With the development of the Internet of Things， the rapid development of miniaturized self-powered electronic products and further micro-modulation greatly stimulate the urgent demand for microscale electrochemical energy storage devices. In each electrochemical energy storage device， the supercapacitor based on the plane pattern shape is highly compatible with modern electronic products in terms of functional features such as miniaturization and integration. In this work， the flexible 3D interdigital electrode symmetric micro capacitor was prepared by the combination of semiconductor preparation technology and electrophoresis printing technology， and the 3D printing was carried out by using oxygen enriched activated carbon ink. The 3D interdigital symmetric electrode was prepared by adjusting and optimizing the electric field strength， line width， number of printing layers and other parameters. The energy dispersive spectrometer （EDS）， scanning electron microscopy（SEM），rheometer，electrochemical workstation and test system were used to characterize materials， pastes and microcapacitor devices， and to explore the influence of materials and pastes on the performance of 3D interdigital microcapacitor. The results that the 3D interdigital supercapacitor prepared by the combination of semiconductor and electrophoresis printing process has good performances， and its area capacitance can reach 22.3 mF·cm^-2. In addition， the device can achieve 96% capacity retention after 2000 cycles through packaging optimization. This simple and controllable 3D jet printing technology provides an effective way to prepare advanced miniaturized electrochemical energy storage devices.

Lithium-ion capacitors are energy storage devices between lithium-ion batteries and supercapacitors, which have both high energy density and high power density, and are considered as one of the most promising energy storage systems. In this paper, the research progress of carbon-based and lithium-embedded cathode materials in recent years was summarized, and the classification and modification methods of carbon-based and lithium-embedded electrode materials were introduced in detail. In order to further improve the performance of lithium-ion capacitors, researchers further optimized the cathode materials by means of microstructure regulation, surface modification, doping modification and composite materials, and carried out cathode and anode dynamic matching to comprehensively improve the electrochemical performance of lithium-ion capacitors. Finally, the research hotspots and development directions of cathode materials for lithium-ion capacitors in the future were reviewed in order to provide good electrochemical properties for the next generation of cathode materials for commercial applications.

Considering that a personal car spends about 95% of its life in parking mode, calendar aging can have a significant impact on battery life. High temperature storage is a common method for rapid evaluation of battery calendar life. In order to obtain reliable results of high temperature accelerated aging test, it is necessary to study the aging mechanism of battery stored at different temperature conditions. In this paper, the calendar aging experiment of graphite-SiO_x/NCM811 pouch cells were carried out within the temperature range of 25-55℃. The differential curve analysis and post-mortem analysis were used to explore the aging mechanism. The results show that the calendar aging of pouch cells is mainly caused by the loss of lithium inventory and the loss of cathode active materials. When cells store at higher temperature, the loss of lithium inventory and the loss of cathode active materials increase, while the loss of anode active materials remains relatively unchanged. Based on various test results, it can be inferred that the parasitic reactions on the surface of electrode lead to the loss of lithium inventory and the increase of SEI. With the increase of storage temperature, this side reaction continues and consumes more lithium inventory. It is worth mentioning that when storage at 55℃, the microcracking develops and even breaks some of the secondary particles of cathode materials. Therefore, the pouch cells suffer severe loss of cathode active materials, which makes it inappropriate to accelerate the aging of batteries at such high temperature.

Owing to the feature of ultrahigh power density, the dielectric capacitors play an increasingly important role in the field of industrial production, basic scientific research, aerospace, and military industry in recent years. However, the relatively low energy storage density of the dielectric capacitors generally leads to their big sizes, which is difficult to meet the miniaturization requirements of future devices. Polymer-ceramic nanocomposites can combine high permittivity of the ceramic fillers and the excellent breakdown strength of the polymer matrix, thus achieving excellent energy storage performance. At present, developing the polymer-ceramic nanocomposites with high energy storage density is the key to realize the miniaturization goal of dielectric capacitors in the future. The current research progress of polymer-ceramic nanocomposites for energy storage capacitor applications from three perspectives was systematically summarized, including regulation of the nanofillers, optimization of the interfaces, and design of the multilayer composite structure. Notably, the influences of the dimension, size, species, hierarchical structure of the nanofillers, interface optimization methods such as surface modification and core-shell structure construction, as well as multilayer structure design such as sandwich structure and gradient structure on the permittivity, breakdown strength and the energy storage density of the nanocomposites were introduced in detail. Meanwhile, the structure-activity relationships between the microstructure of nanocomposites and their energy storage properties were further analyzed and discussed. Finally, based on the challenges and shortcomings of the current research, the important development directions of this field in the future were proposed, including selecting the new 2D nanofillers, enhancing the energy storage efficiency, employing multimode combined optimization strategy, and constructing the corresponding dielectric capacitors.

