Lithium-ion batteries (LIBs) can provide high energy density, while supercapacitors have superior advantages on high power density and long cycle life. Capacitive lithium-ion batteries are constructed by adding slight capacitive carbon materials into the regular cathode materials of LIBs to realize the combination of the LIBs and supercapacitors, and thus the power performance and cycle life of the devices can be substantially improved at the expense of slightly reduced energy density. In this paper, we summarize the recent progress in the development on capacitive lithium-ion batteries and introduce the dominating capacitive lithium-ion battery system and their electrochemical performance. Finally challenges and perspectives of the capacitive lithium-ion batteries are outlined.

Due to the discrepancy among the batteries in the retired battery pack, to implement the classification and matching for batteries through state of health (SOH) estimating technology is a key problem of the industrialization of second use of retired Li-ion batteries. The construction of a SOH estimation system for retired Li-ion batteries involves various technical issues such as battery modelling, battery testing, data processing and algorithm development. Identification of model parameters and health indicators extraction are two main technical routes for SOH system construction. There are many researchers have studied in the battery model simplification, battery test method design, health indicators selection and algorithm optimization. The analysis of the research progress indicates that the major problems of the SOH estimating system are long test time and low generalization ability. The SOH estimation system with better performances would be developed by test method optimization and data fusion technology.

Compared with lithium, sodium is abundant, distributed uniformly and cheap in the crust. Following the limitation of research on lithium-ion batteries, sodium-ion batteries have attracted renewed attention of researchers. Among many electrode materials for sodium ion batteries, tinbased metal oxides have attracted much attention in recent years due to their high theoretical specific capacity (1378 mA·h/g). According to the literature, tin-based oxide materials with different nanostructures exhibit different electrochemical properties. In this paper, starting from the problem that the tin-based metal oxide of sodium ion battery needs to be solved, this paper systematically summarized the nanostructure characteristics and electrochemical properties of tin-based oxides, including tin-based metal oxides with special morphology, tin-based oxide materials with lowdimensional nanostructures, tin-based oxide material composites with three-dimensional structure, and tin-based oxide materials with core-shell structures, composite of tin-based oxide materials with special structure and the challenges faced by tin-based oxides are prospected.

During the operation of the photovoltaic system, how to cool the solar photovoltaic panel to achieve higher efficiency is a key factor to be considered. Proper cooling can increase power efficiency and reduce the rate of battery degradation over time, thus maximizing the lifetime of photovoltaic modules. The natural circulation convection cooling, forced convection circulating cooling, and liquid cooling technology in the traditional cooling technology are reviewed. The new cooling technologies include floating tracking centralized cooling system (FTCC), hybrid PV/T system, hybrid PV/TE system using radiator cooling and through use Phase change materials improve solar panel performance. According to the research focus, contribution and practical application, the advantages and disadvantages of each technology, the fields suitable for the application and the economic characteristics of each technology are analyzed. It is concluded that the future direction of technology development should ensure low, stable and reliable working surface temperature of the photovoltaic panels, no matter which technology is chosen. Meanwhile, the extracted thermal energy can be utilized to improve the overall conversion efficiency. To provide some reference value for the design and application of photovoltaic systems.

So far, electrolytes used in the commercialized lithium ion batteries are mainly based on liquid organic solvents, including ethylene carbonate, methyl-carbonate and propylene carbonate. During the charge/discharge process, decomposition of the electrolyte, uncontrollable formation of lithium dendrites and the leakage of the liquid electrolyte may occur, leading to the low stability and safety issues of the lithium ion batteries. Inorganic solid electrolytes have become a hot topic in the field of energy storage due to many advantages, such as high thermal stability, high electrochemical stability, being compatible with higher potential cathode materials, safety and environmental friendliness. The development of inorganic solid electrolytes with high ion conductivity is the focus and also challenge. In this paper, the last development in ion conductivity of inorganic solid electrolytes, such as LiPON, GARNET, Perovskite and LISICON are reviewed, and the application of these electrolytes in solid-state lithium batteries is summarized.

