Weld-Free Bipolar Solid-State Battery Cell Tab Connection
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Solution Overview
Problem
Bipolar solid-state battery cells with a stacked architecture face reduced durability due to higher current density at welded connections, leading to hot spots and mechanical weakness, especially when fewer current collectors are connected to external tabs.
Innovation Solution
The design incorporates positioning members with rail portions and slots that allow current collectors to be folded and connected to external tabs without welding, using insulating and conducting materials to enhance mechanical robustness and distribute current density, thereby reducing the risk of hot spots and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fewer current collectors are connected to external tabs in bipolar solid-state battery cells, then high output voltage (12V) is achieved, but mechanical strength and durability are reduced due to weaker connections
Solution Approach 1:
The connection structure is segmented into multiple components: positioning members with slots, folded current collectors, and external tabs. This segmentation allows each component to perform its specific function - the positioning member provides structural support and alignment, the folded current collector increases contact area, and the external tab enables electrical connection, collectively resolving the contradiction between achieving high voltage with fewer connections and maintaining mechanical strength
Solution Approach 2:
The current collector is folded to transform a two-dimensional flat connection into a three-dimensional multi-layered connection structure. This dimensional change increases the contact area between the current collector and external tab from a single point to multiple contact points, thereby enhancing mechanical strength while maintaining the bipolar architecture that enables high output voltage
2Power
If fewer current collectors are connected to external tabs, then high output voltage is achieved, but current density increases leading to hot spots and reduced durability
Solution Approach 1:
The folded current collector creates a multi-dimensional connection structure that distributes current across multiple contact areas. This dimensional transformation from a single-point connection to a multi-point connection reduces current density at each contact point, preventing hot spot formation while maintaining the high voltage output capability of the bipolar architecture
Solution Approach 2:
The positioning member with slots provides localized structural support at critical connection points. The slots are strategically positioned to guide and secure the folded current collector, creating localized areas of enhanced mechanical and thermal management that prevent hot spots while enabling the overall high voltage performance
3Reliability
If welding is used to connect current collectors to external tabs, then electrical connection is achieved, but mechanical weakness and reduced durability occur
Solution Approach 1:
The invention merges the electrical connection function and mechanical support function into a single integrated folded current collector structure. This structure simultaneously provides electrical conductivity and mechanical strength, eliminating the need for separate welding operations that create weak points and improve overall durability while maintaining reliable electrical connection
Solution Approach 2:
The welding process (a thermal/mechanical joining method) is replaced with a folded mechanical interlocking structure. The folded current collector creates a mechanically robust connection through physical interlocking and increased contact area, substituting the welding process and thereby improving durability while maintaining electrical connection reliability
Data Source
AI summary
A bipolar battery cell includes a stack including N current collectors, M anode electrodes, S separators, and C cathode electrodes, where N, M, S and C are integers greater than one. A first positioning member is arranged on one side of the stack and includes a first planar portion and a first slot in the first planar portion. A first one of the C current collectors extends through the first slot in the first planar portion and is folded. The first positioning member further includes a first rail portion and a second rail portion. The first rail portion and the second rail portion extend from the first planar portion. A first external tab is arranged between the first rail portion and the second rail portion and connected to the first one of the C current collectors.