Enhanced Cathode Design for Reliable Lithium Batteries
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Summary
Problems
Lithium secondary batteries face issues such as cathode collapse due to lithium ion intercalation and deintercalation, leading to gas generation and degradation in cycle life characteristics, especially during fast charging and discharging.
Innovation solutions
A cathode for secondary batteries comprising a cathode active material layer with lithium iron phosphate and lithium nickel metal oxide, bound by a combination of fluorine-based polymers with hydrophilic functional groups, enhances adhesion and stability, improving cycle life characteristics.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a conventional binder is used in the cathode active material layer, then the manufacturing process is simple, but the adhesion between the cathode active material layer and current collector deteriorates during repeated charging and discharging
Why choose this principle:
The patent uses a composite binder system comprising both a fluorine-based polymer and a carboxymethyl cellulose-based polymer. The fluorine-based polymer provides baseline adhesion and electrochemical stability, while the carboxymethyl cellulose-based polymer enhances interfacial adhesion through its hydrophilic functional groups that form strong bonds with the current collector surface. This composite approach resolves the contradiction by achieving superior adhesion reliability without overly complicating the manufacturing process, as both polymers can be mixed and applied together in a single coating step.
Principle concept:
If the cathode active material undergoes repeated lithium ion intercalation and deintercalation, then the battery capacity is maintained, but the cathode structure collapses leading to gas generation and degradation
Why choose this principle:
The patent employs a specially designed binder system that acts as a protective cushion for the cathode active material particles during repeated lithium ion intercalation and deintercalation. The fluorine-based polymer provides a flexible matrix that absorbs mechanical stress, while the carboxymethyl cellulose-based polymer forms a stable coating around particles. This beforehand cushioning prevents structural collapse and gas generation, allowing the battery to maintain its capacity over extended cycling without degradation.
Application Domain
Data Source
AI summary:
A cathode for secondary batteries comprising a cathode active material layer with lithium iron phosphate and lithium nickel metal oxide, bound by a combination of fluorine-based polymers with hydrophilic functional groups, enhances adhesion and stability, improving cycle life characteristics.
Abstract
A cathode for a secondary battery according to embodiments of the present disclosure includes a cathode current collector and a cathode active material layer, and the cathode active material layer includes a cathode active material and a binder. The cathode active material includes first particles including lithium iron phosphate. The binder includes a first fluorine-based polymer and a second fluorine-based polymer having a hydrophilic functional group bound to the first fluorine-based polymer.