Carbon nanotubes have a one-dimensional tube-like structure with superior electrical and thermal conductivities, as well as mechanical strength. Such a structure makes it suitable for using as the backbone of flexible electrodes and long distance electrically conductive networks, and for creating high reactive surface area for overall performance. As a result, carbon nanotubes have attracted tremendous interest for due to numerous potential applications in the field of energy storage. This article reviews the work on the use of carbon nanotubes in flexible energy storage devices, covering supercapacitors, lithium ion batteries and lithium sulfur batteries. We will show that although there have been considerable amount of research on flexible supercapacitors and lithium ion batteries, little has been done on flexible lithium sulfur batteries. and rapid progress is expected to occur in the near future. In addition, we also briefly cover fabrication of flexible electrodes, and introduce criteria for evaluating electrode performance.

Good battery thermal management systems (BTMSs) are essential for Li­ion batteries for safe, reliability and efficiency. A BTMS needs to ensure not only the temperature of all battery cells within a safe range, but also the maximum temperature difference between different cells within battery pack below 5 ℃. Conventional BTMSs such as active air cooling and liquid cooling require extra power and fail to cope with high density of heat generation. Passive BTMSs make use of latent heat of phase change materials (PCMs) to absorb the heat generated by batteries are proved to be an effective way to maintain the battery temperature within their safety range without the use of extra energy. If combined with expanded graphite or metal foams, thermal conductivity of PCMs could be improved significantly. This can minimize the battery pack temperature difference and achieve an uniform temperature difference between different cells. As it is relatively easy to make PCMs into different shapes, they can be applied to batteries of different shapes and battery systems with a variety of configurations.

With the integration of large scale wind power into electrical network, concerns over frequency regulation, peak load shaving and voltage stability are growing due to fluctuation, randomness and intermittency of wind power. Energy storage systems (ESS) could ease such issues from the generation side (wind farm) to a certain extent through controlling wind power plant output, improving the low voltage ride through capability, and even providing ancillary services to the power system, therefore enabling an increased penetration of wind power. This paper provides a review on the application of ESS technologies in generation (wind farm) side, with emphases on the design, optimization of ESS capacity and control strategy of ESS. Key scientific and technological issues associated with these aspects are also outlined.

This paper is concerned about the charge behavior of a spherical phase change material (PCM) particle for high temperature thermal energy storage in a packed bed. A numerical modeling approach is used in the work. The influences of heat transfer fluid (HTF) temperature, PCM particle size and heat transfer modes (conduction only, combined conduction and natural convection and thermal radiation) on the behavior are examined. The results show that the melting time increases with an increase in the PCM particle size or a decrease in the HTF temperature. Inclusion of the natural convection effect in the PCM region leads to a reduction in the melting time by about 16%. Thermal radiation at the boundary accelerates the melting process of the PCM and intensifies the natural convection.

This paper focuses on riding through cases when a VRB system is partially failed. A comprehensive experimental study and a theoretical analysis have been performed on such a case. Several failure situations have been considered and two operation modes are put forward to respond to the failure including the use of lower rated power and times rated power. The results indicate that two modes of operation for dealing with the VRB partial failure create no significant effect on VRB energy storage system efficiency, and hence providing a way to improve the reliability of VRB energy storage systems under emergency conditions.

Three-dimensional (3D) structured graphene (rGO) has been successfully fabricated from electrochemical reduction of graphite oxide (GO) and ultrasonic treatment. The material was characterized by atomic force microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results show well-defined and cross-linked structures of pores of several micrometers. The 3D-structured graphene was investigated as an electrode material for supercapacitors by using galvanostatic charge/discharge (DC) , cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A specific capacitance as high as 140 F/g has been observed at scan rate of 10 mV/s, indicating excellent properties of high efficiency and cycle performance of the electrode materials.

This paper is concerned about the control strategy of current source converter (CSC) for a superconducting magnetic energy storage system (SMES). First, the CSC topology is improved to simplify traditional tri-logic PWM control structure. A direct current control strategy is then proposed on the basis of PRD (proportional-resonant-derivative) control. The PRD control method is able to achieve zero steady-state error of AC component and high system response speed through increasing the system damping, thus enabling the control of power transfer between the SMES and the grid. Theoretical analyses and MATLAB simulations verify the high dynamic and steady-state performance of the proposed PRD control strategy.

Interfaces play an important role in determining coulombic efficiency, energy efficiency, energy density, power density, cycle performance, service life, safety and self-discharge rate of lithium-ion batteries. We first briefly summarize our understanding of the formation mechanisms and structure of solid electrolyte interphase (SEI). We then introduce experimental techniques for characterizing the SEI including transmission electron microscopy (TEM), atomic force microscopy (AFM), and TG-DSC-MS.

Lead-acid battery was invented before 150 years, because of its unique advantages, such as low cost, ready availability, many types, free maintenance, good float service, safety, high-voltage and high-rate, its applications covers a wide range of fields in industry and daily life. These advantages are formed through long-term historical development. In this paper, the history of lead-acid battery was reviewed, introducing the invention processes and applications of lead-acid battery, the recycle of lead-acid battery was also reviewed based on whole life-time analysis. Finally, the new applications of lead-acid batteries were prospected for the future R&D, the lead-acid battery can benefit the development of new electrochemical energy storage systems.

Lithium ion batteries have been widely used in daily life due to their high energy density and long cycle life. However, when many batteries are connected in series and/or in parallel to form a battery array, much reduced life span is often observed. The main reason is associated with poor quality uniformity of individual cells. This paper provides a brief summary of methods for sorting battery cells according to their consistency. The mechanisms and characteristics of these methods are presented, along with research progress in our group. We will show that electrochemical impedance spectroscopy (EIS) could provide an effective and rapid way to evaluate the uniformity of battery cells.

Phase change materials take/release thermal energy from/to the environment during liquid-solid phase change whereby energy is stored and released. Such a solid-liquid phase change process is capable of withstanding a high pressure. This provides an opportunity for driving underwater gliders working below hundreds of meters of sea surface. The thermal underwater gliders use ocean thermal energy, hence preventing the needs for carrying power sources. The paper explains the mechanism of phase change energy storage,and reviews research and development of phase change energy storage. The example for the phase change processes inside the tube proves the application on driving underwater glider.

The overall wind energy resources in Inner Mongolia is estimated at 1380 GW of which 380 GW can be actually explored. This accounts for 50% of total amount in China. Currently, over 20% of the electrical network capacity in Inner Mongolia is from wind power generation. This study concerns grid integration of large-scale wind power generation into Inner Mongolia power grid. A compressed air energy storage (CAES) system is designed in this work for effective and efficient utilization of the wind power. The CAES system harnesses the abandoned wind power at off peak hours (night) to produce high temperature heat for use on daytime. The effects of heat consumption, charge ratio and efficiency of CAES power recovery on the plant performance are investigated. It is found that high operating pressures and large compressed air storage capacities give high efficiencies of CAES system.