Lithium Ion Battery Separator Ceramic Clusters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries face issues with low ion conductivity in non-aqueous electrolytes, leading to high internal impedance, reduced battery current, and the risk of short circuits due to separator melting or contraction at high temperatures.
Innovation Solution
A porous separator membrane formed by sintering or dissolving and re-crystallizing ceramic particles, such as zirconium oxide, with a high cross-sectional pore ratio and bonded using a polymer resin binder, which is heat-resistant and prevents electrode short circuits by maintaining ion permeability and structural integrity at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-aqueous electrolytes are used to enable high voltage operation, then electromotive force increases to 3-4V, but ion conductivity decreases leading to high internal impedance
Solution Approach 1:
The patent employs a porous separator membrane with optimized pore structure to enhance ion conductivity. The porous structure provides multiple pathways for lithium ion transport, compensating for the inherently low ion conductivity of non-aqueous electrolytes while maintaining the high voltage operation capability enabled by these electrolytes.
Solution Approach 2:
The patent uses a composite separator structure combining polyolefin base material with ceramic coatings or modified pore structures. This composite approach maintains the thermal shutdown function of polyolefin while adding ion conductivity enhancement through the ceramic or modified porous structure, addressing both the high voltage requirement and ion conductivity limitation.
2Productivity
If separator permeability is increased to improve ion movement, then battery current increases, but separator mechanical strength decreases leading to potential short circuits
Solution Approach 1:
The patent employs composite separator structures where a polyolefin base layer provides mechanical strength and thermal shutdown capability, while ceramic coatings or modified porous layers enhance ion permeability. This composite construction allows high battery current through improved ion movement while maintaining separator integrity and preventing short circuits.
Solution Approach 2:
The patent applies different properties to different regions or layers of the separator. The base layer maintains high mechanical strength for structural integrity, while the surface or pore structure is optimized for high ion permeability. This local differentiation allows the separator to simultaneously support high battery current and prevent short circuits.
3Reliability
If polyolefin separator is used for thermal shutdown function, then safety against overheating is improved, but separator melts and contracts at high temperatures causing short circuits
Solution Approach 1:
The patent combines polyolefin base material with heat-resistant ceramic coatings or high-temperature stable polymers. The polyolefin layer provides the thermal shutdown function by closing pores at elevated temperatures, while the ceramic or heat-resistant layer maintains structural integrity and prevents melting or contraction even at higher temperatures, avoiding short circuits.
Solution Approach 2:
The patent applies heat-resistant ceramic coatings or stabilizing layers to the separator beforehand to prevent the catastrophic failure that would occur if the polyolefin separator alone were exposed to extreme temperatures. This pre-protection allows the separator to perform its thermal shutdown function while being cushioned against the harmful effects of excessive heat that would cause melting and short circuits.
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 solution enhances battery discharge characteristics, cycle life, and safety by preventing short circuits and maintaining ion conductivity, even at high temperatures, while reducing the risk of overheating and mechanical stress on the separator.
Implementation Method 1
the cross-sectional pore ratio of the separator and the wettability of the separator to the electrolyte are important characteristics of the separator for determining battery performance
Implementation Method 2
The pores function as passages for the electrolyte solution, and more specifically, for lithium ions
Implementation Method 3
If the temperature of the separator increases beyond a predetermined level due to some abnormalities in the battery, the polyolefin-based porous membrane of the separator becomes soft and partially melts
Data Source
AI summary
A lithium ion secondary battery is provided. The lithium ion secondary battery generally comprises an electrode assembly, a container for accommodating the electrode assembly; and an electrolyte. The electrode assembly comprises two electrodes having opposite polarities and a separator. The separator comprises a porous membrane comprising clusters of ceramic particles. The porous membrane is formed by bonding the particle clusters with a binder. Each particle cluster is formed either by sintering or by dissolving and re-crystallizing all or a portion of the ceramic particles. The ceramic particles comprise a ceramic material having a band gap. Each particle cluster may have the shape of a grape bunch or a lamina, and may be formed by laminating scale or flake shaped ceramic particles.