Composite Solid Electrolyte for Lower-Temperature Co-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, and the use of additives like Ga and Nb can lead to stability issues in batteries.
Innovation Solution
A composite solid electrolyte comprising a lithium garnet-type structure material and LiBSCl, which 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 solid state reaction and sintering methods are used to produce inorganic-based solid state electrolytes, then high ionic conductivity and sufficient density are achieved, but high sintering temperatures (above 1050°C) and long processing times are required
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the solid state electrolyte through doping with specific elements (Al, Ta, Nb) at controlled concentrations. This compositional parameter change enables the material to achieve high ionic conductivity at lower sintering temperatures (900-1000°C) compared to conventional methods requiring above 1050°C
Solution Approach 2:
The patent creates a composite solid state electrolyte system by combining lithium lanthanum zirconium oxide (LLZO) base material with dopant elements (Al, Ta, Nb). This composite approach leverages the synergistic effects of different elements to reduce sintering temperature while maintaining or enhancing ionic conductivity properties
2Use of energy by stationary object
If sintering aids and nanocrystallites are used to reduce sintering temperature, then lower sintering temperatures (950°C) are achieved, but the processing complexity and cost increase due to requirements for nanocrystal production
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific dopants (Al, Ta, Nb) in optimized ratios into the LLZO structure. This compositional modification inherently reduces the sintering temperature to 900-1000°C without requiring external sintering aids or complex nanocrystal synthesis processes
Solution Approach 2:
The patent extracts or removes the need for complex nanocrystal production processes and external sintering aids by achieving temperature reduction through straightforward compositional doping of the bulk material, thereby simplifying the overall manufacturing process
3Use of energy by stationary object
If Ga-doped LLZO nanocrystallites are used to reduce sintering temperature, then ionic conductivity is maintained at lower temperatures, but Ga is expensive and has limited stability against lithium leading to Li-Ga alloy formation
Solution Approach 1:
The patent changes the dopant composition parameters by replacing Ga with alternative elements (Al, Ta, Nb) that offer both temperature reduction capability and superior lithium stability. These alternative dopants prevent Li-Ga alloy formation and maintain structural integrity over long term operation
Solution Approach 2:
The patent substitutes expensive Ga dopant with more cost-effective and stable alternative elements (Al, Ta, Nb) that provide comparable or superior performance in terms of both temperature reduction and long term battery stability, reducing material cost and improving reliability
4Use of energy by stationary object
If Nb is used as additive to reduce sintering temperature to 900°C, then ionic conductivity is achieved, but Nb has limited stability against lithium leading to short circuiting
Solution Approach 1:
The patent optimizes the dopant composition by selecting and combining specific elements (Al, Ta, Nb) in carefully controlled ratios. This compositional parameter optimization achieves the desired sintering temperature reduction while the presence of stabilizing elements (particularly Al and Ta) compensates for the lithium instability of Nb, preventing short circuiting
Solution Approach 2:
The patent creates a multi-element composite dopant system where Nb works synergistically with Al and Ta. This composite dopant approach allows Nb to contribute to temperature reduction while Al and Ta provide lithium stability, preventing the harmful short circuiting effect that would occur with Nb alone
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 electrolyte achieves excellent ionic conductivity (10−3 to 10−6 S/cm) and simplifies the production of all ceramic solid state batteries by allowing simultaneous sintering of anode, cathode, and electrolyte components at lower temperatures.
Implementation Method 1
sintering of green bodies based on LLZO require high sintering temperatures, such as temperatures above 1050° C., in order to obtain an electrolyte having a sufficient density
Implementation Method 2
LLZO (Li7La3Zr2O12), including its doped versions such as Li6.75Al0.25La3Zr2O12, is a promising material for SSEs due to its exceptional ionic conductivity—in the range of 10−4 S/cm
Data Source
AI summary
A composite solid electrolyte mixture including a the lithium garnet-type structure material and LiBSCl, wherein LiBSCl comprises Li3BO3, Li2SO4 and LiCl. Also, a composite solid electrolyte obtained from the mixture, a solid state battery including the composite solid electrolyte, and methods of producing the composite solid electrolyte and the solid state battery.