Opportunity
The increasing global energy demand and the emission of industrial waste gases, particularly nitrogen oxides (NO), pose significant environmental and health challenges. NO₂, a major component of NO, contributes to photochemical smog, stratospheric ozone depletion, and global warming. Current electrochemical methods, such as Li||NO₂ batteries, can capture NO₂ but produce NO as a byproduct, which is another harmful pollutant. There is no existing technology that simultaneously captures NO₂, converts it into value-added chemicals like ammonia (NH), and generates electrical power. This gap in technology motivates the development of the aqueous Zn||NO₂ electrochemical cell, which addresses these limitations by offering a bifunctional solution for NO₂ utilization and energy production.
Technology
The patent introduces an innovative aqueous Zn||NO₂ electrochemical cell comprising a metallic Zn anode, a nano-NiO catalyst-deposited gas diffusion cathode, and a ZnCl₂ aqueous electrolyte. The cell operates on a reversible NO₂/NO₂⁻ redox reaction, where NO₂ is electrochemically reduced to NO₂⁻ and further converted to NH while producing electricity. Key innovations include:
- Nano-NiO Catalyst: Exhibits exceptional electrocatalytic performance with an overpotential of 350 mV at 10 mA/cm² and a Tafel slope below 65 mV/dec, enabling efficient NO₂ reduction and oxidation.
- Bifunctional Design: The electrolyte captures NO₂ and converts it to NO₂⁻, which is then transformed into NH via a self-powered mechanism.
- High Energy Density: Achieves a cell-level energy density of 553.2 Wh/kg and a volumetric density of 1589.6 Wh/L, surpassing conventional batteries.
- Stability: Demonstrates >100 hours of cycling stability with 81.3% energy efficiency under 3 vol.% NO₂/air diffusion.
Advantages
- Dual Functionality: Simultaneously captures NO₂ and generates electricity.
- High Efficiency: Faradaic efficiency of 96.4% for NO₂⁻ production.
- Scalability: Ah-scale (2.4 Ah) pouch cells validated for practical applications.
- Environmental Benefits: Converts NO₂ into NH, a valuable chemical, reducing pollution.
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Cost-Effective: Uses abundant Zn and aqueous electrolytes, avoiding expensive materials.
Applications
- Energy Storage: Grid-scale batteries for renewable energy storage.
- Pollution Control: NO₂ capture and conversion in industrial exhaust systems.
- Ammonia Production: Self-powered Haber-Bosch reactors for green NH synthesis.
- Transportation: Power sources for electric vehicles with integrated emission control.
- Portable Electronics: High-energy-density batteries for consumer devices.
