Positive Electrode Coating for Battery Storage Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries experience deterioration during storage, which affects their performance and lifespan.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a positive electrode with a current collector coated with a conductive material, a positive electrode active material layer containing conductive carbon, and specific surface element ratios to reduce storage deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional positive electrode structure is used, then the battery can be manufactured with simple processes, but the battery experiences significant storage deterioration affecting performance and lifespan
Solution Approach 1:
The positive electrode is segmented into distinct functional layers: a current collector substrate and a positive electrode active material layer with specific composition ratios. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall electrode performance and reducing storage deterioration.
Solution Approach 2:
The positive electrode active material layer is designed with specific local composition characteristics, including controlled ratios of carbon to metal elements (C/M = 3.0 to 15.0) and metal to sulfur+nitrogen elements (M/(S+N) = 1.0 to 5.0). These localized compositional specifications improve storage stability without requiring complete structural redesign of the entire battery.
2Reliability
If the positive electrode active material layer has high carbon content to improve conductivity, then electrical conductivity improves, but the ratio of active material to conductive additive decreases affecting capacity
Solution Approach 1:
The invention optimizes the carbon to metal element ratio (C/M = 3.0 to 15.0) and metal to sulfur+nitrogen element ratio (M/(S+N) = 1.0 to 5.0) in the positive electrode active material layer. By precisely controlling these compositional parameters, the electrode achieves optimal balance between electrical conductivity and active material content, avoiding both excessive carbon addition and insufficient conductivity.
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte solution disposed between the positive electrode and the negative electrode, wherein: the positive electrode includes a current collector and a positive electrode active material layer provided on the current collector, the current collector has, on at least a part of its surface on a side of the positive electrode active material layer, a current collector coating layer comprising a conductive material, the positive electrode active material layer includes positive electrode active material particles and a conductive carbon, and the positive electrode active material layer has surface element ratios wherein C/M, which represents a ratio of carbon element C to metal element M excluding Group 1 elements and Group 2 elements of the periodic table, is 3.0 to 15.0.