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The demand for a sustainable energy storage system with high specific power and long cycle life, particularly using an environmentally friendly aqueous electrolyte to eliminate the risk of explosion, is rapidly growing.

Although genetic Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative disorder, cases of genetic CJD with E200K mutation are being increasingly reported in Korea. However, the clinical features and course of genetic CJD with E200K mutation in Korea remain unclear. We describe the clinical features and course of genetic CJD with E200K mutation in a patient who initially presented with rapid progressive memory impairment and myoclonus.

Protective surface coatings on Si anodes are promising for improving the electrochemical performance of lithium-ion batteries (LIBs). Nevertheless, most coating materials have severe issues, including low initial coulombic efficiency, structural fracture, morphology control, and complicated synthetic processing. In this study, a multifunctional TiO

A 48-year-old woman presented with a 1-day history of aggressive behavior. Hashimoto encephalopathy was first suspected based on elevated levels of serum anti-thyroid peroxidase antibody. Her clinical symptoms did not improve despite treatment with intravenous corticosteroid. Abdominal computed tomography revealed liver cirrhosis, and brain T2-weighted magnetic resonance imaging revealed midbrain hyperintensity, and she was finally diagnosed with Wilson’s disease. The Wilson’s disease should be considered in the differential diagnosis in adults presenting with unexplained hepatic, neurological, or psychiatric abnormalities.

Heterostructured nanocomposites comprising transition metal compounds (TMCs) with different bandgaps are attractive due to their excellent electrochemical performances. Candidates that combine various cations and anions are actively researched. Herein, it is demonstrated for the first time that nickel hydroxy chloride, once transformed into a heterostructured nanocomposite during the initial cycle, can be used as a new anode material for lithium-ion storage. In particular, the reaction mechanism for lithium-ion storage with a metal hydroxy chloride as the anode is demonstrated through various analyses for the first time. The model compound, nickel hydroxy chloride (Ni(OH)Cl), prepared by a one-pot hydrothermal method, is used to investigate the detailed conversion mechanism in Li-ion storage. Through systemically analyzed results, it is demonstrated that Ni(OH)Cl is transformed into Ni(OH)2 and NiCl2 after one cycle and that the layered Ni(OH)2/NiCl2 nanocomposite heterointerface reacts with Li ions from the second cycle onward. Flower-like Ni(OH)Cl microspheres display extremely high and stable cycling performance (1236 mA h g−1 for the 150th cycle at a current density of 0.2 A g−1) and outstanding rate capability (232 mA h g−1) at an extremely high current density of 30 A g−1.

Submicron and micron-sized carbon spheres with high electrical conductivity, micro–mesoporous structure, and empty space are considered ideal sulfur host materials for Li–S batteries. In this study, a new and efficient strategy for the synthesis of yolk-shell-structured carbon microspheres with multishells is introduced. Pitch-derived carbon microspheres with yolk-shell structure, high pore volume, and high electrical conductivity are synthesized by applying yolk-shell-structured Fe2O3 microspheres as a sacrificial template. Pitch-infiltrated Fe2O3 microspheres transform into yolk-shell-structured carbon (YS_C) microspheres with a specific conductivity of 0.9 S cm−1 after post-treatment and etching with an HCl solution. The discharge capacity of the sulfur-loaded YS_C microspheres for the 200th cycle at a current density of 0.5 C is 686 mA h g−1, and their reversible capacity after 800 cycles at a high current density of 2 C is 412 mA h g−1. In addition, the sulfur-loaded YS_C microspheres show excellent cycling performance, despite their very high sulfur loading of 70 wt%. The excellent cycling and rate performances of the sulfur-loaded YS_C microspheres are attributed to the synergistic effect of the high electrical conductivity of YS_C microspheres, loading of amorphous and ultrafine sulfur, and empty shell layers.

