An alternative low-loss stack topology for vanadium redox flow battery: Comparative assessment

Journal of Power Sources

Saccardo

Giomo

et al. 2019

Self Cite

A cell-resolved model that simulates the dynamic thermal behavior of a Vanadium Redox Flow Battery during charge and discharge is presented. It takes into account, at a cell level, the reversible entropic heat of the electrochemical reactions, irreversible heat due to overpotentials, selfdischarge reactions due to ion crossover, and shunt current losses. The model accounts for the heat transfer between cells and toward the environment, the pump hydraulic losses and the heat transfer of piping and tanks. It provides the electrolyte temperature in each cell, at the stack inlet and outlet, along the piping and in the tanks. Validation has been carried out against the charge/discharge measurements from a 9kW/27kWh VRFB test facility. The model has been applied to study a VRFB with the same stack but a much larger capacity, operating at ±400 A for 8 h, in order to identify critical thermal conditions which may occur in next-generation industrial VRFB stacks capable to operating at high current density. The most critical condition has been found at the end a long discharge, when temperatures above 50°C appeared, possibly resulting in # $ precipitation and battery faults. These results call for heat exchangers tailored to assist high-power VRFB systems.

Section: Shunt Current Computationmentioning

confidence: 99%

“…Stack and cells equivalent electric network for shunt current computation[30].Since the cells of a VRFB stack are connected in series, homologous (i.e. positive or negative) cell electrodes have different electric potentials.…”

mentioning

confidence: 99%

Thermal modeling of industrial-scale vanadium redox flow batteries in high-current operations

Journal of Power Sources

Saccardo

Giomo

et al. 2019

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“…2. Each cell was represented as a Thévenin equivalent made of an ideal voltage generator E0 in series with a resistance Ri, both parameters being dependent on the battery state of charge (SOC, later on indicated as s) and the latter also on the solution flow rates Q [29]. Ri result from the resistances which takes into account the cell overpotentials: activation Ra, ohmic (membrane) Ro, and transport Rt [30]: The circuit segments inside the stack, i.e.…”

Section: B Electrical Modelmentioning

confidence: 99%

“…The shunt current energy losses Wsc and cell internal energy losses Wi along a whole operation cycle were obtained by integrating Psc and Pi during charge and discharge. The complete description of the stack electric model is reported in [29] and [31].…”

Section: B Electrical Modelmentioning

confidence: 99%

Maximizing Vanadium Redox Flow Battery Efficiency: Strategies of Flow Rate Control

2019 IEEE 28th International Symposium on Industrial Electronics (ISIE)

Picano

Guarnieri

2019

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Vanadium redox flow batteries (VRFBs) are one of the most promising technologies for large-scale energy storage due to their flexible energy and power capacity configurations. The energy losses evaluation assumes a very important rule on the VRFB characterization in order increase the efficiency of the battery. Very few papers describe the relations between hydraulic, electrical and chemical contributions to the system energy losses, especially in a large size VRFB system. In the first part a fluid dynamics characterization of a 9kW / 27 kWh VRFB test facility has been conducted. In particular, we will consider the internal resistance as the sum of an ohmic and a transport resistance. Secondly, an overall loss assessment based on both numerical and experimental results has been carried out. Finally, some improvements in the battery management strategy and in stack engineering are proposed, that results from this work and can help the future designer to develop more efficient VRFB stack with a compact design.

“…The IS-VRFB stack follows a conventional design with the cells fed hydraulically in parallel and connected electrically in series. At this aim, the cells are interleaved with frames encasing conducting plates (bipolar plates), which work as current collectors interconnecting electrically the cells while separating the solutions of different polarity[53], which is often reported as the most advantageous configuration.…”

mentioning

confidence: 99%

Developing vanadium redox flow technology on a 9-kW 26-kWh industrial scale test facility: Design review and early experiments

Alotto

D'Anzi²,

2018

Applied Energy

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Redox Flow Batteries (RFBs) have a strong potential for future stationary storage, in view of the rapid expansion of renewable energy sources and smart grids. Their development and future success largely depend on the research on new materials, namely electrolytic solutions, membranes and electrodes, which is typically conduced on small single cells. A vast literature on these topics already exists. However, also the technological development plays a fundamental role in view of the successful application of RFBs in large plants. Despite that, very little research is reported in literature on the technology of large RFB systems. This paper reports on the design, construction and early operation of a vanadium redox flow battery test facility of industrial size, dubbed IS-VRFB, where such technologies are developed and tested. In early experiments a peak power of 8.9 kW has been achieved with a stack specific power of 77 W kg-1. The maximum tested current density of 635 mA cm-2 has been reached with a cell voltage of 0.5 V, indicating that higher values can be obtained. The test facility is ready to be complemented with advanced diagnostic devices, including multichannel electrochemical impedance spectroscopy for studying aging and discrepancies in the cell behaviors.