pH-Responsive Electrode Binder Composition for Low-Swelling Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional binder compositions for secondary batteries face challenges in ensuring adequate peel strength and inhibition of swelling of electrodes, while also enhancing cycle characteristics of secondary batteries.
Innovation Solution
A binder composition comprising a binder and water, with specific viscosity change rates at different pH levels, is used to improve the peel strength and inhibition of swelling of electrodes, thereby enhancing the cycle characteristics of secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cross-linked polymer binder is used to improve binding capacity, then peel strength is improved, but electrode swelling increases during repeated charging and discharging
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the binder composition at two different pH levels (pH 8.0 and pH 13.0) and setting the viscosity change rate within a specific range (-45% to 50%). This controlled parameter adjustment allows the binder to maintain optimal binding properties while resisting swelling during battery cycling, resolving the contradiction between peel strength and swelling inhibition.
Solution Approach 2:
The patent uses a composite binder composition that includes a cross-linked polymer binder combined with specific additives and a controlled water content. This composite structure leverages the high binding capacity of cross-linked polymers while using the viscosity control mechanism to counteract swelling, thus achieving both improved peel strength and reduced electrode swelling.
2Strength
If binder composition is optimized for peel strength, then electrode adhesion is improved, but cycle characteristics of secondary battery are insufficient
Solution Approach 1:
The patent optimizes cycle characteristics by controlling the viscosity change rate of the binder composition within a specific range (-45% to 50%) when pH changes from 8.0 to 13.0. This parameter control ensures that the binder maintains its binding properties during the pH fluctuations that occur during battery charging and discharging cycles, thereby improving both peel strength and cycle characteristics simultaneously.
3Ease of manufacture
If conventional binder composition is used, then manufacturing is simple, but peel strength and swelling inhibition are insufficient
Solution Approach 1:
The patent maintains manufacturing simplicity while improving peel strength by controlling the viscosity change rate parameter of the binder composition. Rather than requiring complex multi-component formulations or sophisticated processing steps, the invention achieves enhanced performance through precise control of the viscosity response to pH changes, making the improvement accessible with relatively simple manufacturing processes.
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 proposed binder composition effectively improves the peel strength and inhibition of swelling of electrodes, leading to enhanced cycle characteristics and prolonged service life of secondary batteries.
Implementation Method 1
when viscosity of the binder composition for a secondary battery under conditions of a temperature of 25° C., a solid content concentration of 1.0 mass %, and a pH of 8.0 is taken to be η1, in units of mPa·sec, and viscosity of the binder composition for a secondary battery under conditions of a temperature of 25° C., a solid content concentration of 1.0 mass %, and a pH of 13.0 is taken to be η2, in units of mPa·sec, a viscosity change rate calculated by formula (I)
Data Source
AI summary
Provided is a binder composition for a secondary battery that is capable of forming an electrode for a secondary battery that has excellent peel strength and inhibition of swelling and that can cause a secondary battery to display excellent cycle characteristics. The binder composition for a secondary battery contains a binder and water. When viscosity of the binder composition for a secondary battery under conditions of a temperature of 25° C., a solid content concentration of 1.0 mass %, and a pH of 8.0 is taken to be η1(mPa·sec) and viscosity of the binder composition for a secondary battery under conditions of a temperature of 25° C., a solid content concentration of 1.0 mass %, and a pH of 13.0 is taken to be η2(mPa·sec), a viscosity change rate, calculated by: viscosity change rate={(η2-η1)/η1}×100 [%], is not less than −45% and not more than 50%.