Positive Electrode Current Collector Composition for Crack-Resistant Capacity
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Solution Overview
Problem
Existing positive electrode current collectors for rechargeable lithium batteries face challenges in achieving high electrochemical stability, electrical conductivity, and cost-effectiveness while maintaining structural integrity, particularly when thinned to increase capacity, leading to issues like cracks and pinholes.
Innovation Solution
A positive electrode design incorporating a current collector with 0.17-0.24 wt% Cu and a positive electrode active material layer with a density of 3.9-4.5 g/cc, featuring a thickness ratio with the current collector of 1:1 to 1:50, enhances strength and reduces cracks and pinholes, improving conductivity and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode substrate is thinned to increase capacity, then the energy density is improved, but the substrate is prone to cracks and pinholes
Solution Approach 1:
The patent applies parameter changes by precisely controlling the copper content in the current collector within the range of 0.17-0.24 wt% and the active material layer density within 3.9-4.5 g/cc. These parameter optimizations enhance the mechanical strength and electrochemical stability of the thin substrate, preventing cracks and pinholes while maintaining high capacity
Solution Approach 2:
The patent uses composite materials by combining aluminum-based current collector with controlled copper content and coating it with a positive electrode active material layer. This composite structure provides both the electrical conductivity needed for high capacity and the mechanical strength required to prevent substrate failure
2Strength
If the current collector copper content is increased to improve strength, then the structural integrity is improved, but the electrochemical stability may deteriorate
Solution Approach 1:
The patent resolves this contradiction through precise parameter control, limiting copper content to 0.17-0.24 wt%. This optimized range provides sufficient strength to prevent substrate failure while maintaining electrochemical stability, avoiding the harmful effects of excessive copper content
Data Source
AI summary
A positive electrode for a rechargeable lithium battery, and rechargeable lithium battery including the positive electrode are provided. The positive electrode includes a current collector and a positive electrode active material layer on the current collector, wherein the current collector includes about 0.17 wt % to about 0.24 wt % of Cu based on 100 wt % of the current collector, and the positive electrode active material layer has a density of about 3.9 g/cc to about 4.5 g/cc.