Negative Electrode Active Material Carbon Coating

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing negative electrode active materials for lithium ion batteries have insufficient rate capability and cycle characteristics, particularly in high-current load applications, due to high electrode impedance and volume changes during charge and discharge.

Innovation Solution

A carbon-containing composite is developed by integrating conductive nanofibers and conductive carbon particles with a carbon material, where the mixture is coated using a chemical vapor phase deposition method to reduce contact resistance and prevent path detachment from volume changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional negative electrode active materials are used, then manufacturing is simple, but rate capability and cycle characteristics are insufficient

Engineering Contradiction:

Improverate capability and cycle characteristicsVSAvoidcomposite structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies composite materials by combining active material particles with conductive nanofibers and conductive carbon particles to form a integrated composite structure. This composite approach improves rate capability and cycle characteristics by creating multiple conductive pathways while maintaining structural integrity during charge-discharge cycles, directly resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent merges multiple functional components (active material, conductive nanofibers, conductive carbon particles) into a single integrated composite structure where they work synergistically. The conductive nanofibers and carbon particles are combined with the active material to simultaneously improve electrical conductivity, structural stability, and electrochemical performance, resolving the contradiction between enhanced reliability and increased complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If electrode impedance is reduced by conventional mixing methods, then rate characteristics improve slightly, but contact resistance remains high and paths detach due to volume change

Engineering Contradiction:

Improvecontact resistance and path stabilityVSAvoidcoating process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by coating the conductive nanofibers and carbon particles onto the active material particles before electrode fabrication. This pre-coating ensures that conductive pathways are established in advance, preventing path detachment during subsequent volume changes from lithium insertion/extraction, thus improving contact resistance stability while managing manufacturing complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses thin film coating of conductive materials on active material particles to create flexible conductive networks that can accommodate volume changes during charge-discharge cycles. This thin film approach maintains low contact resistance and prevents path detachment while avoiding the complexity of bulk composite manufacturing.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If carbon nanotubes and thermoplastic resin are mixed and heated to coat carbon, then carbon coating is achieved, but rate capability and cycle characteristics remain insufficient

Engineering Contradiction:

Improverate capability and cycle characteristicsVSAvoidpyrolysis temperature requirement

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by modifying the coating process to use lower temperatures and different chemical vapor deposition conditions compared to conventional pyrolysis methods. This allows for better control of carbon coating thickness and quality, improving rate capability and cycle characteristics while reducing the harsh temperature requirements of traditional pyrolysis approaches.

Inventive Principle:

Principle #35Parameter changes

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 provides negative electrode active materials with enhanced rate characteristics and cycle performance, improving current flow resistance and capacity retention in lithium secondary batteries.

Implementation Method 1

coating the carbon-containing mixture with a carbon material to integrate the active material, the conductive nanofibers and the conductive carbon particles

Methodology Applied

Scientific EffectChemical vapor phase deposition: Chemical Vapour Deposition

Data Source

PatentUS9843045B2Negative electrode active material and method for producing the same

Publication Date: 2017.12.12 NEC CORP

AI summary

It is an object of an exemplary embodiment of the present invention to provide a negative electrode active material having excellent rate characteristics and cycle characteristics. One embodiment according to the present invention is a negative electrode active material comprising a carbon-containing composite, wherein, in the carbon-containing composite, an active material capable of intercalating and deintercalating lithium, conductive nanofibers and conductive carbon particles are coated with a carbon material and are integrated.