Positive Electrode Slurry Composition to Prevent Gel Formation
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Solution Overview
Problem
Lithium ion batteries face challenges in achieving excellent storage performance and safety performance due to issues with gel formation in the positive electrode slurry, which affects the coating and overall performance of the battery.
Innovation Solution
A positive electrode slurry composition is developed, incorporating specific active materials, pre-lithiation materials, and binders with controlled particle sizes and molecular weights to prevent gel formation, ensuring stability and bonding strength, thereby enhancing the storage and safety performance of lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the volume average particle size D10 of the positive electrode active material is less than 0.3 μm, then the energy density of the battery is improved, but the slurry composition becomes unstable and forms gels
Solution Approach 1:
The patent establishes specific parameter ranges for particle size distribution (D10≥0.3μm, D50=0.5-10μm) and binder molecular weight (500k-1.2M) to optimize both energy density and slurry stability. By controlling the D10 parameter at ≥0.3μm, the patent prevents gel formation while maintaining high energy density, resolving the contradiction between fine particle benefits and slurry stability.
Solution Approach 2:
The patent uses a composite binder system consisting of polyacrylic acid and carboxymethyl cellulose sodium in specific ratios, creating a composite material that provides both strong adhesion and slurry stability. This composite approach allows the system to achieve both high energy density and prevented gel formation simultaneously.
2Ease of manufacture
If the volume average particle size D50 of the positive electrode active material is increased to improve slurry stability, then the machinability is improved, but the energy density decreases
Solution Approach 1:
The patent optimizes the D50 parameter to a specific range (0.5-10μm) that balances machinability and energy density. This parameter control ensures the slurry remains stable and easy to process while maintaining sufficient energy density for high-performance batteries.
Solution Approach 2:
The patent applies different particle size requirements to different portions of the particle size distribution. By specifying D10≥0.3μm for fine particles and D50=0.5-10μm for median particles, the patent creates local quality variations that optimize both energy density (from finer particles) and machinability (from coarser particles).
3Device complexity
If conventional binders are used in the positive electrode slurry, then the manufacturing process is simple, but gel formation occurs and bonding strength is insufficient
Solution Approach 1:
The patent employs a composite binder system combining polyacrylic acid and carboxymethyl cellulose sodium in specific ratios. This composite material provides superior bonding strength and prevents gel formation while maintaining manufacturing simplicity, resolving the contradiction between conventional simple binders and performance requirements.
Solution Approach 2:
The patent specifies a molecular weight range (500k-1.2M) for the polyacrylic acid binder, optimizing the molecular weight parameter to achieve both strong bonding and gel prevention. This parameter control allows the binder to form strong bonds without causing the gelation that plagues conventional systems.
4Reliability
If pre-lithiation material is added to the positive electrode slurry to improve storage performance, then the storage performance is enhanced, but the slurry becomes unstable and forms gels
Solution Approach 1:
The patent controls the particle size parameters (D10≥0.3μm, D50=0.5-10μm) of the positive electrode active material to prevent gel formation even when pre-lithiation material is present. This parameter optimization allows the system to achieve both improved storage performance from pre-lithiation and maintained slurry stability.
Solution Approach 2:
The patent uses the controlled particle size distribution and specific binder system as an intermediary that mediates between the pre-lithiation material and the slurry matrix. This intermediary approach allows pre-lithiation to improve storage performance without causing gel formation, as the optimized particle and binder system prevents the instability that would otherwise occur.
Data Source
AI summary
A positive electrode slurry composition, and a positive electrode sheet prepared thereof, a secondary battery, a battery module, a battery pack and a power consumption apparatus are described. The positive electrode slurry composition includes a positive electrode active material, a pre-lithiation material, and a binder, where the binder is shown in Formula (II)where R1, R2, x, y, and z have meanings defined in the specification, a volume average particle size is D10≥0.3 μm, a volume average particle size D50 is 0.5-10 μm. The positive electrode slurry composition includes the binder in Formula (II) and the positive electrode active material with a specific particle size range, which is not easy to agglomerate and has high stability, and is conducive to improving machinability of the positive electrode sheet, and the binder in Formula (II) is conducive to improving bonding strength between the positive electrode active material and the pre-lithiation material.