Closo-Borate Solid-State Electrolytes via High-Temperature Phase Formation
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Solution Overview
Problem
Solid-state electrolytes in lithium-ion batteries face mechanical stress and degradation due to volume changes from repeated Li+ ion insertion and extraction, leading to internal shorting or loss of conductivity, and current lithium closo-borate salts have limited solubility and ionic conductivity.
Innovation Solution
An ultrahigh concentration of lithium closo-borate salts is achieved in soft ionic solid-state electrolytes by heating a mixture beyond the solubility limit at elevated temperatures, forming a partially fluid phase that, upon cooling, results in a solid-state electrolyte with enhanced room temperature conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium closo-borate salt concentration is increased beyond solubility limit, then ionic conductivity is improved, but the mixture cannot be processed without prolonged heating at high temperature
Solution Approach 1:
The patent changes the temperature parameter during processing, heating the mixture to elevated temperatures (e.g., above the melting point of the SISE) to achieve ultrahigh concentration beyond solubility limits, then cooling to form the final solid-state electrolyte with enhanced conductivity
Solution Approach 2:
The patent utilizes phase transitions by heating the mixture to a molten or partially fluid state where ultrahigh concentration is achieved, then cooling it to form the solid-state electrolyte, leveraging the solubility differences between phases
2Duration of action of moving object
If solid-state electrolyte undergoes mechanical stress from volume changes, then battery cycling is enabled, but the electrolyte cracks and fails
Solution Approach 1:
The patent employs soft ionic solid-state electrolytes with flexible molecular structures (ammonium or phosphonium cations with organic groups) that can accommodate volume changes from Li+ insertion/extraction without cracking, maintaining integrity during battery cycling
Solution Approach 2:
The patent creates a composite solid-state electrolyte by combining lithium closo-borate salt with soft ionic solid-state electrolyte materials, achieving both mechanical flexibility to withstand cycling stress and high ionic conductivity for battery operation
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 resulting electrolyte exhibits significantly higher ionic conductivity than the neat lithium closo-borate salt, with a conductivity more than twice that of the saturated solution, indicating the formation of a new phase with lower activation energy for Li+ migration, thus improving battery performance.
Implementation Method 1
heated to at least 160° C. to form a mixture
Implementation Method 2
held at that temperature for a period sufficient to form a partially fluid phase or composition
Implementation Method 3
Upon cooling the LiCB11H12/Py14CB11H12 mixture to room temperature
Data Source
AI summary
An ultrahigh closo-borate concentration solid-state electrolyte is presented that is a combined salt of an alkali metal or alkali earth metal closo-borate and conductivity enhancing SISE. The combined salt allows significantly higher conductivities in the solid state than the included alkali metal or alkali earth metal closo-borate. The combined salt can be prepared by mechanical combination or combination in solution. The salts can be used in solid-state electrochemical devices.