It introduces the research progress in blending modification cathode materials for lithium ion batteries. The cathode material is the most important part of lithium battery. It is becoming the bottleneck to the increase of energy density and the decrease of cost of lithium ion batteries. The blending modification cathode materials has been proven to be a promising approach to improve the electrochemical performance in battery production process. Blending modification cathode materials has the advantages of low-cost and simple preparation process. It has been expected to be a promising approach to design advanced electrodes based on material characteristics for future lithium-ion batteries. The article also points out that the research of properties matching, charging and discharging mechanisms and blend process were urgently needed.

Cycle life of power batteries greatly affects the service life of electric vehicles, which is an important factor of economic benefits. In addition to the cycle life studies of lithium-ion battery cells, the cycle life of module and battery system is more significative due to they are close to practical application. In this paper, using lithium manganate pouch cells as smallest testing unit, the electrochemical characteristics, capacity attenuation and temperature variation of monomer-modulebattery system are systematic analyzed. Results show that in the cooling condition, the relationship among the attenuation of three levels is battery system > module > cell; in terms of cycle temperature, module > cell > system. The results of three-dimensional hierarchical relationship illustrate the interfacial structure-activity relationship in capacity attenuation and temperature variation, which provides a reference for the study of cycle aging process of lithium traction battery system.

The data of charge and discharge current and voltage of 18650 and 26650 lithium iron phosphate batteries show that the voltage remains unchanged during the cycle aging of the battery, although the SOC value at the maximum curvature (inflection point) of the capacity voltage curve. Therefore, in the process of estimating SOC, when the discharge voltage reaches the inflection point voltage, modifying the SOC to the corresponding inflection point SOC can optimize the estimation of the ampere-hour integration method because of the initial SOC to a certain extent. Based on this, a new inflection point correction chronograph integration algorithm is proposed. The effects of temperature, charge and discharge ratio, cycle aging and other factors on the accuracy of SOC estimation are considered. The concept of inflection point of charge and discharge curve is introduced to establish a mathematical model for real-time estimation of SOC. To reduce the cumulative error problem of the ampere-time integral method. Compared with the traditional An-time integral method, the error is 3%, which indicates that the method is feasible in actual conditions, and the estimation accuracy is high, which can provide an important reference for real-time estimation and detection of SOC.

The accuracy of the state of charge (SOC) estimation of battery is a key issue in battery management system, which is very important to the reliability and safety of battery. In most cases, the accuracy of the battery model established is not high enough and the noise statistics of the battery system are unknown or inaccurate, which will greatly influence the SOC estimation. In this paper, the second-order RC equivalent model is adopted to reduce the error caused by the battery model. At the same time, a new SOC estimation method based on Sage-Husa filtering algorithm and untracked Kalman filtering (UKF) algorithm is proposed, an adaptive no-trace Kalman (AUKF) filtering algorithm based on noise statistical estimator can modify the system noise in real time to improve the estimation accuracy of SOC. And the accuracy and validity of the SOC estimation method are verified by comparing AUKF and UKF. The experimental results show that AUKF has a higher SOC estimation accuracy and adaptive ability, and the estimated accuracy can be kept within 4.68% under both pulse discharge and dynamic conditions, which can effectively estimate the SOC value of the battery.

The capacity of lithium battery is the main parameter to evaluate the health status of the battery, but since the battery capacity traceability system has not been established. Based on understanding the principle of battery charging and discharging and a battery capacity measurement uncertainty model, quantitative analysis of the factors that influence the battery capacity measurement is analyzed quantitatively based on the uncertainty analysis of optimization of lithium battery equivalent circuit model modification method. Through the actual measurement of charging voltage, capacity, compared with the model calculation of the voltage, capacity, it is judged whether the calculation value is within the uncertainty of the actual measurement, and avoid the lower reliability of the model caused by actual measurement deviation.

The state of charge (SOC) is one of the key technologies in battery management system. Among many estimation methods, neural network has obvious advantages in accuracy and robustness of estimation. The huge amount of data is an important factor to obtain the accurate value of SOC. To solve the above problems, a method of estimating SOC of power batteries based on BP artificial neural network is proposed. Taking a certain type of batteries as the experimental object, a large amount of data is obtained by collecting the data of voltage, current, internal resistance and temperature of batteries. Equivalent circuit model of battery was established, and the initial data were corrected considering the effects of battery polarization, charge-discharge ratio and temperature. BP artificial neural network model is established based on MATLAB platform, and the data are modified to train the network model, and the feasibility of the model is verified. The model is applied to the prediction of experimental data, and the estimation of SOC is realized by function fitting. Finally, by comparing the predicted and measured values of SOC, the validity of the artificial neural network model for estimating SOC is proved.

