Microemulsion-assisted synthesis of nanosized Li-Mn-O spinel cathodes for high-rate lithium-ion batteries

Li1.16Mn1.84O4 nanoparticles (50-90 nm) with cubic spinel structure are synthesized by combining a microemulsion process to produce ultrafine Mn(OH)2 nanocrystals (3-8 nm) with a solid-state lithiation step. The nanostructured lithium-rich Li1.16Mn1.84O4 shows stable cycling performance and superior rate capabilities as compared with the corresponding bulk material, for example, the nano-sized Li1.16Mn1.84O4 electrode shows stable reversible capacities of 74 mAhg-1 during the 1000th cycle at a high rate of 40 C between 3.0 and 4.5 V. In addition, Li1.16Mn1.84O4 nanoparticles also show high Li storage properties over an enlarged voltage window of 2.0-4.5 V with high capacities and stable cyclability, for example, delivering discharge capacities of 209 and 114 mAhg-1 at rates of 1 and 20 C, respectively

Vanadium based nanoelectrode materials in energy storage systems

The performance and reliability of energy storage systems largely depend on the characteristics and properties of the electrode materials that constitute the system. Nanostructured materials have greatly influenced the overall performance of these systems by enhancing surface processes and improving the transport kinetics of the ions/molecules involved. Vanadium based materials have received considerable attention, particularly as electrode materials in high energy density Lithium ion batteries (LIB) and supercapacitors because of their cost effectiveness, efficient energy utilization and special structural characteristics. In this review, the applications of vanadium based materials as electrode components in energy storage systems have been described; their utilization in LIB and supercapacitors has been particularly highlighted. Recent developments in the field of vanadium based nanoelectrode materials are also discussed

Review of material research and development for vanadium redox flow battery applications

The vanadium redox flow battery (VRB) is one of the most promising electrochemical energy storage systems deemed suitable for a wide range of renewable energy applications that are emerging rapidly to reduce the carbon footprint of electricity generation. Though the Generation 1 Vanadium redox flow battery (G1 VRB) has been successfully implemented in a number of field trials and demonstration projects around the world, it suffers from low energy density that limits its use to stationary applications. Extensive research is thus being carried out to improve its energy density and enhance its performance to enable mobile applications while simultaneously trying to minimize the cost by employing cost effective stack materials and effectively controlling the current operating procedures. The vast bulk of this research was conducted at the University of New South Wales (UNSW) in Sydney during the period 1985–2005, with a large number of other research groups contributing to novel membrane and electrode material development since then. This paper presents a historical overview of materials research and development for the VRB at UNSW, highlighting some of the significant findings that have contributed to improving the battery's performance over the years. Relevant work in this field by other research groups in recent times has also been reviewed and discussed

Li3V2(PO4)3 cathode materials for lithium-ion batteries : a review

The principal challenges facing the development of lithium ion batteries (LIBs) for hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles and for off-peak energy storage are cost, safety, cell energy density (voltage × capacity), rate of charge/discharge, and service life. There are exciting developments in new positive electrode (cathode) materials to replace the LiCoO2 for use in the LIBs over the past decade. Monoclinic Li3V2(PO4)3 (LVP) with promising electrochemical properties including excellent cycling stability, high theoretical capacity (197 mAh g-1), low synthetic cost, improved safety characteristic, and low environmental impact emerges as highly suitable candidate. In this review, we focus on research work related to the LVP and discuss its host structure, mechanism of lithium insertion/extraction, transport properties (i.e., electronic conductivity, and lithium diffusion), synthesis and electrochemical properties. We highlight some recent development of LVP, which shows superior cycling stability and high rate capability and give some vision for the future research of LVP based electrode.Accepted versio

Online monitoring of state of charge and capacity loss for vanadium redox flow battery based on autoregressive exogenous modeling

