The influence of copper foil microscopic appearance on Li-ion battery performance was discussed. Scanning electron microscope (SEM) results showed that there was a spot-like flaw on the defective copper film. Soft-package battery was prepared with the defective and qualified copper foils, respectively. The batteries' performance was evaluated, including electrochemical impedance spectra (EIS) analysis,discharging at both low temperature and room temperature, and cycle performance. It has been concluded from the EIS simulation result that the defective copper foil could have a severe influence on ohm impedance values, which are 31.95 mΩ and 11.78 mΩ for defective and qualified copper film, respectively. Besides, the low-temperature discharge and cycle performance of defective copper film batteries are inferior to that of the qualified copper film battery. It was also found from the disassembled battery that the anode electrode coated by the defective copper foil has poor adherence. The phenomenon also happened in the freshly prepared anode electrode.

By utilizing the advantages of good conductivity and one-dimensional fiber structure of carbon nanotubes (CNTs), nitrogen-doped carbon nanotubes (NCNTs) formed through the thermal conversion of polypyrrole-coated carbon nanotubes (PPy@CNTs) was utilized as an enhanced conducting additive. A composite of LiFePO₄ coated with carbon layers (C@LFP) and NCNTs has been prepared to improve the electrochemical performance of commercial LiFePO₄(LFP). The C@LFP was prepared through the pyrolysis of sucrose. Then the NCNTs-C@LFP and the nitrogen-doped CNTs (NCNTs) were uniformly distributed between the C@LFP particles. X-ray diffractometer and field emission scanning electron microscope (SEM) were used to analyze the crystal structure and microstructure of the samples. NCNTs are uniformly distributed between LFP particles and the preparation process did not change the crystal structure of LiFePO₄. The analysis of the pore structure of the sample by a physical adsorption instrument showed that the nanocarbon modification increases the specific surface area and the volume of small mesopores with the size of 2～5 nm of the NCNTs-C@LFP, which can facilitate the ions migration. Electrochemical tests showed that the carbon coating could improve the electronic conductivity of LFP particles and the NCNTs enhance the conductivity between the LFP particles. The charge transfer impedance of NCNTs-C@LFP shows a decrease of five times as that of LFP. The capacity of NCNT@C@LFP reaches 165 mA·h/g at a 0.1 C rate, which increases by 32% compared with the LFP (125 mA·h/g). The capacity retention rate of NCNTs-C@LFP is 94% after 100 cycles at 1.0 C. The results indicate that the electrochemical performance of LFP can be improved efficiently through constructing the conducting networks by the carbon coating with two-dimensional structure and NCNTs with one-dimensional structure.

Electrolyte is an important part of electrochemical energy storage (EES) equipment that plays a decisive role in device performance. Among a wide variety of electrolytes, water-in-salt (WIS) electrolyte has expanded the electrochemical window of an aqueous solution to above 3.0 V by the virtue of its unique solvent coordination ability. WIS has the advantages of aqueous electrolytes safety, low cost, and environmental protection which is very promising in future applications. The latest research of WIS electrolytes was reviewed here and abroad, including electrolyte salts, electrolyte additives, the application of WIS electrolytes in electrochemistry, and its problems and challenges. For the electrolyte salts, several common fluorides based on sulfonimide and acetate such as potassium acetate, sodium acetate, and lithium acetate are described. The influence of WIS electrolyte prepared in the form of single or multiple salts on the electrochemical performance of capacitors and batteries has been analyzed. The electrolyte additives mainly include acetonitrile (AN), dimethyl carbonate (DMC), propylene carbonate, and other organic solvents, and introduce ionic liquids and carboxymethyl cellulose (CMC) as a cosolvent to improve the performance of electrode materials. The application of WIS electrolyte focuses on the electrode materials which cannot be used in conventional electrolytes or with poor performance, and in the derived solvent-in-salt system. Finally, the current problems and challenges faced by WIS electrolyte and the research directions of this electrolyte are proposed.

This paper focuses on the distributed wind power generation system; photovoltaic power generation system and battery storage system, in the active distribution network. Based on the selected decommissioned power batteries, the capacity configuration model of the distributed power supply and battery storage system is established, which aims at the whole system cost, system load shortage rate, and new energy waste rate. To address these issues, an improved harmony search algorithm is. Through the simulation analysis, the rationality of the retired battery management strategy and the effectiveness of the improved harmony search algorithm is verified. Both the distributed power supply and battery storage system can be optimized at the same time, which can not only effectively support the operation of the distribution network and improve the energy utilization rate but also reduce the cost of economic allocation. Considering the wind speed, solar irradiance, and load demand data of the summer typical day and winter typical day in an active distribution network, the multi-objective optimal allocation model includes the allocation of capacity and cost of the distributed generation and energy storage system, new energy abandoned power rate and loss of power supply probability. The improved harmony search algorithm is used to solve the problem. Finally, the correctness and effectiveness of the harmony search algorithm and optimal allocation model are verified by the configuration results.

In Formula Student Electric China (referred to as FSEC), the power battery box is the core of the car and its internal structural layout and design are very important. Based on selecting the new box material, Simulink was used to simulate the power system of the racing car to determine the capacity of the battery module, followed by the use of CATIA to accurately model the internal components of the racing car power battery box and to analyze the heat generation and heat dissipation of the battery box through ANSYS. Finally, CATIA battery box was manipulated to carry out the overall design and optimize the internal layout. The strength, heat dissipation, power, and durability of the finished battery box were tested to verify the effectiveness of the design. Based on ensuring the heat dissipation efficiency, reliability, and safety of the power battery system, the layout of the internal structure of the power battery box are improved through exploiting the above procedures so that the space utilization rate of the power battery box is greatly improved and the group efficiency of the battery pack reaches 0.723; realizing the lightweight design of the power battery pack and even the whole vehicle.

