Single-Sided Positive Electrode Structure for Short-Circuit Safety
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Solution Overview
Problem
Lithium-ion and sodium-ion batteries are prone to safety incidents such as internal short circuits and thermal runaway, particularly between positive and negative electrode current collectors, which reduce safety performance and impact pass rates.
Innovation Solution
A secondary battery design with a single-sided positive electrode plate featuring a composite current collector and reduced conductive layer thickness, combined with double-sided metal current collectors for adjacent plates, enhances safety by minimizing the risk of dangerous short circuits and maintaining energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional metal current collector is used in the outermost positive electrode plate, then the conductivity and structural strength are ensured, but the thickness of the conductive material layer increases, which increases the risk of short circuits under impact conditions
Solution Approach 1:
The current collector is segmented into a polymer substrate layer and a conductive material layer. The polymer layer provides structural support while the thinner conductive layer provides electrical conductivity, reducing the overall thickness of the conductive material and minimizing short circuit risk under impact.
Solution Approach 2:
A composite current collector is used consisting of a polymer substrate layer and a conductive material layer. This composite structure combines the advantages of polymers (lightweight, flexible, sufficient strength) and conductive materials (electrical conductivity), achieving both safety and conductivity requirements with reduced conductive material thickness.
2Reliability
If composite current collectors are used in all positive electrode plates, then the safety performance is improved, but the manufacturing cost increases
Solution Approach 1:
The outermost positive electrode plates, which are most susceptible to impact and short circuits, use composite current collectors for enhanced safety. The inner positive electrode plates use traditional metal current collectors to reduce cost. This localized application of composite materials optimizes the balance between safety and manufacturing cost.
Data Source
AI summary
A secondary battery includes a stacked electrode assembly with positive and negative electrode plates separated by a separator. The outermost electrode plate is a single-sided positive electrode plate composed of a first positive electrode current collector and a positive electrode active material layer. The current collector consists of a polymer layer and a conductive layer on the interior-facing surface, with the active material layer disposed on the conductive layer. Other positive electrode plates in the assembly are double-sided and include a second positive electrode current collector with active material layers on both sides. At least one of these double-sided current collectors is made of metal.