SnO2-based composite materials have been studied as efficient anode materials for lithium-ion batteries. In this study, pitch-derived carbon coated SnO2–CoO yolk–shell microspheres were synthesized by a spray drying process. Pitch is a widely used source material for electrically conductive carbon. Pitch-infiltrated SnO2–Co3O4 were transformed into SnO2–CoO–C yolk–shell microspheres by a carbothermal reduction. SnO2–CoO–C yolk–shell microspheres with a carbon content of 15 wt% exhibited superior cycling and rate performances compared with those of the bare SnO2–Co3O4 microspheres with the same morphologies. The discharge capacities of SnO2–Co3O4 and SnO2–CoO–C at the 100th cycle were 565 and 812 mA h g−1, while their capacity retentions calculated from the second cycle were 51 and 97%, respectively. Furthermore, SnO2–CoO–C yolk–shell microspheres exhibited high and stable reversible capacities even at an extremely high current density of 30 A g−1. The discharge capacity of SnO2–CoO–C yolk–shell microspheres at the 1000th cycle at a current density of 3.0 A g−1 was 775 mA h g−1. The synergetic effect of the pitch-derived carbon with a high electrical conductivity, catalytic effect of the metallic Co, crystal growth minimization of metallic Co and Sn by reciprocal action, and yolk–shell structure with empty shells provided the SnO2–CoO–C yolk–shell microspheres with excellent lithium-ion storage performances.

This paper reports the effect of the freeze-thaw on the suspension stability, particle size distribution, and thermal conductivity of EG/water-based nanofluids containing Al2O3 nanoparticles that can be used as improved working fluid for cooling systems. The EG/water-based Al2O3 nanofluids were prepared using a two-step method with a nanodisperser and decanting processes. To investigate the effect of freeze-thaw on the suspension stability and thermal conductivity of nanofluids, the prepared nanofluids were frozen at -32°C for 24 hours using a refrigerating chamber, and then they were completely thawed at room temperature for 24 hours. The suspension stability of the thawed nanofluids was quantitatively analysed for over a day using a Turbiscan. In addition, the particle size distributions and deformation of nanoparticles dispersed in the nanofluids were measured using a particle size analyzer (PSA) and TEM. Also, the thermal conductivity of the nanofluids was measured using a transient hot wire (THW) method in temperature from -10 to 70°C. Based on the results, we show that the suspension stability, thermal conductivity, and particle size of EG/water-based Al2O3 nanofluids were not affected by low temperature.

Multishell structured metal oxide microspheres with considerable structural stabilities during repeated cycling and higher volumetric capacities than those of hollow structured microspheres are popular as anode materials for lithium-ion batteries. However, the long-term cycling and rate performances of multishell metal oxide microspheres for lithium-ion storage require further improvement. Herein, novel and unique structured microspheres (Fe3O4–GC) with multishells comprising graphitic carbon (GC)-coated Fe3O4 hollow nanopowders are successfully synthesized. The reduction of pitch-infiltrated Fe2O3 yolk–shell microspheres yields metallic Fe yolk–shell microspheres filled with pitch-derived carbon. Oxidation yields yolk–shell Fe3O4–GC microspheres with multishells comprising hollow nanopowders coated with GC via the selective decomposition of amorphous carbon and oxidation of metallic Fe. Metallic Fe nanocrystals transform into hollow Fe3O4 nanopowders due to nanoscale Kirkendall diffusion. The primary hollow Fe3O4 nanopowders comprising yolk–shell microspheres and GC layer formed by pitch-derived carbon decrease the distance for lithium-ion diffusion and improve the electrical conductivity resulting in outstanding cycling and rate performances of Fe3O4–GC, respectively. The discharge capacity of Fe3O4–GC microspheres for the 1000th cycle at a current density of 2.0 A g−1 is 1018 mA h g−1, and the microspheres exhibit a high reversible capacity of 649 mA h g−1 even at 20 A g−1.

