Where Do Batteries End and Supercapacitors Begin?

Current lithium ion batteries (LIBs) can’t provide sufficient energy density due to a limiting capacity of 372 mAh/g from graphite anode and a low capacity from cathode. Therefore, searching novel electrode materials for large energy storage that can deliver much higher energy density becomes critical. Li-M (M = Si, Al, Sn) alloy batteries are in particular attracting more attention due to the conspicuous advantages on industrial availability, specific capacity and rate capability. Sn has a 3 times greater capacity of ~1000 mAh/g that allows it as one of primary candidates for the next-generation LIBs. Scientists have made numerous attempts to stabilize the Sn alloy geometry by constructing various structures. However, most of these nano-structured particles can’t long survive because of the severe agglomeration and pulverization, nevertheless some types of carbon may limit the particle growth. Here we report a rational design of 2D Sn/MXene hybrid as anode battery with long cycling (over 1000 cycles) and high rate performance (over 5C), which is based on our previous work on Sn (Kang et al Nano Letter 2018; Liu et al Nano Letter 2016; Liu et al Chem Commun 2017) and MXene (Nagui et al Adv Mater 2011). The excellent Li+/e- conductivity and strong chemical/physical bonding of the interface between MXene and Sn lead to the improved half-cell (VS Li) and full-cell (VS NMC) battery performance at both coin and pouch cell scales. The structure evolution of the hybrid composite, the SEI forming and disappearing, and the interface between electrode and electrolyte upon cycling will be investigated via electrochemical measurements and in-situ TEM technique. Our strategy based on the benefits of MXene and the major capacity contribution of loaded metal active material can elevate the development and utilization of this new type of 2D hybrid materials with a high rate capability, high storage capacity, and low voltage, making it a promising candidate for next-generation batteries.

As electric vehicles, portable electronic devices, and tools have increasingly high requirements for battery energy density and power density, constantly improving battery performance is a research focus. Accurate measurement of the structure-activity relationship of active materials is key to advancing the research of high-performance batteries. However, conventional performance tests of active materials are based on the electrochemical measurement of porous composite electrodes containing active materials, polymer binders, and conductive carbon additives, which cannot establish an accurate structure-activity relationship with the physical characterization of microregions. In this review, in order to promote the accurate measurement and understanding of the structure-activity relationship of materials, the electrochemical measurement and physical characterization of energy storage materials at single-particle scale are reviewed. The potential problems and possible improvement schemes of the single particle electrochemical measurement and physical characterization are proposed. Their potential applications in single particle electrochemical simulation and machine learning are prospected. This review aims to promote the further application of single particle electrochemical measurement and physical characterization in energy storage materials, hoping to achieve 3D unified evaluation of physical characterization, electrochemical measurement, and theoretical simulation at the single particle scale to provide new inspiration for the development of high-performance batteries.

Graphene and carbon nanotubes/fibers (CNT/CNF) hybrid structures are emerging as frontier materials for high‐efficiency electronics, energy storage, thermoelectric, and sensing applications owing to the utilization of extraordinary electrical and physical properties of both nanocarbon materials. Recent advances show a successful improvement in the structure and surface area of layered graphene by incorporating another dimension and structural form—three‐dimensional graphene (3DG). In this study, vertically aligned CNFs were grown using plasma enhanced chemical vapor deposition on a relatively new form of compressed 3DG. The latter was synthesized using a conventional thermal chemical vapor deposition. The resulting free‐standing hybrid material is in‐situ N doped during synthesis by ammonia plasma and is produced in the form of a hybrid paper. Characterization of this material was done using electrochemical and spectroscopic measurements. The N doped hybrid showed relatively higher surface area and improved areal current density in electrochemical measurements than compressed pristine 3DG, which makes it a potential candidate for use as an electrode material for supercapacitors, sensors, and electrochemical batteries.

