Measurement of key electrolyte properties for improved performance of the soluble lead flow battery

The soluble lead flow battery utilises the Pb/Pb²⁺ and Pb²⁺/Pb⁴⁺ redox couples. The electrolyte is methanesulfonic acid, in which Pb²⁺ species are soluble, up to 2.6 mol dm^?3. Previous publications have presented data demonstrating differing performances for the electrode and cell reactions. In this paper, electrolyte properties including density, viscosity, ionic conductivity and species concentration are systematically investigated to identify their impact on the efficiency and cycle life of a soluble lead cell under static conditions. The relationship between ionic conductivity and species concentration (Pb²⁺ and methanesulfonic acid) in the starting electrolyte is shown to be key to cell performance. An electrolyte initially containing 0.7 mol dm^?3 Pb(CH₃SO₃)₂ & 1.0 mol dm^?3 CH₃SO₃H is shown to provide optimal electrochemical performance for the soluble lead cell, achieving charge and voltage efficiencies of greater than 80% and 70% respectively along with Pb²⁺ utilisation of over 80%.     

Recent progresses and prospects of lead redox flow battery

铅氧化还原液流电池作为一种新型铅电池,具有一定的应用前景,正在逐渐成为电化学储能领域的一个研究热点。自2004年铅液流电池被提出15年来已经有不少相关研究,本文分析了铅液流电池的理论性能,回顾了其发展历程,介绍了其研发现状。现有研究中,电极面积为100 cm²的铅氧化还原液流电池可实现充电效率为90%和电压效率为80%的100次循环,且已有研究者对电极面积为1000 cm²的电池堆进行了测试。计算与分析表明,铅液流电池与传统铅酸电池相比具有更低的储能成本,仅为0.265 ￥·（kW·h）^-1。铅液流电池目前急需解决的问题包括：①开展放大的试验;②筛选或开发集流体材料进一步降低成本;③研究其失效机理以提高其循环寿命;④找到合适的方法修复失效铅液流电池。     

Dynamic modelling of the effects of ion diffusion and side reactions on the capacity loss for vanadium redox flow battery

The diffusion of vanadium ions across the membrane along with side reactions can have a significant impact on the capacity of the vanadium redox flow battery (VFB) over long-term charge-discharge cycling. Differential rates of diffusion of the vanadium ions from one half-cell into the other will facilitate self-discharge reactions, leading to an imbalance between the state-of-charge of the two half-cell electrolytes and a subsequent drop in capacity. Meanwhile side reactions as a result of evolution of hydrogen or air oxidation of V²⁺ can further affect the capacity of the VFB. In this paper, a dynamic model is developed based on mass balances for each of the four vanadium ions in the VFB electrolytes in conjunction with the Nernst Equation. This model can predict the capacity as a function of time and thus can be used to determine when periodic electrolyte remixing or rebalancing should take place to restore cell capacity. Furthermore, the dynamic model can be potentially incorporated in the control system of the VFB to achieve long term optimal operation. The performance of three different types of membranes is studied on the basis of the above model and the simulation results together with potential operational issues are analysed and discussed.     

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

The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ $0.10 kW^?1 h^?1. There is also a low‐level utility scale acceptance of energy storage solutions and a general lack of battery‐specific policy‐led incentives, even though the environmental impact of RFBs coupled to renewable energy sources is favourable, especially in comparison to natural gas‐ and diesel‐fuelled spinning reserves. Together with the technological and policy aspects associated with flow batteries, recent attempts to model redox flow batteries are considered. The issues that have been addressed using modelling together with the current and future requirements of modelling are outlined. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of the flow field,thermal performance,and heat transfer augmentation in circular tube using different dimple geometrical configurations with internal twisted-tape insert

In this study, a numerical investigation for the fluid flow field analysis using different configuration dimple parameters in conjunction with an internal type insert in pipe is carried out. The effects of the dimple diameters with a center twisted tape on the flow pattern, pressure drop, friction factor, and heat transfer characteristics are investigated. The influence of the latter device on heat performance and thermal-hydraulic performance evaluation factor (PEF) were carried out in a pipe for fully developed flow with range for fully developed flow with range of Reynolds number (Re) of 1573 and 23 592. Experiments with numerical models are performed using different dimpled dimeters by inserting twisted tapes. The outcomes observe that the qualitative analysis for flow fields such as static pressure, dynamic pressure, velocity magnitude, wall shear stress, and turbulent kinetic energy as well as the quantities analysis for pressure drop, heat transfer coefficient friction factor, and Nu number in dimpled pipe fitted with twisted tape are greater than plain pipe. This is because using these devices cause more secondary flow, swirl flow, and flow mixing that lead to higher turbulence, which, in turn, enhance the overall heat transfer. The results indicated that the lower and higher values of thermal PEF are about 0.78 and 1.6, respectively, at the dimple dimmers of 1 mm.