Anode-Free Cell Layout Using Polymer Current Collectors
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Solution Overview
Problem
Anode-free cells face challenges in passing abuse tests due to the structure of the anode current collector, and conventional cell designs follow dimensional restrictions that reduce energy density, introduce safety concerns, and complicate manufacturing.
Innovation Solution
The anode-free cell design includes a cathode with a cathode current collector between two active material layers, an anode current collector, and a separator. A short-circuit limitation configuration is achieved by using polymer current collectors and ensuring the dimensions of the cathode and anode current collector are either the same or the cathode is larger, which alleviates lithium plating concerns and allows for safer dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dimensional restrictions are followed to prevent lithium plating, then safety is improved, but energy density is reduced and manufacturing is complicated
Solution Approach 1:
The patent changes the material parameter of the current collector from conventional metal to polymer material. This parameter change fundamentally alters the cell's dimensional constraints, allowing the cathode dimensions to match the anode current collector dimensions without causing lithium plating, thus improving energy density while maintaining safety
Solution Approach 2:
The patent inverts the conventional dimensional relationship where the anode is typically larger than the cathode. By using polymer current collectors, the cathode can be the same dimension as the anode current collector, reversing the traditional size hierarchy and eliminating the need for excessive anode material that reduces energy density
2Object-generated harmful factors
If the cathode dimensions are restricted to be smaller than the anode current collector, then lithium plating is prevented, but manufacturing precision requirements increase and energy density decreases
Solution Approach 1:
Changing the current collector material to polymer fundamentally changes the dimensional compatibility parameters between cathode and anode. Polymer current collectors allow the cathode to be the same dimension as the anode without causing lithium plating, eliminating the need for precise dimensional control that would otherwise be required
3Reliability
If polymer current collectors are used with matched dimensions, then abuse tolerance is improved, but device complexity may increase due to new material requirements
Solution Approach 1:
The patent employs polymer current collectors which are composite materials combining the benefits of traditional metal current collectors (electrical conductivity) with polymer materials (flexibility, abuse tolerance). This composite approach improves abuse tolerance while the matched dimension design simplifies the overall cell structure
Solution Approach 2:
The polymer current collector serves multiple functions: it provides electrical conductivity like traditional metal collectors, but also adds flexibility, improved abuse tolerance, and enables matched dimension design. This multi-functionality reduces the need for separate safety components, potentially simplifying the overall device structure despite the new material requirements
Data Source
AI summary
An anode-free cell including a cathode, an anode current collector and a separator disposed between the cathode and the anode current collector. It also includes a short-circuit limitation configuration configured by (i) the anode current collector and/or the cathode current collector being a polymer current collector, and/or (ii) the cathode dimension being the same as the anode current collector and/or of the separator dimension, or the dimension of the cathode being larger than the dimension of the anode current collector. The dimension is measured in the X-axis and/or Y-axis. Another cell includes a cathode and an anode and the short-circuit limitation configuration is configured by (i) the anode current collector being a polymer anode current collector and the cathode current collector being a polymer cathode current collector; and (ii) the dimension of the anode active material layer and of the cathode active material layer being the same.