Wei Zi, Shen Yi, Liu Dong, Liu Fuqiang
Department of Mechanical Engineering, University of Massachusetts Lowell, Lowell, MA, 01854, USA.
Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX, 76019, USA.
Sci Rep. 2017 Apr 4;7(1):629. doi: 10.1038/s41598-017-00585-y.
Greater levels of solar energy storage provide an effective solution to the inherent nature of intermittency, and can substantially improve reliability, availability, and quality of the renewable energy source. Here we demonstrated an all-vanadium (all-V) continuous-flow photoelectrochemical storage cell (PESC) to achieve efficient and high-capacity storage of solar energy, through improving both photocurrent and photocharging depth. It was discovered that forced convective flow of electrolytes greatly enhanced the photocurrent by 5 times comparing to that with stagnant electrolytes. Electrochemical impedance spectroscopy (EIS) study revealed a great reduction of charge transfer resistance with forced convective flow of electrolytes as a result of better mass transport at U-turns of the tortuous serpentine flow channel of the cell. Taking advantage of the improved photocurrent and diminished charge transfer resistance, the all-V continuous-flow PESC was capable of producing ~20% gain in state of charge (SOC) under AM1.5 illumination for ca. 1.7 hours without any external bias. This gain of SOC was surprisingly three times more than that with stagnant electrolytes during a 25-hour period of photocharge.
更高水平的太阳能存储为间歇性的固有特性提供了一种有效的解决方案，并且可以显著提高可再生能源的可靠性、可用性和质量。在此，我们展示了一种全钒（all-V）连续流光电化学存储电池（PESC），通过提高光电流和光充电深度来实现高效、高容量的太阳能存储。研究发现，与静止电解质相比，电解质的强制对流使光电流大大增强了5倍。电化学阻抗谱（EIS）研究表明，由于电池曲折蛇形流道U形转弯处的传质更好，电解质的强制对流使电荷转移电阻大大降低。利用提高的光电流和降低的电荷转移电阻，全钒连续流PESC在AM1.5光照下约1.7小时内无需任何外部偏压就能在充电状态（SOC）下产生约20%的增益。在25小时的光充电期间，这种SOC增益比静止电解质的情况高出惊人的三倍。
