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Rechargeable lithium ion batteries have spurred intense research to resolve the ever-increasing energy and environmental issues due to their efficient high energy density. Herein we demonstrate a simple pyrolysis route to fabricate novel hierarchical B-doped tubular carbon nanostructures. The unique tubular nanostructures along with B-doped effect could represent a high activity for surface-dependent electrochemical reaction processes. Experimental results reveal that the as-synthesized B-doped carbon nanotube show excellent electrochemical performances for lithium storage application. The B-doped carbon nanotube could deliver a high initial discharge capacity (2862.8 mAh g−1) with Coulombic efficiency of 43.91% at 100 mA g−1 current density. Even at a higher current density of 500 mA g−1, the B-doped carbon nanotube could exhibit an enhanced initial discharge capacity of 1800.9 mAh g−1, and the reversible lithium storage capacity still retains at 851.3 mAh g−1 over 100 cycles, suggesting a good cycling stability. The excellent electrochemical properties of the as-synthesized B-doped carbon nanotube could be ascribed to the unique tubular architecture, which could offer large active surface with more lithium-insertion channels and significantly reduce lithium ion diffusion distance. The cost-efficient synthesis and excellent lithium storage properties make the B-doped carbon nanotube as a promising anode material for high-performance lithium ion batteries. Image 1 • Novel hierarchical B-doped tubular carbon nanostructures have been fabricated. • B-doped CNTs show excellent electrochemical performances for lithium storage application. • B-doped CNTs deliver a high initial discharge capacity (2862.8 mAh g−1) at 100 mA g−1 current density. • The reversible lithium storage capacity of B-doped CNTs still retains at 851.3 mAh g−1 over 100 cycles. [ABSTRACT FROM AUTHOR]

Abstract A carbon nanotube sheet having homogeneously distributed BaTiO 3 is applied to the Li-S cell system as a pseudo-current collector between the cathode and separator. This interlayer serves as a site distributor, where polysulfide eluted from the cathode continuously reacts, and it is expected to play a role as a more effective current collector by mixing the ferroelectric material. A cell utilizing a ferroelectricity embedded interlayer exhibits a higher capacity (908 mAh g−1) at 0.2C than that of carbon alone (740 mAh g−1) at 200th cycle. This result corresponds to a capacity retention ratio enhancement from 67.5% to 75.6%. Furthermore, it is confirmed that the retention of the coulombic efficiency is effectively maintained in long cycles at 0.5C (94.5%–99.6%). This is not only because the modified interlayer functions as an effective current collector owing to the high affinity of the ferroelectric material to polysulfide, but also because ferroelectricity in the interlayer acts as a polysulfide anchor. The evenly distributed polarization leads to a uniform deposition of sulfur, which results in the prevention of inactive sulfur agglomeration and dissolution of polysulfide. Thus, the utilization of active material can be improved with stabilized reaction. Graphical abstract Image 1 Highlights • Nano-BaTiO 3 embedded MWCNT interlayer is fabricated by vacuum filtration method. • BaTiO 3 interlayer cell performs higher specific capacity and coulombic efficiency. • BaTiO 3 interlayer cell enhances rate capability. • BaTiO 3 interlayer induces homogeneous S distribution with strong affinity. • BaTiO 3 interlayer acts as an efficient pseudo-current collector. [ABSTRACT FROM AUTHOR]

