Laser Welding Exposed Portion With High Melting Point Intermediary Layer
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Solution Overview
Problem
The existing methods for end-surface current collection in electric power storage devices, such as non-aqueous electrolytic secondary batteries, often result in thinning or disconnection at the exposed portions, leading to increased current collecting resistance and reduced reliability, especially during high-rate charging and discharging.
Innovation Solution
A method involving the use of a metal layer with a higher melting point than the collector terminal, positioned between the exposed portion and the collector terminal, which is irradiated with energy to prevent the molten collector terminal from solidifying with the exposed portion, thereby preventing thinning or disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If end-surface current collection is carried out by direct contact welding of collector terminal to exposed portion, then charging and discharging performance at high rate is improved, but thinning or disconnection occurs at exposed portion leading to reduced reliability
Solution Approach 1:
A metal layer with higher melting point than the collector terminal is introduced as an intermediary between the collector terminal and the exposed portion. This metal layer prevents direct contact between the collector terminal and exposed portion during welding, avoiding the harmful effect of direct welding while still enabling electrical connection through the intermediary layer.
Solution Approach 2:
The melting point parameter of the intermediate layer is specifically chosen to be higher than that of the collector terminal. This parameter change allows the intermediate layer to remain solid while the collector terminal melts during welding, preventing the collector terminal from being absorbed into the exposed portion and causing thinning or disconnection.
2Strength
If laser beam irradiation is applied to connect collector terminal to exposed portion, then connection strength is improved, but thermal energy causes melting and absorption of exposed portion into collector terminal
Solution Approach 1:
The metal layer serves as a thermal barrier and intermediary material between the collector terminal and exposed portion. During laser beam irradiation, it absorbs and distributes thermal energy, preventing excessive heat from reaching the exposed portion and causing its melting and absorption into the collector terminal.
Solution Approach 2:
The melting point of the metal layer is specifically selected to be higher than that of the collector terminal. This parameter difference ensures that during laser welding, the metal layer remains solid while the collector terminal melts, allowing strong connection formation without compromising the shape and integrity of the exposed portion.
3Strength
If molten collector terminal contacts exposed portion directly, then welding connection is achieved, but solidification causes thinning at exposed portion
Solution Approach 1:
The metal layer acts as an intermediary that prevents direct contact between the molten collector terminal and the exposed portion. During solidification, the metal layer maintains the dimensional integrity of the exposed portion, preventing thinning while still enabling welding connection through the intermediary layer.
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 approach ensures reliable connection and prevents thinning or disconnection at the exposed portions, maintaining performance and reliability during high-rate charging and discharging by consuming thermal energy in the metal layer and preventing the exposed portion from melting.
Implementation Method 1
consuming thermal energy in the metal layer and preventing the exposed portion from melting
Implementation Method 2
at least a portion of contact of the collector terminal with the metal layer is irradiated with energy
Data Source
AI summary
A method of manufacturing an electric power storage device includes a connection step of connecting an exposed portion, which is provided at one end in a direction of width of an electrode and constructed without a composite material layer being provided in a current collector, and a collector terminal provided on an outer side relative to the exposed portion in the direction of width of the electrode to each other. In the connection step, while a metal layer composed of a second metal higher in melting point than a first metal which forms the collector terminal lies between the exposed portion and the collector terminal, at least a portion of contact of the collector terminal with the metal layer is irradiated with energy.