Current Collector Welding Structure for Cylindrical Cell Leakage Control
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Solution Overview
Problem
Cylindrical secondary cells face limitations in energy density per unit volume due to gaps between the wound electrode assembly and end caps, leading to high resistance and potential liquid leakage during use or accidental drops.
Innovation Solution
An energy storage device design featuring a current collector with a main body and welding portion integrally formed, where the current collector is welded to both the end cap and housing, expanding the electrical connection area and enhancing structural strength, thereby reducing resistance and improving connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current collector uses a traditional connection structure, then the device complexity is low, but the electrical connection area is small leading to high resistance
Solution Approach 1:
The current collector transitions from a traditional planar connection structure to a three-dimensional structure with side surfaces that protrude from the end cap. This dimensional extension creates additional welding surfaces, expanding the electrical connection area from a single plane to multiple surfaces including top and side welding portions, thereby reducing resistance and improving connection reliability.
Solution Approach 2:
The current collector is divided into distinct functional segments: a main body portion for structural support and separate welding portions (top and side) for electrical connection. This segmentation allows each part to optimize its function - the main body maintains structural integrity while the welding portions provide extended electrical contact areas with the end cap and housing.
2Quantity of substance
If gaps exist between the wound electrode assembly and end caps, then the device assembly is simple, but the energy density per unit volume is restricted
Solution Approach 1:
The invention changes the geometric parameters of the current collector, specifically making its outer peripheral side surface protrude beyond the end cap's outer peripheral side surface. This parameter modification allows the current collector to occupy and utilize the gap space between the electrode assembly and end caps, effectively reducing wasted volume and increasing energy density without complicating the assembly process.
3Reliability
If the current collector is not structurally reinforced, then the manufacturing process is simple, but liquid leakage may occur during use or accidental drops
Solution Approach 1:
The current collector employs a composite structure combining a main body made of conductive material (such as aluminum or copper alloy) with welding portions that may have different material properties optimized for bonding. This composite approach provides both electrical conductivity and enhanced mechanical strength, preventing liquid leakage while maintaining manufacturability through standard welding processes.
4Reliability
If the welding portion protrudes too much from the end cap, then the electrical connection area is maximized, but the device overall dimensions increase
Solution Approach 1:
The welding portions protrude partially from the end cap - enough to provide adequate welding surface area for strong electrical connection (0.5mm to 2.0mm protrusion), but not so much as to significantly increase overall device dimensions. This partial action optimizes the balance between connection strength and compactness, providing sufficient welding area without excessive dimensional growth.
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 expanded electrical connection and structural reinforcement improve current flow and connection strength, reducing the likelihood of liquid leakage and enhancing the energy storage device's performance and safety.
Implementation Method 1
perform circumferential laser welding on an outer peripheral side of the current collector to fixedly connect the current collector to both the end cap and the housing
Data Source
AI summary
This disclosure provides an energy storage device, a welding method for an energy storage device, and an electricity-consumption device. The energy storage device includes an end cap, a housing, and a current collector arranged between the end cap and the housing. The current collector includes a main body and a welding portion, and the main body and the welding portion are integrally formed. The main body has a first surface and a second surface facing away from the first surface. The end cap is connected to the first surface of the main body, the housing is connected to the second surface of the main body, and the welding portion is connected to an outer peripheral side surface of the end cap, an outer peripheral side surface of the housing, and an outer peripheral side surface of the main body.