Negative Electrode Slurry with Dual Dispersants for Rapid Charging
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining high cycle performance and dynamic performance, especially under rapid and large current charging conditions, due to instability of the SEI film and premature capacity decline when using polyacrylate as a dispersant alone.
Innovation Solution
A negative electrode slurry comprising a carbon-type active material, a cellulose-type dispersant (A dispersant) for surface coating, and a polyacrylate-type dispersant (B dispersant) to form a stable SEI film, ensuring excellent dynamic and cycle performance by preventing lithium precipitation and maintaining capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If polyacrylate polymer is used as dispersant alone to improve rate capability and precipitation lithium, then dynamic performance is improved, but capacity retention rate decreases quickly and cycle performance deteriorates under low temperature conditions
Solution Approach 1:
The patent combines two types of dispersants: polyacrylate polymer (B dispersant) for improving rate capability and precipitation lithium, and cellulose-type dispersant (A dispersant) for maintaining capacity retention. This combination merges the advantages of both dispersants to achieve both high dynamic performance and excellent cycle performance.
Solution Approach 2:
The patent uses a composite dispersant system comprising both polyacrylate polymer and cellulose-type dispersant. This composite approach creates a synergistic effect where the polyacrylate polymer improves lithium ion conduction and prevents precipitation, while the cellulose-type dispersant maintains structural stability and capacity retention over cycling.
2Quantity of substance
If high energy density is pursued to meet high capacity demands, then energy density increases, but material stability during charging and discharging decreases
Solution Approach 1:
The patent introduces dispersants as intermediary substances that mediate between the negative electrode active material and the electrolyte. These dispersants form protective interfaces that stabilize the material composition during charging and discharging, enabling high energy density to be achieved without compromising material stability.
Solution Approach 2:
The patent optimizes the composition parameters of the negative electrode slurry, including the types and ratios of dispersants, to achieve a balance between energy density and material stability. By adjusting these parameters, the system can maintain stability even at high energy density levels.
3Loss of time
If rapid charging with large current is implemented to reduce charging time, then charging time decreases, but the stability of negative electrode materials, electrolyte and binder during charging and discharging decreases
Solution Approach 1:
The patent applies dispersants in advance during the electrode preparation process to pre-establish protective interfaces and stable structures. This preliminary action ensures that the materials are pre-conditioned to withstand the stress of rapid charging with large current, preventing degradation during operation.
Solution Approach 2:
The dispersants act as intermediary substances that facilitate rapid lithium ion conduction while maintaining material stability. They create stable interfaces that allow large currents to pass during rapid charging without causing material degradation or electrolyte decomposition.
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 combined use of A and B dispersants improves the stability of the SEI film, enhancing the battery's ability to handle rapid charging and extending its cycle life by preventing premature capacity decline and maintaining efficient lithium ion conduction.
Implementation Method 1
A surface of the negative electrode active material is coated with a layer of the A dispersant
Implementation Method 2
improving the stability of the SEI film, enhancing the battery's ability to handle rapid charging
Implementation Method 3
maintaining efficient lithium ion conduction
Data Source
AI summary
The present invention provides a negative electrode slurry, a negative electrode plate and an electrochemical energy storage device. The negative electrode slurry comprises a solvent and a solid component dispersed in the solvent. The solid component comprises a negative electrode active material, a water-soluble binder and a dispersant. The negative electrode active material comprises a carbon-type active material. The dispersant comprises an A dispersant and a B dispersant, the A dispersant is a cellulose-type dispersant, the B dispersant is at least one of poly(acrylic acid)-type dispersant, polyacrylate-type dispersant and polyacrylamide-type dispersant. Under a combined effect of the A dispersant and the B dispersant, they can ensure that the electrochemical energy storage device has excellent dynamic performance, which can prevent lithium (or sodium, magnesium and zinc) from precipitating under condition of rapid and large current charging, meanwhile they can ensure that the electrochemical energy storage device has excellent cycle performance.