The templated self-assembly of block copolymers (BCPs) with a high Flory-Huggins interaction parameter (χ) can effectively create ultrafine, well-ordered nanostructures in the range of 5-30 nm. However, the self-assembled BCP patterns remain limited to possible morphological geometries and materials. Here, we introduce a novel and useful self-assembly method of di-BCP blends capable of generating diverse hybrid nanostructures consisting of oxide and metal materials through the rapid microphase separation of A-B/B-C BCP blends. We successfully obtained various hybridized BCP morphologies which cannot be acquired from a single di-BCP, such as hexagonally arranged hybrid dot and dot-in-hole patterns by controlling the mixing ratios of the solvents with a binary solvent annealing process. Furthermore, we demonstrate how the binary solvent vapor annealing process can provide a wide range of pattern geometries to di-BCP blends, showing a well-defined spontaneous one-to-one accommodation in dot-in-hole nanostructures. Specifically, we show clearly how the self-assembled BCPs can be functionalized via selective reduction and/or an oxidation process, resulting in the excellent positioning of confined silica nanodots into each nanospace of a Pt mesh. These results suggest a new method to achieve the pattern formation of more diverse and complex hybrid nanostructures using various blended BCPs.

A method of microalgae-templated spray drying to develop hierarchical porous Fe3O4/C composite microspheres as anode materials for Li-ion batteries was developed. During the spray-drying process, individual microalgae serve as building blocks of raspberry-like hollow microspheres via self-assembly. In the present study, microalgae-derived carbon matrices, naturally doped heteroatoms, and hierarchical porous structural features synergistically contributed to the high electrochemical performance of the Fe3O4/C composite microspheres, enabling a discharge capacity of 1375 mA&middot, h&middot, g&minus, 1 after 700 cycles at a current density of 1 A/g. Notably, the microalgal frameworks of the Fe3O4/C composite microspheres were maintained over the course of charge/discharge cycling, thus demonstrating the structural stability of the composite microspheres against pulverization. In contrast, the sample fabricated without microalgal templating showed significant capacity drops (up to ~40% of initial capacity) during the early cycles. Clearly, templating of microalgae endows anode materials with superior cycling stability.

In this work, we developed novel titanium oxynitride (TiOxNy) nanoparticles with diameter of 25 ± 2 nm and crystalline size of ∼15 nm on hydrothermally grown one-dimensional (1D) TiO2 nanorod (TNR) arrays. Herein, the TiOxNy nanoparticles were synthesized by facile nitridation using TiO2 powder at 100% NH3 gas atmosphere. Titanium oxynitride composed of potentially energetic metal-nitrogen bonds (Ti N), compared to the weaker Ti O bond, becomes chemically stable in the alkaline environment, and is considered as a suitable material for photoelectrochemical (PEC) system. The PEC performance of TiOxNy decorated TNR (abbreviated as TiOxNy @TNR) films was evaluated in 0.1 M KOH solution under solar illumination condition, and achieved the potentially high photocurrent density (J) of 2.1 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE) (abbreviated as VRHE) in the TiOxNy@TNR arrays, in comparison with the poor photoresponse (0.7 mA/cm2 at 1.23 VRHE) of the pristine TNR arrays. A nearly three-fold enhancement was attained in the TiOxNy decorated TNR arrays, attributed to the high visible light absorption and fast carrier separation, due to the hybridization with the visible active TiOxNy nanoparticles in the cascading band alignment between the TiOxNy and TNR materials. Furthermore, the introduction of TiOxNy layer on the TNR surface quite reduces the interfacial resistance in the solid-liquid interface region, and further, the TiOxNy layer contributes to the passivation of the surface states (e.g., defect, trap sites etc.) where the charge recombination reaction frequently happens, leading to the improvement of PEC performance.

Silicon, as a promising next-generation anode material, has drawn special attention from industries due to its high theoretical capacity (around 3600 mAh g−1) in comparison with conventional electrodes, e.g., graphite. However, the fast capacity fading resulted by a large volume change hinders the pragmatic use of Si anodes for lithium ion batteries. In this work, we propose an efficient strategy to improve the cyclability of upcycled Si nanomaterials through a simple battery operation protocol. When the utilization degree of Si electrodes was decreased, the electrode deformation was significantly alleviated. This directly led to an excellent electrochemical performance over 100 cycles. In addition, the average charge (delithation) voltage was shifted to a lower voltage, when the utilization degree of electrodes was controlled. These results demonstrated that our strategic approach would be an effective way to enhance the electrochemical performance of Si anodes and improve the cost-effectiveness of scaling-up the decent nanostructured Si material.

