Composite Negative Electrode Current Collector for Crack Resistance
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Solution Overview
Problem
Current negative electrode current collectors in electrochemical devices lack sufficient toughness and mechanical stability, leading to breakage and cracking during production and use, which affects the performance and yield of electrochemical devices.
Innovation Solution
A negative electrode current collector is developed with a polymer material-based support layer and a copper-based conductive layer, where the thickness of the copper layer and the tensile strength of the support layer are optimized to achieve a brittleness parameter within a specific range, ensuring high mechanical properties and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional copper foil or metal-based current collector is used, then electrical conductivity is good, but mechanical stability and toughness are insufficient, leading to breakage and cracking during production and use
Solution Approach 1:
The current collector uses a composite structure consisting of a polymer substrate layer and a copper foil layer. The polymer substrate provides mechanical strength and toughness to prevent breakage and cracking, while the copper foil layer ensures good electrical conductivity. This composite material approach resolves the contradiction between mechanical stability and reliability by combining materials with complementary properties.
Solution Approach 2:
The polymer substrate layer acts as a flexible support that provides mechanical stability and toughness to the current collector. The flexible nature of the polymer film prevents brittleness and cracking while maintaining the structural integrity needed during production and use, directly addressing the mechanical stability and reliability issues.
2Reliability
If the copper layer thickness is increased to improve electrical conductivity, then current collecting performance improves, but the brittleness increases and mechanical properties deteriorate
Solution Approach 1:
The patent optimizes the thickness parameters of both the polymer substrate layer and copper foil layer to achieve the best balance between electrical conductivity and mechanical properties. By carefully controlling these dimensional parameters, the current collector achieves sufficient conductivity without excessive copper thickness that would increase brittleness and reduce mechanical strength.
Solution Approach 2:
The composite structure allows the thin copper foil layer (which provides conductivity without excessive brittleness) to be supported by the thicker polymer substrate layer (which provides mechanical strength). This division of functions between layers resolves the contradiction between electrical conductivity and mechanical properties.
3Strength
If the support layer thickness is increased to improve mechanical strength, then toughness improves, but the gravimetric energy density decreases
Solution Approach 1:
The patent optimizes the thickness of the polymer substrate layer to achieve the minimum necessary toughness while minimizing weight. By carefully controlling this parameter, the current collector achieves sufficient mechanical strength without excessive thickness that would reduce gravimetric energy density.
Solution Approach 2:
The use of a thin polymer film substrate provides the necessary mechanical strength and toughness with minimal thickness, thereby minimizing the weight penalty and maximizing gravimetric energy density. The thin film structure achieves the strength-to-weight ratio needed to resolve this contradiction.
Data Source
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AI summary
The present application discloses a negative electrode current collector (10), a negative electrode plate (30), an electrochemical device, and an apparatus. The negative electrode current collector (10) includes a polymer material-based support layer (101) and a copper-based conductive layer (102) disposed on at least one surface of the support layer (101); wherein a thickness D1 of the copper-based conductive layer (102), a tensile strength T of the support layer (101), and a thickness D2 of the support layer (101) satisfy a relational formula 0.01 ≤ (300 × Di)/(T × D2) ≤ 0.5. The negative electrode current collector (10) has relatively high mechanics and mechanical properties, good electrical conductivity and current collection performance and low weight, which can improve preparation yield of the negative electrode current collector (10), the negative electrode plate (30) and the electrochemical device and their reliability during use, and is beneficial to enabling the electrochemical device to have relatively high electrochemical performance and gravimetric energy density.