The molecular dynamics simulation method was used to simulate the amorphous tetradecane hydrocarbon system with COMPASS force field. The system was gradually heated from 270K to 290K under the NPT ensemble. The temperature-dependent diffusion of n-tetradecane molecules in the temperature range was analyzed. The phase transition temperature of the system was obtained at 278.5K. The obtained density value and phase transition temperature value are compared with the experimental results. The density error is 0.8% and the melting point error is 0.23%. The distribution of the terminal distance and the radial distribution function of the n-tetradecane molecular chain before and after the phase transition are also analyzed. It is found that the molecular chain conformation of n-tetradecane in solid state gradually changes from linear to curved with increasing temperature, while the conformation of molecular chain in liquid state gradually changes from curved to linear as the temperature increases. The possibility of presenting other molecules or atoms at 1.11 Å around the atom is the largest, and there are no other atoms in the 0.99 Å around the atom.The research results can be used to compare the changes of the microstructure of other molecular additives in the subsequent research, and to provide certain guidance for finding more efficient and practical phase change energy storage materials.

A novel hybrid liquid air energy storage system(LAES) combined with an organic Rankine cycle (ORC) was proposed to improve the efficiency of a conventional LAES system. The influence of different equipment performance parameters on the thermodynamic characteristics of LAES system was studied using Aspen HYSYS V8.4 process simulation method. The results show that:the influence of isentropic efficiency of cryo-pump and heat exchanger pinch point temperature on LAES system efficiency are small. On the other hand, the effects of isentropic efficiency of turbine and combustor outlet temperature are significant. The LAES system efficiency increases significantly with the increase of the isentropic efficiency of turbine and the combustor outlet temperature. The LAES system efficiency also increases with the increase of the cryo-pump outlet pressure, but the increasing range gradually decreases. The research results can provide important reference and basis for the engineering application and efficiency improvement of LAES system.

The medium-and high-temperature composite heat storage materials were fabricated by the mixed sintering method using mixed carbonates as phase change materials, magnesium oxide as ceramic matrix material, and graphite flakes as heat transfer enhancer. Based on the characterizations of XRD and SEM, the resultant composite materials have shown enhanced chemical stability, as well as more pore structures due to the presence of graphite flakes. By analyzing the thermal properties of the composite materials with different contents of graphite flakes, it can be found that the melting points of the composite materials remain unchanged and their thermal conductivities increase continuously with the increase of the content of graphite flakes. When the content of graphite flakes is up to 25%, the thermal conductivity of the composite material reaches 3.88 W/(m·K) and 2.52 W/(m·K) at 250℃ and 560℃, respectively. The enhancement mechanism of thermal conductivity of the composite materials is further discussed from the view of the microstructure and interface layer theories.

As an important component of the high-speed active magnetic bearing (AMB) system, the non-contact displacement sensor has significant impacts on the overall performance of the system. The traditional inductive displacement sensor signal demodulation circuit which is composed of discrete devices, has a high cost and a large space occupation. In order to develop a low-cost, high-integrated demodulation design of inductive displacement sensor, taking the integrated synchronous demodulation chip as the core, this paper performed tasks including the hardware design and manufacturing, software development and debugging, built the test platform of the inductive displacement sensor and finished evaluation experiments for the integrated synchronous demodulation design. The experimental results showed that the linearity between the synchronous demodulation chip output signal and rotor displacement is less than 2%. It is also shown a sensitivity of 3 V/mm, and a minimum resolution of up to 1 μm, which can meet the displacement detection requirements of general AMB systems.