Silicon is considered an important industrial element, primarily owing to its use in semiconductors, which are key components of various electronic devices; thus, the development of low-cost and efficient purification silicon processes has become a research focus. In this study, we developed a new process using ammonium fluoride (NH4F) to remove residual silica (SiO2) and generate nanopores on raw silicon (Si) materials without the use of highly toxic reagents and expensive procedures. We conducted low-temperature heat treatment of raw Si with NH4F under an inert atmosphere and found that the purity of raw Si was improved to a level similar to that of raw Si treated with hydrofluoric acid solution. Moreover, through this process, the surface area of raw Si was increased by surface tearing and the formation of nanopores. We also proposed a reaction mechanism for removing residual SiO2 from raw Si through X-ray diffraction analysis and demonstrated the safety of the process by analyzing the by-products generated during the heat treatment. When the modified Si material was applied to Li-ion battery anodes, they showed improved capacity, initial coulombic efficiency, and cycle performance as compared with those using raw Si material. We expect that this new NH4F-based method will not only be used to modify various Si materials for their efficient application, but will also be used to obtain nanostructured materials that require the removal of SiO2 during synthesis.

Background and purpose Patients who have acute stroke symptoms present on awakening are ineligible for standard intravenous thrombolysis due to the unclear onset time of symptoms. Some of these wake-up stroke (WUS) patients may benefit from endovascular recanalization. This study aimed to evaluate clinical predictors of outcomes from endovascular recanalization in WUS patients. Methods Forty-one WUS patients with internal carotid (ICA) or middle cerebral artery (MCA) occlusion treated with endovascular recanalization were reviewed. Regression analysis was performed to measure clinical predictors of outcomes from endovascular recanalization in WUS patients. Results The mean initial NIHSS score was 16.41 ± 4.96 (5–24). The mean symptom recognition-to-door time (SRDT) was 108.85 ± 65.80 (19–230) min. Successful recanalization (TICI 2b-3) was achieved in 29 patients (70.7%). Thirty-four patients improved on NIHSS (amount 7.59 ± 4.84, range; 1–17) at 7 days after recanalization. At 90 days after recanalization, a mRS of ≤2 was achieved in 19 patients (46.3%) and a mRS of ≤3 was achieved in 24 patients (58.5%). No symptomatic intracerebral hemorrhage occurred. Multivariate regression analysis identified SRDT (P = 0.019), successful recanalization (P = 0.005), and hypertension (P = 0.013) were factors associated with an improvement of the NIHSS score. For a good functional outcome at 90 days, SRDT (P = 0.036) and initial NIHSS score (P = 0.016) were found to be significant predictors. Conclusions The results of this study suggest that the SRDT is an independent predictor of both an improvement of NIHSS score and a good functional outcome in endovascular recanalization for WUS patients.

We report amorphous iron phosphate with lattice water, namely FePO4·xH2O (x ∼ 2.39), as a promising sodium-ion battery (SIB) cathode. After carbon coating, micrometer-sized FePO4·xH2O exhibits a reversible capacity that is higher than that of its counterpart without lattice water (130.0 vs 50.6 mAh g–1 at 0.15C rate) along with clearly enhanced rate capability and cyclability. The superior electrochemical performance of FePO4·xH2O is attributed to the lattice water that facilitates sodium-ion diffusion via enlarged channel dimensions and the screening of the electrostatic interactions between sodium ions and host anions. The amorphous phase is also advantageous in accommodating the stress created in the host framework during sodium-ion (de)intercalation. The presence of lattice water also protects the oxidation state of Fe from reductive surface carbon coating and slightly lowers the operation voltage via reduced inductive effect. The current study provides a useful insight into how to design SIB electrod...