Accurate monitoring of state of charge (SOC) and capacity loss is critical for the management of vanadium redox flow battery (VRB) system. This paper proposes a novel autoregressive exogenous model for the vanadium redox flow battery, based on which the model-based monitoring of state of charge and capacity loss is investigated. The offline parameterization based on genetic algorithm and the online parameterization based on recursive least squares are investigated for the proposed model to compare the model accuracy and robustness. Leveraging the parameterized model, an H-infinity observer is exploited to estimate the battery state of charge and capacity in real time. Experimental results suggest that the proposed autoregressive exogenous model can accurately simulate the dynamic behavior of vanadium redox flow battery. Compared with the offline model based method, the observer based on online adaptive model is superior in terms of the accuracy of modeling, state of charge estimation and capacity loss monitoring. The proposed method is also verified with high robustness to the uncertain algorithmic initialization, electrolyte imbalance, and the change of system design and work conditions

Real-time monitoring of capacity loss for vanadium redox flow battery

The long-term operation of the vanadium redox flow battery is accompanied by ion diffusion across the separator and side reactions, which can lead to electrolyte imbalance and capacity loss. The accurate online monitoring of capacity loss is therefore valuable for the reliable and efficient operation of vanadium redox flow battery system. In this paper, a model-based online monitoring method is proposed to detect capacity loss in the vanadium redox flow battery in real time. A first-order equivalent circuit model is built to capture the dynamics of the vanadium redox flow battery. The model parameters are online identified from the onboard measureable signals with the recursive least squares, in seeking to keep a high modeling accuracy and robustness under a wide range of working scenarios. Based on the online adapted model, an observer is designed with the extended Kalman Filter to keep tracking both the capacity and state of charge of the battery in real time. Experiments are conducted on a lab-scale battery system. Results suggest that the online adapted model is able to simulate the battery behavior with high accuracy. The capacity loss as well as the state of charge can be estimated accurately in a real-time manner

Thermal hydraulic behavior and efficiency analysis of an all-vanadium redox flow battery

Vanadium redox flow batteries (VRBs) are very competitive for large-capacity energy storage in power grids and in smart buildings due to low maintenance costs, high design flexibility, and long cycle life. Thermal hydraulic modeling of VRB energy storage systems is an important issue and temperature has remarkable impacts on the battery efficiency, the lifetime of material and the stability of the electrolytes. In this paper, a lumped model including auxiliary pump effect is developed to investigate the VRB temperature responses under different operating and surrounding environmental conditions. The impact of electrolyte flow rate and temperature on the battery electrical characteristics and efficiencies are also investigated. A one kilowatt VRB system is selected to conduct numerical simulations. The thermal hydraulic model is benchmarked with experimental data and good agreement is found. Simulation results show that pump power is sensitive to hydraulic design and flow rates. The temperature in the stack and tanks rises up about 10 °C under normal operating conditions for the stack design and electrolyte volume selected. An optimal flow rate of around 90 cm3 s−1 is obtained for the proposed battery configuration to maximize battery efficiency. The models developed in this paper can also be used for the development of a battery control strategy to achieve satisfactory thermal hydraulic performance and maximize energy efficiency

In‐situ tools used in vanadium redox flow battery research - review

Progress in renewable energy production has directed interest in advanced developments of energy storage systems. The all‐vanadium redox flow battery (VRFB) is one of the attractive technologies for large scale energy storage due to its design versatility and scalability, longevity, good round‐trip efficiencies, stable capacity and safety. Despite these advantages, the deployment of the vanadium battery has been limited due to vanadium and cell material costs, as well as supply issues. Improving stack power density can lower the cost per kW power output and therefore, intensive research and development is currently ongoing to improve cell performance by increasing electrode activity, reducing cell resistance, improving membrane selectivity and ionic conductivity, etc. In order to evaluate the cell performance arising from this intensive R&D, numerous physical, electrochemical and chemical techniques are employed, which are mostly carried out ex situ, particularly on cell characterizations. However, this approach is unable to provide in‐depth insights into the changes within the cell during operation. Therefore, in situ diagnostic tools have been developed to acquire information relating to the design, operating parameters and cell materials during VRFB operation. This paper reviews in situ diagnostic tools used to realize an in‐depth insight into the VRFBs. A systematic review of the previous research in the field is presented with the advantages and limitations of each technique being discussed, along with the recommendations to guide researchers to identify the most appropriate technique for specific investigations.Published versio