LiCoO₂ coated with graphene and PSS:PEDOT（GP-LCO）is synthesized by a facile and scalable method. The structure and morphology of LiCoO₂（LCO）and GP-LCO have been investigated by X-ray diffraction（XRD）and scanning electron microscopy（SEM）. Transmission electron microscopy（TEM）further demonstrate the existence of graphene and PSS:PEDOT. The electrochemical properties of the composites are investigated by cyclic voltammetry and AC impedance measurements, which show that the conductive film of graphene（1%）and PSS:PEDOT（2%）on the surface significantly decreases the charge transfer resistance and improves the cycle stability of LiCoO₂. Galvanostatic charge-discharge test reveals that with only 2% Super P as conductive additive, the GP-LCO delivers a capacity of 173.9 mAh/g at 0.1 C and 118.0 mAh/g at 10 C, which are higher than the pristine LCO in the potential range of 3.0-4.5 V（vs. Li/Li⁺）. Moreover, it is clearly noticed that the GP-LCO exhibits a capacity retention of 76.6% after 100 cycles at 0.1C, while the LCO only presents a capacity retention of 41.1%.

As a new generation of energy storage devices, lithium-ion capacitors (LICs) rationally combine high energy density and high power density, providing an alternative solution for multi-functional electronic equipment and state grid system. However, the dynamic mismatch between the battery-type anode and the capacitor-type cathode seriously limits its development and application. Herein, a high performance LIC simultaneously using carbon materials derived from Ethylenediaminetetraacetic Acid Ferric Sodium Salt (EDTA-Na-Fe) was prepared. By calcination of EDTA-Na-Fe in an inert atmosphere, nitrogen-doped carbon frameworks (NCF) can be obtained which possess a high reversible capacity and excellent rate-capability. Using this NCF as the anode and cathode of the LICs, the hybrid devices with a wide voltage window of 0.5-4.0 V are obtained. The employment of the same materials as the anode and cathode can largely simplify the fabrication process. The energy density of LICs can reach 193.4 Wh·kg^-1 at a power density of 225 W·kg^-1. This reasonable dynamic matching strategy can be helpful for the application of LICs.

In order to develop lithium-ion batteries with high energy density, prelithium technology has attracted extensive attention. Li₅FeO₄was successfully prepared by molten salt method with LiNO₃-LiOH mixed lithium salt as reaction medium and lithium source, and nano Fe₂O₃ as iron source in this work. Li₅FeO₄ as cathode prelithiation additive is applied to lithium-ion batteries. The synthesis conditions of Li₅FeO₄ were optimized by orthogonal experiment, and the effect of synthesis conditions on the electrochemical properties of the material was discussed. Li₅FeO₄ was added to the surface of LiFePO₄ positive electrode and assembled with graphite negative electrode to form a full cell. Its effect on the electrochemical performance of the full cells and the mechanism of reducing the initial capacity loss of lithium-ion batteries were studied. The results show that Li₅FeO₄ cathode prelithiation additives with high purity, small particle size and outstanding electrochemical performance can be prepared by molten salt method. When Li₅FeO₄ with a mass fraction of 2.8%(based on the percentage of active materials mass) was added, the discharge specific capacity of first cycle for the LiFePO₄/graphite full cell was 150 mAh·g^-1 at 0.05 C, which was 8.5% higher than that without adding, after 100 cycles at 0.2 C. the capacity still increased by 7.1%, and the irreversible capacity of the svstem was restored.

