All-Solid-State Battery Electrode Slurry With Non-Polar PVDF Binder
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Solution Overview
Problem
Existing methods for preparing electrode slurries for all solid-state batteries face challenges with solvent volatility, toxicity, and moisture absorption, leading to degradation of solid electrolytes and reduced battery capacity, especially at high temperatures.
Innovation Solution
A method involving high shear treatment of a mixture comprising a dispersing agent, a non-polar solvent, and a binder comprising fluoropolymers, such as PVDF, to stabilize the dispersion and prepare electrode slurries with reduced moisture absorption and lower boiling points, allowing for the use of solvents like toluene and xylene, which are less toxic and more environmentally friendly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVDF binder is dissolved in NMP solvent, then good bonding capability and adhesion are achieved, but solvent volatility, flammability, toxicity and moisture absorption cause degradation of solid electrolytes
Solution Approach 1:
The patent changes the solvent parameter from polar (NMP) to non-polar (toluene, xylene, or their mixtures with water content ≤0.1%). This parameter change eliminates moisture absorption issues while maintaining binder performance through the use of fluoropolymer binders that are compatible with non-polar solvents.
Solution Approach 2:
The patent introduces a specific type of fluoropolymer binder as an intermediary substance that can be dissolved in non-polar solvents. This binder acts as a mediator that provides good adhesion and bonding capability without requiring polar solvents, thus avoiding moisture absorption problems.
2Object-affected harmful factors
If non-polar solvents are used to avoid moisture absorption, then solid electrolyte degradation is prevented, but fluoropolymers such as PVDF homopolymer do not dissolve
Solution Approach 1:
The patent uses composite fluoropolymer binders comprising VDF-HFP copolymer and VDF-CTFE copolymer in specific ratios (70-99 wt% VDF-HFP and 1-30 wt% VDF-CTFE). This composite material structure combines the solubility advantages of different copolymers in non-polar solvents while maintaining good bonding performance.
Solution Approach 2:
The patent changes the binder composition parameters by using specific copolymer ratios and molecular weight ranges (10,000-500,000 g/mol) that enable dissolution in non-polar solvents. The controlled composition parameters allow the binder to be soluble in toluene/xylene mixtures while maintaining electrochemical stability.
3Ease of manufacture
If copolymers or terpolymers are used to adjust solubility in non-polar solvents, then binder dissolution is achieved, but solvents still absorb moisture and have high boiling points requiring high energy for evaporation
Solution Approach 1:
The patent optimizes the solvent composition parameters by using toluene/xylene mixtures with specific ratios and controlling water content to ≤0.1%. This parameter optimization reduces the boiling point compared to traditional high-boiling solvents like butyl butyrate, thereby reducing the energy required for evaporation while maintaining binder solubility.
4Ease of manufacture
If PVDF copolymers and terpolymers are used as binders, then solubility in non-polar solvents is improved, but melting point decreases due to low crystallinity and performance at high temperatures deteriorates
Solution Approach 1:
The patent creates a composite binder system using specific copolymer combinations (VDF-HFP and VDF-CTFE) with controlled ratios. This composite structure maintains higher crystallinity and melting point compared to single copolymers, thereby improving high-temperature performance while retaining solubility in non-polar solvents.
Solution Approach 2:
The patent optimizes the molecular weight parameters (10,000-500,000 g/mol) and copolymer composition ratios to balance solubility and thermal stability. By controlling these parameters, the binder achieves adequate solubility in non-polar solvents while maintaining sufficient melting point and high-temperature performance.
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 method results in higher initial charge/discharge capacity and improved performance at 100°C, enhancing the safety and efficiency of solid-state lithium-ion batteries by stabilizing the fluoropolymer binder in non-polar solvents and reducing slurry preparation time.
Implementation Method 1
perform a high shear treatment, to obtain a binder dispersion
Implementation Method 2
preparing a mixture comprising: a dispersing agent, a non-polar solvent, and a binder
Implementation Method 3
a step of drying the applied positive electrode slurry
Data Source
AI summary
The invention relates to a method of preparation of an electrode slurry for all solid-state battery. Another subject matter of the invention is a process for making an electrode for all solid-state battery. The invention also concerns the solid-state lithium-ion batteries manufactured by incorporating said electrode.