Lithium Battery Electrolyte Additive for Polysulfide Shuttle Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-sulfur batteries face issues with low lifetime due to lithium polysulfide dissolution in the electrolyte, leading to capacity loss and decreased ion conductivity, and existing solutions like LiNO3 consume lithium, limiting their effectiveness in repeated charging and discharging.
Innovation Solution
An electrolyte for lithium-secondary batteries incorporating xylylene diamine (XDA) as an additive, which reduces the shuttle phenomenon and enhances charging performance without relying on LiNO3, thereby maintaining lithium metal protection and improving battery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiNO3 is used as an electrolyte additive to form a protective layer on Li metal negative electrode, then the Li negative electrode is protected, but the Li protective layer formation consumes LiNO3 leading to loss of protecting capability after repeated charging and discharging
Solution Approach 1:
The patent changes the chemical composition parameter of the electrolyte additive from LiNO3 to a diamine compound (specifically xylylenediamine or its derivatives). This substitution maintains the protective function on Li metal while eliminating the consumption issue, as the diamine compound forms a stable protective layer without being depleted during cycling.
Solution Approach 2:
The patent replaces the consumable LiNO3 additive with a diamine compound that provides sustained protection. The diamine-based additive creates a stable protective layer that does not require continuous replenishment, effectively transitioning from a disposable protective mechanism to a durable one.
2Productivity
If lithium polysulfide is dissolved in the electrolyte, then electrochemical reaction occurs, but the lithium polysulfide diffuses toward negative electrode causing capacity loss and shuttle phenomenon
Solution Approach 1:
The diamine compound acts as an intermediary substance that mediates between the lithium polysulfide and the electrodes. It forms a protective layer that prevents direct diffusion of lithium polysulfide to the negative electrode while still allowing necessary electrochemical reactions to occur at the positive electrode, thus reducing the shuttle phenomenon and capacity loss.
Solution Approach 2:
The patent converts the harmful effect of lithium polysulfide dissolution and diffusion into a beneficial outcome. By using the diamine compound, the system allows controlled interaction with lithium polysulfide that results in forming a protective layer, thereby transforming the previously harmful shuttle phenomenon into a protective mechanism.
3Stability of the object's composition
If lithium polysulfide reacts with lithium metal negative electrode through continuous charge and discharge, then lithium sulfide is fixed on the lithium metal surface, but reaction activity decreases and potential problems worsen
Solution Approach 1:
The diamine compound serves as an intermediary that controls the interaction between lithium polysulfide and lithium metal. It allows beneficial fixation of lithium sulfide on the lithium metal surface while preventing excessive or harmful reactions, thus maintaining reaction activity and avoiding potential degradation issues.
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 xylylene diamine in the electrolyte effectively reduces the shuttle phenomenon and supports stable charging, maintaining battery performance and extending the battery's lifespan by controlling lithium consumption and enhancing ion conductivity.
Implementation Method 1
Lithium polysulfide (Li2Sx, x=8, 6, 4, 2) is an intermediate product produced during an electrochemical reaction of a lithium-sulfur battery, and has high solubility for an organic electrolyte. The lithium polysulfide dissolved in the electrolyte is gradually diffused toward a negative electrode... attempts have been made to form a layer capable of protecting a Li metal negative electrode using an electrolyte additive such as LiNO3
Implementation Method 2
The lithium polysulfide dissolved in the electrolyte is gradually diffused toward a negative electrode, and is out of an electrochemical reaction area of a positive electrode, and therefore, is not able to participate in an electrochemical reaction of the positive electrode resulting in capacity loss. In addition, lithium polysulfide elution increases viscosity of an electrolyte decreasing ion conductivity
Implementation Method 3
the lithium polysulfide reacts with a lithium metal negative electrode through a continuous charge and discharge reaction fixing lithium sulfide (Li2S) on the lithium metal surface, which causes problems of decreasing reaction activity and worsening potential problems
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to an electrolyte for a lithium-secondary battery including a solvent, a lithium salt and an additive, wherein the additive is a diamine-based compound, and a lithium-secondary battery including the same.