The hydrogenated TiO₂ coated core-shell structure C/Fe₃O₄@rGO (H-TiO₂/C/Fe₃O₄@rGO) composite material with oxygen vacancy defects was prepared by a simple method as high-performance anode material for lithium-ion batteries (LIBs). The volume expansion coefficient of TiO₂ in the process of Li⁺ deintercalation is about 4%, which can alleviate the volume expansion of Fe₃O₄ during charging and discharging, and improve the stability of the anode material structure. At the same time, the lower conductivity of TiO₂ (about 1×10^-12 S·m^-1) is improved by hydrogenation. After 200 cycles, the H-TiO₂/C/Fe₃O₄@rGO specific capacity is 867 mAh·g^-1 at a current density of 0.3 A·g^-1, and the specific capacity is 505 mAh·g^-1 after 700 cycles at a current density of 1 A·g^-1, these results is far greater than the theoretical capacity of graphite (372 mAh·g^-1). These findings indicate that the H-TiO₂/C/Fe₃O₄@rGO composite materials may be used as a suitable anode material for LIBs.

As a kind of rechargeable batteries, alkali metal-ion battery is one of the important energy storage devices at present. Due to the advantages of enhanced energy density, high work potential, no "memory effect", small self-discharge, environment-friendly, alkali metal-ion batteries have attracted extensive attention in recent years. Electrode material is one of the most important factors that influence the electrochemical performances of alkali metal-ion batteries. Therefore, the key to the improvement of alkali metal-ion batteries is to seek electrode materials with high specific capacity and stable structures. Quantum dots/carbon composites (QDs/C), integrating the advantages of quantum dot materials and carbon materials have turned out to be outstanding candidates for electrode materials of alkali metal-ion batteries. In this work, a brief introduction of quantum dot materials was given at first, and then the progress of QDs/C, including element QDs/C, compound QDs/C and heterostructure QDs/C in alkali metal-ion batteries, was summarized respectively. The advantages and disadvantages of QDs/C as electrode materials of alkali metal-ion batteries were discussed in the last part.In view of the shortcoming, the future development goal was proposed: (1)Exploring the innovative approach to slove the agglomeration of quantum dots and the relative composites; (2)Researching the structure and property of SEI film to improve the initial coulombic efficiency; (3)Clarifying the reaction mechanism to obtain the better electrochemical performance.

To meet the requirements of high energy density and fast charge for energy storage systems and electric vehicles, the high-energy and high-power density lithium-ion batteries have attracted numerous attentions.Designing thick-electrode can significantly increase energy density and reduce cost, and is also compatible with various electrode materials, which makes it one of hottest researches for the development of high-energy density lithium-ion batteries.Thick electrodes usually suffer from poor mechanical properties and sluggish reaction kinetics. Therefore, it is very important to construct a thick electrode with good mechanical properties and fast transport network for lithium ion and electron.The electrochemical behavior and key scientific issues of thick electrodes were firstly analyzed in this review, the current strategies for constructing thick electrodes and their advantages were then introduced, and finally the design principles and the development direction of thick electrodes were pointed out.

With the development of electric vehicles, higher requirements for battery energy density are put forward. High nickel/SiO_x-C batteries with high energy density have become the first choice for long-range electric vehicles. However, high nickel/SiO_x-C batteries have the problem of rapid capacity decay in practical use. Non-destructive electrochemical analysis and post-mortem analysis were used to detect the changes in battery capacity and internal resistance during the cycle. The changes in the structure, material morphology and surface composition of positive and negative electrodes before and after the battery cycle were compared, revealing the mechanism of cycling failure of high nickel/SiO_x-C batteries. The results show that the capacity decay of the battery presents three stages: the stationary period, the rapid decay period and the extreme decay period. After cycling, the polarization of the battery is more serious, and the polarization internal resistance of the battery, the surface film resistance of the negative electrode and the charge transfer resistance increase significantly. Through differential curve analysis combined with disassembly analysis, it is found that the high nickel cathode material has less attenuation, and the silica carbon anode material has more attenuation and active lithium-ion loss. The expansion and cracking of silicon oxide particles, the loss of negative electrode active material, and the continuous growth of solid electrolyte interface film on the negative electrode surface consuming too much active lithium are the main reasons for the rapid decline of battery capacity.

