Solid Battery Current Collector Conductive Layer High Temperature Resistance
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Solution Overview
Problem
Existing methods for manufacturing conductive layers in solid batteries face issues such as resistance fluctuations with temperature, uneven dispersion of polyethylene, and difficulty in maintaining high resistance at high temperatures, which affect battery performance and safety.
Innovation Solution
A method involving the mixing of carbon materials, polyvinylidene fluoride (PVDF), and an organic solvent, with water addition to precipitate PVDF, forming a conductive layer that maintains high resistance only above 150°C, ensuring safety by preventing excessive battery reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer is formed using PVDF and organic solvent dispersion, then the layer provides conductivity at low temperatures, but the resistance rapidly decreases at high temperatures (around 190°C) compromising safety
Solution Approach 1:
The patent uses a composite material system consisting of PVDF (polyvinylidene fluoride) and polyethylene in a specific weight ratio range (3:2 to 1:1). This composite conductive layer combines the low-temperature conductivity of PVDF with the high-temperature resistance properties of polyethylene, creating a material that maintains appropriate resistance across a wide temperature range. The composite structure allows the two polymers to work synergistically, with PVDF providing baseline conductivity and polyethylene providing thermal resistance above its melting point.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the weight ratio of PVDF to polyethylene (within 3:2 to 1:1 range) and the thickness of the conductive layer (5μm to 20μm). By adjusting these parameters, the conductive layer's resistance characteristics can be optimized to maintain stability across different temperature conditions. The specific ratio ensures that polyethylene's melting transition at around 100-110°C provides the necessary resistance increase at high temperatures while PVDF maintains conductivity at operating temperatures.
2Reliability
If polyethylene is added to the conductive layer composition, then high-temperature resistance is improved, but uniform dispersion becomes difficult
Solution Approach 1:
The patent uses an organic solvent as an intermediary medium to disperse both PVDF and polyethylene particles uniformly. The organic solvent temporarily solvates or suspends the polymer particles, allowing them to be evenly distributed throughout the composition before film formation. This intermediary approach prevents direct aggregation of polyethylene particles, which would otherwise be difficult to disperse uniformly due to their hydrophobic nature and tendency to clump.
Solution Approach 2:
The patent optimizes the solvent-to-polymer ratio and mixing parameters to achieve uniform dispersion. By controlling the concentration of polymers in the organic solvent and the mixing time/intensity, the patent ensures that polyethylene particles are evenly distributed without aggregation. The specific weight ratios and processing conditions are tuned to balance dispersion uniformity with the desired conductive and thermal properties.
3Productivity
If existing conductive layer compositions are used, then low-temperature conductivity is achieved, but battery performance improvement is limited due to high resistance
Solution Approach 1:
The patent creates a composite conductive layer using PVDF and polyethylene in optimized ratios that simultaneously achieve low resistance at operating temperatures and high resistance at elevated temperatures. This composite approach allows the conductive layer to function effectively as both a conductor during normal battery operation and a safety barrier under thermal stress, thereby improving overall battery performance and reliability.
Solution Approach 2:
The patent optimizes multiple parameters including the PVDF-to-polyethylene weight ratio (3:2 to 1:1), the conductive layer thickness (5μm to 20μm), and the organic solvent content to achieve the desired balance between conductivity and safety. By precisely controlling these parameters, the conductive layer provides minimal resistance during normal operation (improving productivity) while maintaining high resistance at high temperatures (ensuring reliability).
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 conductive layer effectively keeps high resistance at high temperatures, enhancing battery safety by preventing electric conduction and stopping battery reactions when overheated.
Implementation Method 1
mixing water, a carbon material, PVDF, and an organic solvent... mixing the carbon material dispersion solution, the resin dispersion solution, and water, to prepare a composition for conductive layer formation
Data Source
AI summary
Provided is a method for manufacturing a current collector provided with a conductive layer that can keep a high resistance only at a high temperature. The method includes dispersing a carbon material in an organic solvent to prepare a carbon material dispersion solution, dispersing polyvinylidene fluoride in an organic solvent to prepare a resin dispersion solution, mixing the carbon material dispersion solution, the resin dispersion solution, and water, to prepare a composition for conductive layer formation, and forming a conductive layer on a surface of a current collector by applying the composition for conductive layer formation and thereafter drying the composition.