Expanded Graphite Desalination Electrode Ion Storage
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Solution Overview
Problem
Current desalination technologies face challenges such as high energy demands, environmental concerns, and material issues like membrane corrosion, limiting their widespread use for producing fresh water from saline sources.
Innovation Solution
A desalination battery utilizing expanded graphite electrodes with tailored interlayer spacing for graphene layers, which acts as an intercalation host to reversibly store and release ions from saline water, reducing salt concentration and producing fresh water, while also incorporating pillaring agents and polymeric binders for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional desalination processes are used, then fresh water can be produced from saline water, but high energy demands and environmental concerns arise
Solution Approach 1:
The patent changes the fundamental operating parameters of desalination by using a battery-driven electrochemical process instead of thermal or high-pressure membrane processes. The expanded graphite intercalation host enables ion removal at low voltages (0.5-1.5 V), dramatically reducing energy consumption while maintaining fresh water production capability
Solution Approach 2:
The desalination battery enables self-service operation where the system can produce fresh water during charging and generate electricity during discharging. The reversible intercalation-deintercalation process allows the electrodes to automatically store and release ions without external energy input during the regeneration phase
2Productivity
If conventional desalination processes are used, then fresh water can be produced, but material issues related to corrosion of membranes occur
Solution Approach 1:
The patent uses expanded graphite with controlled porosity and interlayer spacing (0.37-0.45 nm) as the intercalation host. This porous structure allows selective ion intercalation while being inherently corrosion-resistant, eliminating the membrane durability issues associated with conventional porous membrane materials
Solution Approach 2:
The electrode comprises a composite material system combining expanded graphite (60-95 wt%), conductivity agents (1-20 wt%), and polymeric binders (1-20 wt%). This composite structure provides both the intercalation functionality and mechanical stability needed for long-term reliable operation without membrane corrosion
3Quantity of substance
If expanded graphite with increased interlayer spacing is used, then sodium ion storage capacity increases, but structural stability may be compromised
Solution Approach 1:
The patent applies local quality modification by selectively expanding only the interlayer spacing of graphite to 0.37-0.45 nm while maintaining the integrity of the graphene layers themselves. The pillaring agents are locally positioned between specific graphene layers to provide structural support exactly where needed, rather than uniformly modifying the entire structure
Solution Approach 2:
The composite electrode structure combines expanded graphite with conductivity agents and polymeric binders that work together to maintain structural stability. The binders hold the expanded graphite framework together, while conductivity agents ensure electrical continuity, preventing structural collapse despite increased interlayer spacing
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 desalination battery achieves a significant increase in sodium ion storage capacity and cycling stability, offering a durable, cost-effective, and scalable solution for producing fresh water with reduced energy consumption and environmental impact.
Implementation Method 1
at least the first intercalation host including expanded graphite having a plurality of graphene layers with an interlayer spacing greater than 0.34 nm... the first and second intercalation hosts reversibly store and release cations and anions from the saline water solution located between the plurality of graphene layers
Data Source
AI summary
A desalination battery includes a container configured to contain a saline water solution having a first concentration c1 of dissolved salts; first and second intercalation hosts, arranged to be in fluid communication with the saline water solution, at least the first intercalation host including expanded graphite having a plurality of graphene layers with an interlayer spacing between the graphene layers in z-direction greater than 0.34 nm; and a power source configured to supply electric current to the first and second intercalation hosts such that the first and second intercalation hosts reversibly store and release cations and anions from the saline water solution located between the plurality of graphene layers to generate a fresh water solution having a second concentration c2 of dissolved salts and a brine solution having a third concentration c3 of dissolved salts within the container such that c3>c1>c2.