Li₄Ti_5-xY_xO₁₂ (x=0, 0.05, 0.10, 0.15, 0.20) anode materials were synthesized by ball milling assisted solid-state method used Li₂CO₃ and anatase TiO₂ as raw materials and yttrium nitrate (Y(NO₃)₃·6H₂O) as yttrium source. The phase and morphology of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical performance and transport characteristics of the materials were tested and analyzed by an electrochemical workstation. The results show that there is no effect of Y³⁺ doping on the spinel structure of LTO material. When x=0.15, the ion and electronic conductivities of the Li₄Ti_4.85Y_0.15O₁₂ sample are 2.68×10^-7 S·cm^-1 and 1.49×10^-9 S·cm^-1, respectively, which are an order of magnitude higher than that of the intrinsic LTO, and present good transport characteristics. Electrochemical tests show that a first discharge capacity of Li₄Ti_4.85Y_0.15O₁₂ sample can reach 171 mAh·g^-1 at 0.1 C rate. The sample still has a higher specific capacity of 102 mAh·g^-1 and 79 mAh·g^-1 at a high rate of 10 C and 20 C, respectively.After 200 cycles, the capacity retention rates are 92.6% and 89.1% respectively, showing good magnification characteristics.

Lithium-sulfur battery is a kind of energy storage system with high specific capacity, low production cost and environmental friendliness. It has great development potential and application prospect in portable electronic device energy storage. However, lithium-sulfur batteries still face the problems of low Coulomb efficiency and short lifespan in practical applications. This is mainly attributed to polysulfide shuttle effect, low electrical conductivity of S₈ and Li₂S and uncontrolled lithium dendrite growth. The inhibition of lithium dendrite growth and the inhibition of the reaction between soluble polysulfide and lithium can not only enhance the safety and electrochemical performance of lithium sulfur batteries, but also play an important role in high-capacity lithium sulfur batteries. In this paper, the development of lithium-sulfur battery is reviewed, and the progress of high-sulfur loaded lithium battery is introduced emphatically. By analyzing the mechanism, we can understand the operation mechanism of lithium sulfur battery and develop improvement methods, including the use of graded porous carbon for cathode and element doping to increase the sulfur loading rate of active substance and reduce the shuttle effect of polysulfide. The development of liquid and solid electrolyte systems and strategies to enhance anode stability are also introduced. In addition, we believe that in-depth understanding of the mechanism of lithium-sulfur batteries can strengthen the cognition of lithium-sulfur batteries and guide the future development of high-sulfur loaded lithium-sulfur batteries. At the same time, improving synergies between components can further advance lithium-sulfur battery technology from button batteries and flexible pack batteries to subsequent commercial scale applications.

With the rapid development of the new energy automotive industry, consumers' requirements for the range of electric vehicles have been increasing. The Ni-rich ternary lithium-ion battery has become the most promising power battery in electric vehicles due to its high specific energy, but the battery system still faces the problem of poor performance at low temperature.The research progress on low temperature performance of Ni-rich ternary power battery in recent years was summarized in this review. The influence factors on the low temperature performance of Ni-rich ternary power battery were summarized emphatically. On the one hand, the effects of low temperature performance from thermodynamics were analyzed, including the structural change of the Ni-rich ternary cathode materials and graphite anode materials, electrolytic phase transformation and solvation structure changes, and glass transition of binder. On the other hand, rate controlling step in the low temperature discharge process in the Ni-rich ternary lithium-ion battery was summed up. According to this, main modification measures of low-temperature performance in Ni-rich ternary power battery were summarized. Low temperature electrolyte was designed by optimizing solvents, improving lithium salts and applying new additives. In order to improve the low temperature performance of electrode materials, three methods were mainly employed: substitution, surface modification and smaller material particle size. The remaining shortcomings of the research on low-temperature performance of the battery were summarized, and the research on the low temperature thermodynamic characteristics of batteries is not clear enough. In addition, the research methods for the low temperature kinetic process of batteries are single, and the influence of the reaction sequence in batteries is insufficiently understood.

