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

减少二氧化碳排放、清洁能源生产及其储存被广泛认为是21世纪最严峻的技术挑战之一。大规模采用清洁能源技术的一个主要缺点是能源生产周期的间歇性（高峰与非高峰）需要高效的储能设备。在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）方面，电化学技术得到了广泛的研究。目前的发现研究计划首次提出将这两个先前分开的领域结合在申请人发明的一种新的氧化还原液流电池技术中，该技术基于负极的CO2 /甲酸（或甲酸阴离子）氧化还原偶对。在使用可再生能源充电的电池中，二氧化碳被还原成甲酸（或甲酸阴离子，取决于pH值），作为储能介质。在正极，通常在液流电池中使用的氧化还原对（例如，溴-溴）被采用。在电池放电循环中，通过反向反应产生电能（例如，在负极甲酸被氧化回二氧化碳）。在298 K下，二氧化碳/甲酸-溴/溴氧化还原液流电池的理论比能量密度为每千克反应物547 Wh。这种方法如果成功，可以为工业二氧化碳排放者（如燃煤电厂、水泥和钢铁制造厂等）提供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.