The solar hot water storage tank is one of the important equipment of the solar energy application system. At present, the research on the performance of the hot water storage tank mainly focuses on the position and shape of the inlet pipe, the flow parameters, the position and geometry of the obstacle in the water tank. There is no report on the influence of the position and size of the opening of obstacles on the thermal stratification in the solar hot water storage tank. This study aims to evaluate the effect of 9 different positions of the opening of obstacles on thermal stratification and to obtain the optimal structure of the solar hot water storage tank and its optimum operating parameters. The results indicate that the tank with one circular opening in the center of the obstacle provides the optimum thermal stratification under the same flow parameters and opening area. For the tanks with multiple openings, the opening position has little effect on thermal stratification in the tank, but a significant effect on thermal energy storage. For the tank with one circular opening in the center of the obstacle, the temperature difference between the hot and cold water outlets increases first and then decreases with the increase of cold water inlet velocity under different flow parameters. When the cold water inlet velocity is greater than 0.9 m·s^-1, it will weaken the stability of thermal stratification.

Used induction melting method to prepare CeMg₁₁Ni as-cast alloy, and the partially alloys through re-melting and rapid solidification to obtain the quenched alloy. The microstructures properties of as-cast and microscopic structures were characterized by X-ray diffraction (XRD) and transmission electron microscopy(HRTEM). The performance of the CeMg₁₁Ni alloy were studied in detail by charge and discharge capacity, cycle stability, electrochemical impedance spectroscopy (EIS) technique and potentiodynamic polarization. The results showed that the as-cast alloy was consists of multi-phase structures, the as-quenched method can promote the formation of a large number of amorphous and nano-crystalline structures, improve the activation properties and electrochemical cycle stability, reduce the alloy's de-hydrogen enthalpy, reduce the alloy's surface activation energy, enhance charge transfer reaction and hydrogen atom diffusion ability, besides, further explain the reason why the alloy has strong electrochemical reaction kinetics.

In this paper, the thermal behavior of supercapacitor cells during charging and discharging under different working conditions is studied, which provides a theoretical basis for the use of supercapacitors. The results show that when the ambient temperature is 25℃, the current changes linearly. The highest internal temperature of the monomer reaches 25.31℃(298.46 K); In 3 times rated current cycle charging and discharging conditions, after 15 cycles of charging and discharging, the highest temperature inside the capacitor monomer reaches 55℃ (328K), charging and discharging process. After 30 cycles, the highest temperature inside the capacitor unit reached 82℃ (355 K).

A novel phase change material based thermal management system coupled with liquid cooling was proposed in order to sustain the temperature rise and distribution within desirable ranges of the lithium-ion battery under 3C discharge rate. A numerical study was conducted to investigate the effects of water flow rate, channel arrangement, the fin width of aluminum frame and ambient temperature on the thermal behavior of the integrated thermal management system. The results showed that increasing the water flow rate can optimize the heat dissipation of the battery pack, but when the flow rate is greater than 0.08 m/s, the increase of the flow rate has no obvious improvement for the integrated thermal management system. Under different water flow rate, Type I cooling mode showed the best performance and met the request of thermal dissipation completely; The maximum temperature of the battery pack can be further reduced 1.6℃ by the integrated thermal management system with fin width of 2 mm; when the ambient temperature from 38℃ to 42℃, the thermal stability of the integrated system was obviously better than that of the liquid cooling system.

The thermal behaviors of lithium-ion capacitor, as a new kind of electrochemical energy devices, have not yet attracted sufficient attentions so far. Therefore, it is significant to study the temperature distribution of lithium-ion capacitor under various conditions. In this paper, the threedimensional finite element model was established and a finite element software Workbench was employed to simulate temperature distribution at different ambient temperatures and discharge rates. The results show that the temperature of capacitor increases gradually with the discharge process going on and the highest temperature appears in the center of cell. Meanwhile, the internal temperature difference are less affected by ambient temperature. More importantly, the comparison between the simulation and experimental results shows that the heat generation model can reflect the temperature variation of the lithium ion capacitor very well during the discharge process, which is helpful to the performance optimization and structure design of lithium ion capacitors.

This article studied the RC equivalent circuit model of lumped parameters for lithium-ion batteries in electric vehicles. On the base of the traditional battery models, this research creates a new dynamic equivalent circuit model of lithium-ion power battery considering the polarization effect and hysteresis voltage characteristics of battery. Model's parameters were identified by tests. The estimated error of this model is 2% through experimental analysis, which is more accurate than the traditional first-order and second-order models and simpler than the third-order RC model.

