Lithium-Calcium Alloy Negative Electrode for Thin Self-Supporting Batteries
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Solution Overview
Problem
The use of metallic lithium in lithium electrochemical generators poses challenges due to its reactivity, handling difficulties, and the inability to achieve thin electrode thicknesses necessary for high power density, leading to safety issues and increased costs.
Innovation Solution
A lithium-carbon fluoride electrochemical generator with a negative electrode made from a lithium-calcium alloy, allowing for thinner electrodes and improved mechanical properties, which can be easily rolled and produced at lower costs, eliminating the need for a current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic lithium is used as negative electrode material, then high mass and volume energy density is achieved, but handling difficulties and safety issues arise due to high reactivity
Solution Approach 1:
The patent uses a lithium-aluminum alloy as the negative electrode material instead of pure metallic lithium. This composite material combines the high energy density of lithium with the mechanical stability and reduced reactivity of aluminum, resolving the contradiction between energy density and handling ease.
2Power
If thin lithium sheets are used to increase power density, then power density improves, but manufacturing cost increases and standard rolling mills cannot achieve the required thickness
Solution Approach 1:
The patent changes the material composition from pure lithium to lithium-aluminum alloy, which fundamentally alters the mechanical properties including rollability and tensile strength. This parameter change enables the production of thin electrodes (10-50 μm) at lower costs using standard rolling mills, while maintaining high power density.
Solution Approach 2:
The lithium-aluminum alloy combines the advantages of both materials: lithium provides high energy density while aluminum improves mechanical properties and rollability, enabling cost-effective production of thin electrodes with high power density.
3Power
If thin lithium electrodes are used, then power density increases, but electrode thickness control becomes impossible with standard rolling mills
Solution Approach 1:
By changing the material composition to lithium-aluminum alloy, the patent fundamentally improves the rollability and mechanical stability of the electrode material. This enables standard rolling mills to precisely control electrode thickness in the 10-50 μm range, achieving both high power density and manufacturing precision.
4Use of energy by moving object
If lithium is used as negative electrode material, then high energy density is achieved, but formation of lithium dendrites and lithium peroxide occurs during charging and discharge
Solution Approach 1:
The lithium-aluminum alloy combines lithium's high energy density with aluminum's ability to suppress dendrite formation and reduce peroxide formation. The aluminum component provides structural stability during charging cycles, preventing the reliability issues associated with pure lithium while maintaining high energy density.
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
The lithium-calcium alloy enables the production of thin, self-supporting negative electrodes with enhanced tensile strength, improving power density and reducing manufacturing costs while maintaining performance comparable to pure lithium electrodes.
Implementation Method 1
the electrodes comprising specific materials capable of reacting according to an oxidation-reduction reaction, whereby there is production of electrons at the origin of the electric current and production of ions which will circulate from one electrode to the other through an electrolyte
Implementation Method 2
a lithium ion conducting electrolyte disposed between said negative electrode and said positive electrode
Data Source
Figure 1
AI summary
The invention relates to an electrochemical generator comprising at least one electrochemical cell comprising a positive electrode comprising, as active material, a carbon fluoride; a negative electrode and a lithium ion conducting electrolyte disposed between said negative electrode and said positive electrode, characterized in that the negative electrode comprises, as active material, a lithium and calcium alloy, in which the calcium is present in the alloy at a level of 2 to 34 atomic%.