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Potassium metal batteries are considered as attractive alternatives beyond lithium-ion batteries. However, uncontrollable dendrite growth on the potassium metal anode has restrained their practical applications. A high-performance potassium anode achieved by confining potassium metal into a titanium-deficient nitrogen-containing MXene/carbon nanotube freestanding scaffold is reported. The high electronic transport and fast potassium diffusion in this scaffold enable reduced local current density and homogeneous ionic flux during plating/stripping processes. Furthermore, as verified by theoretical calculations and experimental investigations, such "potassium-philic" MXene sheets can induce the nucleation of potassium, and guide potassium to uniformly distribute in the scaffold upon cycling. Consequently, the as-developed potassium metal anodes exhibit a dendrite-free morphology with high Coulombic efficiency and long cycle life during plating/stripping processes. Such anodes also deliver significantly improved electrochemical performances in potassium-sulfur batteries compared with bare potassium metal anodes. This work can provide a new avenue for developing potassium metal-based batteries.
Guo, X, Zhang, W, Zhang, J, Zhou, D, Tang, X, Xu, X, Li, B, Liu, H & Wang, G 2020, 'Boosting Sodium Storage in Two-Dimensional Phosphorene/Ti3C2Tx MXene Nanoarchitectures with Stable Fluorinated Interphase', ACS NANO, vol. 14, no. 3, pp. 3651-3659.View/Download from: Publisher's site
Nan, J, Guo, X, Xiao, J, Li, X, Chen, W, Wu, W, Liu, H, Wang, Y, Wu, M & Wang, G 2020, 'Nanoengineering of 2D MXene-Based Materials for Energy Storage Applications.', Small (Weinheim an der Bergstrasse, Germany).View/Download from: Publisher's site
2D MXene-based nanomaterials have attracted tremendous attention because of their unique physical/chemical properties and wide range of applications in energy storage, catalysis, electronics, optoelectronics, and photonics. However, MXenes and their derivatives have many inherent limitations in terms of energy storage applications. In order to further improve their performance for practical application, the nanoengineering of these 2D materials is extensively investigated. In this Review, the latest research and progress on 2D MXene-based nanostructures is introduced and discussed, focusing on their preparation methods, properties, and applications for energy storage such as lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. Finally, the critical challenges and perspectives required to be addressed for the future development of these 2D MXene-based materials for energy storage applications are presented.
Tang, X, Zhou, D, Li, P, Guo, X, Wang, C, Kang, F, Li, B & Wang, G 2019, 'High-Performance Quasi-Solid-State MXene-Based Li-I Batteries.', ACS central science, vol. 5, no. 2, pp. 365-373.View/Download from: Publisher's site
Lithium-iodine (Li-I) batteries have attracted tremendous attention due to their high energy and power densities as well as the low cost of iodine. However, the severe shuttle effect of iodine species and the uncontrollable lithium dendrite growth have strongly hindered their practical applications. Here we successfully develop a quasi-solid-state Li-I battery enabled by a MXene-based iodine cathode and a composite polymer electrolyte (CPE) containing NaNO3 particles dispersing in a pentaerythritol-tetraacrylate-based (PETEA-based) gel polymer electrolyte. As verified by experimental characterizations and first-principle calculations, the abundant functional groups on the surface of MXene sheets provide strong chemical binding to iodine species, and therefore immobilize their shuttling. The PETEA-based polymer matrix simultaneously suppresses the diffusion of iodine species and stabilizes the Li anode/CPE interface against dendrite growth. The NaNO3 particles act as an effective catalyst to facilitate the transformation kinetics of LiI3 on the cathode. Owing to such synergistic optimization, the as-developed Li-I batteries deliver high energy/power density with long cycling stability and good flexibility. This work opens up a new avenue to improve the performance of Li-I batteries.
Guo, X, Zhang, J, Zhao, Y, Sun, B, Liu, H & Wang, G 2019, 'Ultrathin Porous NiCo2O4 Nanosheets for Lithium-Oxygen Batteries: An Excellent Performance Deriving from an Enhanced Solution Mechanism', ACS Applied Energy Materials, vol. 2, no. 6, pp. 4215-4223.View/Download from: Publisher's site
© Copyright 2019 American Chemical Society. Lithium-oxygen batteries are of interest for long-range electric vehicles owing to their high theoretical energy density. However, the poor cycling performance and low round-trip efficiency deriving from the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics severely impede their practical application. Ingenious design of cathode catalysts is imperative to overcome these challenges. Here, we report ultrathin porous NiCo2O4 nanosheets with abundant oxygen vaccines as an efficient cathode catalyst toward both OER and ORR for Li-O2 batteries. From combined theoretical calculation with experimental results, a unique enhanced solution mechanism is proposed in the ether-based electrolyte system. Benefiting from the porous 2D architecture of the cathode and the hierarchical toroidal products, the Li-O2 batteries using NiCo2O4 cathodes deliver a high discharge capacity of 16 400 mAh g-1 at 200 mA g-1 and an excellent cycling performance up to 150 cycles with a restricted capacity of 1000 mAh g-1.