In this study, the active use of bloedite-type material in many different areas has revealed the idea that it can also be used in capacitors as the aqueous electrolyte. In this context, aqueous electrolyte properties of bloedite Na2X(SO4)2·(4H2O) (X = Mg, Ni) samples were investigated. In electrochemical measurements, it has been determined that Ni and Mg-bloedite structures have “rectangular shape” cyclic voltammetry (C–V) characteristics. Ni-bloedite capacitors reached 2.35 F g−1, and Mg-bloedite capacitors reached 2.09 F g−1 capacitance values. As a result of cycle-life studies, Ni-bloedite structure provides higher performance than Mg-bloedite structure with a difference of 0.24 F g−1 at the end of 100 cycles. The research results have shown that Ni and Mg-bloedite materials can be used in supercapacitors as an alternative high-performance aqueous electrolyte. This study could also provide an idea to researchers of using different types of materials in energy storage systems, and helps to produce alternative materials for energy storage systems.

NiF2 as an efficient electrode material with high window potential of 1.8 V for high energy and power density asymmetric supercapacitor

Understanding the nature of electrode materials used in clean energy conversion systems is very important for promoting the comercialization of these systems. Herein, we investigate the essential characteristics of nondoped electrodes for oxygen reduction reaction (ORR) and supercapacitor applications based on three typical types of carbon materials, namely, carbon nanotubes (CNTs, one-dimensional), graphene (G, two-dimensional) and carbon black (BP2000, three-dimensional) by using the corroborated physical characterizations and electrochemical measurements. Several insights are obtained from the relationship between the microstructure and electrochemical performance: (1) the ORR electrocatalytic activity is mainly related to the O content rather than to the specific surface area and the defect degree; (2) G has the largest specific capacitance, most likely due to a better electrical conductivity and its unique two-dimensional microstructure rather than its O content, specific surface area and defect degree. This work confirms that different types of carbon materials are suitable for different applications: CNTs are advantageous for the ORR applications, while G is a promising electrode material for supercapacitor applications.

Polarisable liquid/liquid interfaces have been investigated for over 30 years, mainly in the context of ion and electron transfer reactions. Electrical polarisation of the interface between two immiscible electrolyte solutions (ITIES) generates electrochemical potential gradients capable of promoting ion and electron transfer across the molecular boundary. The potential drop across the liquid/liquid boundary is developed over a region of 1 to 10 nm. The nucleation of metallic structures, catalytic activity e.g. hydrogen and oxygen evolution, the assembly of nanoparticles or catalytic nanoparticles have received a great interest in the last years.1-2 Graphene nanomaterials were prepared in two ways: gravity exfoliation from natural graphite in 1,2-dichloroethane (DCE) dispersion and chemical vapor deposition (CVD) on copper foil. Both types of material were assembled at the interface between two immiscible electrolyte solutions. The graphene materials before and after assembly were characterized by Atomic Force Microscopy (AFM) and Raman spectroscopy. The electrochemical reactivity of assembled graphene materials was probed by model redox species at the ITIES. In situ electrochemical and spontaneous metal deposition of palladium, gold and silver at the interface assembled carbon nanomaterials were studied. The identification and morphology of the deposited metal was determined using electron microscopy. The 2D graphene-based metal nanostructures effects were studied for the model redox species process at the ITIES.The graphene-metal composites preparation procedure at the ITIES opens an alternative way to prepare catalyst materials. Deeper understanding of the behavior of model redox couples on graphene is of primary importance in the exploitation of this material in catalytic processes, such as of the oxidation of low molecular weight alkanes to liquid fuels.1. Fermin, D. J.; Ding, Z.; Duong, H. D.; Brevet, P. F.; Girault, H. H., Journal of Physical Chemistry B, 1998, 102, 10334-10341.2. Dryfe, R. A. W., Physical Chemistry Chemical Physics, 2006, 8, 1869-1883.

