Li-PAA Binder PDI Control for Fast-Charging Battery Stability
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Solution Overview
Problem
Existing lithium ion battery binders face challenges in providing long cycling lifetime and high performance, especially during fast charging, due to issues with molecular weight distribution, lithium content, and pH levels, which affect the mechanical stability and adhesion of electrodes.
Innovation Solution
The development of Li-PAA powder with a polydispersity index (PDI) below 5, lithium content above 7%, and a pH between 8.5 and 9.5 when dissolved 15% w/w in water, prepared by adding a PAA solution to a LiOH solution, precipitating, sieving, and drying, to create a stable and efficient binder for electrodes in lithium ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used in lithium ion batteries, then manufacturing is simpler, but cycling lifetime and fast charging performance deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the PDI of the binder polymer to be below 5, maintaining lithium content above 7%, and adjusting pH to between 8.5 and 9.5. These specific parameter optimizations resolve the contradiction by enabling long cycling lifetime and fast charging performance while using a relatively simple preparation process of mixing PAA solution with LiOH solution.
2Stability of the object's composition
If binder molecular weight distribution is not controlled, then manufacturing is easier, but electrode mechanical stability and adhesion deteriorate
Solution Approach 1:
The patent resolves this contradiction by changing the molecular weight distribution parameter, specifically controlling the PDI to be below 5. This parameter control ensures uniform binder performance and electrode mechanical stability while maintaining a straightforward manufacturing process of solution mixing and precipitation.
3Reliability
If lithium content and pH are not optimized, then binder preparation is simpler, but electrode adhesion and fast charging performance deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing lithium content to be above 7% and pH to be between 8.5 and 9.5. These specific parameter values maximize electrode adhesion and fast charging performance while using a simple preparation method of combining PAA solution with LiOH solution followed by precipitation and drying.
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 Li-PAA powder enhances the mechanical stability and adhesion of electrodes, enabling long cycling lifetime and improved performance in fast charging lithium ion batteries, particularly with metalloid-based anodes, by maintaining lithium binding and reducing molecular weight distribution issues.
Implementation Method 1
lithium content above 7%... maintaining lithium binding
Implementation Method 2
enhances the mechanical stability and adhesion of electrodes
Data Source
AI summary
Li-PAA (lithium poly(acrylic acid)) powders, electrode binders and methods of preparation thereof are provided. The Li-PAA powders have a low PDI (polydispersity index), e.g., smaller than 4 or 5, possibly a high Mw, and are configured to have a lithium content of above 7%, a pH between 8.5 and 9.5, or between 8.7 and 9.1 when dissolved 15% w/w in water and/or possibly a white color. Preparation methods comprise adding a PAA solution into a LiOH solution and stirring a resulting Li-PAA solution, and precipitating Li-PAA from the resulting Li-PAA solution, sieving or filtering and then drying the precipitated Li-PAA to yield the Li-PAA powder, which may be used as binder for forming electrodes. Advantageously, resulting electrodes are uniform and mechanically stable when used with metalloid anode material particles which exhibit high expansion and contraction when used in fast charging lithium ion batteries.