New-generation Energy Research Articles

Catalytically Active Carbon for Oxygen Reduction Reaction in Energy Conversion: Recent Advances and Future Perspectives.

The shortage and unevenness of fossil energy sources are affecting the development and progress of human civilization. The technology of efficiently converting material resources into energy for utilization and storage is attracting the attention of researchers. Environmentally friendly biomass materials are a treasure to drive the development of new-generation energy sources. Electrochemical theory is used to efficiently convert the chemical energy of chemical substances into electrical energy. In recent years, significant progress has been made in the development of green and economical electrocatalysts for oxygen reduction reaction (ORR). Although many reviews have been reported around the application of biomass-derived catalytically active carbon (CAC) catalysts in ORR, these reviews have only selected a single/partial topic (including synthesis and preparation of catalysts from different sources, structural optimization, or performance enhancement methods based on CAC catalysts, and application of biomass-derived CACs) for discussion. There is no review that systematically addresses the latest progress in the synthesis, performance enhancement, and applications related to biomass-derived CAC-based oxygen reduction electrocatalysts synchronously. This review fills the gap by providing a timely and comprehensive review and summary from the following sections: the exposition of the basic catalytic principles of ORR, the summary of the chemical composition and structural properties of various types of biomass, the analysis of traditional and the latest popular biomass-derived CAC synthesis methods and optimization strategies, and the summary of the practical applications of biomass-derived CAC-based oxidative reduction electrocatalysts. This review provides a comprehensive summary of the latest advances to provide research directions and design ideas for the development of catalyst synthesis/optimization and contributes to the industrialization of biomass-derived CAC electrocatalysis and electric energy storage.

Modulating the d-Band Center of RuO2 via Ni Incorporation for Efficient and Durable Li-O2 batteries.

Rechargeable Li-O2 batteries (LOBs) are considered as one of the most promising candidates for new-generation energy storage devices. One of major impediments is the poor cycle stability derived from the sluggish reaction kinetics of unreliable cathode catalysts, hindering the commercial application of LOBs. Therefore, the rational design of efficient and durable catalysts is critical for LOBs. Optimizing surface electron structure via the negative shift of the d-band center offers a reasonable descriptor for enhancing the electrocatalytic activity. In this study, the construction of Ni-incorporating RuO2 porous nanospheres is proposed as the cathode catalyst to demonstrate the hypothesis. Density functional theory calculations reveal that the introduction of Ni atoms can effectively modulate the surface electron structure of RuO2 and the adsorption capacities of oxygen-containing intermediates, accelerating charge transfer between them and optimizing the growth pathway of discharge products. Resultantly, the LOBs exhibit a large discharge specific capacity of 19658mA h g-1 at 200mA g-1 and extraordinary cycle life of 791 cycles. This study confers the concept of d-band center modulation for efficient and durable cathode catalysts of LOBs.

Improving the interfacial stability of ultrahigh-nickel cathodes with PEO-based electrolytes by targeted chemical reactions.

Benefiting from high energy density of ultrahigh-nickel cathode materials and good safety of PEO-based electrolytes, PEO-based ultrahigh-nickel solid-state lithium batteries (SLMBs) are considered to be new-generation energy storage devices. However, the incompatibility of ultrahigh-nickel cathode materials and PEO-based electrolytes is the main challenge due to serious interfacial side reactions. Therefore, the modification of the cathode/electrolyte interface is crucial. Herein, the residual lithium on the surface of LiNi0.9Co0.06Mn0.04O2 is utilized to construct an interfacial coating layer by reacting with H3BO3. The in situ formed xLi2O-B2O3 coating layer (LBO1-NCM) with high ionic conductivity can be regulated with different crystal structures during the sintering process. Besides, an all-solid-state three-electrode cell is fabricated, which verifies that the xLi2O-B2O3 coating can effectively stabilize the interface. Astonishingly, uneven Li anode deposition is observed in SLMBs, which is caused by the breakage of PEO molecular chains due to the strong oxidation of the cathode, while this crosstalk is also suppressed by the xLi2O-B2O3 coating layer. Consequently, Li|PEO|LBO1-NCM achieves a substantially improved electrochemical performance, exhibiting 90.5% of capacity retention after 100 cycles for the coin cell and 80.3% of capacity retention after 200 cycles for the pouch cell. Apparently, the targeted modification of interfaces should be paid as much attention as electrolyte optimization in SLMBs.