Improvement of stability and capacity of Co-free, Li-rich layered oxide Li1.2Ni0.2Mn0.6O2 cathode material through defect control

Carbon Coated MoO3 Nanowires/Graphene oxide Ternary Nanocomposite for High-Performance Supercapacitors

Ternary nanocomposite of TiO2-ZnO/MCM-41: synthesis and electrochemical performance in supercapacitors

Synthesis of M/Al (M = Co, Ni, Zn) layered double hydroxide derived from aluminum fumarate-based MOF as advanced materials for supercapacitor

Improving rural living thermal environment and rural residential energy-saving effect has becomes a hot society issue. As to two main problems of rural kang which are poor regenerative performance and surface temperature uneven,combined with the characteristics of phase change energy storage technologies,phase change energy storage technology was used in kang body. Grasping the properties and characteristics of different types of energy storage materials,according to the requirement of the human body comfort temperature of the kang surface,selecting phase transition temperature of the phase change energy storage materials which should be put forward kang surface comfort temperature between 24 ~ 35°Cphase change heat storage is particularly important. Through the phase change material selection, get three types of phase change thermal storage materials which are suitable for rural kang, which provides analysis method and basic reference for the selection of the phase change material to kang body, enhanced the heat storage capacity of kang,protected kang surface temperature uniformity and improved the energy-saving efficiency of housing in rural areas.

The recent development of synthesis processes for three-dimensional (3D) graphene-based structures has tended to focus on continuous improvement of porous nanostructures, doping modification during thin-film fabrication, and mechanisms for building 3D architectures. Here, we synthesized novel snowflake-like Si-O/Si-C nanostructures on 3D graphene/Cu foam by one-step low-pressure chemical vapor deposition (CVD). Through systematic micromorphological characterization, it was determined that the formation mechanism of the nanostructures involved the melting of the Cu foam surface and the subsequent condensation of the resulting vapor, 3D growth of graphene through catalysis in the presence of Cu, and finally, nucleation of the Si-O/Si-C nanostructure in the carbon-rich atmosphere. Thus, by tuning the growth temperature and duration, it should be possible to control the nucleation and evolution of such snowflake-like nanostructures with precision. Electrochemical measurements indicated that the snowflake-like nanostructures showed excellent performance as a material for energy storage. The highest specific capacitance of the Si-O/Si-C nanostructures was ∼963.2 mF/cm2 at a scan rate of 1 mV/s. Further, even after 20,000 sequential cycles, the electrode retained 94.4% of its capacitance.

Materials for energy storage: Review of electrode materials and methods of increasing capacitance for supercapacitors

Mg rechargeable batteries (MgRBs) represent a safe and high-energy battery technology but suffer from the lack of suitable cathode materials due to the slow solid-state diffusion of the highly polarizing divalent Mg ion. Previous methods improve performance at the cost of incompatibility with anode/electrolyte and drastic decrease in volumetric energy density. Herein we report interlayer expansion as a general and effective atomic-level lattice engineering approach to transform inactive intercalation hosts into efficient Mg storage materials without introducing adverse side effects. As a proof-of-concept we have combined theory, synthesis, electrochemical measurement, and kinetic analysis to improve Mg diffusion behavior in MoS2, which is a poor Mg transporting material in its pristine form. First-principles simulations suggest that expanded interlayer spacing allows for fast Mg diffusion because of weakened Mg-host interactions. Experimentally, the expansion was realized by inserting a controlled amount of poly(ethylene oxide) into the lattice of MoS2 to increase the interlayer distance from 0.62 nm to up to 1.45 nm. The expansion boosts Mg diffusivity by 2 orders of magnitude, effectively enabling the otherwise barely active MoS2 to approach its theoretical storage capacity as well as to achieve one of the highest rate capabilities among Mg-intercalation materials. The interlayer expansion approach can be leveraged to a wide range of host materials for the storage of various ions, leading to novel intercalation chemistry and opening up new opportunities for the development of advanced materials for next-generation energy storage.