Gelled Lithium Battery Electrolyte Using Lithium Nitrate for Longer Cycle Life
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Solution Overview
Problem
Lithium-metal-polymer batteries require high operating temperatures and suffer from lithium foam formation at the negative electrode, leading to reduced battery lifetime due to inadequate passivation layers, and lithium-sulfur batteries face redox shuttle issues with polysulfide ions, limiting their cyclability.
Innovation Solution
Employing lithium nitrate as the sole lithium salt in a gelled rechargeable lithium metal battery without polysulfide ions improves the quality of the passivation layer and extends battery lifetime by enhancing the electrolyte-negative electrode interface, with lithium nitrate present in the gelled non-aqueous electrolyte or positive electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-metal-polymer batteries use conventional lithium salts and solid polymer electrolytes, then ion conductivity is maintained, but the batteries require high operating temperatures (60-80°C) and form lithium foam at the negative electrode, reducing battery lifetime
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using lithium nitrate as the sole lithium salt in a gelled electrolyte system, replacing conventional lithium salts. This parameter change enables the battery to operate at lower temperatures (0-60°C) while improving passivation layer quality and reducing lithium foam formation, thus resolving the contradiction between operating temperature and battery lifetime.
Solution Approach 2:
The patent employs a composite gelled electrolyte material combining lithium nitrate with gel matrix components, creating a new material system that exhibits both low-temperature operability and improved electrode interface properties. This composite material approach simultaneously addresses the temperature requirement and lifetime reliability issues.
2Reliability
If lithium nitrate is used as sole lithium salt in gelled electrolyte, then passivation layer quality improves and battery lifetime extends, but ion conductivity may be reduced compared to conventional lithium salts
Solution Approach 1:
The patent optimizes the concentration and purity parameters of lithium nitrate in the gelled electrolyte to achieve a balance between passivation layer formation and ion conductivity. By precisely controlling these parameters, the system maintains adequate ion conductivity while maximizing the beneficial effects of lithium nitrate on electrode interface quality and battery lifetime.
3Temperature
If gelled electrolyte is used instead of solid polymer electrolyte, then operating temperature range expands to 0-60°C, but lithium foam forms at the negative electrode due to poor passivation layer quality
Solution Approach 1:
The patent changes the chemical composition parameter by selecting lithium nitrate as the lithium salt, which fundamentally alters the electrochemical behavior at the negative electrode interface. This parameter change promotes the formation of high-quality passivation layers even at low temperatures, preventing lithium foam formation while maintaining the expanded operating temperature range of the gelled electrolyte 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
The use of lithium nitrate as the sole lithium salt in gelled lithium batteries improves the lithium deposit quality and battery performance, achieving stable discharge capacity and coulombic efficiency over multiple cycles, even at lower operating temperatures.
Implementation Method 1
lithium nitrate as sole lithium salt providing the ion conductivity
Implementation Method 2
a lithium foam is formed at the surface of the negative electrode. This lithium foam is due to an electrodeposit of poor quality
Data Source
AI summary
The invention relates to the use of lithium nitrate as sole lithium salt providing the ion conductivity in a gelled rechargeable lithium metal battery not comprising polysulfide ions, for improving its lifetime.