Silicon Anode Binder pH Tuning to Prevent Gelation and Gas
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Solution Overview
Problem
Lithium batteries face issues such as paste gelation, gas generation, and high selectivity to binders due to the reaction between prelithiated silicon oxide materials and acidic binders, leading to reduced capacity and efficiency.
Innovation Solution
A negative electrode plate for lithium batteries using a polyacrylic acid-based binder with a pH of 4.5 to 8.5 and viscosity of 3500 Pa·s to 30000 Pa·s, combined with an alkaline additive like sodium lignosulfonate, to improve the performance of prelithiated silicon oxide materials, reducing paste gelation and gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prelithiated silicon oxide materials are used as negative electrode materials, then initial efficiency and cycle stability are improved, but paste gelation and gas generation occur due to reaction with acidic binder
Solution Approach 1:
The patent changes the pH parameter of the binder from highly acidic (pH<3) to weakly acidic (pH 4.5-8.5), which fundamentally alters the chemical interaction between the binder and prelithiated silicon oxide. This parameter change eliminates the harmful gelation reaction while preserving the binding function, thereby resolving the contradiction between cycle stability improvement and paste gelation prevention.
Solution Approach 2:
The patent introduces an alkaline additive (such as lithium hydroxide, sodium hydroxide, or potassium hydroxide) as an intermediary substance that mediates the interaction between the acidic binder and alkaline prelithiated silicon oxide. The alkaline additive neutralizes the excessive acidity of the binder, preventing harmful reactions while maintaining adequate binding performance, thus resolving the gelation issue without sacrificing reliability.
2Productivity
If prelithiated silicon oxide materials are used as negative electrode materials, then initial efficiency is improved, but gas generation occurs due to reaction with acidic binder
Solution Approach 1:
By adjusting the pH parameter of the binder to a weakly acidic range (4.5-8.5), the patent eliminates the violent chemical reaction between the binder and prelithiated silicon oxide that causes gas generation. This parameter modification maintains the high initial efficiency benefit while preventing the harmful gas generation side effect.
Solution Approach 2:
The patent converts the harmful acidic property of the binder into a beneficial weakly acidic property through pH adjustment. The modified binder maintains its binding functionality while the reduced acidity prevents the harmful gas-generating reaction with prelithiated silicon oxide, effectively turning a harmful characteristic into a beneficial one.
3Strength
If traditional acidic binder is used with prelithiated silicon oxide, then binding function is provided, but high selectivity to binder is required limiting material choices
Solution Approach 1:
The patent makes the binder universally applicable to different negative electrode materials by adjusting its pH to a weakly acidic range. This modified binder can now work with prelithiated silicon oxide, silicon-carbon composites, and other alkaline materials without causing gelation or gas generation, eliminating the need for highly selective binder-material matching and expanding design flexibility.
Solution Approach 2:
By changing the pH parameter of the binder from highly acidic to weakly acidic, the patent broadens the compatibility range of the binder with various negative electrode materials. This parameter modification allows the same binder formulation to be used across different material systems, reducing selectivity constraints and improving adaptability.
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 solution enhances the capacity and efficiency of lithium batteries by minimizing paste gelation and gas generation, while expanding the applicability of weakly acidic polyacrylic acid-based binders, thus improving the overall performance and storage stability of the negative electrode materials.
Implementation Method 1
a polyacrylic acid-based binder having a pH of 4.5 to 8.5 and a viscosity of 3500 Pa·s to 30000 Pa·s
Data Source
AI summary
The present disclosure provides a negative electrode plate for a lithium battery and a lithium-ion secondary battery comprising same. The negative electrode plate includes a negative electrode current collector and a negative electrode material, wherein the negative electrode material includes: a negative electrode active material including a silicon-based material or a mixture of graphite and silicon-based material; a conductive agent; and a polyacrylic acid-based binder having a pH of 4.5 to 8.5 and a viscosity of 3500 Pa·s to 30000 Pa·s.