Recent Advances in Photochargeable Integrated and All-in-One Supercapacitor Devices.

Photoassisted energy storage systems, which enable both the conversion and storage of solar energy, have attracted attention in recent years. These systems, which started about 20 years ago with the individual production of dye-sensitized solar cells and capacitors and their integration, today allow more compact and cost-effective designs using dual-acting electrodes. Solar-assisted batterylike or hybrid supercapacitors have also shown promise with their high energy densities. This review summarizes all of these device designs and conveys the cutting-edge studies in this field. Besides, this review aims to emphasize the effects of point, extrinsic, intrinsic, and 2D-planar defects on the performance of photoassisted energy storage systems since it is known that defect structures, as well as electrical, optical, and surface properties, affect the device performance. Here, it is also targeted to draw attention to how critical the design, material selection, and material properties are for these new-generation energy conversion and storage devices, which have a high potential to see commercial examples quickly and to be recognized by more readers.

Construction of binder-free 3-D porous NiMn LDH electrode materials for high performance asymmetric supercapacitors using dynamic hydrogen bubbles as template

Three-dimensional porous Ni/NiMn layered double hydroxides (3-D Ni/NiMn LDH) with enhanced specific capacitance and superior cycle stability were loaded on nickel foam (NNM/NF) by combining dynamic hydrogen bubble template (DHBT) and electrodeposition methods. The optimized NNM-2/NF electrode for supercapacitors (SCs) possessed high specific capacitance (2755.36 F g–1 at 1 A g–1) and considerable capacitance retention (71.25% after 5000 consecutive cycles at 20 A g–1). When NNM-2/NF and active carbon (AC) were used to construct an asymmetric supercapacitor (ASC) device, it achieves a high specific energy density of 41.75 Wh kg–1 at a power density of 2700.09 W kg–1 and an excellent cycling performance (109.85% capacitance retention after 5000 cycles at 20 A g–1). The practical energy storage applicability of this device was demonstrated by the lighting of an LED bulb when two NNM-2/NF//AC devices were connected in series. This work provided potential strategy to promote the further application of porous Ni/NiMn LDH electrodes in new-generation energy storage.

Recent Progress for Concurrent Realization of Shuttle-Inhibition and Dendrite-Free Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have become one of the most promising new-generation energy storage systems owing to their ultrahigh energy density (2600Wh kg-1 ), cost-effectiveness, and environmental friendliness. Nevertheless, their practical applications are seriously impeded by the shuttle effect of soluble lithium polysulfides (LiPSs), and the uncontrolled dendrite growth of metallic Li, which result in rapid capacity fading and battery safety problems. A systematic and comprehensive review of the cooperative combination effect and tackling the fundamental problems in terms of cathode and anode synchronously is still lacking. Herein, for the first time, the strategies for inhibiting shuttle behavior and dendrite-free Li-S batteries simultaneously are summarized and classified into three parts, including "two-in-one" S-cathode and Li-anode host materials toward Li-S full cell, "two birds with one stone" modified functional separators, and tailoring electrolyte for stabilizing sulfur and lithium electrodes. This review also emphasizes the fundamental Li-S chemistry mechanism and catalyst principles for improving electrochemical performance; advanced characterization technologies to monitor real-time LiPS evolution are also discussed in detail. The problems, perspectives, and challenges with respect to inhibiting the shuttle effect and dendrite growth issues as well as the practical application of Li-S batteries are also proposed.

Advanced Li/Na-CO2 Batteries Enabled by the γ-MnO2 Catalyst with Enhanced Carbonate Decomposition.

