Composite Current Collector Layout for Safer Lithium Secondary Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries face issues with heat generation and ignition due to short circuits, particularly when using aluminum as a positive electrode current collector, which compromises safety and output characteristics.
Innovation Solution
A lithium secondary battery structure incorporating a combination of metal and composite conductive current collectors, with a specific ratio and alternating arrangement, to enhance stability and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum is used as a conventional positive electrode current collector, then conductivity is improved, but safety deteriorates due to contact with negative electrode active material causing ignition
Solution Approach 1:
The patent uses a composite current collector consisting of a metal current collector (aluminum or copper) coated with an organic conductive material layer. This composite structure combines the high conductivity of metal with the safety benefits of organic materials that do not ignite upon contact with negative electrode active material, thereby resolving the contradiction between conductivity and safety.
Solution Approach 2:
The organic conductive material layer acts as an intermediary between the metal current collector and the negative electrode active material. This intermediate layer prevents direct contact between aluminum and the negative electrode active material, eliminating the ignition risk while maintaining electrical conductivity through the composite structure.
2Reliability
If a composite current collector with organic conductive material is used, then safety is improved, but resistance increases and output characteristics deteriorate
Solution Approach 1:
The patent optimizes the thickness of the organic conductive material layer to a specific range (0.1-10 μm) to balance safety and conductivity. By controlling this parameter, the organic layer provides sufficient safety protection while minimizing resistance increase, thereby maintaining acceptable output characteristics.
Solution Approach 2:
The composite current collector combines metal and organic conductive materials in a layered structure that leverages the advantages of both materials. The metal provides high conductivity and structural strength, while the organic layer provides safety without excessive resistance, achieving a balance between safety and output characteristics.
3Power
If metal current collector is used, then output characteristics are improved, but stability deteriorates due to short-circuit resistance and ignition risk
Solution Approach 1:
The composite current collector structure combines metal and organic conductive materials to achieve both high output characteristics and short-circuit stability. The organic layer prevents direct metal-to-active-material contact during short circuits, stabilizing the system's behavior under fault conditions while maintaining good conductivity for normal operation.
Data Source
AI summary
A lithium secondary battery structure having a first electrode including a first conductive current collector having an active material layer formed on at least one surface; a second electrode including a second conductive current collector having an active material layer formed on at least one surface; and a plurality of battery units including a separator formed between active material layers of the first and second electrodes facing each other is provided. The first or second conductive current collector is a metal current collector, or a composite conductive current collector having a metal layer formed on a polymer substrate for each battery unit. The metal current collector to composite conductive current collector ratio within the total battery structure is in a range of 5:1 to 1:5.