Secondary Battery Weld Layout for Lower DCR
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Solution Overview
Problem
High Direct Current Resistance (DCR) in secondary batteries leads to increased heat generation, reduced performance, and accelerated degradation, affecting efficiency, lifespan, and safety.
Innovation Solution
A secondary battery design with a current collecting member welded to a bent surface area of the electrode assembly, featuring extended weld marks and controlled layer connections to reduce DCR, and a housing structure that optimizes electrical conductivity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the current collecting member is welded to the electrode assembly with traditional weld mark configuration, then the welding process is simple, but the DCR is high and electrical conductivity is poor
Solution Approach 1:
The patent extends the weld mark configuration from a single-plane arrangement to a three-dimensional spatial distribution. The first weld mark is arranged on the first electrode sheet while the second weld mark is arranged on the second electrode sheet, creating a multi-dimensional current collection path that reduces DCR without significantly increasing manufacturing complexity
Solution Approach 2:
The current collecting member is divided into multiple welding zones with distinct weld mark configurations. The first weld mark connects to the first electrode sheet and the second weld mark connects to the second electrode sheet, segmenting the current collection function to optimize electrical conductivity and reduce energy loss
2Reliability
If the weld mark extends to increase connection layers, then electrical conductivity improves, but the risk of weld-through and separator damage increases
Solution Approach 1:
The patent applies different weld mark configurations to different locations and electrode sheets. The first weld mark on the first electrode sheet has different dimensional constraints compared to the second weld mark on the second electrode sheet, optimizing local current collection while preventing excessive penetration that could damage the separator
Solution Approach 2:
The patent uses controlled partial welding where the weld marks extend beyond certain thresholds (e.g., extending beyond 50% of the electrode sheet width) to ensure adequate electrical connection without excessive penetration. This partial action approach balances conductivity improvement with safety margin maintenance
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 design effectively reduces DCR, enhancing electrical conductivity, safety, and energy density while minimizing the risk of weld-through and separator damage.
Implementation Method 1
The current collecting member is welded to the bent surface area and forms a first weld mark and a second weld mark
Data Source
AI summary
A secondary battery, a battery pack, and an electronic device are provided. The secondary battery includes a housing, an electrode assembly, and a current collecting member. The electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator. A part of the bare foil area is bent along a radius direction of the electrode assembly to form a bent surface area including an overlapping layer of the bare foil area. The current collecting member is welded to the bent surface area, and forms first and second weld marks. Along an axial direction of the electrode assembly, the number of layers of part of the second weld mark that extends beyond the first weld mark along the radius direction of the electrode assembly connected to the bare foil area is less than the number of layers of the first weld mark connected to the bare foil area.