Li-Ion Battery Positive Electrode Using Mixed Carbon Nanotubes
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Solution Overview
Problem
Current methods for producing lithium-ion rechargeable battery positive electrodes face challenges in achieving both high electrical conductivity and sufficient adhesion of active material particles to the current collector, often resulting in suboptimal battery characteristics due to the use of insulating binders or high-cost electrolytic deposition techniques.
Innovation Solution
A positive electrode is developed using a conductive material comprising a mixture of short and elongated carbon nanotubes, which form a reticulated network structure to enhance conductivity and adhesion without the need for binders, allowing for a higher proportion of active material particles and improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an insulating binder is used in the electrode substance, then adhesion between active material particles and current collector is improved, but electrical conductivity of the electrode deteriorates
Solution Approach 1:
The invention extracts and eliminates the insulating binder component from the electrode substance. By using only conductive materials (carbon nanotubes and conductive carbon powder) without any insulating binders, the electrode achieves both sufficient adhesion and high electrical conductivity, resolving the contradiction between these two properties.
Solution Approach 2:
The invention uses a composite conductive material system consisting of carbon nanotubes and conductive carbon powder. This composite structure provides both mechanical adhesion through the network formation and excellent electrical conductivity through the conductive carbon pathways, eliminating the need for insulating binders.
2Reliability
If no binder is used to reduce resistance, then electrical conductivity is improved, but adhesion between current collector and active material particle deteriorates
Solution Approach 1:
The invention introduces conductive carbon materials (carbon nanotubes and conductive carbon powder) as intermediary substances that perform both adhesion and conductivity functions. These conductive intermediaries replace the traditional dual-role of binders (adhesion only) by providing both mechanical bonding and electrical pathways simultaneously.
3Strength
If electrolytic deposition is used to deposit active material, then adhesion is improved, but production cost increases
Solution Approach 1:
The invention replaces the expensive electrolytic deposition process with a simpler, more cost-effective method using conductive carbon materials as disposable intermediaries. The conductive carbon powder and nanotubes are mixed with the active material and applied to the current collector, providing both adhesion and conductivity without requiring complex electrolytic equipment or processes.
4Reliability
If carbon nanotubes are used as conductive material, then electrical conductivity is improved, but adhesion between active material particles deteriorates
Solution Approach 1:
The invention merges carbon nanotubes with conductive carbon powder to create a synergistic conductive system. The carbon nanotubes provide excellent electrical conductivity and structural framework, while the conductive carbon powder fills gaps and enhances particle-to-particle adhesion, achieving both high conductivity and strong adhesion simultaneously.
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 achieves exceptional electrical conductivity and adhesion, leading to enhanced battery characteristics, including increased energy density and high output capacity, while eliminating the need for insulating binders and reducing production costs.
Implementation Method 1
a conductive material that connects the active material particles to each other... the conductive material includes a first elongated carbon material having a first length and a second elongated carbon material having a second length larger than the first length
Implementation Method 2
exceptional electrical conductivity and adhesion of an electrode active material... high adhesion between the active material particles and sufficient adhesion of the active material particles to the current collector are exhibited
Data Source
AI summary
There is provided a positive electrode for a lithium-ion rechargeable battery in which it is possible to achieve both exceptional electrical conductivity and adhesion of an electrode active material to a current collector and it is possible to dramatically improve battery characteristics compared to those in the related art. A positive electrode for a lithium-ion rechargeable battery includes a current collector; and an electrode active material-containing layer provided on the current collector, wherein the electrode active material-containing layer contains active material particles and a conductive material that connects the active material particles to each other; wherein the mass ratio of the active material particles:the conductive material:other components in the electrode active material-containing layer is 95 to 99.7:0.3 to 5:0 to 1, wherein the conductive material includes a first elongated carbon material having a first length and a second elongated carbon material having a second length larger than the first length, and wherein the ratio of the second length to the first length is 2 or more and 50 or less.