Active-Material-Free Battery Anode Using CNT-Polyurethane Layer
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Solution Overview
Problem
The negative electrode active material in nonaqueous electrolyte secondary batteries contributes significantly to the mass of the battery, and its removal could potentially reduce the weight of the battery while improving coulombic efficiency.
Innovation Solution
A negative electrode composed of a current collector with a layer containing polyurethane resin and single-walled carbon nanotubes, without a negative electrode active material, is used, where the polyurethane resin may contain lithium or sodium salts and alicyclic polyisocyanate, with a specific mass ratio and thickness of the layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a negative electrode active material layer is formed on the current collector, then the battery can store and release energy, but the mass of the negative electrode increases
Solution Approach 1:
The invention extracts and removes the negative electrode active material from the electrode structure, retaining only the current collector and a conductive layer. This eliminates the heavy active material while preserving essential electrode functions through the conductive layer's ability to facilitate electron transport and lithium ion insertion/extraction.
Solution Approach 2:
The invention changes the fundamental composition parameters of the negative electrode by replacing traditional active materials with a conductive layer made of conductive polymer and carbon nanotubes. This parameter change transforms the electrode from an energy-storing component to an energy-transmitting component, achieving weight reduction while maintaining electrochemical functionality.
2Weight of moving object
If the negative electrode active material is removed to reduce mass, then the weight of the battery decreases, but the coulombic efficiency may deteriorate
Solution Approach 1:
The invention employs a composite structure combining conductive polymer and carbon nanotubes in the conductive layer. This composite material system provides both electrical conductivity for electron transport and sufficient surface area for lithium ion insertion/extraction, ensuring high coulombic efficiency while maintaining the weight-reduced design without active material.
Solution Approach 2:
The conductive layer acts as an intermediary between the current collector and the electrolyte, facilitating the transfer of electrons and lithium ions. This intermediary structure compensates for the absence of traditional active material by providing a functional interface that maintains efficient charge transfer and high coulombic efficiency.
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
This configuration enhances coulombic efficiency without increasing the mass of the negative electrode, utilizing an ionic liquid electrolyte for improved charge/discharge performance.
Implementation Method 1
a layer containing a polyurethane resin and a single-walled carbon nanotube placed on the current collector
Implementation Method 2
the polyurethane resin contains a lithium salt and/or a sodium salt of an anionic polyurethane resin
Data Source
AI summary
A negative electrode for a nonaqueous electrolyte secondary battery which can improve the coulombic efficiency without a negative electrode active material is provided. The negative electrode for a nonaqueous electrolyte secondary battery according to an embodiment has a current collector and a layer containing a polyurethane resin and single-walled carbon nanotubes placed on the current collector and does not contain a negative electrode active material.