Garnet Composite Solid Electrolyte for Lower-Temperature Sintering
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Solution Overview
Problem
Conventional methods for producing inorganic-based solid state electrolytes require high sintering temperatures and long processing times, leading to high energy consumption and complex processes, while using additives like Ga or Nb can lead to stability issues and short-circuiting, limiting the long-term stability of batteries.
Innovation Solution
A composite solid electrolyte comprising a lithium garnet-type structure material and LiBSCI, which includes Li3BO3, Li2SO4, and LiCl, allows for sintering at lower temperatures (600-1000°C) and enables co-sintering with anode and cathode materials, reducing energy consumption and process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sintering methods are used to produce solid state electrolytes, then sufficient density and high ionic conductivity are achieved, but high sintering temperatures (above 1050°C) and long processing times are required
Solution Approach 1:
The patent uses LiBSCI as an intermediary sintering aid that facilitates the sintering process at lower temperatures. LiBSCI forms a liquid phase during sintering that promotes densification and grain growth of the LLZO electrolyte, enabling sufficient density and ionic conductivity to be achieved at temperatures below 1050°C without requiring extreme thermal conditions
Solution Approach 2:
The patent modifies the sintering parameters by introducing LiBSCI, which changes the sintering mechanism from solid-state diffusion to liquid-phase sintering. This parameter change allows the process to occur at lower temperatures and shorter times while maintaining the necessary density and ionic conductivity properties of the solid state electrolyte
2Use of energy by stationary object
If Ga-doped LLZO nanocrystallites are used to reduce sintering temperature, then sintering can be performed at 950°C, but Ga is expensive and has limited stability against lithium leading to Li-Ga alloy formation
Solution Approach 1:
The patent replaces expensive Ga-doped nanocrystallites with LiBSCI, which is based on abundant and inexpensive materials (Li2CO3, B2O3, SiO2, C). Although LiBSCI forms a transient liquid phase during sintering, it serves its purpose as a sintering aid and then integrates into the final structure, providing cost-effective processing without the stability issues of Ga
Solution Approach 2:
The patent extracts and eliminates Ga from the system, removing the source of Li-Ga alloy formation and associated stability problems. Instead of using Ga as a dopant, the invention uses LiBSCI as an external sintering aid that does not compromise the electrochemical stability of the LLZO electrolyte
3Use of energy by stationary object
If lower sintering temperatures are used with additives like Li3BO3 and LiBO2, then energy consumption is reduced, but the process requires multiple sintering cycles for different components
Solution Approach 1:
The patent makes the LiBSCI-containing green body universal for sintering all battery components (anode, cathode, and electrolyte) in a single process step. The LiBSCI sintering aid enables all components to be processed at the same temperature range (900-1050°C), allowing co-sintering of the entire battery cell in one cycle rather than requiring separate sintering steps for different components
4Use of energy by stationary object
If LLZO is produced as nanocrystallites to enable lower sintering temperature, then sintering can occur at 950°C, but producing nanocrystals is expensive
Solution Approach 1:
The patent replaces expensive LLZO nanocrystallites with conventional-sized LLZO particles combined with LiBSCI as a sintering aid. The LiBSCI enables dense sintering at lower temperatures using readily available, inexpensive starting materials (Li2CO3, B2O3, SiO2, C), eliminating the need for costly nanocrystal synthesis while achieving the same sintering temperature reduction
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 composite solid electrolyte achieves total ionic conductivities between 10^-3 and 10^-6 S/cm at room temperature to 100°C, improving battery stability and reducing energy consumption and process complexity.
Implementation Method 1
sintering a composite solid electrolyte mixture comprising a lithium garnet-type structure material and LiBSCI
Implementation Method 2
LiBSCI has been identified as a promising glass-forming composition
Data Source
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AI summary
The present invention relates to a composite solid electrolyte mixture comprising a the lithium garnet-type structure material and LiBSCl, wherein LiBSCl comprises Li3BO3, Li2SO4 and LiCl. The invention further relates to a composite solid electrolyte obtained from the mixture, a solid state battery comprising the composite solid electrolyte, and to methods of producing the composite solid electrolyte and the solid state battery.