Song, J, Guo, X, Zhang, J, Chen, Y, Zhang, C, Luo, L, Wang, F & Wang, G 2019, 'Rational design of free-standing 3D porous MXene/rGO hybrid aerogels as polysulfide reservoirs for high-energy lithium-sulfur batteries', Journal of Materials Chemistry A, vol. 7, no. 11, pp. 6507-6513.View/Download from: Publisher's site
© 2019 The Royal Society of Chemistry. Lithium-sulfur (Li-S) batteries with a high theoretical energy density are attracting increasing attention as promising candidates for next-generation energy storage systems. However, the insulating nature and undesirable shuttle effect of sulfur species dramatically impede their practical applications. Herein, a unique 3D porous Ti3C2Tx MXene/rGO (MX/G) hybrid aerogel is rationally designed and applied for the first time as a free-standing polysulfide reservoir to improve the overall performance of Li-S batteries. In this strategy, highly conductive MXene and rGO are integrated into a 3D interconnected porous aerogel structure with efficient 2D polar adsorption interfaces, enabling fast Li+/electron transport and strong chemical anchoring of lithium polysulfides as well as enhanced redox reaction kinetics. The robust MX/G aerogel electrodes deliver excellent electrochemical performances including a high capacity of 1270 mA h g-1 at 0.1C, an extended cycling life up to 500 cycles with a low capacity decay rate of 0.07% per cycle, and a high areal capacity of 5.27 mA h cm-2.
Zhang, F, Xiong, P, Guo, X, Zhang, J, Yang, W, Wu, W, Liu, H & Wang, G 2019, 'A nitrogen, sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline coating for high-performance sodium-selenium batteries', Energy Storage Materials, vol. 19, pp. 251-260.View/Download from: Publisher's site
© 2019 Elsevier B.V. Sodium-selenium (Na-Se)battery has been emerging as a new rechargeable energy storage system with high capacity, low cost and high rate capability. However, the shuttling of polyselenides from the cathode to the anode causes dramatic capacity decay, severely impeding their practical applications. Herein, we report a combinational strategy of nitrogen and sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline (PANI)coating to incorporate Se as stable cathodes (i-PANI@NSHPC/Se)for Na-Se batteries. Ex situ characterizations and density functional theory (DFT)calculations demonstrate that the i-PANI@NSHPC/Se cathode can provide both physical diffusion barrier and strong chemical affinity for polyselenides. In addition, the interconnected conductive polyaniline network enhances the conductivity for electrons and ions. With this strategy, the i-PANI@NSHPC/Se cathode delivered a high reversible capacity of 617 mAh g −1 after 200 cycles at 0.2C with a low capacity decay rate of 0.013% per cycle and an excellent rate capability at 20 C. Importantly, stable cycling performances were achieved with high capacities at different Se areal mass loadings (1.2, 2.3, 3.5 mg cm −2 ). This work could provide an efficient approach for developing Na-Se batteries with high active material mass loading, high rate capacity and long cycle life.
Zhang, J, Sun, B, Zhao, Y, Tkacheva, A, Liu, Z, Yan, K, Guo, X, McDonagh, AM, Shanmukaraj, D, Wang, C, Rojo, T, Armand, M, Peng, Z & Wang, G 2019, 'A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries.', Nature communications, vol. 10, no. 1.View/Download from: Publisher's site
Due to the high theoretical specific energy, the lithium-oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge-charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life (> 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air.
Zhao, Y, Wang, S, Liu, H, Guo, X, Zeng, X, Wu, W, Zhang, J & Wang, G 2019, 'Porous Mo2C nanorods as an efficient catalyst for the hydrogen evolution reaction', Journal of Physics and Chemistry of Solids, vol. 132, pp. 230-235.View/Download from: Publisher's site
© 2019 Elsevier Ltd Generate hydrogen fuel from electrochemical water splitting has been considered as a promising approach. However, to obtain the low-cost and high performance catalysts towards hydrogen evolution reaction (HER)which can be applied in both alkaline and acid solution remains a challenge. Herein, we synthesized an active and stable HER catalyst composed of Mo2C nanocrystals embedded in the nanocarbon layers (Mo2C@C)by using MoO3 nanorods as precursor. Benefiting from the porous one dimensional structure and ultrafine Mo2C nanocrystals, Mo2C@C exhibits high HER catalytic activity for 10 mA cm−2 with the overpotential of 119 mV in 1 M KOH solution and 170 mV in 0.5 M H2SO4 solution, respectively. Moreover, Mo2C@C displays long durability during the HER process with almost no decay and maintains the porous one dimensional architecture after the HER stability test. This study offers the guideline for the further design and fabrication of the nanostructured HER electrocatalysts in wide pH range.
