Redox Flow Batteries using Carbon Dioxide; from electrocatalysis to cell engineering

减少二氧化碳排放、清洁能源的产生及其储存被广泛认为是二十一世纪最严峻的技术挑战之一。大规模采用许多清洁能源技术的主要缺点是需要高效能量存储设备的能量产生周期（峰值与非峰值）的间歇性。电化学技术被广泛研究用于清洁能源的产生和储存（例如，各种电池、燃料电池和超级电容器）和二氧化碳转化为有用的化学品（通过电还原）。本发现研究计划首次提出将这两个先前独立的领域结合在由申请人发明的基于负电极处的CO2 /甲酸（或甲酸根阴离子）氧化还原对的新型氧化还原液流电池技术中。在使用可再生能源的电池充电期间，CO2被还原为甲酸（或甲酸根阴离子，取决于pH值），其充当能量存储介质。在正电极处，通常用于液流电池的氧化还原对（例如，溴-溴）。在电池放电循环中，通过反转反应（例如，在负电极处，甲酸被氧化回CO2）。二氧化碳/甲酸-溴化物/溴氧化还原液流电池的理论比能量密度在298 K下为547 Wh/kg反应物。这种方法，如果成功的话，可以提供工业二氧化碳排放（例如，燃煤发电厂、水泥和钢铁制造厂等）采用碳中和的能源生产和储存技术，同时减少向大气排放的二氧化碳。换句话说，这是一种将二氧化碳废物转化为能源的新方法。

Mitigation of carbon dioxide emissions, clean energy generation and its storage are widely recognized as among the most stringent technological challenges of the twenty first century. A major drawback for large scale adoption of many clean energy technologies is the intermittent nature of the energy generation cycle (peak vs. off-peak) requiring efficient energy storage devices. Electrochemical technologies are intensely investigated for both clean energy generation and storage (e.g., various batteries, fuel cells and supercapacitors) and CO2 conversion to useful chemicals (by electro-reduction). The present discovery research program proposes to unite for the first time these two previously separate fields in a novel redox flow battery technology invented by the applicant based on the CO2 / formic acid (or formate anion) redox couple at the negative electrode. During battery charging using renewable energy source, CO2 is reduced to formic acid (or formate anion, depending on pH), which acts as energy storage medium. At the positive electrode, a redox couple commonly used in flow batteries (e.g., bromide – bromine) is employed. In the battery discharge cycle electric power is produced by reversing the reactions (e.g., at the negative electrode formic acid is oxidized back to CO2). The theoretical specific energy density of the carbon dioxide/formic acid – bromide/bromine redox flow battery is 547 Wh per kg of reactants at 298 K. This approach, if successful, could provide industrial CO2 emitters (e.g., coal fired power plants, cement and steel manufacturing plants etc.) with a carbon-neutral energy generation and storage technology, while reducing the CO2 emitted to the atmosphere. In other words, it is a novel approach for conversion of CO2 waste to energy.