Electrolyte Precursor Solution for Low-Temperature Solid Electrolytes
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Solution Overview
Problem
The existing methods for producing silicon-containing lithium lanthanum titanate composite solid electrolytes face challenges with lithium evaporation and byproduct generation during high-temperature sintering, leading to increased grain boundary resistance and decreased ion conductivity.
Innovation Solution
An electrolyte precursor solution containing a metallic compound, a solvent, and an anionic surfactant with a sulfate group is used to improve ion conductivity by bonding the sulfate group to active material particles, allowing for lower temperature firing and maintaining desired composition, with a specific concentration of the anionic surfactant and inclusion of a hydrophobic group to enhance wettability and ion conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering (1100-1400°C) is performed to reduce grain boundary resistance, then ion conductivity is improved, but lithium evaporation and byproduct generation occur
Solution Approach 1:
The patent changes the temperature parameter from high-temperature sintering (1100-1400°C) to low-temperature firing (900-1000°C), combined with changing the chemical composition by incorporating silicon-containing compounds and specific ratios of Li2SiO3 and Li2SiO2. This parameter change allows achieving good sintering and low grain boundary resistance without causing lithium evaporation
Solution Approach 2:
The patent creates a composite solid electrolyte material containing lithium lanthanum titanate (LLTO) combined with silicon-containing compounds (Li2SiO3, Li2SiO2, and SiO2). This composite structure reduces grain boundary resistance through the silicon-containing phases while enabling lower processing temperatures, thus preventing lithium evaporation
2Loss of substance
If sintering temperature is reduced to suppress lithium evaporation, then lithium loss is prevented, but grain boundary resistance increases and ion conductivity decreases
Solution Approach 1:
The patent uses a composite material system combining LLTO with silicon-containing compounds (Li2SiO3, Li2SiO2, SiO2) that enables effective sintering at lower temperatures (900-1000°C). The silicon-containing phases form low-resistance grain boundary regions, maintaining high ion conductivity even at reduced sintering temperatures, thus preventing lithium evaporation while preserving electrical performance
Solution Approach 2:
The patent creates local quality differences by having silicon-containing compounds concentrate at grain boundaries, forming regions with different properties from the bulk crystal grains. This local modification of grain boundary regions reduces resistance specifically at interfaces without requiring high bulk sintering temperatures, enabling low-temperature processing with maintained conductivity
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 enhances ion conductivity and energy density while preventing lithium evaporation and byproduct generation, ensuring a stable electrolyte composition and improved battery performance.
Implementation Method 1
an anionic surfactant having a sulfate group is contained... when active material particles to be used as an electrode material of a battery and the electrolyte precursor solution are brought into contact with each other and reacted with each other, a sulfate group which is a hydrophilic group is bonded to the surface of the active material particle
Implementation Method 2
a metallic compound containing elements constituting an electrolyte, a solvent capable of dissolving the metallic compound
Implementation Method 3
the anionic surfactant contains a hydrophobic group having 4 or more carbon atoms or a fluorinated alkyl group... to enhance wettability
Data Source
AI summary
An electrolyte precursor solution includes a metallic compound containing elements constituting an electrolyte, a solvent capable of dissolving the metallic compound, and an anionic surfactant having a sulfate group (SO42−) bonded to a hydrophobic group R. By reacting such an electrolyte precursor solution with active material particles containing lithium, lithium sulfate derived from the anionic surfactant is interposed at the interface between the surface of the active material particle and the electrolyte so as to enhance the dissociation of lithium ions at the interface, and thus, an excellent ion conductivity can be realized.