Bao, W, Shuck, CE, Zhang, W, Guo, X, Gogotsi, Y & Wang, G 2019, 'Boosting Performance of Na-S Batteries Using Sulfur-Doped Ti3C2Tx MXene Nanosheets with a Strong Affinity to Sodium Polysulfides', ACS NANO, vol. 13, no. 10, pp. 11500-11509.View/Download from: Publisher's site
Choi, S, Seo, DH, Kaiser, MR, Zhang, C, Van Der Laan, T, Han, ZJ, Bendavid, A, Guo, X, Yick, S, Murdock, AT, Su, D, Lee, BR, Du, A, Dou, SX & Wang, G 2019, 'WO 3 nanolayer coated 3D-graphene/sulfur composites for high performance lithium/sulfur batteries', Journal of Materials Chemistry A, vol. 7, no. 9, pp. 4596-4603.View/Download from: Publisher's site
© 2019 The Royal Society of Chemistry. The lithium-sulfur (Li-S) system is one of the most promising rechargeable battery systems for portable electronics and electrification of vehicles due to a high theoretical capacity and energy density, as well as the low cost and availability of non-toxic sulfur. Polysulfide dissolution however hinders cycling performance and is the main limitation to the stability of the Li-S system. Here, we tackle this challenge by synthesizing 3D-graphene foam from soybean oil through a thermal chemical vapor deposition (CVD) process, which is subsequently loaded with sulfur to form a 3D-graphene-sulfur composite (denoted as S@G composite). The synthesized S@G composite shows high initial discharge capacity (∼1300 mA h g -1 at 0.8 A g -1 ) and capacity retention (∼80% after 200 cycles). Furthermore, a thin layer (∼100 nm) of tungsten oxide (WO 3 ) on the S@G composite dramatically improves the cycling performance of the Li-S system with an initial capacity of 1425 mA h g -1 and approximately 95% capacity retention after 500 cycles. The analysis and theoretical calculation results prove that the novel material and approach can enhance the electrochemical performance of rechargeable Li-S batteries and shed light on developing high-performance energy storage devices for a variety of applications.
Li, P, Li, P, Guo, X, Wang, S, Zang, R, Li, X, Man, Z, Liu, S, Wu, Y & Wang, G 2019, 'Two-dimensional Sb@TiO 2-: X nanoplates as a high-performance anode material for sodium-ion batteries', Journal of Materials Chemistry A, vol. 7, no. 6, pp. 2553-2559.View/Download from: Publisher's site
© 2019 The Royal Society of Chemistry. Alloy-based anode materials, including antimony (Sb), with high electronic conductivity and high capacity show great potential for sodium-ion batteries. However, the significant volume change of Sb leads to pulverization of active material and rapid capacity decay. Herein, two-dimensional (2D) Sb@TiO 2-x nanoplates, consisting of an amorphous TiO 2-x layer coated with ultra-small Sb nanocrystals, are prepared by a facile salt-template method. The incorporation of electrochemical/thermally-stable TiO 2-x is helpful to buffer the volume change of Sb and stabilize the SEI layer. In addition, the 2D structure of the Sb@TiO 2-x nanoplates can facilitate sodium ion diffusion and electronic transport during cycling. As a result, the 2D-Sb@TiO 2-x electrodes deliver a high reversible capacity of 568 mA h g -1 at 100 mA g -1 , good rate capability (429 mA h g -1 at 3200 mA g -1 ) and stable cycling performance with a capacity retention of 95.2% after 100 cycles.
Zang, R, Li, P, Guo, X, Man, Z, Zhang, S, Wang, C & Wang, G 2019, 'Yolk-shell N-doped carbon coated FeS2 nanocages as a high-performance anode for sodium-ion batteries', Journal of Materials Chemistry A, vol. 7, no. 23, pp. 14051-14059.View/Download from: Publisher's site
© 2019 The Royal Society of Chemistry. Pyrite FeS2 displays brilliant prospects for sodium storage because of its high theoretical capacity (894 mA h g-1), low cost and eco-friendly properties. The practical application of FeS2, however, has been thwarted by poor cycle life derived from the large volume change and active sulfide loss upon sodiation/desodiation. Herein, we fabricated yolk-shell nitrogen-doped carbon-coated FeS2 nanocages (PFS@NC) by a facile thermal-sulfurization of polypyrrole-coated Prussian blue precursors for sodium-ion batteries. The yolk-shell structure affords enough space to buffer the volumetric change of FeS2 nanoparticles during the sodiation process. Therefore, the structural integrity of PFS@NC can be preserved without deforming the carbon shell. Additionally, the nitrogen-doped carbon not only improves the electronic conductivity of the composite, but also effectively traps the soluble reduced products of FeS2, contributing to its stable cycling performance. As a result, a high specific capacity of 375 mA h g-1 has been achieved up to 1000 cycles at 5 A g-1 (92% capacity retention). The PFS@NC composite could be an excellent anode material for sodium storage and the as-developed synthetic strategy is expected to be utilized for improving the performance of other metal sulfide electrode materials.
