Abstract: Graphite, as the most common anode for commercial Li-ion batteries, has been reported to have a very low capacity when used as a Na-ion battery anode. It is well known that electrochemical insertion of Na(+) into graphite is significantly hindered by the insufficient interlayer spacing. Here we report expanded graphite as a Na-ion battery anode. Prepared through a process of oxidation and partial reduction on graphite, expanded graphite has an enlarged interlayer lattice distance of 4.3 A yet retains an analogous long-range-ordered layered structure to graphite. In situ transmission electron microscopy has demonstrated that the Na-ion can be reversibly inserted into and extracted from expanded graphite. Galvanostatic studies show that expanded graphite can deliver a high reversible capacity of 284 mAh g(-1) at a current density of 20 mA g(-1), maintain a capacity of 184 mAh g(-1) at 100 mA g(-1), and retain 73.92% of its capacity after 2,000 cycles.

Abstract: For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on highcapacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g –1 )a nd the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm –2 .T he Coulombic efficiency improves to ∼99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

Abstract: Silicon is a promising anode material for lithium ion batteries, but suffers from poor cyclability especially at high mass loading. Here, Li et al. synthesize mesoporous silicon sponge-like structures, which show promising performance at the deep lithiation and high loading conditions required for practical applications.

Abstract: Rechargeable non-lithium-ion (Na+, K+, Mg2+, Ca2+, and Al3+) batteries have attracted great attention as emerging low-cost and high energy-density technologies for large-scale renewable energy storage applications. However, the development of these batteries is hindered by the limited choice of high-performance electrode materials. In this work, MXene nanosheets, a class of two-dimensional transition-metal carbides, are predicted to serve as high-performing anodes for non-lithium-ion batteries by combined first-principles simulations and experimental measurements. Both O-terminated and bare MXenes are shown to be promising anode materials with high capacities and good rate capabilities, while bare MXenes show better performance. Our experiments clearly demonstrate the feasibility of Na- and K-ion intercalation into terminated MXenes. Moreover, stable multilayer adsorption is predicted for Mg and Al, which significantly increases their theoretical capacities. We also show that O-terminated MXenes can decom...

Abstract: Although being the standard anode material in lithium-ion batteries (LIBs), graphite so far is considered to fail application in sodium-ion batteries (NIBs) because the Na-C system lacks suitable binary intercalation compounds. Here we show that this limitation can be circumvented by using co-intercalation phenomena in a diglyme-based electrolyte. The resulting compound is a stage-I ternary intercalation compound with an estimated stoichiometry of Na(diglyme)2C20. Highlights of the electrode reaction are its high energy efficiency, the small irreversible loss during the first cycle, and a superior cycle life with capacities close to 100 mAh g−1 for 1000 cycles and coulomb efficiencies >99.87 %. A one-to-one comparison with the analogue lithium-based cell shows that the sodium-based system performs better and also withstands higher currents.

Abstract: MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries. By controlling the cut-off voltage to the range of 0.4–3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS2 nanoflower electrode shows high discharge capacities of 350 mAh g−1 at 0.05 A g−1, 300 mAh g−1 at 1 A g−1, and 195 mAh g−1 at 10 A g−1. An initial capacity increase with cycling is caused by peeling off MoS2 layers, which produces more active sites for Na+ storage. The stripping of MoS2 layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na+ ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high-rate capability. Therefore, MoS2 nanoflowers with expanded interlayers hold promise for rechargeable Na-ion batteries.

Abstract: Stable cycling of lithium metal anode is challenging due to the dendritic lithium formation and high chemical reactivity of lithium with electrolyte and nearly all the materials. Here, we demonstrate a promising novel electrode design by growing two-dimensional (2D) atomic crystal layers including hexagonal boron nitride (h-BN) and graphene directly on Cu metal current collectors. Lithium ions were able to penetrate through the point and line defects of the 2D layers during the electrochemical deposition, leading to sandwiched lithium metal between ultrathin 2D layers and Cu. The 2D layers afford an excellent interfacial protection of Li metal due to their remarkable chemical stability as well as mechanical strength and flexibility, resulting from the strong intralayer bonds and ultrathin thickness. Smooth Li metal deposition without dendritic and mossy Li formation was realized. We showed stable cycling over 50 cycles with Coulombic efficiency ∼97% in organic carbonate electrolyte with current density and areal capacity up to the practical value of 2.0 mA/cm(2)and 5.0 mAh/cm(2), respectively, which is a significant improvement over the unprotected electrodes in the same electrolyte.