Despite the high theoretical capacity, silicon (Si) anodes in lithium-ion batteries have difficulty in meeting the commercial standards in various aspects. In particular, the huge volume change of Si makes it very challenging to simultaneously achieve high initial Coulombic efficiency (ICE) and long-term cycle life. Herein, we report spray pyrolysis to prepare Si-SiOx composite using an aqueous precursor solution containing Si nanoparticles, citric acid, and sodium hydroxide (NaOH). In the precursor solution, Si nanoparticles are etched by NaOH with the production of [SiO4]4-. During the dynamic course of spray pyrolysis, [SiO4]4- transforms to SiOx matrix and citric acid decomposes to carbon surface layer with the assistance of NaOH that serves as a decomposition catalyst. As a result, a Si-SiOx composite, in which Si nanodomains are homogeneously embedded in the SiOx matrix with carbon surface layer, is generated by a one-pot process with a residence time of only 3.5 s in a flow reactor. The optimal composite structure in terms of Si domain size and Si-to-O ratio exhibited excellent electrochemical performance, such as reversible capacity of 1561.9 mAh g-1 at 0.06C rate and ICE of 80.2% and 87.9% capacity retention after 100 cycles at 1C rate. J.W.C. acknowledges the financial support by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (NRF-2015R1A2A1A05001737). This work was also made possible by NPRP Grant No. NPRP 7-301-2-126 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus

Li-rich cathode materials have intrinsically poor rate capability along with low electronic conductivity, which remain as unsolved drawbacks limiting their use in applications that require cathode material with layered structures. Here, we prepared surface-modified Li-rich cathode materials to address these drawbacks via reductive treatment. After reductive treatment, we confirmed that these samples feature better electrochemical performance; the reductive treated samples show higher capacity and better capacity retention during cycling compared to samples treated only in air. In particular, the reductive treated samples showed excellent rate capability of 168 mAh g−1 at a current density of 400 mA g−1 compared to 138 mAh g−1 for the air treated sample. We confirmed that reductive treatment reduces the resistance for charge transfer based on electrochemical impedance spectroscopy analysis. We also investigated the effects of reductive treatment on the cathode structure of both samples using x-ray diffraction as well as x-ray photoelectron spectroscopy.

All-solid-state batteries (ASSBs) are gaining prominence for their ability to overcome the intrinsic drawbacks of conventional liquid-based counterparts, such as electrolyte leakage, flammability, and limited voltage window. Nevertheless, ASSBs have so far been mainly investigated using lab-scale dry mixing processes and therefore suffer from limitation of scalability and agglomeration of active particles in the composite electrodes. Here, we report a systematic investigation on ASSBs fabricated by a solution-based casting process. By screening a wide range of binders and solvents, acrylonitrile butadiene rubber and para-xylene were a suitable binder and solvent, respectively, compatible with sulfide glass-ceramic solid electrolyte. This binder-solvent combination facilitates homogeneous dispersion of the solid electrolyte in the slurry and electrolyte layer, offering high adhesion between electrode materials and comparable lithium ionic conductivity to that of the dry mixing-based counterpart. When solution-based casting processes were adopted for both electrolyte and composite cathode (containing LiNi0.8Co0.1Mn0.1O2) layers, the solution-processed cell exhibits decent performance in rate capability and cyclability due to higher homogeneity of the electrode components, originating from the appropriate combination of solvent and binder.

