BN Nanotube Separator Coating for Stable Li-Ion Transport
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Solution Overview
Problem
The charge/discharge efficiency and charging time of lithium ion secondary batteries are affected by the ionic conductivity of lithium ions, necessitating an improvement in this conductivity to enhance battery performance.
Innovation Solution
A lithium ion secondary battery design incorporating a separator with a coating layer of boron nitride nanotubes, which are surface-treated for hydrophilicity or hydrophobicity, and attached at an angle to the separator surface, forming a passage for lithium ion transport, thereby improving ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is added to the separator to improve ionic conductivity, then lithium ion transport rate increases, but device complexity increases
Solution Approach 1:
The coating layer incorporates boron nitride nanotubes with high porosity (aspect ratio of 20-6000) that create numerous channels for lithium ion transport. The porous structure allows ions to move through the coating layer efficiently while maintaining a relatively thin overall layer, thus improving ionic conductivity without proportionally increasing complexity.
Solution Approach 2:
The separator is enhanced by combining it with a coating layer containing boron nitride nanotubes, forming a composite structure. This composite approach leverages the unique properties of BN nanotubes (high aspect ratio, thermal stability) to improve ionic conductivity while the coating layer serves multiple functions simultaneously (ion transport, thermal management).
2Use of energy by moving object
If the separator operates at high temperature, then battery energy density increases, but thermal shrinkage of the separator increases
Solution Approach 1:
The coating layer fundamentally changes the thermal properties of the separator by incorporating boron nitride nanotubes with exceptional thermal stability. This material parameter change allows the separator to maintain its dimensional stability at elevated temperatures (60°C and above) where conventional separators would shrink, enabling the battery to operate at higher temperatures for improved energy density.
Solution Approach 2:
The boron nitride nanotube coating layer compensates for the thermal expansion and shrinkage tendencies of the base separator material. The BN nanotubes maintain their structural integrity at high temperatures and provide a stabilizing effect that counteracts the thermal shrinkage of the separator, allowing safe operation at elevated temperatures that improve battery energy density.
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 battery exhibits enhanced ionic conductivity across various temperatures, minimizing performance degradation and increasing stability, with improved lithium ion transport rates and reduced thermal shrinkage of the separator.
Implementation Method 1
the charge/discharge efficiency and charging time of lithium ion secondary batteries are affected by the ionic conductivity of lithium ions
Implementation Method 2
the boron nitride nanotubes may be surface-treated to have hydrophilicity or hydrophobicity
Implementation Method 3
improved lithium ion transport rates and reduced thermal shrinkage of the separator
Data Source
AI summary
Provided is a lithium ion secondary battery including an electrode assembly including an anode, a cathode, and a separator disposed between the anode and the cathode, a case accommodating the electrode assembly, and an electrolyte filling the case, wherein the separator includes a coating layer on at least one of both sides of the separator, and the coating layer includes boron nitride nanotubes.