The depletion of traditional energy resourcesas well as the desire to reduce high CO 2 emissions associated with their use has led to significant interest in developing sustainable and clean energy products, [1][2][3][4] such as electricity produced from wind-or solar-based technologies. Because of the intermittent availabilityof these resources the realization of their full potential will also require the development of new and advanced energy-storage and delivery systems. Supercapacitors, as a new class of energy storage devices, are now attracting intensive attention [2] because of their ability to store energy comparable to certain types of batteries, but with the advantage of delivering the stored energy much more rapidly than batteries.[3] This property makes supercapacitor ideal to augment traditional batteries in many different applications. However, to become primary devices for power supply, supercapacitors must be developed further to improve their abilities to deliver, simultaneously, high energy and power. [5] To realize this objective, nanostructured electrodes have been developed from a variety of different functional materials.[6-10] Despite significant progress, however, most of the processes for the fabrication of electrodes are either too delicate, [11][12][13][14] which makes them less viable for large-scale industrial applications, or require additives, [15,16] which deteriorates the performance of the electrodes. In addition, previously reported electrode materials with the desirable specific capacitance typically show high resistances, [9,13,17] which not only restrict the power performance but also prevent the utilization of thick electrodes. Based on these considerations, the goal of the present work was to build an advanced supercapacitor electrode using a simple and scalable fabrication technique and to optimize the electrode performance using a controlled functional material and a well-defined electrode network with minimum resistivity. First, Ni nanoparticles were synthesized using a modified polyol process.[18] After a simple mechanical compaction of the as-prepared (AP) nanoparticles and a subsequent lowtemperature annealing process, monolithic and mechanically robust, stable, and low-resistivity NiO/Ni nanoporous composite electrodes were obtained with both maximized energy and power densities.The structure of the AP Ni particles was characterized by X-ray diffraction (XRD; Figure 1 a) and electron diffraction (ED; Figure 1 b). The particle size estimated from the Scherrer method was 4.4 nm, and several particles formed larger aggregates with a diameter smaller than 20 nm (Figure 1 b); these findings are in agreement with the measured Brunauer-Emmett-Teller (BET) surface area of 40 m 2 g À1 . The AP particles were then mechanically compacted into monolithic pellets and used as prototype electrodes. These pellets are stable, easy to handle, and did neither require additives nor a supporting substrate. Scanning electron microscopic images obtained at both the surface and crosssection...

kinetics of Mg 2+ in cathode materials due to the strong electrostatic interactions, thus limiting the capacity of the cathode materials. [4] One solution to solve this problem is to replace kinetically sluggish Mg 2+ intercalation/deintercalation with kinetically more efficient Li + using a dual salt electrolyte. [5] With this design, Li + intercalation/deintercalation occurs at the cathode with a fast kinetic rate, whereas the advantages of using Mg anode are retained since only magnesium deposition/dissolution occurs at the anode due to its high redox potential. [6] However, in such a hybrid battery system, the asymmetric use of Mg 2+ and Li + on each electrode requires a large amount of electrolyte as an ion reservoir to supply Li + and receive Mg 2+ during discharging and charging. Besides, the most commonly used Li salts in the Mg 2+ /Li + battery (MLIB) have either a limited solubility in solvent or a narrow electrochemical window, leading to a low efficiency. Therefore, it is desirable to develop a cathode that can accommodate both Mg 2+ and Li + .2D transition metal dichalcogenides (TMDCs) with weak interlayer van der Waals (vdW) interactions offer the privilege of introducing foreign atoms or molecules between the layers via an intercalation mechanism. [7] Among various TMCDs, molybdenum disulfide (MoS 2 ) with large interlayer spacing (0.62 nm) has been intensively investigated as an electrode material for rechargeable batteries. [8] Although bulk MoS 2 does not favor large Mg 2+ intercalations, the exfoliated MoS 2 with an increased interlayer spacing can largely improve Mg 2+ diffusion and storage. [9] Many methods can be applied to prepare exfoliated MoS 2 , such as mechanical cleavage, [10] liquid exfoliation, [7c,11] and electrochemical exfoliation. [12] Especially, the Li-intercalation exfoliated MoS 2 contains a high ratio of metallic 1T phase, which is in favor of various ion intercalation, including Mg 2+ . [9,13] Thus, controlling the cathode structure by enlarging the ion transport channel and maximizing the exposure of active edge sites is of paramount importance.Herein, we report the growth of interlayer expanded MoS 2 nanosheets on graphene foam (GF) via a hydrothermal method as cathodes for both, MRB and MLIB. The obtained freestanding MoS 2 /graphene foam composite (hereafter referred to as E-MG) displays an interlayer spacing of 1.01 nm (0.62 nm for Bulk-MoS 2 ) with a high ratio of metallic 1T phase. An MRB constructed using this cathode showed pronounced solid-state Mg 2+ diffusion and ion storage capacity than Bulk-MoS 2 . Further, a hybrid MLIB fabricated using the E-MG as cathode,The hybrid Mg 2+ /Li + battery (MLIB) is a very promising energy storage technology that combines the advantage of the Li and Mg electrochemistry. However, previous research has shown that the battery performance is limited due to the strong dependence on the Li content in the dual Mg 2+ /Li + electrolyte. This limitation can be circumvented by significantly improving the diffusion kinetics of Mg 2+ in...

