A Mathematical Model for the Soluble Lead-Acid Flow Battery

Abstract

The soluble lead-acid battery is a redox flow cell that uses a single reservoir to store the electrolyte and does not require a microporous separator or membrane, allowing a simpler design and a substantial reduction in cost. In this paper, a transient model for a reversible, lead-acid flow battery incorporating mass and charge transport and surface electrode reactions is developed. The charge-discharge behavior is complicated by the formation and subsequent oxidation of a complex oxide layer on the positive electrode surface, which is accounted for in the model. The full charge/discharge behavior over two cycles is simulated for many cases. Experiments measuring the cell voltage during repeated charge-discharge cycles are described, and the simulation results are compared to the laboratory data, demonstrating good agreement. The model is then employed to investigate the effects of variations in the current density on the performance of the battery. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3328520͔ All rights reserved. The pressing demand for clean and efficient energy conversion, storage, and delivery, particularly the demand for renewable energy, has generated considerable interest in bulk energy storage technologies. Promising candidates for meeting the future energy-storage needs, including microgeneration, include redox flow batteries ͑RFBs͒ and flow batteries. In conventional batteries, such as the static lead-acid and lithium-ion cells, energy is stored entirely in the electrode structure. Redox flow batteries store energy either in a liquid electrolyte solution containing different redox couples, as in the all-vanadium battery, or in both an electrolyte and on the electrode surfaces in the form of deposits, as in the zinc-cerium system. The bulk of the electrolyte is stored in ͑typically two͒ reservoirs external to the cell. 1 The energy capacity of the system is determined by the volume of electrolytes in the tanks, the reactant concentrations, and the active area of the electrodes, while the system power is limited mainly by the size of the stacks and the active electrode surface area. Flow batteries can use a porous electrode ͑flow-through design͒, or the electrolyte can flow past an activated electrode ͑flow-by design͒.The applications of RFBs are not limited to the exploitation of renewable energy resources from the environment on large scales. RFBs can potentially be used for load leveling and peak shaving, uninterruptible power supply, and emergency backup.2 Demand for electricity is variable, requiring that some power generation installations are operated only during periods of high demand, a highly expensive and inefficient solution. An integrated energy-delivery system that includes an energy storage capability would improve reliability and enhance the quality of the electricity supply. For the supplier, it affords greater flexibility and savings in costs. Surplus installations could be decommissioned with the remaining installations operated at an almost constant load; storage cells...

Development of the all-vanadium redox flow battery for energy storage: a review of technological, financial and policy aspects

“…In the last decade, much of the funding for emerging energy technologies has been aligned towards fuel cells, despite the more immediate potential benefits of redox flow batteries. Shah and coworkers have developed detailed, physics-based models of the all-vanadium [103][104][105][106] and soluble lead-acid [107] cells using the conservation principles of charge, thermal energy, mass and momentum applied to a single cell and electrolyte tanks [103 -106]. The multi-dimensional, dynamic equations were solved for a range of operating conditions (including temperature, mean electrolyte flow rate, initial reactant concentration) and validated against experimental data.…”

“…A similar model was recently developed by Shah and co-workers for the all-vanadium system [111]. Although not able to capture the same level of detail at the unit cell scale as the models in [103][104][105][106][107][108], the equivalentcircuit approach is the ideal basis for control applications and stack/system-level modelling [112,113].…”

Fundamental models for flow batteries

“…The redox reactions for the Pb/ Pb(II) and PbO 2 /Pb(II) electrodes were described in the ButlereVolmer expressions [60]:…”

Membrane divided soluble lead battery utilising a bismuth electrolyte additive

“…As a consequence, the incorporation of a membrane into the soluble lead system would only be beneficial if; (1) the added cost of the membrane was offset by extended operational lifetime and (2) the increased cell resistance associated with the membrane was offset by improved efficiency or an increased cell potential (hence higher battery voltage and power). Currently, cycle life and efficiency limitations of the soluble lead battery are primarily associated with; (1) morphology of the electrode deposits (dendritic/spongy Pb and creeping PbO 2 formations) and (2) reversibility of the positive electrode reaction [1,[4][5][6]. The use of electrolyte additives can be employed to improve the efficiency and reversibility of the electrode reactions.…”