Hydrocarbon Solvent Synthesis for Lithium Ion Solid Electrolytes
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Solution Overview
Problem
Current methods for producing lithium ion conductive solid electrolytes are inefficient and costly, requiring special equipment and solvents, and often result in residual solvent contamination that lowers ion conductivity and battery performance.
Innovation Solution
A method using a hydrocarbon-based solvent to react lithium sulfide with phosphorous, germanium, or silicon sulfides at controlled temperatures, followed by heat treatment, to produce a lithium ion conductive solid electrolyte without the need for special equipment or solvents, reducing solvent residue and improving ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a polar solvent such as N-methyl-2-pyrrolidone is used to increase reactivity, then the solubility and reactivity of phosphorous sulfide is improved, but the solvent remains in the lithium sulfide product and lowers ion conductivity
Solution Approach 1:
The patent changes the solvent type from polar (N-methyl-2-pyrrolidone) to non-polar (hydrocarbon-based), fundamentally altering the solvent's polarity parameter. This change allows the reaction to proceed while preventing solvent residue contamination that would otherwise degrade ion conductivity, thus resolving the contradiction between reactivity and ion conductivity.
2Productivity
If a polar solvent is used to maintain reactivity, then the reaction efficiency is improved, but multiple washing or distillation steps are required which prolong the production process
Solution Approach 1:
The patent uses a non-polar hydrocarbon-based solvent that can be easily removed without requiring multiple washing or distillation steps. The solvent serves its purpose during the reaction and can be cleanly eliminated, reducing the number of processing steps and overall production time while maintaining reaction efficiency.
3Loss of substance
If a polar solvent is distilled off by normal method, then the solvent is removed, but significant lowering in ion conductivity occurs and stable product supply cannot be ensured
Solution Approach 1:
The patent changes the solvent's polarity parameter from polar to non-polar, which fundamentally alters how the solvent interacts with the product. Non-polar solvents do not contaminate the lithium sulfide product and can be removed without the high temperatures that would otherwise degrade ion conductivity, ensuring both effective solvent removal and stable product supply.
4Loss of substance
If high temperature is used to distill off polar solvent, then the solvent is removed, but ion conductivity of solid electrolyte is lowered due to reaction with solvent
Solution Approach 1:
The patent changes the solvent type to non-polar hydrocarbon-based solvent, which eliminates the chemical reactivity issue between solvent and solid electrolyte. This allows solvent removal at lower temperatures that do not degrade ion conductivity, resolving the contradiction between complete solvent removal and maintaining high ion conductivity.
5Temperature
If special equipment such as tumbling mill is used to treat raw material at low temperature, then the reaction can proceed at relatively low temperature, but production efficiency is lowered due to adhesion of raw material powder to apparatus wall
Solution Approach 1:
The patent uses a liquid non-polar solvent system that allows raw materials to be suspended and reacted in a fluid medium, eliminating the adhesion problem to apparatus walls that occurs with dry powder processing in tumbling mills. This hydraulic approach maintains low temperature processing while significantly improving production efficiency.
6Reliability
If non-polar solvent or multiple distillation steps are used to remove polar solvent, then residual solvent is reduced, but the production process is prolonged
Solution Approach 1:
The patent uses a non-polar hydrocarbon-based solvent that naturally does not contaminate the product and can be easily removed in a single step. This eliminates the need for multiple washing or distillation steps required when using polar solvents, reducing both production time and complexity while ensuring thorough solvent residue removal.
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 method enables the efficient production of lithium ion conductive solid electrolytes with stable ion conductivity and improved battery performance, eliminating the need for special equipment and reducing production time and costs.
Implementation Method 1
bringing one or more compounds selected from phosphorous sulfide, germanium sulfide, silicon sulfide and boron sulfide into contact with lithium sulfide in a hydrocarbon-based solvent
Implementation Method 2
solvents which have a relatively strong polarity such as N-methyl-2-pyrrolidone easily dissolve phosphorous sulfide
Implementation Method 3
the solid electrolyte obtained by the contact process is further subjected to a heat treatment at a temperature of 200°C or higher and 400°C or lower
Data Source
AI summary
A method for producing a lithium ion conductive solid electrolyte including the step of bringing one or more compounds selected from phosphorous sulfide, germanium sulfide, silicon sulfide and boron sulfide into contact with lithium sulfide in a hydrocarbon-based solvent.