Hybrid Battery Separator Structure for Lithium Dendrite Suppression
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in suppressing the growth of lithium dendrites, maintaining ionic conductivity, and ensuring mechanical properties, especially during repeated charging and discharging cycles.
Innovation Solution
A hybrid separator is introduced, comprising a lithium ion conductive flexible polymer layer disposed on at least one surface of a porous substrate, which enhances lithium ionic conductivity and mechanical properties while suppressing dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyolefin-based porous substrate is used as separator, then mechanical strength and thermal stability are improved, but lithium dendrite growth suppression and ionic conductivity at low porosity are worsened
Solution Approach 1:
The patent applies composite materials by combining a polyolefin-based porous substrate with a flexible polymer layer to create a hybrid separator. The polyolefin substrate provides mechanical strength and thermal stability, while the flexible polymer layer suppresses lithium dendrite growth and enhances ionic conductivity. This composite structure resolves the contradiction by integrating materials with complementary properties, allowing the separator to simultaneously achieve high mechanical strength and effective dendrite suppression.
Solution Approach 2:
The patent applies local quality by creating a flexible polymer layer with specific properties (high elasticity, lithium ion conductivity) that is disposed on the surface of the porous substrate. This layer has different local properties from the substrate itself, providing dendrite suppression and ionic conductivity enhancement at the critical interface where lithium ions interact with the separator, while the bulk substrate maintains its mechanical strength.
2Productivity
If separator thickness is reduced to increase battery capacity, then energy density is improved, but mechanical properties and safety are worsened
Solution Approach 1:
The hybrid separator combines a thin polyolefin substrate with a flexible polymer layer to achieve high energy density while maintaining mechanical properties. The composite structure allows the separator to be made thinner than conventional separators because the flexible polymer layer provides reinforcement and dendrite suppression functionality that compensates for the reduced substrate thickness, thereby improving energy density without sacrificing mechanical strength or safety.
Solution Approach 2:
The patent applies flexible shells and thin films by using a flexible polymer layer that can be disposed in a thin configuration on the porous substrate. This flexible layer maintains mechanical integrity and provides dendrite suppression even when the overall separator thickness is reduced, enabling the battery to achieve higher energy density while preserving safety and mechanical properties.
3Strength
If porosity is reduced to maintain mechanical properties, then mechanical strength is improved, but lithium ionic conductivity is worsened
Solution Approach 1:
The patent applies composite materials by combining a porous substrate with a flexible polymer layer that has high lithium ion conductivity. The porous substrate provides mechanical strength with reduced porosity, while the flexible polymer layer compensates for the reduced ionic conductivity by providing alternative pathways for lithium ion transport. This composite structure allows the separator to maintain both mechanical strength and adequate ionic conductivity.
Solution Approach 2:
The flexible polymer layer acts as an intermediary that facilitates lithium ion transport between the porous substrate and the electrolyte. Even when the substrate porosity is reduced to maintain mechanical strength, the flexible polymer layer provides a conductive pathway for lithium ions, mediating the transport process and ensuring adequate ionic conductivity is maintained.
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 hybrid separator effectively maintains high lithium ionic conductivity (10−4 to 10−2 S/cm) and mechanical strength, significantly reducing dendrite growth and improving battery stability and lifespan.
Implementation Method 1
a lithium ion conductive flexible polymer layer disposed on at least one surface of a porous substrate
Implementation Method 2
a porous substrate... configured to physically separate the positive and negative electrodes while allowing ions to pass through
Implementation Method 3
hybrid separator... capable of suppressing the growth of lithium dendrites
Data Source
AI summary
Hybrid separators and lithium secondary batteries including the hybrid separators are disclosed. In an embodiment, a lithium secondary battery includes a negative electrode, a positive electrode, a separator disposed between the negative electrode and the positive electrode, and a liquid electrolyte, wherein the separator is a hybrid separator including a porous substrate and a lithium ion conductive flexible polymer layer disposed on at least one surface of the porous substrate, and a lithium ionic conductivity of the hybrid separator is 10−4 to 10−2 S/cm. The hybrid separator that includes the flexible polymer layer based on some embodiments of the disclosed technology can improve the mechanical strength of the separator and significantly reduce the formation of lithium dendrites during charging and discharging cycles.