Aiming for increased nickel and lower cobalt content in layered transition metal oxide cathodes (NCM) is a feasible strategy for achieving increased energy density and cost competitiveness in commercial lithium-ion batteries. However, the practical long-term cycling of NCM cathodes suffers from severe capacity degradation due to irreversible interface phase transformation and unavoidable crack formation. Herein, an in situ modification strategy is used to form a uniform and conformal Li 1.8 Sc 0.8 Ti 1.2 (PO 4 ) 3 (LSTP) protective layer by interconnecting the single-crystal-layered LiNi 0.6 Co 0.1 Mn 0.3 O 2 (SC-NCM) particles. LSTP surface modification helps to construct a robust cathode-electrolyte interphase thin film between the cathode and the electrolyte, which can prevent SC-NCM corrosion by electrolyte, and the stability of the mechanics can improve the intergranular cracks caused by long cycles under harsh conditions. Moreover, the LSTP conductive modification layer facilitates the lithium-ion transport among cathode particles, effectively enhancing the rate capability. Impressively, the LSTP modified SC-NCM exhibits a high reversible capacity of 144.3 mAh g −1 at the high discharge rate of 5 C and maintains a capacity retention of 90.27% even at the ultrahigh charge voltage of 4.6 V operation after 500 cycles. Moreover, in a pouch-type full battery, the graphite/LSTP modified SC-NCM maintains a capacity retention of 89.6% after 1700 cycles.

The depletion of traditional energy resourcesas well as the desire to reduce high CO 2 emissions associated with their use has led to significant interest in developing sustainable and clean energy products, [1][2][3][4] such as electricity produced from wind-or solar-based technologies. Because of the intermittent availabilityof these resources the realization of their full potential will also require the development of new and advanced energy-storage and delivery systems. Supercapacitors, as a new class of energy storage devices, are now attracting intensive attention [2] because of their ability to store energy comparable to certain types of batteries, but with the advantage of delivering the stored energy much more rapidly than batteries.[3] This property makes supercapacitor ideal to augment traditional batteries in many different applications. However, to become primary devices for power supply, supercapacitors must be developed further to improve their abilities to deliver, simultaneously, high energy and power. [5] To realize this objective, nanostructured electrodes have been developed from a variety of different functional materials.[6-10] Despite significant progress, however, most of the processes for the fabrication of electrodes are either too delicate, [11][12][13][14] which makes them less viable for large-scale industrial applications, or require additives, [15,16] which deteriorates the performance of the electrodes. In addition, previously reported electrode materials with the desirable specific capacitance typically show high resistances, [9,13,17] which not only restrict the power performance but also prevent the utilization of thick electrodes. Based on these considerations, the goal of the present work was to build an advanced supercapacitor electrode using a simple and scalable fabrication technique and to optimize the electrode performance using a controlled functional material and a well-defined electrode network with minimum resistivity. First, Ni nanoparticles were synthesized using a modified polyol process.[18] After a simple mechanical compaction of the as-prepared (AP) nanoparticles and a subsequent lowtemperature annealing process, monolithic and mechanically robust, stable, and low-resistivity NiO/Ni nanoporous composite electrodes were obtained with both maximized energy and power densities.The structure of the AP Ni particles was characterized by X-ray diffraction (XRD; Figure 1 a) and electron diffraction (ED; Figure 1 b). The particle size estimated from the Scherrer method was 4.4 nm, and several particles formed larger aggregates with a diameter smaller than 20 nm (Figure 1 b); these findings are in agreement with the measured Brunauer-Emmett-Teller (BET) surface area of 40 m 2 g À1 . The AP particles were then mechanically compacted into monolithic pellets and used as prototype electrodes. These pellets are stable, easy to handle, and did neither require additives nor a supporting substrate. Scanning electron microscopic images obtained at both the surface and crosssection...

PPy was firstly formed on the surface of GO modified by CTAB, and the as-prepared PPy/GO-CTAB was further reduced to synthesize PPy/rGO-CTAB composite by vitamin C under a mild condition.

No abstract

No abstract

No abstract