Lithium Air Battery Additive Triple Phase Boundary
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Solution Overview
Problem
Lithium air batteries face challenges in forming a boundary that contacts with air due to the hydrophilic properties of the electrolyte and hydrophobic properties of the porous carbon material, leading to reduced charge/discharge capacity, efficiency, and discharge voltage.
Innovation Solution
Incorporating an additive with a structure that has affinity for both the electrolyte and porous carbon material, such as compounds or copolymers with specific aromatic rings and ether functional groups, to form a triple phase boundary that enhances oxygen permeability and fills cathode pores with Li2O2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a small amount of electrolyte is used to improve oxygen permeability, then oxygen permeability is improved, but the charge/discharge capacity, charge/discharge efficiency, and discharge voltage are reduced due to difficulty in forming a boundary that contacts with air
Solution Approach 1:
A porous coating layer is introduced as an intermediary component between the electrolyte and the porous carbon material. This coating layer has hydrophobic properties that enable it to contact with air, while also being permeable to oxygen. The coating layer acts as a mediator that resolves the incompatibility between the hydrophilic electrolyte and hydrophobic carbon material, allowing the formation of a functional triple phase boundary that improves both oxygen permeability and charge/discharge capacity
Solution Approach 2:
The cathode is designed as a composite structure combining porous carbon material with a porous coating layer. This composite structure integrates the high oxygen permeability of the porous carbon material with the air-contacting capability of the hydrophobic coating layer, creating a synergistic effect that simultaneously achieves high oxygen permeability and high charge/discharge capacity
2Speed
If a small amount of electrolyte is used to improve oxygen permeability, then oxygen permeability is improved, but charge/discharge efficiency is reduced
Solution Approach 1:
The porous coating layer serves as a mediator that facilitates efficient charge/discharge reactions by providing a hydrophobic interface for air contact while maintaining oxygen permeability. This intermediary structure reduces energy losses by enabling effective oxygen reduction reactions at the cathode, thereby improving charge/discharge efficiency without compromising oxygen permeability
3Speed
If a small amount of electrolyte is used to improve oxygen permeability, then oxygen permeability is improved, but discharge voltage is reduced
Solution Approach 1:
The porous coating layer acts as a mediator that maintains high discharge voltage by facilitating efficient oxygen transport and electrochemical reactions. The hydrophobic nature of the coating layer enables it to contact with air and promote oxygen reduction reactions, while its porosity ensures adequate oxygen permeability, thereby maintaining high discharge voltage without sacrificing oxygen permeability
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
This approach improves the charge/discharge capacity, charge/discharge efficiency, and discharge voltage of the lithium air battery by expanding the triple phase boundary and increasing oxygen concentration, thereby maximizing discharge capacity and voltage.
Implementation Method 1
the hydrophilic property of the electrolyte and the hydrophobic properties of a porous carbon material included in the cathode
Implementation Method 2
an additive with a structure having an affinity to both a porous carbon material and an electrolyte
Implementation Method 3
permeability of oxygen used as a cathode active material
Implementation Method 4
an anode for intercalating/deintercalating lithium ions
Data Source
AI summary
A lithium air battery including an anode for intercalating/deintercalating lithium ions; a cathode having oxygen as a cathode active material, a lithium ion conductive solid electrolyte membrane disposed between the anode and the cathode; and an electrolyte, wherein the electrolyte is disposed between the lithium ion conductive solid electrolyte membrane and the cathode, and wherein the electrolyte includes at least one compound selected from a compound represented by Formula 1 and a copolymer including a repeating unit represented by Formula 2 as an additive:wherein in Formulae 1 and 2, groups CY1, CY2, a, b, c, b, R1 to R18, and variables t, u, and v are defined in the specification.