Abstract: Growing market demand for portable energy storage has triggered significant research on high-capacity lithium-ion (Li-ion) battery anodes. Various elements have been utilized in innovative structures to enable these anodes, which can potentially increase the energy density and decrease the cost of Li-ion batteries. In this review, electrode and material parameters are considered in anode fabrication. The periodic table is then used to explore how the choice of anode material affects rate performance, cycle stability, Li-ion insertion/extraction potentials, voltage hysteresis, volumetric and specific capacities, and other critical parameters. Silicon (Si), germanium (Ge), and tin (Sn) anodes receive more attention in literature and in this review, but other elements, such as antimony (Sb), lead (Pb), magnesium (Mg), aluminum (Al), gallium (Ga), phosphorus (P), arsenic (As), bismuth (Bi), and zinc (Zn) are also discussed. Among conversion anodes focus is placed on oxides, nitrides, phosphides, and hydrides. Nanostructured carbon (C) receives separate consideration. Issues in high- capacity research, such as volume change, insufficient coulombic efficiency, and solid electrolyte interphase (SEI) layer stability are elucidated. Finally, advanced carbon composites utilizing carbon nanotubes (CNT), graphene, and size preserving external shells are discussed, including high mass loading (thick) electrodes and electrodes capable of providing load-bearing properties.

Abstract: A porous hard carbon material was synthesized by the simple pyrolysis of H3PO4-treated biomass, i.e., pomelo peels, at 700 °C in N2. The as-obtained hard carbon had a 3D connected porous structure and a large specific surface area of 1272 m2 g−1. XPS analysis showed that the carbon material was functionalized by O-containing and P-containing groups. The porous hard carbon was used as an anode for sodium ion batteries and exhibited good cycling stability and rate capability, delivering a capacity of 181 mA h g−1 at 200 mA g−1 after 220 cycles and retaining a capacity of 71 mA h g−1 at 5 A g−1. The sodium storage mechanisms of the porous hard carbon can be explained by Na+ intercalation into the disordered graphene layers, redox reaction of the surface O-containing functional groups and Na+ storage in the nanoscale pores. However, the porous hard carbon demonstrated a low coulombic efficiency of 27%, resulting from the formation of a solid electrolyte interphase film and the side reactions of surface phosphorus groups.

Abstract: Do We Have Any Alternative for Pt or Pt−Ru? Nitul Kakati,† Jatindranath Maiti,† Seok Hee Lee,† Seung Hyun Jee,† Balasubramanian Viswanathan,*,‡ and Young Soo Yoon*,† †Department of Chemical Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-701, Republic of Korea ‡National Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India

Abstract: Structural phase transitions can be used to alter the properties of a material without adding any additional elements and are therefore of significant technological value. It was found that the hexagonal-SnS2 phase can be transformed into the orthorhombic-SnS phase after an annealing step in an argon atmosphere, and the thus transformed SnS shows enhanced sodium-ion storage performance over that of the SnS2, which is attributed to its structural advantages. Here, we provide the first report on a SnS@graphene architecture for application as a sodium-ion battery anode, which is built from two-dimensional SnS and graphene nanosheets as complementary building blocks. The as-prepared SnS@graphene hybrid nanostructured composite delivers an excellent specific capacity of 940 mAh g–1and impressive rate capability of 492 and 308 mAh g–1 after 250 cycles at the current densities of 810 and 7290 mA g–1, respectively. The performance was found to be much better than those of most reported anode materials for Na-ion ...

Abstract: The LiMn1.5Ni0.5O4 spinel is an attractive cathode candidate for next generation lithium-ion batteries as it offers high power capability with an operating voltage of ∼4.7 V and a capacity of ∼135 mA h g−1. However, its commercialization is plagued by severe capacity fade, particularly at elevated temperatures, in full cells employing a graphite anode. This perspective article provides an overview of the recent developments on understanding various factors that influence the electrochemical performance of the high-voltage spinel cathodes. The factors include the degree of cation ordering, Mn3+ content, morphology, and surface planes/compositions in contact with the electrolyte, which are influenced by synthesis and annealing conditions as well as cation doping. For example, samples with a {111} family of surface planes show superior performance. Recent magnetic measurements and examination of discharge profiles below 3 V have become valuable to get a more precise measure of the degree of cation ordering. Also, surface modifications and electrolyte additives have shown marginal gains. Although acceptable performances have been obtained in half-cells with a metallic lithium anode, capacity fade is seen in full cells with a graphite anode due to metal dissolution at the high operating voltage of 4.7 V and Li+ consumption by the steadily forming solid–electrolyte interphase (SEI) layer promoted by Mn/Ni deposition on the graphite surface. Based on the current understanding, future directions are pointed out.