Metal-CO2 batteries, especially Li-CO2 and Na-CO2 batteries, are regarded as ideal new-generation energy storage systems owing to their high energy density and extraordinary CO2 capture capability. However, the advancement of metal-CO2 batteries is still at an early stage. The problems caused by accumulation of carbonates during charge-discharge cycles, such as large polarization and poor reversibility, restrict their practical application. Therefore, designing efficient catalysts is crucial for promoting the decomposition of carbonate to improve the electrochemical performance of metal-CO2 batteries. Herein, we first adopted sea urchin-like γ-MnO2 as the cathode material for Li/Na-CO2 batteries. Benefiting from the unique structure and excellent catalytic activity of γ-MnO2, the as-prepared Li-CO2 and Na-CO2 batteries can achieve low overpotentials of 1.28 and 1.36 V, respectively, at a current density of 100 mA g-1 with a cutoff capacity of 1000 mA h g-1. The overpotentials are lower than those of most of the state-of-the-art catalysts in previous reports. After 100 and 50 cycles of Li-CO2 and Na-CO2 batteries, respectively, their charging termination voltages remain at around 4.1 and 3.9 V, respectively; such a low charging platform indicates the excellent catalytic activity of the γ-MnO2 cathode on the discharge products. Our findings offer a promising guideline to design efficient electrocatalysts for high-performance metal-CO2 batteries.

Enhancing sodium-ion batteries performance enabled by three-dimensional nanoflower Sb2S3@rGO anode material

Sodium-ion batteries (SIBs) gradually become ideal substitutes to lithium-ion batteries (LIBs) as a result of higher applicability in new-generation energy storage system. However, the controlled preparation of superior electrode materials for obtaining high-performance SIBs remains a challenge. In this study, a composite structure comprising three-dimensional nanoflower Sb2S3 and reduced graphene oxide (rGO) was successfully manufactured by applying a hydrothermal method as an emerging anode material for SIBs. Nanoflower Sb2S3@rGO exhibited excellent electrochemical performance, yielding 544.8 mAh/g at a rate of 100 mA/g, and sustained stability in the later 200 cycles, which was 75.4% of the initial value for the specific capacity. Even the current density is 2000 mA/g, a specific energy capacity of 433.4 mAh/g was obtained. The sodium storage mechanism was explored using cyclic voltammetry at different sweep speeds to clearly point out the electrochemical process of forming nanoflower Sb2S3@rGO. The results indicate that the high performance is ascribed to the particular flower-like three-dimensional structure, which provides cache space for Sb2S3 volume expansion during charge/discharge, while the addition of rGO effectively improves the overall electrical conductivity of the electrode. This work furnishes a new insight into the construction of specially structured anode materials to promote the development of SIBs.

High-Entropy Materials: Features for Lithium–Sulfur Battery Applications

The emergence of various electronic devices and equipment such as electric vehicles and drones requires higher energy density energy storage devices. Lithium–sulfur batteries (LSBs) are considered the most promising new-generation energy storage system owing to its high theoretical specific capacity and energy density. However, the severe shuttle behaviors of soluble lithium polysulfides (LiPSs) and the slow redox kinetics lead to low sulfur utilization and poor cycling stability, which seriously hinder the commercial application of LSBs. Therefore, various catalytic materials have been employed to solve these troublesome problems. High entropy materials (HEMs), as advanced materials, can provide unique surface and electronic structures that expose plentiful catalytic active sites, which opens new ideas for the regulation of LiPS redox kinetics. Notwithstanding the many instructive reviews on LSBs, this work aims to offer a complete and shrewd summary of the current progress in HEM-based LSBs, including an in-depth interpretation of the design principles and mechanistic electrocatalysis functions, as well as pragmatic perspectives.

