Conductive Material Coating in Secondary Batteries for Cycle Stability
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Solution Overview
Problem
Conventional secondary batteries face issues with insufficient cycle characteristics related to discharge capacity and electrode resistance due to reactions between electrode constituent materials and the electrolyte, leading to deterioration over charge-discharge cycles.
Innovation Solution
A secondary battery design where at least a part of the conductive material is covered with a specific covering material, forming a conductive material covering structure, which improves chemical stability and prevents reactions with the electrolyte, thereby maintaining discharge capacity and reducing electrode resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive material is not covered with covering material, then electrode resistance is low and electrical conductivity is good, but the conductive material reacts with electrolyte to generate gas and by-products, causing deterioration of cycle characteristics
Solution Approach 1:
A covering material layer is introduced as an intermediary between the conductive material and the electrolyte. This covering material prevents direct contact and reaction between the conductive material and electrolyte, thereby eliminating gas generation and by-product deposition while maintaining electrical conductivity through the covering layer's design.
Solution Approach 2:
A thin film covering material is applied to the surface of the conductive material particles. This thin film acts as a protective shell that prevents harmful reactions with the electrolyte while maintaining the electrical conductivity function of the conductive material, thus improving cycle characteristics without significantly increasing resistance.
2Stability of the object's composition
If conductive material is covered with covering material, then chemical stability is improved and reactions with electrolyte are prevented, but electrode resistance increases and discharge capacity decreases
Solution Approach 1:
The covering amount of the covering material is precisely controlled within a specific range (0.0008 mmol/m2 to 0.06 mmol/m2). By optimizing this parameter, the covering material provides sufficient chemical stability and protection against electrolyte reactions while maintaining low enough resistance to preserve discharge capacity and avoid excessive energy loss.
Solution Approach 2:
Instead of completely covering the conductive material with a thick layer, a partial and controlled amount of covering material is applied. This partial covering provides just enough protection to improve chemical stability and prevent harmful reactions, while minimizing the impact on electrical conductivity and discharge capacity.
3Reliability
If covering material is applied to conductive material, then cycle characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The covering material application process is merged with the existing electrode manufacturing process. The covering material is applied to the conductive material particles during the electrode slurry preparation stage, combining multiple functions (conductive material coating, covering material application, and electrode formation) into a single integrated manufacturing step, thereby reducing overall manufacturing complexity.
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 conductive material covering structure significantly enhances the cycle characteristics by maintaining discharge capacity and preventing increases in electrode resistance, leading to improved battery performance and longevity.
Implementation Method 1
The secondary battery of the present disclosure, in an embodiment, has sufficiently improved chemical stability
Implementation Method 2
a part of a positive electrode active material and a conductive material contained in a positive electrode is covered with lithium ion conductive glass. It is shown that the covering can suppress oxidative decomposition of the electrolyte
Data Source
AI summary
A secondary battery is provided and including an electrode containing an electrode active material and a conductive material, in which at least a part of the conductive material is covered with a covering material, and a covering amount of the covering material is 0.0008 mmol/m2 or more and 0.06 mmol/m2 or less.