Reactive Drying of Battery Separators for Residual Moisture Removal
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Solution Overview
Problem
Existing lithium-ion battery manufacturing processes are inefficient in removing residual water, which leads to electrolyte decomposition, increased resistance, and potential thermal runaway due to the hygroscopic nature of ceramic-coated separators, affecting performance and safety.
Innovation Solution
A Reactive Drying (RD) process is integrated into the battery manufacturing process to scavenge water using moisture-reactive precursors, applying a non-uniform ceramic phase within the electrodes and separators to reduce moisture content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal drying steps are used to remove water from separators, then some moisture is removed, but the process is inefficient and inadequate to further reduce retained water in the cells
Solution Approach 1:
The patent changes the drying mechanism from thermal to chemical by introducing reactive precursors that chemically react with water molecules. This parameter change from thermal energy to chemical reaction enables more effective moisture removal at lower temperatures, resolving the contradiction between reliability of moisture removal and productivity of the drying process
Solution Approach 2:
The patent replaces the thermal drying mechanism with a chemical vapor deposition-based reactive drying system. The mechanical/thermal system is substituted with a chemical system where precursors react with water to form volatile products, achieving superior moisture removal efficiency and effectiveness
2Stability of the object's composition
If ceramic coating is applied to separators to improve performance, then separator stability is enhanced, but the hygroscopic nature of ceramic-coated separators increases moisture retention
Solution Approach 1:
The patent changes the chemical composition and surface properties of the ceramic coating by applying reactive precursors that modify the ceramic material's hygroscopic characteristics. This parameter change reduces the coating's affinity for water while maintaining its structural stability, resolving the contradiction between separator stability and moisture content
Solution Approach 2:
The patent converts the harmful hygroscopic property of ceramic coatings into a beneficial feature by using the ceramic surface as a substrate for reactive drying. The same ceramic coating that causes moisture retention becomes the target for chemical reaction with precursors, transforming it into a moisture-scavenging surface that actively removes water
3Quantity of substance
If humidity-controlled environment is used during battery assembly to minimize water, then moisture uptake is reduced, but manufacturing time and cost increase
Solution Approach 1:
The patent applies reactive drying to separators and electrodes before assembly, performing the moisture removal action in advance. This preliminary action ensures that components are pre-dried to low moisture levels, eliminating the need for extended humidity-controlled assembly environments and reducing manufacturing time and cost
Solution Approach 2:
The patent introduces reactive precursors as intermediaries that facilitate moisture removal during a brief exposure period. These precursors act as mediators between the separator surface and water molecules, enabling rapid moisture extraction without requiring prolonged humidity control during assembly
4Ease of manufacture
If residual water is present in batteries, then manufacturing is simpler, but electrolyte decomposition and thermal runaway risks increase
Solution Approach 1:
The patent converts the presence of residual water from a harmful factor into a useful reactant. By introducing reactive precursors that specifically target and react with water molecules, the manufacturing process utilizes the residual water as a substrate for chemical reaction, transforming it into volatile products that are easily removed, thereby eliminating the harmful effects while maintaining manufacturing simplicity
Solution Approach 2:
The patent changes the chemical state of residual water from a stable, harmful impurity to a reactive intermediate that participates in chemical reactions with precursors. This parameter change from stable water to reactive water enables selective removal of moisture through chemical vapor deposition, reducing electrolyte decomposition risks without complicating the manufacturing process
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 RD process effectively reduces water content in batteries, enhancing performance and safety by minimizing electrolyte decomposition and thermal risks, while potentially reducing manufacturing time and costs.
Implementation Method 1
exposing the upper region of the porous sheet to a gaseous precursor, wherein the gaseous precursor comprises one or more elements selected from the group consisting of Li, B, C, Na, Mg, Al, Si, K, Ca, Sc, Ti, Zn, Ga, Ge, Sr, Y and Zr, and is reactive with water
Implementation Method 2
the porous sheet having two major surfaces and being defined by three mutually-perpendicular directions of thickness, height and width
Data Source
AI summary
Methods and apparatus are described that reduce water during the manufacture of battery cells. A Reactive Drying (RD) manufacturing process is described that is incorporated in a battery manufacturing process. A RD process that is used to scavenge water can also provide beneficial ceramic phases within the electrode or substrate that is being treated. This process can be incorporated into the battery manufacturing process to reduce the amount of water in a finished battery.