Aluminum Alloy Negative Terminal for Low Internal Resistance Batteries
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries with copper-based current collectors face issues of increased internal resistance and reduced energy density due to corrosion and dissolving reactions in high temperature and high humidity environments, leading to decreased battery performance and reliability in overdischarge conditions.
Innovation Solution
The use of aluminum foil or aluminum alloy with a purity of 99 wt.% or more as the current collector, combined with a negative electrode terminal made of aluminum alloy containing Mg, Cr, Mn, Cu, Si, Fe, or Ni, to reduce internal resistance and enhance mechanical and chemical stability, thereby improving battery performance and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If copper foil is used as current collector, then electrical conductivity is improved, but corrosion resistance deteriorates in high temperature and high humidity environments
Solution Approach 1:
The patent changes the material parameter from copper to aluminum, fundamentally altering the chemical properties to achieve both high conductivity and corrosion resistance. Aluminum naturally forms a protective oxide layer that prevents further corrosion while maintaining excellent electrical conductivity, resolving the contradiction between conductivity and corrosion resistance in high temperature and humidity environments.
Solution Approach 2:
The patent employs aluminum alloy materials that combine aluminum with other elements to optimize both conductivity and corrosion resistance. The composite material structure provides enhanced protective characteristics while maintaining the necessary electrical properties for battery operation, addressing the contradiction through material composition optimization.
2Reliability
If aluminum foil is used as current collector, then corrosion resistance is improved, but internal resistance increases
Solution Approach 1:
The patent optimizes the aluminum purity parameter to 99 wt.% or more, ensuring that the material maintains excellent electrical conductivity while preserving the corrosion resistance benefits of aluminum. This precise parameter control resolves the contradiction by eliminating impurities that would increase internal resistance while retaining the protective oxide layer properties.
3Reliability
If protective circuit is installed to prevent overdischarge, then battery reliability is improved, but energy density is reduced
Solution Approach 1:
The patent implements self-service protection mechanisms where the aluminum-based current collector and terminal materials inherently resist corrosion and degradation, providing built-in protection against overdischarge damage without requiring additional protective circuits. The material properties themselves serve the protective function, eliminating the need for separate protective components that would reduce energy density.
4Weight of moving object
If thin metal can is used to reduce battery weight, then weight is reduced, but swelling increases during overdischarge
Solution Approach 1:
The patent uses aluminum alloy materials that combine light weight with high strength characteristics. The composite material structure provides enhanced mechanical strength to resist swelling during overdischarge while maintaining the weight reduction benefits of thin metal cans, resolving the contradiction between weight and strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a nonaqueous electrolyte secondary battery with an internal resistance of 10 mΩ or less, maintaining high energy density and output performance even under extreme conditions, with enhanced corrosion resistance and reliability in battery modules.
Implementation Method 1
aluminum with a purity of 99 wt. % or more... aluminum alloy with an aluminum purity of less than 99 wt. % containing at least one metal selected from the group consisting of Mg, Cr, Mn, Cu, Si, Fe and Ni... enhanced corrosion resistance
Implementation Method 2
a negative electrode contained in the container and having an active material for intercalating lithium ions at a potential of 0.4 V or more with respect to an electrode potential of lithium
Implementation Method 3
a nonaqueous electrolyte contained in the container... nonaqueous electrolyte secondary battery
Data Source
AI summary
A nonaqueous electrolyte secondary battery, having an internal resistance of 10 mΩ or less as an alternating-current impedance value of 1 kHz, comprises a metal outer container, a nonaqueous electrolyte contained in the container, a positive electrode contained in the container, a negative electrode contained in the container, a separator interposed between the negative electrode and the positive electrode, a negative electrode lead having one end connected to the negative electrode, and a negative electrode terminal attached to the outer container so as to be connected electrically to the other end of the negative electrode lead, at least the surface of the negative electrode terminal which is connected to the negative electrode lead being formed of aluminum alloy with an aluminum purity of less than 99 wt. % containing at least one metal selected from the group consisting of Mg, Cr, Mn, Cu, Si, Fe and Ni.