Abstract: The development of the next generation of advanced lithium-ion batteries (LIBs) requires new & advanced materials and novel fabrication techniques in order to push the boundaries of performance and open up new and exciting markets. Structured carbon materials, with controlled pore features on the micron and nanometer scales, are explored as advanced alternatives to conventional graphite as the active material of the LIB anode. Mesoporous carbon materials, carbon nanotube-based materials, and graphene-based materials have been extensively investigated and reviewed. Morphology control (e.g., colloids, thin films, nanofibrous mats, monoliths) and hierarchical pores (particularly the presence of large pores) exhibit an increasing influence on LIB performance. This tutorial review focuses on the synthetic techniques for preparation of porous carbon spheres and carbon monoliths, including hydrothermal carbonization, emulsion templating, ice templating and new developments in making porous carbons from sustainable biomass and metal-organic framework templating. We begin with a brief introduction to LIBs, defining key parameters and terminology used to assess the performance of anode materials, and then address synthetic techniques for the fabrication of carbon spheres & monoliths and the relevant composites, followed, respectively, by a review of their performance as LIB anode materials. The review is completed with a prospective view on the possible direction of future research in this field.

Abstract: Nitrogen-doped activated porous carbon fibres (ACFs) were prepared as anode materials for Na-ion batteries. They exhibit excellent electrochemical performance, especially rate performance. The excellent rate performance is ascribed to the fibre-like morphology and the facilitated charge transfer. The influence of nitrogen functionalities on charge transfer and electrochemical performance of N-doped carbon anodes for Na ion batteries is discussed.

Abstract: In this Letter, we reported on the preparation and Li-ion battery anode application of ultrasmall Sn nanoparticles (∼5 nm) embedded in nitrogen-doped porous carbon network (denoted as 5-Sn/C). Pyrolysis of Sn(Salen) at 650 °C under Ar atmosphere was carried out to prepare N-doped porous 5-Sn/C with the BET specific surface area of 286.3 m2 g–1. The 5-Sn/C showed an initial discharge capacity of 1014 mAh g–1 and a capacity retention of 722 mAh g–1 after 200 cycles at the current density of 0.2 A g–1. Furthermore, a reversible capacity of ∼480 mAh g–1 was obtained at much higher current density of 5 A g–1. The remarkable electrochemical performance of 5-Sn/C was attributed to the effective combination of ultrasmall Sn nanoparticles, uniform distribution, and porous carbon network structure, which simultaneously solved the major problems of pulverization, loss of electrical contact, and particle aggregation facing Sn anode.

Abstract: Iron oxides, such as Fe2O3 and Fe3O4, have recently received increased attention as very promising anode materials for rechargeable lithium-ion batteries (LIBs) because of their high theoretical capacity, non-toxicity, low cost, and improved safety. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrode materials. Here, recent research progress in the rational design and synthesis of diverse iron oxide-based nanomaterials and their lithium storage performance for LIBs, including 1D nanowires/rods, 2D nanosheets/flakes, 3D porous/hierarchical architectures, various hollow structures, and hybrid nanostructures of iron oxides and carbon (including amorphous carbon, carbon nanotubes, and graphene). By focusing on synthesis strategies for various iron-oxide-based nanostructures and the impacts of nanostructuring on their electrochemical performance, novel approaches to the construction of iron-oxide-based nanostructures are highlighted and the importance of proper structural and compositional engineering that leads to improved physical/chemical properties of iron oxides for efficient electrochemical energy storage is stressed. Iron-oxide-based nanomaterials stand a good chance as negative electrodes for next generation LIBs.

Abstract: Na-ion batteries are an attractive alternative to Li-ion batteries for large-scale energy storage systems because of their low cost and the abundant Na resources This Review provides a comprehensive overview of selected anode materials with high reversible capacities that can increase the energy density of Na-ion batteries Moreover, we discuss the reaction and failure mechanisms of those anode materials with a view to suggesting promising strategies for improving their electrochemical performance

Abstract: Silicon has attracted ever-increasing attention as a high-capacity anode material in Li-ion batteries owing to its extremely high theoretical capacity. However, practical application of silicon anodes is seriously hindered by its fast capacity fading as a result of huge volume changes during the charge/discharge process. Here, an interpenetrated gel polymer binder for high-performance silicon anodes is created through in-situ crosslinking of water-soluble poly(acrylic acid) (PAA) and polyvinyl alcohol (PVA) precursors. This gel polymer binder with deformable polymer network and strong adhesion on silicon particles can effectively accommodate the large volume change of silicon anodes upon lithiation/delithiation, leading to an excellent cycling stability and high Coulombic efficiency even at high current densities. Moreover, high areal capacity of ∼4.3 mAh/cm2 is achieved based on the silicon anode using the gel PAA–PVA polymer binder with a high mass loading. In view of simplicity in using the water soluble gel polymer binder, it is believed that this novel binder has a great potential to be used for high capacity silicon anodes in next generation Li-ion batteries, as well as for other electrode materials with large volume change during cycling.

