Sealed Battery Collector Protrusion for Reliable Resistance Welding
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Solution Overview
Problem
High-output batteries for electric and hybrid vehicles face challenges in achieving reliable resistance welds without edge part melting, spark generation, or fusion bonding, especially when using copper or aluminum alloys, which require high energy and can lead to internal short-circuits and substrate damage.
Innovation Solution
A sealed battery design with flat electrode assemblies featuring collectors and collector receiving parts made of copper or aluminum alloys, incorporating planar, first bent, and second bent parts to act as radiating fins, preventing edge part melting and fusion bonding, and ensuring reliable resistance welds by controlling current density during resistance welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance welding is used to join collectors and substrates in high-output batteries, then electrical connection is achieved, but edge part melting and spark generation occur due to high current density
Solution Approach 1:
The patent applies local quality by creating a protrusion at the specific location where welding occurs on the collector. This localized structural modification concentrates the welding current at the protrusion tip, enabling reliable electrical connection while preventing harmful current distribution across the entire collector surface that would cause edge part melting and sparks.
Solution Approach 2:
The patent changes the geometric parameter of the collector by adding a protrusion with specific dimensions (height of 0.01 to 0.5 mm). This parameter change modifies the current density distribution during resistance welding, concentrating current at the protrusion tip to achieve reliable welding while preventing harmful effects like edge part melting and spark generation.
2Loss of energy
If copper or aluminum alloys are used for collectors and substrates, then electrical resistance is reduced, but large amounts of energy are required for welding
Solution Approach 1:
The patent applies local quality by concentrating the welding operation at the protrusion tip rather than across the entire collector surface. This localized approach reduces the total energy required for welding while maintaining low electrical resistance in the overall battery system, as the protrusion provides a focused connection point without requiring high energy input across large areas.
Solution Approach 2:
The patent employs the skipping principle by using the protrusion to rapidly establish electrical connection through concentrated current density. The protrusion geometry enables the welding process to complete quickly with reduced total energy input, as the localized contact point allows for efficient current transfer without prolonged energy application across the entire collector surface.
3Strength
If high current is applied during resistance welding to achieve firm welds, then welding strength is improved, but fusion bonding of collectors and electrode bars occurs
Solution Approach 1:
The patent applies local quality by concentrating the welding current at the protrusion tip, which has smaller cross-sectional area. This localized current concentration achieves the necessary welding strength at the connection point without distributing high current across the entire collector surface, thereby preventing fusion bonding between collectors and electrode bars while maintaining strong welds at the protrusion location.
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 achieves highly reliable resistance welds without edge part melting or fusion bonding, reducing internal resistance and enabling higher current output while preventing substrate damage and internal short-circuits, thus enhancing the performance and reliability of lithium-ion non-aqueous electrolyte secondary batteries.
Implementation Method 1
a first bent part extending from the planar part and bent at the bottom side of the substrates into a direction away from the substrates; and a second bent part provided at the leading side of the substrates
Implementation Method 2
resistance welding, which is joining by fusion
Data Source
AI summary
A sealed battery according to an aspect of the invention includes: a flat electrode assembly 11 having a plurality of copper or copper alloy negative electrode substrate exposed portions 15 at one end; and a copper or copper alloy collector 181 attached to one side of the exposed portions 15 and a copper or copper alloy collector receiving part 182 attached to the other side. The collector 181 and the collector receiving part 182 respectively include: a planar part 18a including a part in contact with and resistance-welded to the exposed portions 15; a first bent part 18b extending from the planar part 18a and bent at the bottom side of the exposed portions 15 into a direction away from the substrates; and a second bent part 18c provided at the leading side of the negative electrode substrate exposed portions 15.