Carbon Negative Electrode Coating for Battery Resistance and Efficiency
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Solution Overview
Problem
Lithium ion secondary batteries using carbon materials as negative electrode active materials face issues with increased irreversible capacity, interface resistance, and poor cycle characteristics due to insufficient adhesiveness and ionic conductivity of polymer coatings, leading to suboptimal charge/discharge efficiency and capacity loss.
Innovation Solution
A negative electrode active material comprising a carbon material coated with an organic compound having a basic group, a lithium ion-coordinating group, and a specific structure such as a graft, star, or three-dimensional network structure, which enhances adhesion, ionic conductivity, and prevents reductive decomposition, thereby improving charge/discharge efficiency and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer coating is applied to the carbon material surface, then the decomposition of the electrolytic solution is prevented, but the adhesiveness of the coating to the carbon material is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material by introducing an organic compound with specific functional groups (amino group for adhesion, oxyalkylene group for ionic conductivity) instead of using conventional polymers. This parameter change resolves the contradiction by achieving both good adhesiveness and electrolyte stability simultaneously.
Solution Approach 2:
The patent creates a composite coating material that combines the adhesion properties of amino groups with the ionic conductivity of oxyalkylene groups. This composite approach allows the coating to simultaneously achieve strong adhesion to carbon material and maintain good ionic conductivity, resolving the contradiction between stability and adhesiveness.
2Reliability
If a stable SEI coating film is formed on the carbon material surface, then the chemical stability of the negative electrode surface is maintained, but the interface resistance at the negative electrode increases
Solution Approach 1:
The patent changes the chemical structure parameters of the coating by incorporating an oxyalkylene group which provides both chemical stability and ionic conductivity. This parameter change allows the formation of a stable SEI film that does not increase interface resistance, thereby maintaining good input/output characteristics while achieving chemical stability.
Solution Approach 2:
The organic compound with oxyalkylene group acts as an intermediary between the carbon material and the electrolyte, forming a stable SEI film that facilitates ion transport. This intermediary layer provides chemical stability while maintaining low interface resistance, resolving the contradiction between stability and ease of operation.
3Productivity
If a polymer coating is applied to prevent electrolyte decomposition, then the initial charge/discharge efficiency is improved, but the cycle characteristics remain insufficient due to poor adhesiveness
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material to include an amino group that provides strong adhesion to the carbon material surface. This parameter change ensures the coating remains firmly attached during cycling, thereby improving cycle characteristics while maintaining good initial charge/discharge efficiency.
Solution Approach 2:
The patent creates a composite coating structure that combines amino groups for strong adhesion with oxyalkylene groups for ionic conductivity. This composite material simultaneously achieves good initial efficiency and excellent cycle characteristics by ensuring both strong attachment and sustained ion transport capability throughout cycling.
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 proposed solution effectively reduces negative electrode resistance, enhances initial charge/discharge efficiency, and minimizes capacity loss during cycles, resulting in improved battery performance.
Implementation Method 1
the organic compound (B) has a basic group and a lithium ion-coordinating group
Implementation Method 2
the coating layer formed of an ion-conducting polymer or a water-soluble polymer fulfil the function of preventing decomposition of the nonaqueous electrolyte layer
Data Source
AI summary
The present invention is to provide a negative electrode active material for nonaqueous secondary batteries, which prevents increase in negative electrode resistance and improves initial charge/discharge efficiency and the effect of preventing gas generation and which is excellent in cycle characteristics. The present invention relates to a negative electrode active material for nonaqueous secondary batteries, which comprises an active material (A) capable of occluding and releasing lithium ions and an organic compound (B), wherein the organic compound (B) has a basic group and a lithium ion-coordinating group, and has a specific structure (S).