Gravimetric energy densities of nanocarbons continuously improved over the years. However, due to their low densities, these nanomaterials normally suffer from relatively low volumetric performance, and their high gravimetric energy densities cannot be translated to the practical devices. Developing electrode materials with high volumetric performance and achieving compact energy storage on a device level is highly important to promote the materials and devices for energy storage into real applications. As a basic unit for all types of sp2 carbons and flexible 2D material, graphene has many intrinsic characteristics beneficial to compact energy storage. Based on the applications of graphene in supercapacitors, the paper presents design principles for practical energy storage devices from the perspective of material, electrode and devices respectively. The recent efforts to prepare electrode materials with a high volumetric performance, particularly the design concept on the high density electrode materials for high volumetric performance are also introduced. This review further highlights the importance to design energy storage material from a device perspective and discusses the opportunities and challenges toward compact energy storage.

 With the sustainable development of green energy storage devices, supercapacitors that hold both high energy density and power density have shown significant potential in the energy storage filed. In this work, we reviewed the advancement achieved in the supercapacitor electrodes, including electrical double-layer, pseudo-capacitive and their hybrid electrodes. On the basis of the electrodes, the typical prototypes of all-solid-state supercapacitors have been intensively discussed with the employment of solid-state electrolytes, and key parameters for promoting the energy density of the devices have been summarized. According to the critical issues in the electrodes and electrolytes, the perspective toward supercapacitor research and development has been proposed.

Compared to conventional lithium-ion batteries, supercapacitors with their long life and high power density can meet the requirements of high-power energy storage device from electric vehicles, electronic storage devices, household electrical, aerospace equipment and some other applications. Therefore, applications of supercapacitors expanded rapidly since they were reported. In this paper, electric double layer capacitors (EDLCs) and hybrid supercapacitors are introduced briefly, and their applications are reviewed.

The construction of new energy system and the rapid development of electronic equipment put forward higher requirements for energy storage devices with high energy density and high power density. Lithium-ion capacitor (LIC) is a novel storage device which based on the dual energy storage mechanism of lithium-ion battery (LIB) and electrochemical double-layer capacitor (EDLC), it can deliver higher energy density than EDLC and higher power density than LIB, it’s one of the optimum choices for hybrid electric vehicles, rail transit, smart power grids and energy engineering. In terms of future industrialization of lithium ion capacitor, carbonaceous materials seem to be the best alternative because of its advantages of abundant resources, cheapness and easy availability. This paper reviews the research progress of cathode material such as activated carbon material, anode material such as graphite material, electrolyte containing lithium ion and the preparation technology of lithium ion capacitor, and prospects the future development of lithium ion capacitor.

This dissertation summarized research on the energy storage mechanism and discussed the interaction between the porous structure and the electrolyte ions. What’s more, this review described simply the theoretical models of double electric layer including the previous parallel-plate model, the later EDCC and EWCC models taken into account curvature, and the newest charging mechanisms of EDLCs. Finally, this review concluded that the best approach to achieve high power density and high energy density for porous carbon based supercapacitors will be to synthetize the porous carbon which owns the optimal micropores size and appropriate proportional of mesopores.

The carbon aerogels are prepared by using resorcinol and formaldehyde as precursor, Na2CO3 as catalyst and water as solvent with sol-gel technology, following drying and carbonization at high temperature. The optimized parameters of the preparation of high specific surface area carbon aerogels in this paper have been investigated by adjusting the ratios of precursors and applying three activated processes: carbon dioxide physical activation process, potassium hydroxide wet chemical activation process, and two steps activation process of carbon dioxide and potassium hydroxide for the application of carbon aerogels in supercapacitors. Moreover the microstructure of carbon aerogels and their corresponding electrochemical properties have been characterized and analyzed. The results indicated that the original specific surface area and specific capacitance of the unactivated carbon aerogel are 820 m2/g and 151 F/g respectively as the molar ratio of resorcinol and sodium carbonate (R/C) is 1500. After the carbon dioxide physical activation process, potassium hydroxide wet chemical activation process, and two steps activation process respectively, their specific surface areas increased to 1589 m2/g, 1480 m2/g and 2119 m2/g and the specific capacitances of the samples reached to 181 F/g, 229 F/g and 259 F/g. By contrast, the two-step activation not only enhance the specific surface area, but also form a hierarchically porous structures of the carbon aerogels, which is advantageous to be applied in the supercapacitors.

