Lithium-Ion Battery Electrolyte and Separator for Steam Sterilization
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Solution Overview
Problem
Current lithium ion batteries used in surgical tools cannot withstand the extreme temperatures of steam autoclave cycles, leading to performance degradation and loss of capacity, as components like polyethylene separators melt and electrolyte salts decompose at high temperatures.
Innovation Solution
Development of lithium ion batteries with unique combinations of current collectors, electrolytes, and separators that have a melt temperature above 150°C, using lithium bis(trifluoromethanesulfonimide) as a lithium salt and a solvent with a boiling point below 140°C, along with a hermetically sealed encasement, to maintain capacity and power performance after exposure to high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If standard lithium ion battery components (polyethylene separator, LiPF6 electrolyte salt, linear carbonate solvents) are used, then the battery can operate at application temperature, but the components cannot withstand steam autoclave temperatures (134°C) and degrade rapidly
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte system. Specifically, it replaces LiPF6 with LiTFSI (lithium bis(trifluoromethanesulfonimide)) and uses a mixture of cyclic carbonate (EC, PC) and chain carbonate (DMC, DEC) solvents instead of pure linear carbonates. This parameter change allows the electrolyte to remain stable at autoclave temperatures while maintaining good performance at application temperatures.
Solution Approach 2:
The patent employs composite material strategies in multiple aspects: (1) The separator uses a composite structure with heat-resistant ceramic coating on polyolefin base, providing both shutdown function and high-temperature stability; (2) The electrolyte is a composite system combining cyclic and chain carbonates with multiple lithium salts; (3) The electrode materials use composite structures such as ceramic-coated active materials. These composite materials enable the battery to withstand autoclave conditions.
2Stability of the object's composition
If the battery is designed to withstand high temperatures (melt temperature >150°C), then sterilization capability is achieved, but the complexity of battery construction increases
Solution Approach 1:
The patent applies local quality by using a tri-layer separator structure where only the heat-resistant ceramic coating layer provides high-temperature stability, while the underlying polyolefin layers maintain their shutdown function at lower temperatures. This localized application of heat-resistant properties allows the battery to achieve autoclave resistance without completely redesigning all components.
Solution Approach 2:
The patent uses a moderate amount of LiTFSI (0.5-1.0 M concentration) combined with LiBOB and LiPF6 in specific ratios, rather than using purely heat-resistant but performance-poor materials. This partial approach achieves sufficient thermal stability for sterilization while maintaining good electrochemical performance, avoiding excessive complexity.
3Ease of manufacture
If current commercial battery components are used, then ease of manufacture is maintained, but corrosion of metal current collectors accelerates at high temperatures leading to delamination
Solution Approach 1:
The patent applies beforehand cushioning by coating the metal current collectors with corrosion-resistant materials (such as carbon or ceramic coatings) before assembly. This protective layer is applied in advance to prevent high-temperature corrosion during autoclave sterilization, thereby preventing subsequent delamination and maintaining manufacturing simplicity.
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 batteries retain at least 80% of their capacity and power performance after exposure to temperatures up to 140°C for several cycles, enabling safe sterilization and continued usability in surgical tools.
Implementation Method 1
a separator that includes a material having a melt temperature of greater than 150° C.
Implementation Method 2
a hermetically sealed encasement
Data Source
AI summary
A lithium ion battery is provided that includes: a positive electrode; a negative electrode; a separator comprising a material having a melt temperature of greater than 150° C.; and an electrolyte including an organic solvent and a lithium salt. A method for sterilizing a lithium ion battery is also provided that includes: providing a lithium ion battery (particularly one as described herein); either charging or discharging the battery to a state of charge (SOC) of 20% to 100%; and steam sterilizing the battery to form a sterilized lithium ion battery.