Lithium-ion batteries (LIBs) have become promising energy storage devices for the consumer electronics and electric vehicles due to their high energy and power density. Anode materials such as Si, Sn and Ge which are alloying with Li+ ions have been attracted as alternatives to conventional graphite due to their very high theoretical capacities. Among the possible candidates, Sn has been thought to be a great anode material that shows high theoretical Li ion storage capacity of 994mAh g-1 and high electrical conductivity. However, the major drawback of tin based anode is their poor cycling stability because of large volme changes (260% for Li22Sn5) during lithiation resulting in pulverization and loss of electrical contact within the electrode. Especially, the repetitive formation and rupture of solid electrolyte interface (SEI) layer continuously deplete the electrolyte. Nanocrystallization can effectively decrease the absolute volume change of every single particle and mitigated the strain improving the cycling stability of Sn anodes. However, preparation methods of nano-Sn have some negative factors, such as the high cost, complex process and reaggregation after cycling. In order to take full advantage of nano-Sn, many studies introduce suitable matrix. These matrix acts as a buffer agents and avoids side reactions by preventing the direct contact of Sn and electrolyte. The common one is carbon matrix works as a conducting medium and enhances the rate performance of electrode. Another one is active metals including Ge-Sn, Sb-Sn and Ag-Sn that can contribute to the overall capacity of the electrodes and long cycling life. Yet these comes with loss of charge storage capacity or large volume expansion. The quest for suitable matrix with high Li ion storage, low volume expansion and sufficient electronic conductivity is important. In this study, silicon oxycarbide (SiOC) was adapted for Sn based anodes. The SiOC consists of silica tetrahedral SiO2, SiOC glass phase and free carbon. This matrix features a high charge storage capacity (~800mAh g-1), low voulme expansion (~7%) and sufficient mechanical strength contributed by SiO2 domains to accommodate the high volume expansion without capacity fading of Sn anode. In particular, the SiOC can suppress the aggreation of metallic Sn at high temperature remaining nano size. First, we obtained the Sn@SiOC nanocomposite with uniformly coated SiOC layer containing metallic Sn nanoparticle by spray pyrolysis and a subsequent carbonization process. The spray pyrolysis is scalable and facile method to synthesize various nanostructure functional materials via one-pot process. Also it can be easily scaled up for mass production. During the spray pyrolysis process, the tin(II) acetate and diphenylsilanediol (DPSD), the starting materials of Sn and SiOC, can be easily vaporized due to its low boiling point. The tin acetate nucleates first due to lower boiling point than DPSD and formates many clusters. Subsequently, DPSD vapors can be deposited onto the Sn clusters via aerosol assisted chemical vapor depsition (AACVD) mechanism. The deposited DPSD vapors lead to formation of coating layer by nucleation, growth and coagulation. Then, the spray pyrolyzed Sn@SiOC nanocomposite thermally treated at the inert atmosphere for growth of carbon network. This approach yields unifomly coated SiOC matrix with Sn nanoparticles of sizes on the order of 40-50nm. Anodes of the Sn@SiOC nanocomposite demonstrate high capacities and better stability against volume change during lithiation and delithiation cycling.

Status epilepticus is a severe neurological disease associated with substantial mortality and health-care cost. Treatment of status epilepticus should proceed without delay even in the pre-hospital setting because prolonged generalized convulsive seizures may lead to neuronal injury, pharmacoresistance, and poor prognosis. These concepts have led to the establishment of an updated treatment algorithm emphasizing a more rapid escalation to third-line therapy for refractory convulsive status epilepticus. This article reviews the guidelines and current evidence for the management of status epilepticus.

Various porous materials have shown a great promise as dry sorbents for carbon dioxide (CO2) capture utilizing their large surface areas. Although there have been considerable efforts to find optimal pore size and geometry for a variety of porous materials, systematic experimental study covering various key parameters beside CO2 uptake, such as isosteric heat and selectivity against other gas, is unavailable. Here, we systemically investigate the pore size effect on the CO2 uptake and selectivity for porous activated carbon. We found that at each temperature and pressure, there exists an optimal intermediate activation condition that makes the pore size most appropriate for CO2 uptake and selectivity. Further activation increases the pore size and weakens CO2-wall interaction. This study provides an important lesson that the pore activation of porous carbon should be controlled at an optimal intermediate point to maximize CO2-wall interaction.

Background Hashimoto's encephalopathy (HE) and anti N-methyl-D-aspartate receptor (NMDAR) encephalitis have clinical overlaps. Case report A 70-year-old woman presented with acutely developed confusion, disorientations and psychosis. HE was suspected based on goiter, markedly elevated anti-thyroglobulin and anti-thyroid peroxidase antibody. She was placed on high dose steroid and intravenous immunoglobulins administration, which did not ameliorate her symptoms. After the antibodies to the NMDAR were identified, weekly 500 mg of rituximab with 4 cycles were started. The current followed up indicated a complete recovery. Conclusions The possible associations between NMDAR antibody and autoimmune thyroid antibodies in anti-NMDAR encephalitis with positive thyroid autoantibodies remain unclear. However, a trend toward a higher incidence of NMDAR antibody in patients with autoimmune thyroid antibodies than without has been observed. Cases of encephalitis with only NMDAR antibody (pure anti-NMDAR encephalitis) also occur. Therefore, it is important for clinicians to know the clinical and pathogenic differences between anti-NMDAR encephalitis with positive thyroid autoantibody and pure anti-NMDAR encephalitis for relevant treatment, predicting prognosis, and future follow-up.

