and lithium-supplementing agent improves, but the slurry viscosity increases which may affect processability
Solution Approach 1:
The patent optimizes the binder's weight-average molecular weight to a specific range (500,000-1,200,000) to achieve adequate bonding strength while maintaining acceptable slurry viscosity for coating processes. This parameter optimization balances bonding and processability.
Solution Approach 2:
The binder provides localized bonding strength at the interfaces between active material particles and lithium-supplementing agent, rather than requiring uniformly high viscosity throughout the entire slurry. This allows strong bonding with manageable overall slurry flow properties.
Data Source
AI summary
A positive electrode slurry composition of the present application may comprise a positive electrode active material, a lithium-supplementing agent and a binder, whereinthe positive electrode active material may include a lithium-containing phosphate represented by formula (I),LiFe1-b1-c1Mnb1M1c1PO4 formula (I)in which 0≤b1≤1, 0≤c1≤0.1, and M1 is selected from at least one of transition metal elements and non-transition metal elements in addition to Fe and Mn;the lithium-supplementing agent may be selected from one or more of lithium metal oxides of Lia1M2O0.5(2+a1), Li2M3O3, Li2M4O4, Li3M5O4, Li5M6O4, and Li5M7O6, andthe binder may be represented by formula (II):in which R1 and R2 are independently H or F, x, y, and z are all positive integers, and 0.52≤(4x+3y+2z)/(4x+4y+4z)≤0.7.