High electrochemical performance of MnCo2O4.5 nanoneedles/NiCo LDH nanosheets as advanced electrodes of supercapacitor

MnCo2O4.5@NiCo layered double hydroxides (LDHs) are synthesized on nickel foam (NF) using the hydrothermal-calcination-hydrothermal method. It retains MnCo2O4.5 nanoneedles and NiCo LDH nanosheets structures, improving its electrochemical performance. The composite has an excellent specific capacity (1266 C g−1 when current density is 2 A g−1) and deliver an outstanding initial capacity retention (96.8% when current density is 20 A g−1). Moreover, the self-assembled MnCo2O4.5@NiCo LDH/NF//AC (actived carbon) asymmetric supercapacitor (ASC) provides the highest energy density of 33.3 W h kg−1 when the power density is 798 W kg−1 and has a long cycle life of 81% at 5 A g−1 after 7000 cycles. The above results provide a useful strategy for new-generation energy storage devices with excellent properties.

In-situ-foaming synthesis of cheese-like Fe3S4/Ti3C2Tx electrode material with both high energy and power density for Al/Zn-ion supercapacitors

Although supercapacitor technology has been proposed as a promising new-generation energy means for its rapid charging speed and high operation safety, the shortcoming of low energy density has long been a big obstacle due to the low voltage window and storage capacity. In this study, a new kind of electrode material of Fe3S4/Ti3C2Tx has been proposed by a facile in-situ-foaming strategy through the reaction of Na2S with Fe(NO3)3. Herein, the byproducts of trace H2S and H2 gases were found to appear and expel, creating a lot of pores inside the Fe3S4/Ti3C2Tx composites with a cheese-like heterostructure. Therefore, the maximum specific capacity of Fe3S4/Ti3C2Tx-42% is measured up to 305.8 C g−1 at 2 A g−1, 3.4 times that of Fe3S4 and 5.9 times that of Ti3C2Tx. When Fe3S4/Ti3C2Tx-42% is assembled as a cathode for the Al-ion capacitors and Zn-ion capacitors, the devices both possess superior electrochemical performance. Especially for the Zn-ion capacitors, the device exhibits a high power density of 5500 W kg−1 at a maximum energy density of 61 W h kg−1 and a high stability after 10,000 cycles, showing a distinct advantage over previously reported literatures. Density functional theory (DFT) simulation and XPS analysis are used to validate the beneficial transformation mechanism of reactive sites, thus providing a novel idea for solving the poor structural stability of sulfide materials and MXene-based nanomaterials.

Bacteria-loaded graphene bioanode for renewable energy generation

The high electrical conductivity and low dimensionality of graphene is essential for the development of novel lightweight bioanodes for new-generation energy technologies. However, the integration of graphene in biointerfaces presents a formidable challenge, especially because the surface energy of graphene is not compatible with living matter. Here we propose a sustainable chemical control method to reach the demanded surface hydrophilicity and conductivity of graphene nanowalls to form a lightweight, graphene-based, sponge bioanode. The few-nanometer–thick conductive graphene nanowalls create biocompatible hydrophilic microconfinements to harvest the biomass density of electrogenic Shewanella Oneidensis MR-1. The graphene-based bioanode shows a stable and rapid response with a steady-state biocurrent density of 135.35 mA m−2 realized within a few hours. Our novel and sustainable graphene-based material provides a revolutionary energy opportunity for the establishment of new energy-related graphene industries as well as facilitates many startups.

Phenazine-Based Compound as a Universal Water-Soluble Anolyte Material for the Redox Flow Batteries

Aqueous organic redox flow batteries (AORFBs) are emerging energy storage technologies due to their high availability, low cost of organic compounds, and the use of eco-friendly water-based supporting electrolytes. In the present work, we demonstrate a unique phenazine-based material that shows redox reversibility in neutral, basic, and acidic conditions with the redox potentials of −0.85 V (1.0 M KOH), −0.67 V (1.0 M NaCl), −0.26 V, and 0.05 V (1.0 M H2SO4) vs. the Ag/AgCl reference electrode and two-electron transfer process at all pH values. High solubility of the phenazine compound in water-based electrolytes up to 1.3 M is achieved by introducing quaternary amonium-based substituents, leading to the outstanding theoretical volumetric capacity of 70 Ah L−1. Laboratory redox flow batteries in neutral and acidic electrolytes presented >100 cycles of stable operation with a capacity loss of 0.25 mAh L−1 and 1.29 mAh L−1 per cycle, respectively. The obtained results demonstrate a material with the potential for not only fundamental understanding but also the practical application of AORFBs in the development of new-generation energy storage technologies.