According to the unique characteristics of Li-rich manganese-based cathode materials during the first cycle charge, a pulse formation process was designed to reduce the gas production during the formation process and improve the electrochemical performance of the Li-rich/Si@C batteries. The GC-MS, SEM, XPS and electrochemical test results show that, compared with the traditional formation process by optimizing the formation process, the gas production of the batteries under the pulse formation is reduced by about 37%. After pulse formation, a dense film structure can be formed on the surface of the positive and negative active materials, the stress of the cells during the formation process can be relieved. The pulse formation process can also effectively save the formation time, shorten the time from 102.6 h to 81.5 h. In addition, the electrochemical stability during cycle is improved, after 500 cycles, both the capacity retention rate and the median voltage have been significantly improved.

In order to better promote the research and development of high energy storage density and high efficiency lead-free ceramic dielectric capacitors, a comprehensive introduction to the energy storage principle and classification of ceramic dielectric energy storage materials was presented, the research progress, main research systems and performance advantages and disadvantages of linear dielectric, ferroelectric, relaxed ferroelectric and antiferroelectric energy storage materials in recent years were comparatively analyzed. The current challenges faced by ceramic energy storage materials and strategies to improve their energy storage were summarized. The current challenges of ceramic energy storage materials and the strategies to improve their energy storage performance were summarized, and their future development and applications were also presented.

Four kinds of fluorinated carbon cathodes were fabricated with the industrial carbon materials (activated carbon, spherical graphite, expanded graphite and industrial graphene) to realize the universal applications of lithium/fluorinated carbon primary battery. The morphology, crystalline structure, chemical structure and electrochemical performance were systematically studied by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectra (Raman), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectro scopy(XPS), N₂ adsorption-desorption isotherms and electrochemical test, etc. It was found that the fluorinated industrial graphene shows the highest specific capacity (945.4 mAh·g^-1) at the discharge current density of 20 mA·g^-1, which may benefit from the monofluorocarbon structure, high specific area and stable carbon structure. The fluorinated active carbon has the highest initial discharge voltage due to the abundant semi-covalent C—F bond, but its discharge voltage declines rapidly caused by the unstable structure. Although the fluorinated spherical graphite and fluorinated expanded graphite have the similar structure with the fluorinated industrial graphene, their specific capacities are lower, due to the presence of the highly fluorinated carbon atoms (CF₂ and CF₃). However, at high discharge current density, the fluorinated spherical graphite and fluorinated expanded graphite possess the similar value with the fluorinated industrial graphene. Considering the cost, they may be more suitable for the high power applications.

With the increasing demand for lithium-ion batteries, lithium-ion batteries with high energy density and high power density have become one of the research hotspots. Material modification and new material development can effectively increase the energy density of lithium-ion batteries. In addition, the microstructure parameters of the electrode such as porosity, pore size and distribution, tortuosity and electrode composition distribution are also factors that determine the performance of the electrode and battery. Improving the performance of high specific energy batteries by optimizing the electrode structure design has gradually become the focus of attention. The research progress of porous electrode structure design optimization for lithium ion batteries was reviewed in this article, the design factors and preparation methods of porous electrode structure were summarized. Then the future development of electrode structure design optimization and the promotion of novel preparation technologies for large-scale application in the field of high specific energy lithium ion batteries were prospected in the field of high specific energy lithium ion batteries.

Carbon nanotubes(CNTs), as an important discovery in the research of nanomaterials, have become a research hotspot in the field of carbon materials since their birth. With its unique porous structure, metal-organic frameworks (MOFs) has been developed into one of the frontiers of research in recent years. With the continuous development of materials science in recent years, the research on composite technology of materials with different functional characteristics has become one of the main methods to solve key problems in the field of materials applications.CNTs and MOFs are two very important types of nanomaterials in the current material field. Combining the high electrical conductivity of CNTs with the high specific surface area and rich pore distribution characteristics of MOFs through composite technology is an inevitable trend for future research and application in the field of materials. In this paper, the main composite forms and preparation methods of MOFs and CNTs in recent years were reviewed, and the latest research progress of composites in the fields of supercapacitors, lithium battery electrodes, catalysis, adsorption, etc. was summarized. The synergistic improvement of the performance of the two materials was discussed and analyzed, and it was pointed out that the composite of CNTs and MOFs materials and the growth and distribution of CNTs have a high degree of randomness, and further control of them is the focus of future technical research.