Guo, X, Zhang, J, Song, J, Wu, W, Liu, H & Wang, G 2018, 'MXene encapsulated titanium oxide nanospheres for ultra-stable and fast sodium storage', Energy Storage Materials, vol. 14, pp. 306-313.View/Download from: Publisher's site
© 2018 Sodium-ion batteries with high power density present tremendous potential for large-scale energy storage applications. However, it remains a big challenge to develop suitable anode materials for ultrafast and highly reversible sodium ion storage. Herein, for the first time, we report a novel strategy to fabricate highly conductive MXene Ti3C2Txencapsulated titanium oxide spheres (TiO2@Ti3C2Tx) as an excellent anode material for sodium-ion batteries. The MXene layers significantly improve the electronic conductivity of the whole electrode and protect the structural integrity of the TiO2spheres from electrochemical pulverization, which hence contributes to the formation of a stable solid-electrolyte interface. Meanwhile, the pseudocapacitance of the as-fabricated TiO2@Ti3C2Txcomposites enables high-rate capability and long cycle life in sodium-ion batteries. As a result, the hybrid electrode delivers a high reversible capacity of 116 mAh g-1at 960 mA g-1up to 5000 cycles. By coupling with a NaCrO2cathode, a prototype Na-ion full cell achieved a capacity of 103.4 mAh g-1at 960 mA g-1and an excellent cycling performance with 73.5% capacity retention after 1000 cycles.
Song, J, Zhang, C, Guo, X, Zhang, J, Luo, L, Liu, H, Wang, F & Wang, G 2018, 'Entrapping polysulfides by using ultrathin hollow carbon sphere-functionalized separators in high-rate lithium-sulfur batteries', Journal of Materials Chemistry A, vol. 6, no. 34, pp. 16610-16616.View/Download from: Publisher's site
© 2018 The Royal Society of Chemistry. Lithium-sulfur batteries (LSBs) have been regarded as the most promising technology for next generation energy storage systems owing to their high energy density and low cost. However, the undesirable shuttle effect and low utilization of sulfur caused by dissolution and migration of polysulfide intermediates greatly restrict their practical application. Herein, we report a functional separator modified with novel ultrathin hollow carbon spheres (UHCSs) to improve the overall performance of LSBs and demonstrate for the first time that nonporous hollow structured carbon materials are ideal candidates for modifying the separator due to their unique properties. The ultrathin and nonporous shell of the coated UHCSs can act as a physical and a chemical barrier to effectively entrap lithium polysulfides owing to fewer diffusion sites. The UHCSs can also enhance the electron transfer for sulfur and accommodate the large volume change of sulfur as upper current collectors. When applying such UHCSs functionalized separators, the LSBs achieved a significantly improved electrochemical performance including a high capacity of 1346.3 mA h g-1 at 0.2C and high rate capability with a discharge capacity of 458 mA h g-1 even at 5C upon 1000 cycles.
Zhang, J, Zhao, Y, Guo, X, Chen, C, Dong, CL, Liu, RS, Han, CP, Li, Y, Gogotsi, Y & Wang, G 2018, 'Single platinum atoms immobilized on an MXene as an efficient catalyst for the hydrogen evolution reaction', Nature Catalysis, vol. 1, no. 12, pp. 985-992.View/Download from: Publisher's site
© 2018, The Author(s), under exclusive licence to Springer Nature Limited. Single-atom catalysts offer a pathway to cost-efficient catalysis using the minimal amount of precious metals. However, preparing and keeping them stable during operation remains a challenge. Here we report the synthesis of double transition metal MXene nanosheets—Mo 2 TiC 2 T x , with abundant exposed basal planes and Mo vacancies in the outer layers—by electrochemical exfoliation, enabled by the interaction between protons and the surface functional groups of Mo 2 TiC 2 T x . The as-formed Mo vacancies are used to immobilize single Pt atoms, enhancing the MXene’s catalytic activity for the hydrogen evolution reaction. The developed catalyst exhibits a high catalytic ability with low overpotentials of 30 and 77 mV to achieve 10 and 100 mA cm −2 and a mass activity about 40 times greater than the commercial platinum-on-carbon catalyst. The strong covalent interactions between positively charged Pt single atoms and the MXene contribute to the exceptional catalytic performance and stability.