Abstract: Despite the great advantages of hollow structures as electrodes for lithium-ion batteries, one apparent common drawback which is often criticized is their compromised volumetric energy density due to the introduced hollow interior. Here, we design and synthesize bowl-like SnO2@carbon hollow particles to reduce the excessive hollow interior space while retaining the general advantages of hollow structures. As a result, the tap density can be increased about 30 %. The as-prepared bowl-like SnO2@carbon hollow particles with conformal carbon support exhibit excellent lithium storage properties in terms of high capacity, stable cyclability and excellent rate capability.

Abstract: Hierarchical MoS2 microboxes constructed by ultrathin nanosheets are synthesized by a facile template-assisted strategy. The first step involves the L-cysteine assisted uniform growth of hierarchical MoS2 nanosheets on MnCO3 microcube templates which are at the same time converted to MnS. Hierarchical MoS2 microboxes can be obtained by selectively dissolving MnS through acid washing. When evaluated as an anode material for lithium-ion batteries, the hierarchical MoS2 microboxes manifest high specific capacity and excellent cycling performance. The hierarchical MoS2 microboxes also show enhanced electrocatalytic activity for electrochemical hydrogen evolution from water.

Abstract: New types of energy storage are needed in conjunction with the deployment of renewable energy sources and their integration with the electrical grid. We have recently introduced a family of cathodes involving the reversible insertion of cations into materials with the Prussian Blue open-framework crystal structure. Here we report a newly developed manganese hexacyanomanganate open-framework anode that has the same crystal structure. By combining it with the previously reported copper hexacyanoferrate cathode we demonstrate a safe, fast, inexpensive, long-cycle life aqueous electrolyte battery, which involves the insertion of sodium ions. This high rate, high efficiency cell shows a 96.7% round trip energy efficiency when cycled at a 5C rate and an 84.2% energy efficiency at a 50C rate. There is no measurable capacity loss after 1,000 deep-discharge cycles. Bulk quantities of the electrode materials can be produced by a room temperature chemical synthesis from earth-abundant precursors.

Abstract: Porous carbon nanofiber (CNF)-supported tin-antimony (SnSb) alloys are synthesized and applied as a sodium-ion battery anode. The chemistry and morphology of the solid electrolyte interphase (SEI) film and its correlation with the electrode performance are studied. The addition of fluoroethylene carbonate (FEC) in the electrolyte significantly reduces electrolyte decomposition and creates a very thin and uniform SEI layer on the cycled electrode surface, which an promote the kinetics of Na-ion migration/transportation, leading to excellent electrochemical performance.

Abstract: Room temperature sodium-ion batteries are of great interest for high-energy-density energy storage systems because of low-cost and natural abundance of sodium. Here, we report a novel phosphorus/graphene nanosheet hybrid as a high performance anode for sodium-ion batteries through facile ball milling of red phosphorus and graphene stacks. The graphene stacks are mechanically exfoliated to nanosheets that chemically bond with the surfaces of phosphorus particles. This chemical bonding can facilitate robust and intimate contact between phosphorus and graphene nanosheets, and the graphene at the particle surfaces can help maintain electrical contact and stabilize the solid electrolyte interphase upon the large volume change of phosphorus during cycling. As a result, the phosphorus/graphene nanosheet hybrid nanostructured anode delivers a high reversible capacity of 2077 mAh/g with excellent cycling stability (1700 mAh/g after 60 cycles) and high Coulombic efficiency (>98%). This simple synthesis approach and...

Abstract: Efficient and low-cost thermal energy-harvesting systems are needed to utilize the tremendous low-grade heat sources. Although thermoelectric devices are attractive, its efficiency is limited by the relatively low figure-of-merit and low-temperature differential. An alternative approach is to explore thermodynamic cycles. Thermogalvanic effect, the dependence of electrode potential on temperature, can construct such cycles. In one cycle, an electrochemical cell is charged at a temperature and then discharged at a different temperature with higher cell voltage, thereby converting heat to electricity. Here we report an electrochemical system using a copper hexacyanoferrate cathode and a Cu/Cu(2+) anode to convert heat into electricity. The electrode materials have low polarization, high charge capacity, moderate temperature coefficients and low specific heat. These features lead to a high heat-to-electricity energy conversion efficiency of 5.7% when cycled between 10 and 60 °C, opening a promising way to utilize low-grade heat.