Separator Microcapsules Additive Release
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Solution Overview
Problem
Lithium ion polymer batteries face challenges with low capacities and insufficient low-temperature discharge capacities compared to lithium ion batteries, and existing separators do not effectively control the release of additives to prevent side reactions and enhance thermal stability.
Innovation Solution
A separator with a porous substrate and a porous coating layer containing inorganic particles and a binder polymer, along with microcapsules dispersed within, which release additives such as those for forming a solid electrolyte interface, inhibiting side reactions, and improving thermal stability in a controlled manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives are continuously present in the electrolyte solution to improve cycle performance, then cycle stability is improved, but side reactions increase causing capacity fading
Solution Approach 1:
The patent applies preliminary action by pre-loading additives into microcapsules that are embedded in the separator before battery assembly. The additives are prepared in advance but kept encapsulated and inactive during normal operation. When needed (e.g., during thermal runaway or abnormal conditions), the microcapsules rupture and release the additives immediately, providing the beneficial effects without continuous presence that would cause side reactions.
Solution Approach 2:
The microcapsules serve as an intermediary carrier between the additive and the electrolyte solution. Instead of adding additives directly to the electrolyte where they would continuously cause side reactions, the patent uses microcapsules as a mediating structure that controls the timing and location of additive release, allowing the additive to act only when and where needed.
2Reliability
If more additives are added to the electrolyte solution to ensure safety during abnormal operation, then safety is improved, but the complexity of battery assembly increases
Solution Approach 1:
The patent merges the safety function into the separator structure by embedding microcapsules containing additives directly within the separator matrix. This integration eliminates the need for separate additive addition steps during electrolyte preparation and battery assembly. The separator itself becomes the delivery system for safety additives, reducing assembly complexity while maintaining enhanced safety.
Solution Approach 2:
The separator with embedded microcapsules provides self-service safety functionality. During normal operation, the separator performs its primary function of ion transport and physical separation. During abnormal conditions (thermal runaway, internal short circuit), the microcapsules automatically rupture and release additives without requiring external intervention or additional safety systems, making the battery self-protecting.
3Temperature
If lithium ion polymer batteries use polymer electrolytes to improve safety, then thermal stability is improved, but capacity density and low-temperature discharge capacity decrease
Solution Approach 1:
The patent applies local quality by maintaining the polymer electrolyte structure for thermal stability in the bulk separator, while locally introducing microcapsules containing performance-enhancing additives at strategic positions within the separator. This allows different regions of the battery to have different functional characteristics: the polymer matrix provides thermal stability, while the localized additive release zones enhance capacity and low-temperature performance without compromising safety.
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 controlled release of additives minimizes side reactions and maintains optimal performance of electrochemical devices by ensuring additives are released only when needed, enhancing thermal stability and cycle performance.
Implementation Method 1
microcapsules having a controlled release characteristic, and an electrochemical device having the same
Data Source
AI summary
The present invention refers to a separator, comprising a porous substrate having multiple pores; a porous coating layer formed on at least one area selected from at least one surface of the porous substrate and the pores of the porous substrate, and comprising multiple inorganic particles and a binder polymer, the binder polymer being existed on a part or all of the surface of the inorganic particles to connect and immobilize the inorganic particles therebetween; and microcapsules dispersed in at least one area selected from the pores of the porous substrate and pores formed by vacant spaces between the inorganic particles present in the porous coating layer, and containing therein an additive for improving the performances of an electrochemical device, and an electrochemical device having the same.