Zhao, Y, Zhang, J, Wu, W, Guo, X, Xiong, P, Liu, H & Wang, G 2018, 'Cobalt-doped MnO2 ultrathin nanosheets with abundant oxygen vacancies supported on functionalized carbon nanofibers for efficient oxygen evolution', Nano Energy, vol. 54, pp. 129-137.View/Download from: Publisher's site
© 2018 Elsevier Ltd Developing low-cost and efficient catalysts for oxygen evolution reactions (OER) with both excellent activity and robust stability remains a great challenge. Herein, we report a facile spontaneous redox reaction to grow cobalt-doped MnO2 ultrathin nanosheets in situ with abundant oxygen vacancies vertically aligned on cobalt/nitrogen co-functionalized carbon nanofibers (Co-MnO2|OV) as an efficient OER catalyst. It is confirmed that metallic cobalt plays a critical role in the formation of long and ultrathin MnO2 nanosheets during the redox reaction. Furthermore, the cobalt ions doped into MnO2 significantly enhance the catalytic activity of MnO2 nanosheets. Benefiting from the collaborative advantages of doping strategy, fast charge transfer kinetics and strong synergistic coupling effects, Co-MnO2|OV composites exhibit an excellent catalytic activity and a good durability for electrochemical water oxidation, reaching 10 mA cm−2 at an overpotential of 279 mV. According to the density functional theory (DFT) calculations, the enhanced catalytic activity mainly originates from a better conductivity and the decreased adsorption energy barrier of OH- on the O sites neighboring the doped Co and oxygen vacancies. Our findings suggest that the control over the structure and composition of the materials can achieve highly efficient oxygen evolution electrocatalysts.
Bao, W, Tang, X, Guo, X, Choi, S, Wang, C, Gogotsi, Y & Wang, G 2018, 'Porous Cryo-Dried MXene for Efficient Capacitive Deionization', Joule, vol. 2, no. 4, pp. 778-787.View/Download from: Publisher's site
© 2018 Elsevier Inc. Aerogel-like, porous Ti 3 C 2 T x MXene architecture electrode displayed a high electroadsorption capacity for capacitive deionization of saline water. A vacuum freeze-drying process was employed to prevent the restacking of MXene nanosheets due to van der Waals forces, leading to the formation of a porous structure with a large specific surface area. When applied as electrode materials for capacitive deionization, porous MXene demonstrated a high specific capacitance of 156 F/g and a volumetric capacitance of 410 F/cm 3 in 1 M sodium chloride (NaCl) electrolyte. The porous Ti 3 C 2 T x MXene electrodes can deliver a high electroadsorption capacity of 118 mg/cm 3 (45 mg/g) in 10,000 mg/L NaCl solution (applied voltage: 1.2 V) and excellent cycling stability (up to 60 cycles) in comparison with the restacked MXene and activated carbon electrodes, indicating its promising potential for desalination applications. We report a rationally designed process to produce an aerogel-like porous MXene electrode material for capacitive deionization. The intercalation-delamination of organic compounds and a vacuum freeze-drying technique were employed to prevent the restacking of MXene nanosheets due to van der Waals forces. The porous Ti 3 C 2 T x is hydrophilic and has a well-defined porous structure with a high surface area and high electrical conductivity. When applied as electrodes in a capacitive deionization cell, porous Ti 3 C 2 T x MXene electrodes exhibited an impressively high ion adsorption capacity of 118 mg/cm 3 in a salt solution with the concentration of 10,000 mg/L, which is more than 12 times higher than previously reported carbon-based electrode materials. The porous MXene materials may open a new avenue for high-performance capacitive desalination. Porous Ti 3 C 2 T x MXene architectures were prepared and used as electrode materials with a high electrosorption capacity for capacitive deionization of saline or brackish water. The porous ...
Duan, J, Jiang, L, Guo, X, Chen, S, Wang, G & Zhao, C 2018, 'Mxene-Directed Dual Amphiphilicity at Liquid, Solid, and Gas Interfaces.', Chemistry, an Asian journal, vol. 13, no. 24, pp. 3850-3854.View/Download from: Publisher's site
MXenes represent a category of two-dimensional functional nanomaterials with remarkable structural and chemical properties, which have been manipulated into different architectures for versatile applications. These manipulation processes generally take place at the interfaces between liquid, solid, and gas; and therefore, the investigation of the interfacial property of MXenes is the key. Here we show that MXenes exhibit amphiphilic behaviours at interfaces. Different from common amphiphiles, MXenes have the dual function of both colloidal and molecular activities owing to their two abrupt structural length scales: their large lateral sheet size allows for behaving like colloidal amphiphiles for creating emulsions, while their small sheet thickness allows for serving as molecular amphiphiles for dispersing solid substances. Further, such dual colloidal-molecular amphiphility has driven MXenes to accumulate at the interfaces of water and nitrogen gas, and the assembly into thin film electrodes for electrochemical energy storage. All these findings open up enormous opportunities for processing various MXenes-related functional materials and devices.
Guo, X, Li, K, Bao, W, Zhao, Y, Xu, J, Liu, H & Wang, G 2018, 'Highly Reversible Lithium Polysulfide Semiliquid Battery with Nitrogen-Rich Carbon Fiber Electrodes', Energy Technology, vol. 6, no. 2, pp. 251-256.View/Download from: Publisher's site
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Freestanding nitrogen-doped carbon fiber (NCF) webs saturated with lithium polysulfide solution were prepared as semiliquid cathodes for lithium–sulfur batteries. The NCF webs not only facilitated the transportation of electrons and ions but also immobilized the polysulfide at the cathode side because of strong affinity between the polysulfide and the N-doped carbon. As a result, these semiliquid cells demonstrated superior electrochemical performance at various current loads. A high reversible capacity of 900 mAh g−1was achieved after 200 cycles at a current rate of 1 C.
