Secondary Battery Electrode Welding Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion batteries face high internal resistance due to non-uniform intervals between welded points in the current-collecting plate and electrode plate group, leading to defects in welding and reduced high-rate discharge efficiency.
Innovation Solution
A secondary battery design with band-shaped positive and negative electrodes, where active material non-covered parts are bent to form flat surfaces and overlapped for stable welding, and a concentric or spiral pattern of welded points on the current-collecting plates, reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is used to join the current-collecting plate to the electrode plate group in the radial direction, then the current-collecting efficiency is improved, but the intervals between welded points become non-uniform and long at the outer periphery, resulting in high internal resistance
Solution Approach 1:
The patent divides the welding process into two distinct stages: first welding the current-collecting plate to the central part of the electrode plate group, then welding the current-collecting plate to the outer peripheral part. This segmentation allows optimization of welding parameters for each region, ensuring uniform current distribution and reducing internal resistance while maintaining high current-collecting efficiency.
2Ease of manufacture
If the end of the electrode plate group is pressed to form a flat surface for welding, then the welding surface is prepared, but wrinkles and voids are inevitably generated, causing defects in welding
Solution Approach 1:
The patent performs preliminary actions to prevent welding defects: (1) The electrode plate group is pre-formed with a flat end surface through controlled deformation before welding, avoiding wrinkles and voids. (2) The current-collecting plate is pre-positioned and fixed at the central part before outer peripheral welding. (3) Welding parameters are pre-optimized for different regions to ensure defect-free welding while maintaining manufacturing efficiency.
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 stable welding of current-collecting plates and end surfaces, significantly reducing internal resistance, enabling high-power battery performance.
Implementation Method 1
the positive electrode active material non-covered part is joined to the positive electrode current-collecting plate at one end of the electrode wound body, the negative electrode active material non-covered part is joined to the negative electrode current-collecting plate at the other end of the electrode wound body
Implementation Method 2
a current-collecting plate is joined by laser welding to a current collector protruded to one side of an electrode plate group obtained by winding a positive electrode plate and a negative electrode plate stacked with a separator interposed therebetween
Data Source
AI summary
Provided is a secondary battery, where a positive electrode includes a covered part covered with a positive electrode active material layer and a positive electrode active material non-covered part on a band-shaped positive electrode foil, and a negative electrode includes a covered part covered with a negative electrode active material layer and a negative electrode active material non-covered part on a band-shaped negative electrode foil, the positive electrode active material non-covered part is joined to the positive electrode current-collecting plate at one end of an electrode wound body, and the negative electrode active material non-covered part is joined to the negative electrode current-collecting plate at the other end of the electrode wound body, any one or both of the positive electrode active material non-covered part and the negative electrode active material non-covered part have a flat surface formed by bending toward a central axis of the wound structure and overlapping.