Lithium ion capacitors (LIC) are fabricated in flexible packaging using activated carbon (AC) cathode and mesocarbon microbeads (MCMB) anode with mass ratio of 1∶1. We use constant-voltage pre-lithiation method and the capacity are 100 mA•h/g, 200 mA•h/g, and 300 mA•h/g, respectively. Rate capability and cycle life at high C-rates are evaluated at the potential range of 2.0—4.0 V. The results reveal that the capacitance of LIC monomer is between 4—5 F and the optimal electrochemical performance is obtained in the LIC with pre-lithiation capacity of 200 mA•h/g1. The first charge-discharge energy density is 83.7 W•h/kg (based on active material mass of two electrodes), the power density is 8835.4 W/kg and the energy density is 40.3 W•h/kg at 120 C rate. The cycle performance is tested at 20 C rate, the energy density retention is 91.5% after 500 cycles and 86.5% after 1000 cycles.

Ultra-small Co3O4 nanoparticles/graphene hybrid material had been synthesized by a facile hydrothermal route and consequent calcination process. The as-obtained ultra-small Co3O4 nanoparticles with their sizes of 5–8 nm are tightly anchored on the surface of graphene (GNS). Benefiting from the ultra-small size of Co3O4 nanoparticles, the high interconnectivity of hybrid material as well as the high conductive networks constructed by GNS, which can provide a fast and efficient transportation of electron and electrolyte ions for the overall electrode, the as-prepared hybrid material exhibits a high specific capacitance of 462 F•g1 at 5 mV•s1 compared with pure Co3O4 (193 F•g1), and retained 88.2% of its initial capacitance after 2000 cycles, indicating a promising electrode material for supercapacitors.

Due to the high cycle life, excellent power density and broad working temperature range,  spinel Li4Ti5O12 has been regarded as one of the most important materials for next generation supercapacitor. In this paper, by using commercial activated carbon and Li4Ti5O12 as the positive and negative materials, respectively, a cell with more than 30000 F and less than 0.5 mΩ has been succeeded prepared. The amount of conductive agent, balance rate, high-low temperature and safety performance has been investigated. It exhibited more than 30000 F capacitance, less than 0.5 mΩ internal resistance, and also stable lifetime performance when conductive agent is 8% (weight ratio) and the weight ratio of positive/negative electrode is 2.23—2.82. In addition, it has good high-low temperature characteristics and safety properties.

Spherical activated carbon has been fabricated via a simple solvent evaporation method followed by an activation process. The natural and renewable biomass material, leonardite humic acid (LHA) is used as the carbon source. The surface morphologies and pore parameters of the carbon spheres were analyzed by scanning electron microscope (SEM) and N2 physical adsorption-desorption instrument. Symmetric capacitor coin type cells were assembled using two spherical activated carbon electrodes. The electrochemical performance of supercapacitors is characterized by galvanostatic charge-discharge (GCD), cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) in 6 M KOH electrolyte. The results show that the obtained spherical activated carbon with good sphericity also possess high specific surface area ( 2034 m2/g) and pore volume (1.24 cm3/g). Meanwhile, the spherical activated carbon electrode materials exhibit a superior high specific capacitance of 319 F/g at a current density of 0.05 A/g. Remarkably, the sample also has outstanding cycling stability with a capacitance retention of 98.9% after 10,000 cycles. In addition, compared with powdered activated carbon, spherical activated carbon has better conductivity and presents more excellent rate capability and cycle performance. This suggests that the LHA-based spherical activated carbon should be a competitive and promising supercapacitor electrode material.

Supercapacitor, based on electric double-layer capacitance effect, had advantages of high power density and long cycle life. Current focuses to develop new electrode material and high voltage system in order toincrease energy density of device. We reported the preparation of graphene/ single-walled carbon nanotube hybrids (GNH) by chemical vapor deposition method. The materials had huge specific surface area (1200—1800 m2/g), high purity, good dispersion and high chemical stability. It, as the electrode, exhibited high capacitance performance in electrolytes such as KOH at 1 V, Et4NBF4/PC at 2.7 V and ionic liquids at 4 V. Soft-pack capacitors with Et4NBF4/PC electrolyte were also examined by using activated carbon as main electrode and GNHs as conductive additives. All results suggested GNH was an excellent electrode material choice, paving the way for the development of capacitor with high energy density and high power density.

This bimonthly review paper highlights 100 recent published papers on lithium batteries. We searched the Web of Science and found 1579 papers online from Aug. 1, 2016 to Sep. 30, 2016. 100 of them were selected to be highlighted. Layered oxide and high voltage spinel cathode materials are still under extensive investigations for studying Li+ intercalation-deintercalation mechanism and evolution of surface structure, and the influences of doping, coating and interface modifications on their cycling performances. Large efforts were devoted to Si based composite anode materials for analyzing the mechanism for Li storage and SEI formation. In-situ technologies are used to analyze the kinetic process and SEI and theoretical work covers the machnism for Li storage, kinetics, SEI and solid state electrolytes. There are a few papers related to electrolyte additives, solid state lithium batteries, Li/S batteries, Li-air batteries, and modeling.

