Disiloxane Electrolyte for Lithium Battery Safety and Conductivity
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Solution Overview
Problem
Lithium batteries face challenges with the volatility, flammability, and chemical reactivity of organic carbonate electrolytes, and polysiloxane-based electrolytes have limitations in ionic conductivity and cycling performance, restricting their use in high-rate applications.
Innovation Solution
The development of disiloxanes with a backbone of two silicon atoms, where one silicon is linked to a poly(alkylene oxide) or cyclic carbonate moiety, enhancing ionic conductivity and cycling properties by forming electrolytes with lower viscosity and improved electrode wetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic carbonate electrolytes are used, then ionic conductivity is improved, but volatility, flammability, and chemical reactivity worsen
Solution Approach 1:
The patent converts the typically harmful flammability issue by incorporating flame-retardant disiloxane structures into the electrolyte. The siloxane backbone with specific substituents provides inherent flame resistance while the lithium salt composition maintains high ionic conductivity, effectively transforming a safety hazard into a safety feature
Solution Approach 2:
The electrolyte uses composite formulation combining disiloxane solvents with lithium salts and optional cyclic carbonate additives. This composite structure achieves the high ionic conductivity of carbonate-based systems while the disiloxane framework provides superior safety profile with reduced flammability and volatility
2Duration of action of stationary object
If polysiloxane-based electrolytes are used, then viscosity is reduced, but electrode wetting and cycling performance worsen
Solution Approach 1:
The patent optimizes the balance between viscosity and wetting by adjusting disiloxane molecular structure (varying R1-R6 groups), controlling electrolyte temperature, and optimizing lithium salt concentration. This parameter optimization ensures viscosity remains low enough for good electrode wetting while maintaining the safety advantages of siloxane structures
Solution Approach 2:
The electrolyte composition is optimized to have different local properties: the bulk electrolyte maintains low viscosity for safety and flow, while the electrode interface achieves optimal wetting through controlled composition and surface interaction, allowing simultaneous satisfaction of both requirements in different regions of the system
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
Disiloxanes yield electrolytes with high ionic conductivity and enhanced cycling properties, enabling batteries to retain over 90% discharge capacity after 100 cycles, suitable for high-energy and long-cycle-life applications like biomedical devices and satellites.
Implementation Method 1
polysiloxane based electrolytes typically have a low ionic conductivity... Disiloxanes yield electrolytes with high ionic conductivity
Implementation Method 2
forming electrolytes with lower viscosity and improved electrode wetting
Data Source
AI summary
One example of the disiloxanes include a backbone with a first silicon and a second silicon. The first silicon is linked to a first substituent selected from a group consisting of: a first side chain that includes a cyclic carbonate moiety; a first side chain that includes a poly(alkylene oxide) moiety; and a first cross link links the disiloxane to a second siloxane and that includes a poly(alkylene oxide) moiety. In some instance, the second silicon is linked to a second substituent selected from a group consisting of: a second side chain that includes a cyclic carbonate moiety, and a second side chain that includes a poly(alkylene oxide) moiety.