A New Voltage-Multiplier-Based Power Converter Configuration Suitable for Renewable Energy Sources and Sustainability Applications

The sustainability of new-generation energy sources has become one of the most critical challenges in recent years as renewable energy sources (RESs) rapidly replace old fossil sources. Integration between RESs and the grid should be completed through power electronics converters and optimized control techniques. RESs have many advantages, such as having increased reliability and sustainability, being environmentally friendly, and having cheaper maintenance costs and more reasonable energy prices. Photovoltaic (PV) panels are among the most popular RESs. A PV array’s generated voltage level is unsuitable for direct load or grid connection and has to be enhanced via a DC-DC boost converter. After that, an inverter should be used to change the generated DC voltage to AC voltage for the grid or loads. In order to reach higher voltage gains, different structures have been proposed in the literature, such as cascaded converters, non-isolated converters (including transformers), and positive- and negative-voltage-lift Luo converters. These converters have some disadvantages, such as including a large number of semiconductor devices and inductors, heavy and bulky structures, and the need for intermediate converters to convert DC to AC voltage and vice versa. Besides the efficiency and high DC voltage gain feature, to achieve more reliability and sustainability and a longer lifetime of the PV source, the current drawn from these sources should be as ripple-free as possible. This study considers all these details by presenting a novel DC-DC power boost converter. The steady-state analysis, simulation, and test results are presented. The most important features of the proposed converter include the lack of need for a transformer, intermediate inverter, rectifier converters, and bulky and heavy components, while still ensuring that high voltage gains and high efficiencies are possible. Simulation results showed that for duty ratios from D = 0.05 to D = 0.15 for the switch S3, the gain of the converter was 22, 35, and 70 times greater than the input voltage, respectively. The desired 200 VDC and 400 VDC voltages for the output nodes were obtained using 12 VDC as the input voltage with and without the switched-capacitor cell, respectively. A limited number of the voltages between −47 and 12 V dropped across the inductors, and a reversed voltage from −12 to −48 V was reported for the power diodes. Additionally, an efficiency close to 96.88% was obtained for the proposed converter. According to the experimental results, a voltage close to 198 VDC was obtained with a 12 VDC input voltage source without using the switched-capacitor cell. A current with a maximum of 7 A was reported for the output diode, and more than 96% efficiency was reported. The results showed that the primary source of the power losses was the semiconductors, and the switching losses made up around 69% and 88% of the total losses for the switches and diodes, respectively. The present topology has three power switches. Two of the switches are activated and deactivated simultaneously. The third switch is activated or deactivated in reverse with the other switches. The results showed that for short-duty ratios such as 0.5 for switches S1 and S2 and 0.35 for switch S3, DC voltage gains close to 35 were obtained theoretically. The generated voltage could be doubled by applying fourth and fifth power switches by making a switched-capacitor-based topology. All of these details are illustrated in this study in detail. The proposed circuit was set up and tested in a laboratory environment. The test results confirm the simulation and theoretical analysis.

