Lithium-Sulfur Battery Solid Nitrate Holder for Shuttle Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-sulfur batteries face a decrease in coulombic efficiency due to the dissolution of lithium polysulfides in the electrolyte solution, leading to a shuttle phenomenon that reduces discharge capacity and increases charge capacity, and existing additives like lithium nitrate are consumed quickly, limiting the number of cycles with high efficiency.
Innovation Solution
Incorporating a lithium nitrate holder in a solid state, positioned on the outermost layer of the cell stack, to continuously supply lithium nitrate during battery operation, maintaining high coulombic efficiency for a long cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium nitrate is added to the electrolyte solution to prevent shuttle phenomenon, then coulombic efficiency is improved, but lithium nitrate is gradually consumed resulting in rapid decrease in efficiency after consumption
Solution Approach 1:
The lithium nitrate holder enables the system to self-replenish lithium nitrate during battery operation. The holder automatically supplies lithium nitrate to the electrolyte solution as it dissolves, maintaining a stable concentration without external intervention, thus resolving the contradiction between improving efficiency and extending cycle life.
Solution Approach 2:
Lithium nitrate is pre-loaded in the holder in a solid state before battery operation begins. This preliminary preparation ensures that lithium nitrate is readily available to be supplied to the electrolyte solution when needed, preventing the shuttle phenomenon from the start and maintaining efficiency throughout extended cycling.
2Reliability
If lithium polysulfide dissolves in electrolyte solution, then electrochemical reaction area is reduced, but adding lithium nitrate additive is consumed quickly
Solution Approach 1:
The lithium nitrate is extracted from the electrolyte solution and stored separately in the holder in solid state. This separation allows the lithium nitrate to be replenished on-demand from the holder, preventing its rapid consumption while maintaining its function of reducing lithium polysulfide dissolution and protecting capacity.
3Duration of action of stationary object
If lithium nitrate holder is positioned on outermost layer of cell stack, then continuous supply is achieved, but device structure becomes more complex
Solution Approach 1:
The lithium nitrate holder is designed to perform multiple functions: it stores lithium nitrate in solid state, controls its dissolution rate, and positions itself on the outermost layer for optimal supply to the electrolyte solution. This multi-functionality achieves continuous supply while minimizing structural complexity by integrating these functions into a single component.
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 lithium nitrate holder in a solid state ensures continuous supply of lithium nitrate, preventing a decrease in coulombic efficiency and maintaining it at 98% or more for 200 cycles or more, thereby enhancing the battery's lifetime and performance.
Implementation Method 1
lithium nitrate holder in a solid state... continuously supply lithium nitrate during the operation of battery
Implementation Method 2
lithium polysulfide having a high sulfur oxidation number is a material with strong polarity, and is readily dissolved in an electrolyte solution including a hydrophilic organic solvent
Implementation Method 3
Lithium polysulfide dissolved in the electrolyte solution diffuses from a positive electrode due to a difference in the concentration
Implementation Method 4
an oxidation reaction of lithium occurs in a negative electrode of a lithium-sulfur battery, and a reduction reaction of sulfur occurs in a positive electrode
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a lithium secondary battery comprising a lithium nitrate holder in a solid state, which is capable of continuously supplying lithium nitrate while operating the battery, thereby maintaining high coulombic efficiency for a long period of time.