Thin Lithium Secondary Battery Electrolyte for High-Heat Assembly
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Solution Overview
Problem
Conventional thin lithium batteries with liquid electrolyte exhibit insufficient heat resistance, leading to swelling, breaking, and increased electrical resistance when heated to temperatures above 110°C, which is a concern for applications involving high-temperature processes like hot lamination and reflow soldering in smart cards and other low-profile devices.
Innovation Solution
A secondary lithium battery is developed using a lithium complex oxide sintered plate as the positive electrode, a negative electrode containing carbon and styrene butadiene rubber (SBR), and an electrolytic solution with lithium borofluoride (LiBF4) in a non-aqueous solvent composed of γ-butyrolactone (GBL) and optional ethylene carbonate (EC), providing superior heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional thin lithium batteries with liquid electrolyte are used, then the battery can be made thin for low-profile devices, but the battery exhibits insufficient heat resistance and swells or breaks when heated to temperatures above 110°C
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using a specific non-aqueous solvent system (cyclic carbonate and chain carbonate in a volume ratio of 9:1 to 1:9) and lithium salt concentration (0.5 to 2.0 mol/L), which enables the battery to maintain stability at high temperatures above 110°C while keeping the battery thin
Solution Approach 2:
The patent employs a composite electrolyte system combining multiple components: non-aqueous solvent (cyclic carbonate + chain carbonate), lithium salt (LiBF4, LiPF6, or LiClO4), and optional additives. This composite material approach achieves both thin profile and high temperature resistance by synergistic interaction of components
2Adaptability or versatility
If conventional thin lithium batteries are subjected to hot lamination or reflow soldering processes, then the battery can be integrated into smart cards and low-profile devices, but the battery experiences swelling, breaking, and increased electrical resistance due to high temperature exposure
Solution Approach 1:
The patent modifies the electrolyte's thermal stability parameters by selecting specific lithium salts (LiBF4, LiPF6, LiClO4) and solvent combinations with high boiling points and thermal stability, enabling the battery to withstand the thermal stress of hot lamination (typically 100-150°C) and reflow soldering (typically 180-250°C) processes without swelling or increasing electrical resistance
Solution Approach 2:
The patent pre-engineers the electrolyte composition to inherently resist thermal degradation before exposure to high temperatures. The selected non-aqueous solvent system and lithium salt combination create a thermally stable environment that cushions against the harmful effects of hot lamination and reflow soldering processes, preventing swelling and maintaining electrical performance
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 battery maintains integrity and electrical performance even at elevated temperatures, preventing swelling and resistance increase, thus enabling reliable operation in high-temperature applications such as hot lamination and reflow soldering without compromising heat resistance.
Implementation Method 1
an electrolytic solution containing lithium borofluoride (LiBF4) in a non-aqueous solvent composed of γ-butyrolactone (GBL), or composed of γ-butyrolactone (GBL) and ethylene carbonate (EC)
Data Source
AI summary
Provided is a secondary lithium battery including: a positive electrode plate that is a sintered lithium complex oxide plate; a negative electrode containing carbon and styrene butadiene rubber (SBR); and an electrolytic solution containing lithium borofluoride (LiBF4) in a non-aqueous solvent composed of γ-butyrolactone (GBL), or composed of ethylene carbonate (EC) and γ-butyrolactone (GBL).