In order to make full use of the porous structure and overcome the shortcoming of low mechanical strength of nanofiber-based separators, polyacrylonitrile (PAN) separator was prepared directly on the surface of graphite anode by the electrospinning method. And an integrated separator/anode assembly (SAA) was formed. The microstructure, mechanical strength, electrolyte wettability, thermal resistance and battery performance were systematically investigated. The results show that the nanofibers in PAN separator are tightly bonded to the rough surface of graphite anode, resulting in a well-integrated interface structure (tensile strength higher than 200 MPa). Compared with polyolefin separators, SAA exhibits better electrolyte affinity and higher ion conductivity (1.9 mS/cm). The above advantages endow the LiCoO₂/SAA full cell with better C-rate (capacity retention 44.3% at 32 C compared with that at 0.5 C) and cycling performances (capacity retention 98% after 200 cycles at 0.2 C) compared with those of LiCoO₂/polyolefin separator/graphite battery. Consequently, this work provides an advanced separator/anode assembly and the corresponding fabrication method, which may be a new strategy for improving the charge-discharge performance and assembly efficiency of lithium-ion batteries.

Lithium-rich manganese-based cathode material is a promising next-generation lithium-ion battery cathode material, however, it exhibits significant differences in electrochemical performance at different temperatures, which severely limits the application in practical environments. A variety of electrochemical measures were used to characterize the difference in electrochemical performance of lithium-rich material within the temperature range of 5-45℃. The influencing factors of material properties and temperature dependence were analyzed from the perspective of polarization. The results show that the charge/discharge capacity of lithium-rich material decreases with decreasing temperature, which is mainly due to the significant increase in the polarization of the oxygen/manganese ion reaction in the high-voltage and low-voltage ranges with decreasing temperature, resulting in a severe decrease in its capacity contribution.The significantly increased polarization is mainly caused by the poor intrinsic kinetic performance of oxygen/manganese ions, which leading to high apparent activation energy of the charge transfer process. In addition, the participation of oxygen and manganese ions in the charge compensation reaction changes the structure of the material seriously.It induces changes in the composition of the interface film, which increases the apparent activation energy of lithium ion transmission at the interface in the low voltage interval. Moreover, it causes bulk diffusion of lithium ions at the end of the charge and discharge process having higher apparent activation energy. Therefore, improving the oxygen/manganese ion reaction kinetics of lithium-rich material is the main method to enhance its environmental adaptability.

The rapid development of new energy vehicles places a more and more urgent demand for high-performance lithium-ion batteries. As an important part of lithium-ion battery, the electrode performance has a significant impact on the overall performance of lithium-ion battery. In the electrode, the uniformity and stability of the slurry, which is a multi-component mixture, own a great influence on the performance of the electrode sheet. However, most of the current researchers' interests are usually placed after the slurry process, that is, only focus on the performance of the electrode, but ignore the slurry which is the preconditions of the performance of the electrode. Uniformity of the electrode is determined by the uniformity and stability of slurries. However, as a complicated mixture of multicomponent suspended particles, it's hard to measure the uniformity and stability of the slurry directly. At present, the rheological property test of the slurry is the most effective method to characterize the uniformity and stability of the slurry. In this paper, the effects of active materials, binders, conductive agents, solvents, dispersing additives, pH value, temperature, mixing steps on the rheological properties of the slurry during the manufacturing of lithium ion battery electrode pastes were reviewed. The influence of these factors on the rheological properties of the slurry was summarized, which provides a certain guiding role for fabricating slurries with higher uniformity and stability and developing high performance Li-ion batteries.