Lithium Gel Battery Salt Mixture for Foam-Free Electrodeposition
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Solution Overview
Problem
Lithium-metal-gel batteries face issues with lithium foam formation due to poor electrodeposition, leading to reduced lifespan and robustness of the passivation layer, and existing solutions are not entirely satisfactory, especially when polysulfide ions are absent, as seen in lithium-sulfur batteries without a sulfur-based positive electrode.
Innovation Solution
A mixture of salts with a nitrate anion and a second lithium salt, such as lithium bis(trifluoromethanesulfonyl)imide, is used as ionic conductivity promoters in a gelled metallic lithium rechargeable battery, maintaining a molar ratio greater than 1.5, to improve the quality and stability of the passivation layer and extend battery lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a gel electrolyte is used in lithium-metal batteries, then the operating temperature range is improved (0 to 60°C), but lithium foam forms on the negative electrode due to poor electrodeposition quality
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific mixture of lithium salts (lithium nitrate and lithium perchlorate in a molar ratio between 1:4 and 1:10). This parameter change modifies the electrodeposition process to produce high-quality lithium metal without foam formation, while maintaining the beneficial low-temperature operating characteristics of gel electrolytes.
Solution Approach 2:
The patent uses a composite electrolyte system combining gel matrix with a specific dual-salt composition. The combination of lithium nitrate and lithium perchlorate creates a synergistic effect that improves electrodeposition quality while preserving the gel electrolyte's wide temperature operating range, solving both thermal performance and deposition quality requirements.
2Reliability
If lithium nitrate is added to improve passivation layer quality, then the passivation layer robustness is improved, but the solution is not satisfactory when polysulfide ions are absent
Solution Approach 1:
The patent modifies the electrolyte composition by establishing a specific molar ratio between lithium nitrate and lithium perchlorate (1:4 to 1:10). This parameter optimization ensures that lithium nitrate effectively improves passivation layer robustness without causing issues related to polysulfide presence, making the solution universally applicable to various lithium-metal battery systems regardless of polysulfide content.
Solution Approach 2:
Lithium perchlorate acts as an intermediary substance that works synergistically with lithium nitrate. This combination allows the system to achieve robust passivation layer formation without the complications associated with polysulfide ions, enabling the solution to be applied broadly across different battery chemistries including non-sulfur based systems.
3Reliability
If the passivation layer quality is insufficient, then the battery lifespan is reduced, but improving it requires expensive lithium salts with limited cycle lives
Solution Approach 1:
The patent optimizes the concentration and ratio parameters of lithium salts in the electrolyte. By using lithium nitrate and lithium perchlorate in a specific molar ratio (1:4 to 1:10), the system achieves robust passivation layer formation that extends battery lifespan, while avoiding the use of excessively expensive salts with limited cycle stability. This parameter optimization balances cost, performance, and longevity requirements.
Solution Approach 2:
The patent employs a composite salt system combining lithium nitrate and lithium perchlorate that provides both cost-effectiveness and long cycle life. This composite approach creates a synergistic effect where the combination of salts delivers superior passivation layer quality and extended battery lifespan without the drawbacks of using单一 expensive salts, achieving both economic and performance objectives.
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 this salt mixture enhances the ionic conductivity and stability of the passivation layer, leading to improved cycling performance and extended battery lifespan, even in the absence of polysulfide ions, by maintaining a robust and conductive layer on the lithium electrode.
Implementation Method 1
A mixture of salts with a nitrate anion and a second lithium salt is used as ionic conductivity promoters in a gelled metallic lithium rechargeable battery
Implementation Method 2
the use of this salt mixture enhances the ionic conductivity and stability of the passivation layer, leading to improved cycling performance and extended battery lifespan
Data Source
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AI summary
The invention relates to the simultaneous use of a first salt comprising a nitrate anion (NO 3 -) and a second salt comprising an anion other than nitrate, wherein at least one of the first and second salts is a lithium salt, as ionic conductivity promoters in a rechargeable lithium-metal-gel battery. The invention also relates to a lithium-gel battery comprising a mixture of said first salt and said second salt, to a non-aqueous gel electrolyte comprising such a mixture, and to a positive electrode for a lithium battery comprising said mixture.