Electrode Slurry Potential Difference Control for All-Solid-State Battery Manufacturing
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Solution Overview
Problem
The challenge in manufacturing all-solid-state batteries is the weight variation and battery capacity issues caused by the gelation of fluorine-containing polymers in electrode slurries, which is influenced by eluted components from lithium compounds, making it difficult to predict and control the ion conductivity and stability of sulfide solid electrolytes.
Innovation Solution
A method involving the use of a pH response electrode and a reference electrode to measure the potential difference within a predetermined range during the preparation of the electrode slurry, adjusting the adding speed of the electrode active material to maintain the potential difference within a specific range (−360 mV to −12 mV) to inhibit gelation and elution, thereby reducing weight variation and ensuring desired battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the concentration of hydrogen ions is increased to inhibit gelation of the fluorine-containing polymer, then the gelation is suppressed and viscosity is reduced, but the elution of Li+ from the electrode active material is promoted which reduces battery capacity
Solution Approach 1:
The patent changes the measurement parameter from pH (which requires water as a reference) to potential difference that can be measured directly in the organic solvent-based electrode slurry. By maintaining the potential difference within a specific range (−360 mV to −12 mV), the patent controls the elution of basic components without requiring hydrogen ion concentration adjustment, thus preventing Li+ elution while suppressing gelation.
2Stability of the object's composition
If the concentration of hydrogen ions is increased to inhibit gelation, then the polymer remains soluble, but the sulfide solid electrolyte is degraded which decreases ion conductivity
Solution Approach 1:
The patent introduces a new control parameter (potential difference range of −360 mV to −12 mV) that directly correlates with the stability of sulfide solid electrolyte. By controlling the potential difference during slurry preparation, the patent prevents both gelation of the binder and degradation of the sulfide solid electrolyte, maintaining both slurry stability and electrolyte reliability without requiring excessive hydrogen ions.
3Stability of the object's composition
If the concentration of hydrogen ions is excessively high to prevent gelation, then gelation is inhibited, but hydrogen sulfide gas is generated from the sulfide solid electrolyte requiring additional recovery or treatment apparatus
Solution Approach 1:
The patent establishes a potential difference control range (−360 mV to −12 mV) that prevents the chemical reactions leading to hydrogen sulfide gas generation. By maintaining the potential difference within this range during slurry preparation, the patent suppresses gelation without causing sulfide solid electrolyte decomposition, thus eliminating harmful gas generation without requiring additional treatment apparatus.
4Measurement precision
If pH of water dispersion is used as an indicator to control eluted components, then the amount of basic components can be estimated, but it is difficult to predict elution in organic solvent-based electrode slurry
Solution Approach 1:
The patent introduces potential difference as an intermediary parameter that bridges the measurement need (controlling eluted components) with the actual system (organic solvent-based slurry). Unlike pH which requires water as a medium, potential difference can be measured directly in the organic solvent system using a pH response electrode and reference electrode, providing accurate real-time monitoring without requiring water or empirical pH correlations.
5Productivity
If the adding speed of electrode active material is not controlled, then the preparation process is faster, but the potential difference varies causing weight variation in the electrode
Solution Approach 1:
The patent implements a feedback control system where the potential difference is continuously monitored during the addition of electrode active material. Based on the measured potential difference, the adding speed is dynamically adjusted to maintain the potential difference within the target range (−360 mV to −12 mV). This feedback mechanism ensures uniform elution control and consistent slurry composition, achieving both high productivity and precise weight uniformity.
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
This approach effectively reduces capacity variation in all-solid-state batteries by minimizing the influence of eluted components, maintaining the stability of sulfide solid electrolytes, and achieving a desired battery capacity by controlling the potential difference during the slurry preparation process.
Implementation Method 1
measuring, with a pH response electrode and a reference electrode, a potential difference between the pH response electrode and the reference electrode in the electrode slurry
Data Source
AI summary
An electrode slurry is prepared by mixing at least an electrode active material, a sulfide solid electrolyte, a binder, and an organic solvent. The electrode slurry is coated on a surface of a substrate to manufacture an electrode. The electrode active material includes a lithium compound. The binder includes a fluorine-containing polymer. During the preparation of the electrode slurry, the variation range of a potential difference between a pH response electrode and a reference electrode in the electrode slurry is maintained within a predetermined reference range.