The discard rates of water, wind, and photovoltaic for renewable energy power are high for many years due to the fast growth of installed capacity for renewable energy power. The "Generation-Grid-Load-Storage" interactive control is an effective way to use the integrated coordinated control to decrease the discard rate of water, wind, and photovoltaic, and to improve the energy utilization efficiency. In this paper, the characteristics of renewable energy power are presented, The application of storage system and flexible controllable load is also discussed. Besides, the control mode of "Generation-Grid-Load-Storage" is proposed, Finally, to reduce the discard rate of renewable energy power, the improvement of "Generation-Grid-Load-Storage" interactive control with a rapid response is given.

In 2019, the ratio of oil importation reached 72% in China and automotive vehicle exhaust is the main source of urban air pollution. The promotion of electrification in the transportation sector therefore has strategic significance to the energy transition of China. According to statistics from the State Information Center, the sales of electric vehicles (including BEV and PHEV) in China reached 1.2 million in 2019, and China remains the world's largest electric vehicle market. Since the development of power electronics technology, the use of electric vehicles as a new energy storage facility allows a bidirectional power flow between grid and vehicle through V2G (Vehicle to grid) mode, and this could be an important mean to increase the flexibility and reliability of power gird. This article sorts out the grid application of V2G, and analyzes the benefits and costs of V2G service providers participating in various applications based on the current electricity price policy and power battery cost through calculation examples. The economics of V2G mode is strongly impacted by electricity price policies, and depends on the maturity of electricity spot market and related ancillary service market. The promotion of V2G in the future will rely on the design of reasonable electricity market entry barriers and electricity price compensation mechanisms.

Advanced military energy storage equipment has become an indispensable part of modern high-tech wars. At present, various forms of energy storage technology are rapidly innovated and are widely used in many military fields. At the same time, they continue to lead the upgrade of military equipment and even change the battlefield pattern. This article focuses on military fields such as land warfare, navy warfare, air warfare, space warfare, cyberwarfare, strike, and logistics support, and is mainly dedicated to energy storage technologies such as electricity storage, thermal storage, and hydrogen storage. The planned deployment and application of international military groups on energy storage technology were analyzed and summarized. This article also looks forward to the future development trends of military energy storage and gives recommendations for our country.

In order to promote the development of a solar photothermal conversion for heavy oil thermal recovery and reduce the development costs. The key technologies of heavy oil thermal recovery via tower solar photothermal conversion are systematically studied. This work demonstrates the feasibility of applying solar photothermal conversion technology in the main heavy oil-producing regions in China which gives the system composition of tower solar photothermal conversion heavy oil thermal recovery and optimizes the heat storage materials. This work focuses on the key equipment selection and design points of concentrating the heat collection system, heat storage system, and steam generation system. The technical economy of the photothermal conversion technology and the steam injection boiler are comprehensively compared and selected. The results showed that binary mixed nitrate could be used as an energy storage material for photothermal conversion for heavy oil thermal recovery. Besides, It has been found that circulating convection regulating valve is the preferred type of important parts of heat collection system. Also, optimizing VS1 molten salt pump can meet the operation requirements of hot and cold molten salt. On the other hand, a double-walled jacketed molten salt storage tank could be the mainstream design in the future. The thermal insulation design of a high-temperature foundation should ensure that the temperature of base concrete does not exceed 70 ℃. Finally, the combined heat transfer of preheater, steam generator, and superheater can meet the steam index of heavy oil thermal recovery, and strengthening the material selection of each unit is the key to ensure the safe operation of the whole system.

The impact of surge phenomenon is one of the biggest disadvantageous inherent factors in the normal operation of the core key component of air compressor. To address this issue, this work was performed through the investigation and discussion of the domestic and foreign-related literature to analyzes the parameter change and hardware inducement of the compressor surge to explore the external performance characteristics of the compressor surge phenomenon. It has been found that surge location is uncertain and the size structure of the system has a great effect on surge behavior, and the empirical critical value B is explained. This paper summarizes and puts forward anti-surge technical measures of the hardware and software, expounds on the impact of infrastructure, diffuser, impeller, shell, and other hardware structures on the surge, and points out the corresponding anti-surge measures and implementation effect. The principles of the fixing limit flow method, variable limit flow method and active control method with software and hardware were introduced in this work. The advantages, characteristics, and functions of these technologies are compared and analyzed, then the technical means of surge detection are summarized and classified. Finally, the computational fluid dynamics (CFD) technology is mainly introduced followed by the recent advancement in anti-surge technology and their future predictions are summarized. Comprehensive analysis shows that CFD combined with active control anti-surge technology will play a more important role in the future, which will help stall and surge research from qualitative to quantitative and achieve high-efficiency design and development of compressed air energy storage air compressor and normal high-performance operation.

In this review, we introduce the basic principles of solid-state nuclear magnetic resonance (NMR) spectroscopy, focusing on magic angle spinning and cross-polarization, which can reduce or eliminate partial interactions in the nuclear spin system to improve the resolution of NMR spectra. Several solid-state NMR techniques for obtaining ion migration dynamics information are summarized, including pulsed-field gradient NMR, central transition line width analysis, relaxation time analysis, 2D exchange NMR, and spin alignment echo NMR. Further, we review the application of these techniques to a series of typical cases, such as cathode materials, anode materials, LISICON, Thio-LISICON, NASICON, and garnet type solid electrolyte materials. A comparison of the advantages and disadvantages of each technology is also included. Finally, the recent developments in the field of solid-state NMR spectroscopy for the study of the mechanism of ion diffusion in batteries is discussed.