Polymer-Base Current Collector Interconnection for Weld Continuity
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Solution Overview
Problem
Conventional current collectors in lithium-metal cells, especially those with polymer bases, pose challenges in forming electrical connections due to interference with welding processes, leading to potential short circuits and safety issues.
Innovation Solution
The use of current collectors with metal layers and polymer bases, where the metal layers are interconnected through strategically designed openings and welding, allowing direct and indirect interfaces to maintain electrical continuity while the polymer bases provide mechanical support and safety features like localized fusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer base is used in a current collector to mitigate short circuits, then safety is improved, but the ability to form electrical connections through welding is worsened
Solution Approach 1:
The current collector is segmented into distinct functional layers: a polymer base layer for safety and a separate metal layer for electrical connection. This segmentation allows each layer to perform its specialized function without interfering with the other, resolving the contradiction between safety and weldability.
Solution Approach 2:
The current collector uses a composite structure combining polymer and metal materials. The polymer base provides safety through localized fusing, while the metal layer (aluminum, copper, or nickel) provides weldability and electrical conductivity. This composite approach allows both safety and manufacturing ease to coexist.
2Weight of moving object
If metal layers are made thinner to reduce weight, then gravimetric capacity is improved, but mechanical strength and continuity are worsened
Solution Approach 1:
The composite structure uses a polymer base that can be thicker and more mechanically robust while keeping the metal layers thin. The polymer provides the mechanical strength and structural integrity, allowing the metal layers to be optimized for weight reduction without compromising overall structural continuity.
Solution Approach 2:
The polymer base acts as an intermediary that bridges and supports the thin metal layers. It provides mechanical continuity and structural support that compensates for the reduced thickness of the metal layers, maintaining overall strength while enabling weight reduction.
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
This solution enables reliable electrical connections and enhanced safety in lithium-metal cells by ensuring continuous electrical pathways and isolating potential short circuits, while also providing weight savings and improved gravimetric capacity.
Implementation Method 1
a first polymer base positioned between and supporting both the first metal layer and the first additional metal layer
Implementation Method 2
The second current collector comprises a second-collector contact opening with at least one of the first current collector and the third current collector protruding into the second-collector contact opening and forming a through-second-collector contact interface between the first additional metal layer and the third metal layer
Data Source
AI summary
Described herein are electrochemical cells fabricated with current collectors comprising polymer bases and metal layers and methods of interconnecting these current collectors or, more specifically, interconnecting their metal layers. For example, a current collector, positioned between two other current collectors, can have an opening allowing these two other current collectors to form a direct interface. This interface not only directly interconnects the metal layers on these two current collectors but also indirectly interconnects the two metal layers of the middle current collector, which are positioned on the opposite sides of the polymer base of this current collector. In some examples, the metal layers of current collectors are reinforced by external metal foils that help to maintain continuity and/or repair any discontinuities in the metal layers when these metal layers are welded together. For example, welding may push portions of the polymer bases away from the weld zone.