Polymer-Shell SEI Capsule for Lithium-Sulfur Battery Longevity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The lithium-sulfur secondary battery faces rapid efficiency reduction and discharging capacity lowering due to damage to the solid electrolyte interface layer (SEI layer) on the negative electrode, which is exacerbated by the exposure of lithium metal to the electrolyte solution.
Innovation Solution
A capsule comprising a core with materials like LiNO3 for forming and restoring the SEI layer, encapsulated in a polymer shell formed by crosslinking an epoxy compound and a crosslinking agent, is used to maintain a constant level of the additive in the battery, preventing SEI layer damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of additive material is increased to prevent damage to the solid electrolyte interface layer, then the protection of SEI layer is improved, but the energy density is lowered due to the additive acting as a resistor
Solution Approach 1:
The capsule structure pre-positions the additive material in a controlled state before it is needed. The shell maintains the additive in an encapsulated form that prevents premature reaction, while the core contains the additive material ready for controlled release when SEI layer damage occurs, thus protecting the layer without continuously consuming additive that would act as a resistor
Solution Approach 2:
The invention changes the physical state and release parameters of the additive material by enclosing it in a capsule with a specific shell structure. The additive is maintained in a controlled environment within the capsule, allowing it to be released in controlled amounts rather than being present in high concentrations throughout the electrolyte, thus maintaining energy density while providing SEI layer protection
2Reliability
If the content of additive material is increased to restore the solid electrolyte interface layer, then the restoration capability is improved, but the lifespan is shortened due to the additive acting as a resistor
Solution Approach 1:
The capsule structure enables the additive material to serve itself by automatically releasing when and where it is needed - when SEI layer damage occurs at the negative electrode. The capsule无需 external control and self-regulates the additive release based on the battery's actual needs, providing restoration capability without the continuous presence of excessive additive that would shorten lifespan
Solution Approach 2:
The capsule shell acts as an intermediary between the additive material and the electrolyte solution. It controls the interaction between the additive and the battery environment, allowing the additive to perform its restoration function when needed while preventing it from continuously acting as a resistor that would reduce battery lifespan
3Reliability
If a capsule with polymer shell is used to maintain additive at constant level, then the SEI layer maintenance is improved, but the device complexity is increased
Solution Approach 1:
The invention segments the additive material from the electrolyte solution by enclosing it in a separate capsule structure. This segmentation allows the additive to be maintained at a constant level within the capsule while still providing protection to the SEI layer, achieving reliable maintenance without requiring complex external control systems
Solution Approach 2:
The polymer shell of the capsule provides a flexible yet protective barrier that maintains the additive at a constant level while allowing the capsule to integrate into the battery structure. The shell's properties enable it to maintain the additive without adding excessive complexity to the overall device
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 capsule effectively maintains the SEI layer on the negative electrode for a longer time, preventing lithium metal exposure, thus suppressing efficiency drops and capacity degradation, thereby improving the lithium-sulfur secondary battery's lifetime characteristic.
Implementation Method 1
a shell made of a polymer surrounding the core
Implementation Method 2
a solid electrolyte interface layer (SEI layer) is formed by the reaction of the additive with the lithium metal
Data Source
AI summary
A capsule for a lithium-sulfur secondary battery, wherein the capsule includes a core containing a material required for formation and restoration of a solid electrolyte interface layer (SEI layer) and a shell including a polymer surrounding the core. The shell maintains the material required for formation and restoration of the solid electrolyte interface layer (SEI layer) at a constant level during operation of the battery, thereby exhibiting the effect of maintaining the solid electrolyte interface layer (SEI layer) on the negative electrode for a long time.