Tang, X, Guo, X, Wu, W & Wang, G 2018, '2D Metal Carbides and Nitrides (MXenes) as High-Performance Electrode Materials for Lithium-Based Batteries', ADVANCED ENERGY MATERIALS, vol. 8, no. 33.View/Download from: Publisher's site
Tang, X, Liu, H, Guo, X, Wang, S, Wu, W, Mondal, AK, Wang, C & Wang, G 2018, 'A novel lithium-ion hybrid capacitor based on an aerogel-like MXene wrapped Fe2O3nanosphere anode and a 3D nitrogen sulphur dual-doped porous carbon cathode', Materials Chemistry Frontiers, vol. 2, no. 10, pp. 1811-1821.View/Download from: Publisher's site
© 2018 the Partner Organisations. Lithium-ion capacitors (LICs) have emerged as promising energy storage devices with both high energy density and high power density. However, due to the mismatch of charge-storage capacity and electrode kinetics between battery-type anodes and capacitor-type cathodes, the application of lithium-ion capacitors has been limited. In this work, interconnected aerogel-like MXene wrapped Fe2O3nanospheres have been prepared and investigated as battery-type anode materials for lithium-ion capacitors. In this rationally designed hybrid electrode, the Ti3C2TxMXene matrix is capable of providing fast transport of electrons and suppressing the volume change of Fe2O3. Simultaneously, Fe2O3hollow nanospheres offer large specific capacity and prevent restacking of the MXene layers, synergizing to boost the electrochemical performances of such hybrid electrodes. Meanwhile, the three-dimensional (3-D) nitrogen and sulphur dual-doped porous carbon (NS-DPC) derived from biomass has also been fabricated as a capacitor-type cathode material for lithium-ion capacitors. Consequently, the lithium-ion capacitors can demonstrate a high energy density of 216 W h kg-1at a power density of 400 W kg-1and a high power density of 20 kW kg-1at an energy density of 96.5 W h kg-1. This work elucidates that both high energy density and power density can be achieved in hybrid lithium-ion capacitors.
Zhang, J, Sun, B, McDonagh, AM, Zhao, Y, Kretschmer, K, Guo, X & Wang, G 2017, 'A multi-functional gel co-polymer bridging liquid electrolyte and solid cathode nanoparticles: An efficient route to Li–O2batteries with improved performance', Energy Storage Materials, vol. 7, pp. 1-7.View/Download from: Publisher's site
© 2016 Lithium-oxygen (Li–O 2 ) batteries have the highest theoretical energy density amongst all rechargeable batteries and have attracted significant attention. However, large over-potentials originating from sluggish reaction kinetics often lead to low round-trip energy efficiency and short cycle life. We report here a novel multi-functional gel co-polymer that efficiently enhances the discharge and charge performances in Li–O 2 batteries by intimately connecting the liquid electrolyte and solid cathode nanoparti cles. On one hand, the co-polymer material, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate-co-methyl methacrylate) (P(TMA-MMA)), functions as a binder during the fabrication of the cathode and forms a gel polymer membrane to retain liquid electrolyte and to increase ionic conductivity. On the other hand, the TMA units, containing N–O radical groups that catalyse Li 2 O 2 formation and decomposition during charge and discharge cycles, are distributed throughout the polymer membrane. This allows more effective formation and decomposition of Li 2 O 2 than surface bound catalytic units. The combination of gelable MMA and catalytic TMA moieties enhances the interface between liquid electrolyte and solid cathode by functioning as a medium both to transport Li + (enhancing discharge process) and to carry electrons (reducing charge over-potential). Consequently, the optimized P(TMA-MMA) co-polymers provide exceptional electrochemical performance in Li–O 2 batteries.
Zhao, Y, Zhang, J, Guo, X, Fan, H, Wu, W, Liu, H & Wang, G 2017, 'Fe3C@nitrogen doped CNT arrays aligned on nitrogen functionalized carbon nanofibers as highly efficient catalysts for the oxygen evolution reaction', Journal of Materials Chemistry A, vol. 5, no. 37, pp. 19672-19679.View/Download from: Publisher's site
© 2017 The Royal Society of Chemistry. Fe 3 C based catalysts are found to be one of the most promising electrocatalysts for the oxygen evolution reaction (OER). Herein, we report on a nanoarchitectured material composed of Fe 3 C nanoparticles encapsulated at the tip of nitrogen-enriched carbon nanotubes (NCNTs), which are aligned on one dimensional (1D) nitrogen-doped carbon nanofibers (Fe 3 C@NCNTs-NCNFs) by a scalable electrospinning technique, as a high performance OER catalyst. The unique 3D hierarchical architecture of Fe 3 C@NCNTs-NCNFs leads to highly exposed active sites, enhanced electron transfer properties and strong synergistic coupled effects. Fe 3 C@NCNTs-NCNFs exhibit an outstanding catalytic performance with a high current density (10 mA cm -2 at an overpotential of 284 mV), a low Tafel slope (56 mV dec -1 ), a low charge transfer resistance and strong durability in 1 M KOH solution. The electrochemical evaluation demonstrates that the Fe 3 C@NCNTs-NCNF composite is a promising electrocatalyst for the OER in alkaline solution.