To reduce the contact between the cathodes and electrolyte, the surface of the LiNi_1/3Co_1/3Mn_1/3O₂ (NCM) cathode was modified with graphite by screen printing. The X-ray diffraction (XRD) test results show that the crystalline structure of the modified NCM cathodes did not change obviously. The morphology of the pristine and modified NCM cathodes were characterized by scanning electron microscopy (SEM), and the results revealed that flake graphite were detected on the surface of the modified NCM cathodes. The performance of both cathodes were evaluated by galvanostatic charge and discharge tests, and it could be concluded that the modified NCM cathodes have better cycling performance and high rate capability than the pristine NCM samples at a cut-off voltage of 4.3V. The results of the CV and EIS test showed that the additional graphite could slow down the increase of electrochemical polarization. In conclusion, the rate capability and cycling performance of the modified NCM were improved.

This bimonthly review paper highlights 100 recent published papers on lithium batteries. We searched the Web of Science and found 3486 papers online from Jun. 1, 2019 to Jul. 31, 2019.100 of them were selected to be highlighted. Layered oxide including Ni-rich oxides and lithium cobalt oxide are still under extensive investigations for studying the influences of doping and coating on their cycling performances. Large efforts were devoted to improve the cycling performance and coulombic efficiency of Si based and metallic lithium anode by optimizing their 3D electrode structure, surface and electrolyte. Sulfide, halide containing sulfide and polymer based solid state electrolyte are drawn large attentions. Additives are added to liquid electrolyte to form stable CEI and reduce the effects of the dissolved transition metal ions from the cathode to SEI at the anode. The studies of solid state battery are focus on the designs of composite electrode and 3D structure for both cathode and anode, so as to the Li-S battery. In-situ ex-situ technologies are used to analyze the fading mechanism of Liion battery and solid state lithium battery. There are few papers related to theoretical calculations and recycling of lithium ion batteries, too.

Aiming at the problems of management of lithium-ion batteries, the characteristics of Liion battery and on-orbit requirements are analyzed. The autonomous health management system of lithium-ion battery is designed.The validity of the designed system is verified through on-orbit data analysis of a MEO satellite. The self-management proposed in this paper can provide experience for the subsequent and orbiting management of Li-ion batteries.

Distributed energy storage is changing the structure of power supply and demand. Distributed energy storage not only helps users resolve power stability issues and decrease electricity costs, it can also lower peak capacity demands for power distribution, remedy the negative impact that distributed resource spontaneity has to the grid, and drive greater investment returns across the entire grid. However, across the globe, distributed energy storage development models still remain in the exploratory stage. The question of how to fully develop the value of distiributed energy storage is one that requires further research and exploration from all countries. At present, a variety of innovative business models have already been established in domestic and overseas markets. In addition to support from a good market environment and incentive policies, such emerging business models usually need to meet certain conditions in order to be successful. First, the business model should be compatible with demand response resources. Second, the model should provide solutions that can resist change brought about by external policies or the market environment. Third, the model should be easy for customers to accept. A good business model can stand the test of the market only when both its internal and external conditions are excellent.

This report analyzed the patent application for silicon-based anode including the annual distribution of applied patents, main competitive countries and patent applicants, patent for origin and target country analysis, etc. The characters of patent application of main competitive countries and patent applicants were also studied. As a result, We found that the patent applications were mainly from China, America, Japan and Korea. Applicants from America, Japan and Korea focused on filing patents in the above four countries, while most applicants from our country filed at home only. The applicants from abroad had filed a large number of patents in our country. Based on these, the report puts forward some suggestions of Science & Technology innovation and patent application and protection for industrial developments about silicon-based anode.

Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) are important physical characterization methods. They are widely used in the field of electrochemistry, especially in the field of lithium batteries. They are commonly used to analyze molecular valence bonds, functional group vibration and rotational energy level transition states, phase structure changes, stability, surface phenomena and reaction mechanism, the correlation spectroscopy data can calculate the bond energy, bond length, bond angle, etc. of the chemical bond. This paper introduces the basic principles, test methods, test precautions, common test equipment and test procedures of Raman and infrared spectroscopy, and analyzes Raman and infrared spectroscopy in lithium battery electrode materials, electrolytes and binders. The application of isocomponent analysis and its influence on the electrochemical stability of the product formed in the charge and discharge cycle.