A nano rod-like α-MnO2 supported on carbon nanotubes modified separator inhibiting polysulfide shuttle in Li-S batteries

Lithium-sulfur (Li-S) batteries have attracted enormous attentions as new-generation energy storage devices due to their high theoretical energy density, high theoretical specific capacity, low cost and environmental friendliness. However, polysulfide shuttle and the growth of lithium dendrites significantly restrain the practical application of the Li-S batteries. In this work, a modified PP separator with nanoscale rod-like α-MnO2 supported on carbon nanotubes was prepared. The α-MnO2 @CNT modified separator can effectively inhibit the shuttle of polysulfide, enhance the electrochemical activity and accelerate the transfer of ions and electrons. The density functional theory (DFT) calculations demonstrate that α-MnO2 @CNT can efficiently adsorb and catalyze the conversion of polysulfides. Due to these advantages, the α-MnO2 @CNT-based Li-S battery delivers a initial discharge capacity of 1469 mAh g−1 at 0.05 C, 1039 mAh g−1 at 0.5 C and the capacity can still maintain 648 mAh g−1 over 500 cycles at 0.5 C (capacity decay rate of 0.075%). Expressly, the capacity decay rate is only 0.022% after 600 cycles at a high current density of 2 C. The excellent performance could be attributed to the α-MnO2 @CNT modified separator not only accelerating the transmission of electrons but also effectively inhibiting the shuttle of polysulfides. Moreover, this work provides a better idea for practical applications of lithium-sulfur batteries in the future.

High-entropy perovskite oxide BaCo0.2Fe0.2Zr0.2Sn0.2Pr0.2O3-δ with triple conduction for the air electrode of reversible protonic ceramic cells

Reversible protonic ceramic cells (RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stability of air electrodes exposed to concentrated vapor under operating conditions. Herein, we report a high-entropy air electrode with the composition BaCo0.2Fe0.2Zr0.2Sn0.2Pr0.2O3-δ (BCFZSP), which shows integrated electronic, protonic and oxygenic conduction in a single perovskite phase and excellent structural stability in concentrated steam. Such triple conduction can spread the electrochemically active sites of the air electrode to the overall electrode surface, thus optimizing the kinetics of the oxygen reduction and evolution reactions (0.448 Ω cm2 of polarization resistance at 550 °C). As-prepared RPCCs with a BCFZSP air electrode at 600 °C achieved a peak power density of 0.68 W/cm2 in fuel-cell mode and a current density of 0.92 A/cm2 under a 1.3 V applied voltage in electrolysis mode. More importantly, the RPCCs demonstrate an encouragingly high stability during 120 h of reversible switching between the fuel-cell and electrolysis modes. Given their excellent performance, high-entropy perovskites can be promising electrode materials for RPCCs.

B/N/O/Zn doped porous carbon materials for supercapacitor with high performance

• B/N/O doped porous carbon materials were prepared by organic ligand to ensure the sustainable acquisition of raw materials and avoid uneven doping. • Synergic effects between heteroatoms and appropriate pore structure provide more active sites and wettability, which is conducive to electrolyte penetration and electron transport. • A high capacitance and high specific energy were obtained. • B, O and N co-doping offers pseudocapacitance for enhancing the capacitive properties. Owing to the need for new-generation energy storage equipment and industrial application, the development of carbon electrode materials with comprehensive electrochemical performances and convenient production processes has become a top priority. In this study, B/N/O/Zn doped carbon materials were prepared using a simple one-step method with 4-(2,4,6-tricarboxylphenyl)-2,2′:6′,2′’-terpyridine (TT) as a raw material. Owing to the doping of many heteroatoms, particularly boron atoms, the optimized TT(Zn/B)-700 exhibits a large specific surface area, proper pore distribution from micropore to macropore, and high degree of graphitization. These structural and morphological features ensure high capacitance performance, such as a specific capacitance of 418.75F/g at 0.5 A/g, and a specific energy of 83.75 Wh/kg at 300 W/kg. In addition, the assembled symmetric supercapacitor exhibits excellent specific energy (5.88 Wh/kg at 150 W/kg, and 5.00 Wh/kg at 3000 W/kg) and specific capacitance (117.5 F/g at 0.5 A/g, and 100.0 F/g at 10 A/g). These carbon electrode materials demonstrate great potential for applications in high-performance supercapacitors.

Thiol-Containing Metal-Organic Framework-Decorated Carbon Cloth as an Integrated Interlayer-Current Collector for Enhanced Li-S Batteries.