Bao, W, Xie, X, Xu, J, Guo, X, Song, J, Wu, W, Su, D & Wang, G 2017, 'Confined Sulfur in 3 D MXene/Reduced Graphene Oxide Hybrid Nanosheets for Lithium-Sulfur Battery.', Chemistry - A European Journal, vol. 23, no. 51, pp. 12613-12619.View/Download from: Publisher's site
Three-dimensional metal carbide MXene/reduced graphene oxide hybrid nanosheets are prepared and applied as a cathode host material for lithium-sulfur batteries. The composite cathodes are obtained through a facile and effective two-step liquid-phase impregnation method. Owing to the unique 3 D layer structure and functional 2 D surfaces of MXene and reduced graphene oxide nanosheets for effective trapping of sulfur and lithium polysulfides, the MXene/reduced graphene oxide/sulfur composite cathodes deliver a high initial capacity of 1144.2 mAh g-1 at 0.5 C and a high level of capacity retention of 878.4 mAh g-1 after 300 cycles. It is demonstrated that hybrid metal carbide MXene/reduced graphene oxide nanosheets could be a promising cathode host material for lithium-sulfur batteries.
Guo, X, Sun, B, Su, D, Liu, X, Liu, H, Wang, Y & Wang, G 2017, 'Recent developments of aprotic lithium-oxygen batteries: functional materials determine the electrochemical performance', Science Bulletin, vol. 62, no. 6, pp. 442-452.View/Download from: Publisher's site
© 2017 Lithium oxygen battery has the highest theoretical capacity among the rechargeable batteries and it can reform energy storage technology if it comes to commercialization. However, many critical challenges, mainly embody as low charge/discharge round-trip efficiency and poor cycling stability, impede the development of Li-O 2 batteries. The electrolyte decomposition, lithium metal anode corrosion and sluggish oxygen reaction kinetics at cathode are all responsible for poor electrochemical performances. Particularly, the catalytic cathode of Li-O 2 batteries, playing a crucial role to reduce the oxygen during discharging and to decompose discharge products during charging, is regarded as a breakthrough point that has been comprehensive investigated. In this review, the progress and issues of electrolyte, anode and cathode, especially the catalysts used at cathode, are systematically summarized and discussed. Then the perspectives toward the developments of a long life Li-O 2 battery are also presented at last.
Guo, X, Xie, X, Choi, S, Zhao, Y, Liu, H, Wang, C, Chang, S & Wang, G 2017, 'Sb2O3/MXene(Ti3C2Tx) hybrid anode materials with enhanced performance for sodium-ion batteries', Journal of Materials Chemistry A, vol. 5, no. 24, pp. 12445-12452.View/Download from: Publisher's site
Li, C-S, Sun, Y, Gebert, F & Chou, S-L 2017, 'Current Progress on Rechargeable Magnesium-Air Battery', ADVANCED ENERGY MATERIALS, vol. 7, no. 24.View/Download from: Publisher's site
Liu, H, Liu, X, Li, W, Guo, X, Wang, Y, Wang, G & Zhao, D 2017, 'Porous Carbon Composites for Next Generation Rechargeable Lithium Batteries', Advanced Energy Materials, vol. 7, no. 24, pp. 1-11.View/Download from: Publisher's site
Rechargeable Mg–air batteries are a promising alternative to Li–air cells owing to the safety, low price originating from the abundant resource on the earth, and high theoretical volumetric density (3832 A h L−1 for Mg anode vs 2062 A h L−1 for Li). Only a few works are related to the highly reversible Mg–air batteries. The fundamental scientific difficulties hindering the rapid development of secondary Mg–air cells are attributed to the poor thermodynamics and kinetics properties mainly owing to the MgO or MgO2 insulating film as the initial discharge product on air–breathing cathode, contributing to the increase of a large overpotential and a high polarization. Very recently, remarkable progress on rechargeable Mg–air batteries is trying to overcome the major limitations in organic electrolytes via the combination of the first–principle calculation and experimental study. Therefore, this progress report highlights a comprehensive and concise survey of the major progress in the history of secondary Mg–air batteries, and the detailed illustrations of corresponding reaction mechanisms. The overview is devoted to open up a new area for manipulating the nanostructures to control the ideal reaction pathway in novel cell configuration and to fully understand the future Mg–air battery with improved energy density and cycling ability.