Dodecylamine (DDA) was functionalized on Fe2O3 nanocrystals (NCs) by a solvothermal process to allow electrostatic interaction on Bronsted acid sites induced on the surface of NCs, followed by carbonization to convert DDA into a thin layer of carbon on single Fe3O4 NCs. The obtained carbon composite (IOC-Fe3O4) is composed of Fe3O4 NCs a few nanometers in size, each uniformly coated with a thin carbon layer. The carbon coating reduces the resistance at the NC-to-NC interface within the composite and retains a short lithium diffusion length by inhibiting crystal growth, as well as accommodating the volume change of Fe3O4 during charge–discharge. The composite electrode exhibited a high reversible capacity of 1027 mA h g−1 in a lithium ion battery, as well as 100% capacity retention after 300 cycles and rate performance of 563 mA h g−1 at 3 A g−1, which was achieved with only 4.2 wt% carbon in the composite. The relationship between the enhanced diffusion kinetics of IOC-Fe3O4 and excellent electrochemical performances is demonstrated through a voltammetric charge technique.

Hierarchically well-developed porous graphene nanofibers comprising N-doped graphitic C (NGC)-coated cobalt oxide hollow nanospheres are introduced as anodes for high-rate Li-ion batteries. For this, three strategies, comprising the Kirkendall effect, metal-organic frameworks, and compositing with highly conductive C, are applied to the 1D architecture. In particular, NGC layers are coated on cobalt oxide hollow nanospheres as a primary transport path of electrons followed by graphene-nanonetwork-constituting nanofibers as a continuous and secondary electron transport path. Superior cycling performance is achieved, as the unique nanostructure delivers a discharge capacity of 823 mAh g-1 after 500 cycles at 3.0 A g-1 with a low decay rate of 0.092% per cycle. The rate capability is also noteworthy as the structure exhibits high discharge capacities of 1035, 929, 847, 787, 747, 703, 672, 650, 625, 610, 570, 537, 475, 422, 294, and 222 mAh g-1 at current densities of 0.5, 1.5, 3, 5, 7, 10, 12, 15, 18, 20, 25, 30, 40, 50, 80, and 100 A g-1 , respectively. In view of the highly efficient Li+ ion/electron diffusion and high structural stability, the present nanostructuring strategy has a huge potential in opening new frontiers for high-rate and long-lived stable energy storage systems.

Copper-based materials as electrode materials have been attracted attention for their various merits such as nature abundance, low-cost, easy preparation, chemical stability, high theoretical specific capacity, and environmental friendliness. Metal selenite materials transforming into heterostructured metal oxide and selenide during the first cycle was considered as efficient anode materials for lithium-ion batteries. Herein, copper selenite microspheres were synthesized by applying facile spray pyrolysis process and for the first time, their conversion reaction mechanism with lithium-ions was systematically comprehended by various in-situ and ex-situ analysis. The selenization of spray pyrolysis product (Cu nitrate-polyvinylpyrrolidone composite) yielded cooper selenide (CuxSe)-C composite. Subsequently, partial oxidation process produced carbon-free hollow cooper selenite (Cu2O(SeO3)) microspheres. Through the various technical measurements, the following reversible reaction mechanism of Cu2O(SeO3) phase could be confirmed from the second cycle onward: CuO + CuSe + 4Li+ + 4e− ↔ 2Cu + Li2O + Li2Se. Moreover, hollow Cu2O(SeO3) microspheres showed excellent cycling and rate performances. The discharge capacity of Cu2O(SeO3) for 500th cycle at a current density of 3.0 A g−1 is 645 mA h g−1 and exhibited a stable reversible capacity even at extremely high current density of 30 A g−1.