Lithium-sulfur (Li-S) batteries hold great promise for new-generation energy storage technologies owing to their overwhelming energy density. However, the poor conductivity of active sulfur and the shuttle effect limit their widespread use. Herein, a carbon cloth decorated with thiol-containing UiO-66 nanoparticles (CC@UiO-66(SH)2) was developed to substitute the traditional interlayer and current collector for Li-S batteries. One side of CC@UiO-66(SH)2 acts as a current collector to load active materials, while the other side serves as an interlayer to further restrain polysulfide shuttling. This two-in-one integrated architecture endows the sulfur cathode with fast electron/ion transport and efficient chemical confinement of polysulfides. More importantly, rich thiol groups in the pores of UiO-66(SH)2 serve to tether polysulfides by both covalent interactions and lithium bonding. Therefore, the Li-S battery equipped with this integrated interlayer-current collector not only delivers an enhanced specific capability (1209 mAh g-1 at 0.1 C) but also exhibits prominent cycling stability (an attenuation rate of 0.037% per cycle for 1000 cycles at 1 C). Meanwhile, the battery achieves a high discharge capacity of 795 mAh g-1 at a sulfur loading of 3.83 mg cm-2. The new metal-organic framework (MOF)-based electrode material reported in this study undoubtedly provides insights into the exploration of functional MOFs for robust Li-S batteries.

Na0.76V6O15@Boron Carbonitride Nanotube Composites as Cathodes for High-Performance Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) are considered one of the most promising new-generation energy storage devices because they combine the advantages of lithium-ion batteries and supercapacitors. However, the widely used commercial carbon cathode greatly limits the electrochemical performance of existing LICs due to its limited specific capacity. Improving the specific capacity of the cathode is one of the keys to solving this problem. To this end, the Na0.76V6O15 (NaVO)@boron carbonitride nanotube (BCNNT) cathode has been successfully synthesized via a facile solid phase reaction and hydrothermal reaction followed by annealing. Benefitting from the synergy between the high conductivity of BCNNTs and the high capacity of NaVO, the NaVO@BCN cathode exhibits excellent capacity and good cyclic stability. A LIC was assembled by a prefabricated NaVO@BCN cathode and a prelithiated commercial hard carbon (HC) anode. Notably, the NaVO@BCN−1//HC LIC delivered an energy density of 238.7 Wh kg−1 at 200 W kg−1 and still delivered 81.9 Wh kg−1 even at 20 kW kg−1. Therefore, our strategy provides a novel idea for designing high-performance LICs.

N/P/O doped porous carbon materials for supercapacitor with high performance

Owing to the need for new-generation energy storage equipment and industrial application, the development of carbon electrode materials with comprehensive electrochemical performances and convenient production processes has become a top priority. In this study, N/P/O doped carbon materials are prepared using a simple one-step method with 4-(2,4,6-tricarboxylphenyl)-2,2′:6′,2″-terpyridine (TT) as a raw material. Owing to the doping of many heteroatoms, particularly phosphorus atoms, the optimized TT(Zn/P)-700 exhibits a large specific surface area (2164.7 cm2/g), proper pore distribution from micropore to macropore, and high degree of graphitization. These structural and morphological features ensure excellent comprehensive capacitance performance, such as a high specific capacitance (366.25 F/g at 0.5 A/g), and high specific energy (73.25 Wh/kg at 300 W/kg). In addition, the specific capacitance of the symmetric supercapacitor assembled with TT(Zn/P)-700 electrode reaches 143.3 and 121.7 F/g at specific currents of 0.5 and 10 A/g, respectively. The specific current is increased 20 times, and the capacitance retention rate reaches 84.9%, improving the rate performance. When the specific power increases to 150 and 3000 W/kg, the specific energy reaches 7.17 and 6.08 Wh/kg, respectively. After 5000 charge/discharge cycles, the capacitance retention rate is 92.7%. These high-performance N/P/O-doped carbon electrode materials demonstrate great potential in industrial applications and new-generation energy storage equipment.