Current Collector Safety Layer for Short-Circuit and Lithium Plating
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Solution Overview
Problem
Lithium ion batteries face issues with short circuits and lithium plating, which can lead to thermal runaway, due to the need for flexible electrodes that prevent mechanical failures and exposure of current collectors.
Innovation Solution
The development of electrodes with a carbonized polymer that forms a self-supporting film with silicon particles, using a safety layer to reduce exposure of the current collector and prevent short circuits, and methods for forming these electrodes with specific attachment substances like polyamideimide and polyvinylidene fluoride to enhance mechanical durability and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are made flexible to prevent mechanical failures during rolling, then ease of manufacture is improved, but current collector exposure and short circuits may occur
Solution Approach 1:
The patent applies flexible thin film coatings on current collectors to prevent short circuits while maintaining electrode flexibility for rolling. The film coating acts as a protective barrier that prevents current collector exposure during mechanical deformation, resolving the contradiction between ease of manufacture (rolling) and reliability (short circuit prevention).
Solution Approach 2:
The patent uses composite material structures combining current collectors with protective film coatings. This composite approach maintains the mechanical flexibility needed for rolling while adding the electrical insulation properties necessary to prevent short circuits, thus resolving the technical contradiction.
2Quantity of substance
If silicon particles are added to increase energy density, then energy density is improved, but lithium plating and thermal runaway risks increase
Solution Approach 1:
The patent introduces film coatings as intermediary layers between silicon particles and the electrolyte environment. These intermediary films control lithium ion transport, preventing excessive lithium plating while allowing silicon to maintain its high energy density benefits, thus resolving the contradiction between energy density improvement and harmful lithium plating.
3Reliability
If film coatings are applied to prevent short circuits, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs self-service mechanisms where the film coating process is integrated into existing manufacturing workflows. The current collector undergoes standard processing steps that simultaneously apply the protective film, eliminating the need for separate complex manufacturing operations and thus resolving the contradiction between reliability improvement and manufacturing complexity.
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 solution effectively reduces the occurrence of short circuits and lithium plating, enhancing the cycle life and energy density of lithium ion batteries by allowing for expansion without mechanical failure and maintaining electrical contact.
Implementation Method 1
an electrode attachment substance that adheres the film to the current collector
Implementation Method 2
at least some of the electrode attachment substance may be within the porosity of the film
Data Source
AI summary
An example method of reducing short circuits from occurring in a battery can include providing a current collector coated with a safety layer. The method can include providing an electrochemically active material film on the safety layer such that the safety layer is configured to reduce exposure of the current collector to an opposing electrode. The method can also include adhering the electrochemically active material film to the current collector via the safety layer.