Abstract
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.
Highlights
IntroductionProvided that kinetically-fast redox species have been employed in the system, the key to improving conversion efficiency and extending state of charge (SOC) in solar energy storage is to design an effective continuous-flow cell that utilizes forced convective transport of the reactants throughout the cell as much as possible, such that diffusive transport is only required over short dimensions
Of photocharge was achieved[12]
Provided that kinetically-fast redox species have been employed in the system, the key to improving conversion efficiency and extending state of charge (SOC) in solar energy storage is to design an effective continuous-flow cell that utilizes forced convective transport of the reactants throughout the cell as much as possible, such that diffusive transport is only required over short dimensions
Summary
Provided that kinetically-fast redox species have been employed in the system, the key to improving conversion efficiency and extending SOC in solar energy storage is to design an effective continuous-flow cell that utilizes forced convective transport of the reactants throughout the cell as much as possible, such that diffusive transport is only required over short dimensions. The impact of forced convective flow on cell performance such as photocurrent, solar energy conversion, electrochemical as well as PEC reactions has been investigated. 3D numerical simulation has been conducted to gain more insights into the cell operation. Compared to those using stagnant electrolytes, the continuous-flow PESC shows great advantages in enhancing the photocurrent and remarkably 3.3 times improvement in photocharging depth
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