Advanced Membrane-Free Electrochemical Energy Storage Devices (Phase 1)

要使风能和太阳能等可再生能源发电可调度，就需要能源储存。各种各样的储能技术在技术上已经成熟，并且可以商业化。其中，钒电化学氧化还原液流电池（rfb）具有独立调节功率和能量密度的独特优势，因此是电网和离网固定储能应用的有希望的候选产品。然而，当前一代的rfb存在操作效率低下的问题，主要是由于使用了分离阳极电解质和阴极电解质的Nafion膜。然而，为了支持电化学的基本原理，质子在膜上的运动是必要的。该膜无法阻止钒离子通过其交叉，导致电解质稀释和效率损失，并限制了电池的工作温度范围，一般在40℃以上。此外，Nafion膜价格昂贵，约占电池堆成本的40%。我们提出了一种彻底创新的RFB/VRFB设计，其中膜以及相关的技术问题都被消除了。在我们的设计中，用金属氧化物（SnO/SnO2）制成的辅助电极（AE）代替膜，在充放电过程中改变其氧化态（Sn2+/Sn4+），平衡阳极液和阴极液中的电荷，并为电化学储能提供必要的电化学。AEs消除了电解质隔室之间的离子运动，完全防止了电解质交叉，而不会对电池性能产生负面影响。这种新颖的设计还提供了在灵活的操作条件下在RFB系统中使用高能量密度电解质的机会。五名hqp将在该项目期间接受RFB技术培训。这些hqp将熟练掌握储能技术和业务方面的知识，适合不久的将来在工业和学术界的高需求储能职位。

Energy storage is required for making renewable electricity generation, such as wind and solar, dispatchable. A variety of energy storage technologies are technically mature and commercially available. Among these, redox flow batteries (RFBs) operating with vanadium electrochemistry (vanadium redox flow battery, VRFB) offer a unique advantage of independently sizing power and energy density, and are therefore a promising candidate for grid and off-grid stationary energy storage applications. However, the current generation of RFBs suffer from operational inefficiency, primarily due the use of Nafion membrane that separates the anolyte and catholyte. Yet it is necessary to allow the movement of protons across the membrane to support the fundamentals of electrochemistry. The membrane is incapable of preventing vanadium ion crossover through it resulting in electrolyte dilution and efficiency loss, and limiting the battery operating temperature range, generally above 40°C. Additionally, the Nafion membrane is costly and approximately represents 40% of the cell stack cost. We are proposing a radically innovative RFB/VRFB design in which the membrane as well as the associated technical issues are eliminated. In our design, the membrane is replaced with auxiliary electrodes (AE's) made of metal oxides (SnO/SnO2), that change their oxidation states (Sn2+/Sn4+) during charging/discharging, balance the charges in the anolyte and catholyte, and provide the necessary electrochemistry for the electrochemical energy storage. AEs eliminate ionic movement between electrolyte compartments and completely prevent electrolyte crossover without negatively impacting cell performance. This novel design also provides an opportunity to use high-energy-dense electrolytes in the RFB system with flexible operating conditions. Five HQPs will be trained in the RFB technology during this project. These HQPs will be skilled in technical and business aspects of energy storage and suitable for high-demand energy storage positions in industry and academia in the near future.