Current collectors for rechargeable lithium batteries, electrode including the same, and rechargeable lithium batteries
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Solution Overview
Problem
Rechargeable lithium batteries with high energy density are prone to electric short circuits, thermal runaway, and explosions due to physical and chemical deformations, which existing current collectors fail to adequately address.
Innovation Solution
A current collector design with a functional layer containing a polymer and a foaming agent is inserted between two metal layers, which activates to form a foam upon Joule heating, isolating deformed areas and preventing further damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional current collector is used in high energy density lithium batteries, then energy density is improved, but safety deteriorates due to electric short circuits and thermal runaway from physical/chemical deformations
Solution Approach 1:
An intermediate layer is introduced between the positive and negative electrode active material layers. This intermediate layer acts as a mediator that prevents direct contact between electrodes during deformations, thereby preventing electric short circuits while allowing the battery to maintain high energy density with thin electrode structures.
Solution Approach 2:
The intermediate layer is pre-positioned between the electrode active material layers before battery assembly. This preliminary placement ensures that protective action is already in place before any deformations occur, preventing electric short circuits and thermal runaway from the outset rather than responding after damage occurs.
2Quantity of substance
If electrode thickness is increased to improve energy density, then capacity is improved, but susceptibility to deformations and short circuits increases
Solution Approach 1:
The intermediate layer serves as a protective mediator that allows electrodes to be positioned closer together, effectively increasing the active material content per unit volume. This enables higher capacity without increasing overall electrode thickness, thereby maintaining mechanical stability and reducing susceptibility to deformations.
Solution Approach 2:
The intermediate layer is designed as a thin film structure that provides mechanical flexibility and deformation tolerance. This thin film acts as a flexible barrier that can accommodate minor deformations without causing short circuits, enabling higher electrode density while maintaining safety.
3Reliability
If a protective layer is added between electrodes to prevent short circuits, then safety is improved, but device complexity increases
Solution Approach 1:
The intermediate layer is integrated directly into the electrode assembly structure, merging the protective function with the existing electrode layers. This integration approach adds the safety function without creating a separate, complex protective system, thereby minimizing increases in device complexity while maintaining improved safety.
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 effectively reduces or suppresses short circuits, thermal runaway, and explosions by rapidly responding to deformations, ensuring safe operation of high-energy density lithium batteries.
Implementation Method 1
activates to form a foam upon Joule heating
Implementation Method 2
activates to form a foam upon Joule heating
Data Source
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AI summary
Disclosed are a current collector for a rechargeable lithium battery, an electrode including the current collector, and a rechargeable lithium battery including the current collector. The current collector for a rechargeable lithium battery includes a first metal layer, a second metal layer, and a functional layer between the first metal layer and the second metal layer, the functional layer including a polymer and a foaming agent.