Composite Closo-Borate Electrolytes for Low-Activation Ion Transport
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Solution Overview
Problem
Sulfide-based electrolytes in solid-state batteries are prone to forming toxic gases upon exposure to moisture, while polymeric and organic electrolytes exhibit inferior ionic mobility at technologically relevant temperatures below 60°C, and existing closo-borate salts have high activation energies for cationic mobility.
Innovation Solution
A composite salt mixture of halogen-free and halogenated closo-borate salts with specific cations and anions, providing a cationic conductivity at least one order of magnitude greater than individual salts and low activation energies below 0.65 eV, achieved through mechanochemical synthesis or solution-based methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide-based electrolytes are used to achieve high ionic conductivity, then ionic conductivity is improved, but toxic gas formation occurs upon exposure to moisture
Solution Approach 1:
The patent uses composite materials by combining organic electrolyte components (imidazolium salts, borate anions) with inorganic components to create a solid-state electrolyte that achieves high ionic conductivity without the toxic gas formation issues of sulfide-based electrolytes. The composite structure allows beneficial properties from both organic and inorganic phases while avoiding their respective drawbacks.
2Object-generated harmful factors
If polymeric and organic electrolytes are used to avoid toxic gas formation, then safety is improved, but ionic mobility deteriorates at temperatures below 60°C
Solution Approach 1:
The patent changes key parameters of the electrolyte system by using imidazolium cations with specific alkyl group configurations and borate anions with particular structures. These parameter changes enable the electrolyte to maintain low activation energy (0.20-0.40 eV) and high ionic conductivity at room temperature and below, overcoming the temperature-dependent mobility limitation of conventional polymeric electrolytes.
Solution Approach 2:
The patent applies local quality by designing specific molecular structures with localized functional groups. The imidazolium cations contain specific alkyl substitutions at particular positions, and the borate anions have specific structural configurations. These localized structural features create favorable interactions that enhance ion mobility specifically in the regions where charge transport occurs, achieving high conductivity without requiring high temperatures.
3Stability of the object's composition
If conventional closo-borate salts are used to achieve solid-state stability, then mechanical stability is improved, but activation energy for cationic mobility increases
Solution Approach 1:
The patent changes the chemical composition parameters of closo-borate salts by selecting specific anions (B10H10 2−, B11H12 −, B12H12 2−) and pairing them with imidazolium cations. This parameter change results in a solid-state electrolyte with exceptional stability while maintaining remarkably low activation energy (0.20-0.40 eV) for cationic mobility, resolving the trade-off between stability and energy requirement for ion transport.
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 exhibits enhanced cationic conductivity and low activation energies, maintaining high performance even at sub-ambient temperatures, surpassing individual closo-borate salts by several orders of magnitude.
Implementation Method 1
the composite salt mixture exhibits a cationic conductivity that is at least one order of magnitude greater than a cationic conductivity of the halogen-free closo-borate salt and a cationic conductivity of the halogenated closo-borate salt
Data Source
AI summary
An electrolyte includes a composite salt mixture formed from a halogen-free closo-borate salt and a halogenated closo-borate salt. The halogen-free closo-borate salt includes a first cation selected from Li+, Na+, Mg2+, or Ca2+, and a closo-borate anion with the structure [ByH(y−z)Rz]2−, [CB(y−1)H(y−z)Rz]−, [C2B(y−2)H(y−t−1)Rt]−, [C2B(y−3)H(y−t)Rt]−, or [C2B(y−3)H(y−t−1)Rt]2−, and a second cation selected from Li+, Na+, Mg2+, or Ca2+, and a halogenated closo-borate anion with the structure [ByH(y−z−i)RzXi]2−, [CB(y−1)H(y−z−i)RzXi]−, [C2B(y−2)H(y−t−j−1)RtXj]−, [C2B(y−3)H(y−t−j)RtXj]−, or [C2B(y−3)H(y−t−j−1)RtXj]2−. The parameter y is an integer within a range of 6 to 12, z is an integer within a range of 0 to y, t is an integer within a range of 0 to (y−1), z+i is an integer within a range of 0 to y, t+j is an integer within a range of 0 to y−1, R is a linear, branched-chain, or cyclic C1-C18 alkyl or fluoroalkyl group, and X is F, Cl, Br, and/or I.