Composite Alkali Ion Conductive Electrolyte Membrane
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Solution Overview
Problem
Alkali ion-conductive ceramic membranes, such as NaSICON, become less efficient or inoperable under acidic conditions and can be damaged by chemically reactive solutions, leading to reduced efficiency and shortened lifespan in electrochemical cells.
Innovation Solution
A composite alkali ion-conductive electrolyte membrane with a layer of alkali compounds, such as carbon-based intercalation compounds or alkali metal amalgams, is used to protect the membrane from adverse chemical reactions, maintaining alkali ion conductivity and stability under various conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an alkali ion-conductive ceramic membrane (e.g., NaSICON) is used in an electrochemical cell, then alkali ion selectivity and conductivity are improved, but the membrane becomes less efficient or inoperable under acidic conditions (pH < 5) and can be damaged by chemically reactive solutions
Solution Approach 1:
The patent introduces an intermediary protective layer between the alkali ion-conductive ceramic membrane and the chemically reactive electrolyte environment. This protective layer acts as a mediator that is chemically resistant to acidic and basic conditions while still permitting alkali ion transport, thereby protecting the membrane from direct contact with harmful chemicals that would otherwise cause degradation and reduce efficiency
Solution Approach 2:
The patent employs a composite structure combining the alkali ion-conductive ceramic membrane with a chemically resistant protective layer. This composite material approach integrates two materials with complementary properties: the ceramic provides ion conductivity while the protective layer provides chemical stability, resolving the contradiction between maintaining membrane efficiency and resisting chemical degradation
2Adaptability or versatility
If the membrane is exposed to chemically reactive solutions (acidic, basic, organic compounds), then the cell can operate under diverse conditions, but the membrane efficiency decreases and lifespan is shortened
Solution Approach 1:
The protective layer serves as a chemical intermediary that allows the membrane to adapt to diverse operating conditions (acidic, basic, organic) without direct exposure to harmful substances. This mediator enables versatility in operating conditions while protecting the membrane from degradation, thereby extending its operational lifespan
Solution Approach 2:
The protective layer creates a chemically inert environment around the membrane by being resistant to acidic, basic, and organic compounds. This inert barrier allows the cell to operate under diverse chemical conditions while the membrane itself remains protected from direct chemical attack, maintaining both adaptability and longevity
3Productivity
If organic solvents (e.g., ethylene glycol, hexanol) are used in the cell, then specific chemical reactions can be achieved, but a resistive film forms on the membrane reducing cell efficiency
Solution Approach 1:
The protective layer acts as a chemical intermediary between the organic solvent and the membrane surface. It prevents direct interaction between the organic compounds and the membrane, thereby stopping the formation of resistive films that would otherwise reduce cell efficiency while still allowing the desired chemical reactions to proceed
4Reliability
If fluorinated compounds (e.g., LiPF6) and trace water are present, then electrolyte function is achieved, but hydrofluoric acid (HF) is produced reducing pH and causing membrane inefficiency
Solution Approach 1:
The protective layer serves as a chemical barrier that intercepts hydrofluoric acid (HF) produced from the reaction of fluorinated compounds with trace water. This intermediary prevents the acid from reaching and degrading the membrane, maintaining membrane efficiency despite the presence of fluorinated electrolytes
Solution Approach 2:
The protective layer converts the harmful effect of HF production into a manageable situation by absorbing or resisting the acid attack. The layer essentially sacrifices itself or resists degradation to protect the membrane, turning the harmful chemical reaction into a non-critical event that does not compromise overall cell performance
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 composite membrane effectively protects the alkali ion-conductive material from chemical degradation, allowing it to function efficiently even under acidic, basic, and reactive conditions, extending its lifespan and maintaining performance in electrochemical cells.
Implementation Method 1
NaSICON membranes selectively transport sodium cations, while LiSICON (Li Super Ion CONducting) and KSICON (K Super Ion CONducting) membranes selectively transport lithium and potassium cations, respectively
Implementation Method 2
a layer of alkali compound which is electrically or ionically conductive and which is chemically stable upon exposure to the anolyte solution or catholyte solution thereby protecting the layer of alkali ion-conductive material from unwanted chemical reaction
Implementation Method 3
water (H2O) can be split at the anode 118 to form oxygen gas (O2) and protons (H+)
Implementation Method 4
water (H2O) can be split at the cathode 220 to form hydrogen gas (H2) and hydroxyl ions (OH-)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An electrochemical cell (210) having a composite alkali ion-conductive electrolyte membrane (215). Generally, the cell (210) includes a catholyte compartment (214) and an anolyte compartment (212) that are separated by the composite alkali ion-conductive electrolyte membrane (215). The composite electrolyte membrane (215) includes a layer of alkali ion-conductive material (216) and one or more layers of alkali intercalation compound (222) which is chemically stable upon exposure to a chemically reactive anolyte solution or catholyte solution thereby protecting the layer of alkali ion-conductive material (216) from unwanted chemical reaction. The layer of alkali intercalation compound (222) conducts alkali ions. The cell (210) may operate and protect the alkali ion-conductive material (216) under conditions that would be adverse to the material if the intercalation compound were not present. The composite membrane (215) may include a cation conductor layer having additional capability to protect the composite electrolyte membrane (215) from adverse conditions.