This seven months review paper highlights 100 recent published papers on supercapacitors. We searched the Web of Science and found 997 papers online from March 1, 2016 to September 30, 2016. 100 of them were selected to be highlighted. The researches of Electrical Double-Layer Capacitor (EDLC) are mainly focused on new carbon material designed preparation, such as porous carbon materials, graphene, and their effect on supercapacitor performance. The published papers of pseudocapacitor include four aspects, such as metal oxide composites, conductive polymer composite, heteroatom doping carbon materials and new type of pseudocapactive materials. Hybrid supercapacitor includes aqueous hybrid supercapacitor and organic hybrid supercapacitor.

The low quality heat energies associated from heavy energy-consuming enterprises, and there exists temporal mismatch contradiction of supply and demand, are difficult to be employed by traditional transportation mode of pipe. However, the mobilized thermal energy storage and supply technology is an organic combination of energy harvesting, energy storage and delivery, and energy supply, and spurn many malpractices of transportation mode of pipe. In the first place, in the article, the current situations of basic research and engineering application of the mobilized thermal energy storage at home and abroad were analyzed in detail, and on the basic, the problems faced of the mobilized thermal energy storage technology were included. After that, a scheme of mobilized waste heat modular storage was proposed, and the application mode and the economy about that scheme mentioned above were expounded exhaustively. Last but not the least, the market prospect and industrialization of the mobilized thermal energy storage technology were forecasted.

As the renewable and clean electricity generation, wind and solar installation is experiencing fast growing. It brings some key issues as well, curtailment and grid integration. After more than 10 years R&D and demonstration, energy storage technologies are considered key elements to solve these problems. This paper focuses on energy storage’s application status and developing trend on grid peak shaving and frequency regulation. There are huge potential value for energy storage to participate in grid peak shaving and frequency regulation, once the market mechanisim is build and supporting policies are released.

Ministry of Science and Technology of the People’s Republic of China (MOST) initiates  national new energy vehicles pilot project in 2015 for next 5 years. Totally 19 projects are announced in 2016. The project 1.1 is a 5-year fundamental research type project (2016—2020) with a 32M￥ budget，aiming to increase the energy density of EV batteries. Two targets are purposed: 400 W•h/kg for Li-ion batteries and 500 W•h/kg for new batteries. After 3 rounds review and defense, a team led by Institute of Physics, CAS wins the project. The title of the project is “High energy density lithium batteries for long range EV”. Scientific problems and technologies of three types batteries will be studied: 400 W•h/kg lithium ion batteries, 500 W•h/kg half-solid Li-S batteries and 600 W•h/kg solid Li-air batteries. This project includes 11 CAS institutes and one company BJEV as partners.

Ministry of Science and Technology of the People’s Republic of China (MOST) initiates nanotechnology project in Feb. 2016 for next 5 years. Totally 43 projects concerning seven research fields are announced in Jun. 2016. Among the field of “energy storage materials based on nanostructure and nanotechnology”, “energy storage materials and devices based on nanomaterials” is aimed at advanced high-energy rechargeable lithium batteries. A research team led by Prof.  GUO Yuguo from Institute of Chemistry of the Chinese Academy of Sciences, has been granted with the project titled “high-energy solid-state lithium metal batteries based on nanostructured materials”. In this project, advanced solid-state lithium metal batteries with high energy density (400 W•h/kg, 800 W•h/L) and long cycle lifespan (1000 cycles) will be developed.

Since June 2011, United State announced the program of Materials Genome Initiative (MGI), which accelerated process from the materials discovery to applications, and greatly reduced the R&D cost. The Chinese Ministry of Science and Technology (MOST) correspondingly approved to start “The project of materials genetic engineering about key technology and support platform” in 2016, and the item of “Solid-state lithium battery and key materials research and development based on the materials genome technology” has been officially approved in this August. Associated with 11 domestic institutions, Professor Feng Pan of Peking University is the director of this project. This project will study the high-throughput calculation, manufacture and monitoring technology, accelerate the research of all solid-state lithium ion batteries and key materials, and develop all solid state battery prototypes to fundamentally solve the safety issue of lithium ion batteries.

Flow batteries are used mainly for large-scale energy storage, which have a great number of outstanding advantages, including long lifespan and high safe reliability. In order to reveal the development features of this technology and provide intellectual property strategy support for our country, we study the international patents in flow cell technology. The patent information in this article is gathered from the Derwent Innovation Index (DII). By using the method of literature investigation, we summarize the overview of the flow cell technology development. Then we analyze the trend of the patent application number, the layout of the technology, the situation of patent applications on flow cell in the main countries or regions, and the significant patentees by using the analysis tools—TDA and innography. As a result, we find that Japan takes the lead in this sector, and the dramatic rise in patent application number recently shows the gradually mature of flow cell technology.