Laser Welding Lithium Metal Negative Electrode
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Solution Overview
Problem
The practical use of lithium metal as the negative electrode in lithium batteries requires a method to form a robust physical and electrical bond with a metallic current collector without compromising the mechanical integrity of the lithium metal layer or triggering undesirable chemical reactions.
Innovation Solution
A laser welding process is used to bond a lithium metal layer with a metallic current collector layer, where the lithium metal layer is melted to form a weld pool that wets the current collector's surface, creating a solid weld joint without using flux, filler, or solder, and optionally, a laser ablation process is used to pretreat the current collector surface to enhance the bond strength by forming a metal oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bonding methods are used to attach lithium metal to current collector, then bonding strength may be improved, but mechanical integrity of lithium metal layer deteriorates due to its soft and reactive nature
Solution Approach 1:
The invention changes the bonding mechanism from mechanical adhesion to metallurgical bonding by controlling the bonding process parameters (temperature, pressure, time) to create a weld joint that is structurally integrated with the lithium metal layer, thereby maintaining mechanical integrity while achieving strong bonding
Solution Approach 2:
The invention replaces conventional mechanical bonding methods (which rely on adhesives or physical attachment) with a thermal welding process that creates a metallurgical bond, eliminating the need for separate bonding agents that would compromise the lithium metal's mechanical properties
2Strength
If conventional bonding methods are used to attach lithium metal to current collector, then bonding strength may be improved, but chemical stability deteriorates due to triggering undesirable chemical reactions
Solution Approach 1:
The invention employs an inert or controlled atmosphere during the bonding process to prevent unwanted chemical reactions between the lithium metal layer and environmental contaminants, while still allowing the bonding process to proceed and create strong adhesion
Solution Approach 2:
The invention replaces chemical bonding methods (which would involve reactive chemicals or adhesives) with a physical welding process that creates bonds through metallurgical fusion, thereby avoiding the introduction of foreign chemicals that could react with the lithium metal
3Strength
If laser welding is used to bond lithium metal layer with current collector, then bonding strength is improved, but manufacturing complexity increases due to precise process control requirements
Solution Approach 1:
The invention utilizes the inherent properties of the lithium metal and current collector materials, along with their natural thermal and electrical conductivities, to facilitate the welding process without requiring complex external control systems or additional processing steps
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 method establishes a strong physical and chemical bond between the lithium metal and the current collector, maintaining the structural integrity of both layers and preventing delamination, while allowing for the free flow of electrons, thus enhancing the durability and performance of the lithium metal battery electrodes.
Implementation Method 1
A laser beam may be directed at the outer surface of the current collector layer at the weld site to melt a portion of the lithium metal layer adjacent the faying surface of the current collector layer and produce a lithium metal molten weld pool
Implementation Method 2
to melt a portion of the lithium metal layer adjacent the faying surface of the current collector layer and produce a lithium metal molten weld pool
Implementation Method 3
The laser beam may be terminated to solidify the molten weld pool into a solid weld joint that physically bonds the lithium metal layer and the current collector layer together at the weld site
Implementation Method 4
optionally, a laser ablation process is used to pretreat the current collector surface to enhance the bond strength
Data Source
AI summary
A negative electrode for an electrochemical cell of a lithium metal battery may be manufactured by welding together a lithium metal layer and a metallic current collector layer. The lithium metal layer and the current collector layer may be arranged adjacent one another and in an at least partially lapped configuration such that faying surfaces of the layers confront one another and establish a faying interface therebetween at a weld site. A laser beam may be directed at an outer surface of the current collector layer at the weld site to melt a portion of the lithium metal layer adjacent the faying surface of the current collector layer and produce a lithium metal molten weld pool. The laser beam may be terminated to solidify the molten weld pool into a solid weld joint that physically bonds the lithium metal layer and the current collector layer together at the weld site.