Guo, X, Sun, B, Zhang, J, Liu, H & Wang, G 2016, 'Ruthenium decorated hierarchically ordered macro-mesoporous carbon for lithium oxygen batteries', JOURNAL OF MATERIALS CHEMISTRY A, vol. 4, no. 25, pp. 9774-9780.View/Download from: Publisher's site
Wang, Y, Kretschmer, K, Zhang, J, Mondal, AK, Guo, X & Wang, G 2016, 'Organic sodium terephthalate@graphene hybrid anode materials for sodium-ion batteries', RSC ADVANCES, vol. 6, no. 62, pp. S7098-S7102.View/Download from: Publisher's site
Bao, W, Su, D, Zhang, W, Guo, X & Wang, G 2016, '3D Metal Carbide@Mesoporous Carbon Hybrid Architecture as a New Polysulfide Reservoir for Lithium-Sulfur Batteries', ADVANCED FUNCTIONAL MATERIALS, vol. 26, no. 47, pp. 8746-8756.View/Download from: Publisher's site
Feng, X, Zou, H, Xiang, H, Guo, X, Zhou, T, Wu, Y, Xu, W, Yan, P, Wang, C, Zhang, J-G & Yu, Y 2016, 'Ultrathin Li4Ti5O12 Nanosheets as Anode Materials for Lithium and Sodium Storage', ACS APPLIED MATERIALS & INTERFACES, vol. 8, no. 26, pp. 16718-16726.View/Download from: Publisher's site
Song, J, Su, D, Xie, X, Guo, X, Bao, W, Shao, G & Wang, G 2016, 'Immobilizing Polysulfides with MXene-Functionalized Separators for Stable Lithium-Sulfur Batteries', ACS APPLIED MATERIALS & INTERFACES, vol. 8, no. 43, pp. 29427-29433.View/Download from: Publisher's site
Chen, JJ, Li, ZD, Xiang, HF, Wu, WW, Guo, X & Wu, YC 2015, 'Bifunctional effects of carbon coating on high-capacity Li1.2Ni0.13Co0.13Mn0.54O2 cathode for lithium-ion batteries', Journal of Solid State Electrochemistry, vol. 19, no. 4, pp. 1027-1035.View/Download from: Publisher's site
© 2014, Springer-Verlag Berlin Heidelberg. Coating the Li-rich layered oxide cathode Li1.2Ni0.13Co0.13Mn0.54O2 with small amount of conductive carbon is realized by low-temperature sucrose carbonization in air. Carbon coating gives rise to a small amount of Mn3+ on the surface of the Li1.2Ni0.13Co0.13Mn0.54O2. The 1.2 wt% carbon-coated Li1.2Ni0.13Co0.13Mn0.54O2 shows obviously enhanced electrochemical performances, especially in improving rate capability and suppressing the voltage fading during long-term and high-rate cycling. According to the analysis from cyclic voltammetry (CV) and electrochemical impedance spectra (EIS), the improvements on the electrochemical performances are mainly because the coated carbon layer can function by not only increasing the electronic conductivity at the interface with electrolyte but also improving bulk electronic and ionic conductivity by small amounts of Mn3+. Therefore, carbon coating is a promising approach to improve the cyclic stability of the Li-rich layered oxides.
Zhou, TP, Feng, XY, Guo, X, Wu, WW, Cheng, S & Xiang, HF 2015, 'Solid-state synthesis and electrochemical performance of Ce-doped Li4Ti5O12 anode materials for lithium-ion batteries', ELECTROCHIMICA ACTA, vol. 174, pp. 369-375.View/Download from: Publisher's site
Guo, X, Xiang, HF, Zhou, TP, Ju, XK & Wu, YC 2014, 'Morphologies and structures of carbon coated on Li4Ti5O12 and their effects on lithium storage performance', ELECTROCHIMICA ACTA, vol. 130, pp. 470-476.View/Download from: Publisher's site
Guo, X, Xiang, HF, Zhou, TP, Li, WH, Wang, XW, Zhou, JX & Yu, Y 2013, 'Solid-state synthesis and electrochemical performance of Li4Ti5O12/graphene composite for lithium-ion batteries', ELECTROCHIMICA ACTA, vol. 109, pp. 33-38.View/Download from: Publisher's site
Guo, X, Zhang, YC & Xiang, HF 2013, 'Synthesis and electrochemical property of flowerlike LiFePO4 by Poly(ethylene glycol)-assisted hydrothermal process', Chinese Journal of Chemical Physics, vol. 26, no. 3, pp. 337-340.View/Download from: Publisher's site
Flowerlike LiFePO4 particles self-assembled by plate-like crystals with about 200 nm thickness were prepared by the poly(ethylene glycol)-assisted hydrothermal synthesis. Poly(ethylene glycol) in the hydrothermal system played an important role in reducing the thickness of the plate-like LiFePO4 crystals as a co-solvent and forming the flower-like structure as a soft template. The flowerlike LiFePO4 exhibits high discharge capacity of 140 mAh/g and shows quite good cycling performance in the lithium-ion batteries. Considering that the conductive carbon in the obtained LiFePO4 is negligible, the excellent cell performance suggests that the flowerlike LiFePO4 is a promising cathode material for the lithium-ion batteries. © 2013 Chinese Physical Society.