Lithium Air Battery Positive Electrode Using Ionic Liquid
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Solution Overview
Problem
Lithium air batteries face reduced discharge capacity and stability due to solid-state byproducts like Li2O2 blocking pores and instability of aprotic electrolytes during charging and discharging, leading to irreversible byproducts such as Li2O3 or Li2O.
Innovation Solution
A positive electrode for lithium air batteries is developed using a conductive material and an ionic liquid with specific cations and anions, combined with a polymer electrolytic membrane and separator, to reduce side reactions and improve stability, comprising a slurry admixture of graphite or carbon nanotubes with ionic liquids like EMIM-TFSI, and a method of manufacturing this electrode that includes coating and drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If aprotic electrolyte is used in lithium air battery, then battery structure is simple and energy density is high, but solid-state Li2O2 byproduct blocks pores and reduces discharge capacity
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from solid-state (aprotic) to liquid-state (ionic liquid), which fundamentally alters the discharge product morphology from solid Li2O2 that blocks pores to soluble species that do not block pores, thereby maintaining high energy density while improving discharge capacity
Solution Approach 2:
The ionic liquid acts as an intermediary medium that facilitates the reaction between oxygen and lithium ions while preventing the formation of blocking solid byproducts. The ionic liquid mediates the charge-discharge process by dissolving reaction intermediates and products, allowing continuous ion transport without pore blockage
2Device complexity
If aprotic electrolyte is used in lithium air battery, then battery structure is simple, but electrolyte decomposes during charging and discharging, generating irreversible byproducts like Li2O3 or Li2O
Solution Approach 1:
The patent changes the chemical composition parameter of the electrolyte from aprotic organic electrolytes to ionic liquids with specific cation-anion combinations, which fundamentally improves electrochemical stability during charge-discharge cycles while maintaining acceptable battery structure simplicity
Solution Approach 2:
The patent uses composite ionic liquid systems combining specific cations (EMIM, BMIM, PYR14, etc.) with specific anions (TFSI, FSI, OTf, etc.) to create a stable electrolyte composition that resists decomposition during battery operation, improving reliability without significantly complicating the overall battery structure
3Ease of manufacture
If conventional positive electrode manufacturing process is used, then manufacturing is straightforward, but side reactions occur reducing capacity and lifespan characteristics
Solution Approach 1:
The patent changes the slurry composition parameters by replacing conventional solvents and binders with ionic liquids, which suppresses side reactions during electrode manufacturing and battery operation, thereby improving capacity and lifespan characteristics while maintaining ease of manufacture through similar coating and drying processes
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 enhances the capacity and lifespan of lithium air batteries by reducing side reactions and improving stability, with higher discharge capacities and economic efficiency through a simplified manufacturing process.
Implementation Method 1
a lithium ion conductive electrolyte provided between the positive electrode and the negative electrode
Implementation Method 2
a conductive material and an ionic liquid
Implementation Method 3
a positive electrode using oxygen in air as a positive electrode active material and including an oxygen redox catalyst
Data Source
AI summary
Disclosed are a positive electrode for lithium air batteries with excellent stability, a method of manufacturing the same, and a lithium air battery including the same, and a lithium air battery with improved stability by including the positive electrode. The positive electrode may include a conductive material and an ionic liquid such that the process of manufacturing the lithium air battery may be simplified, and the stability of the lithium air battery may be further improved as the result of inhibition of side reactions.