Abstract This work explores the compound Li 1+z/3 Ni 1/2-z/2 Ti 1/2+z/6 O 2 (z = 0, 0.1, 0.2, 0.3, 0.4, 0.5) and compares the electrochemical performance difference with z to the proposed percolation network. X-ray diffraction combined with Rietveld refinements show that rock-salt structure is obtained by the simple sol-gel process, and the lattice parameters are increased with the increasing level of Li-excess. Micromorphology observation reveals that particles are irregular and the size is distributed within 100 nm. In addition, a detailed reaction mechanism is examined by X-ray photoelectron spectroscopy and cyclic voltammetry, which exhibits the evolution of Ni, Ti and O in the initial charge-discharge process and confirms that they all make contributions to capacities. Electrochemical performance test shows that the discharge capacities increase with the amount of Li and Li 1.17 Ni 0.25 Ti 0.58 O 2 delivers the discharge capacities up to 223.9 mAh g−1. At the current density of 400 mA g−1, it still provides a large capacity of 120 mAh g−1. Furthermore, Li 1.17 Ni 0.25 Ti 0.58 O 2 has the highest lithium ion diffusion coefficient among all samples. Graphical abstract Image 1 Highlights • The good crystallized Li 1+z/3 Ni 1/2-z/2 Ti 1/2+z/6 O 2 is prepared by a facile method. • The detailed redox process of Ni, Ti and O during the first cycle. • Stable structure and 0-TM network improve performance. • Li 1.17 Ni 0.25 Ti 0.58 O 2 exhibits high capacities and good rate capability. [ABSTRACT FROM AUTHOR]

Highlights • A new hexagonal prisms CoO was assembled on reduced graphene oxide. • CoO in the composite is pure purity. • The composite performed high capacity as anode materials of lithium ion batteries. Abstract In this research, we use a modified sol-gel method to obtain a pure phase new hexagonal CoO on reduced graphene oxide by leading of polar solvent. In the electrochemical test, the CoO/rGO composite shows a remarkable performance of capacity as an anode of a lithium ion battery. The electrochemistry performance shows that the capacity of the composite can remain at 1300 mAh/g in 100 cycles without damping. The pure phase of CoO and its hexagonal morphology have been characterized by XRD, SEM and TEM. [ABSTRACT FROM AUTHOR]

Abstract Poly(vinylidene fluoride- co -hexafluoropropylene) (P(VDF-HFP))-based composite polymer electrolytes (CPEs) doped with different amounts of CaTiO 3 inorganic fillers are prepared by phase inversion. With adding the CaTiO 3 fillers into the P(VDF-HFP) polymer matrix, the CPE membranes show more abundant and uniform micro-pore structure with lower crystallinity, better thermal stability and mechanical strength. The characterization results show that the ionic conductivity at room temperature and electrochemical working window of the CPE doped with 5 wt% CaTiO 3 fillers (CPE-5) can be up to about 3.557 mS cm−1 and 5.1 V, respectively. The interfacial resistance of the Li/CPE-5/Li simulated cell can quickly stabilize at 750 Ω after 5 days storage, and the assembled LiCoO 2 /CPE-5/Li coin cell shows excellent rate and cycle performance. Moreover, the CPE-5 membrane can still well maintain the original micro-pore structure after 100 cycles at 1.0 C without visible cracks. Those results suggest that the as-fabricated CPE doped with 5 wt% CaTiO 3 inorganic fillers may become a promising polymer electrolyte for the lithium ion battery Graphical abstract Cycling performance and coulombic efficiency plots of the LiCoO 2 /CPE-5/Li battery after 100 cycles at 1.0 C (The insert are the SEM images and digital photographs of the CPE-5 before and after cycle). Unlabelled Image Highlights • P(VDF-HFP)-based CPE membranes doped with different amounts of CaTiO 3 ceramics are fabricated by phase inversion. • The electrolyte uptake and ionic conductivity of the CPE-5 can be up to 187.4% and 3.557 mS cm−1. • The Li/CPE-5/Li simulated cell possesses good interfacial stability. • The assembled LiCoO 2 /CPE-5/Li battery shows good rate and cycle performance. [ABSTRACT FROM AUTHOR]

Abstract This work is focused on applying structural concepts and basic chemical principles to model two N -heterocyclic lithium salts, based on trifluoromethyl substituted pyrazolide anions. An easily upscalable preparation method without difficult purification steps was also developed. In a comparative study, the physicochemical properties of the two new lithium salts were investigated, particularly the effect of an additional BF 3 -group at the nitrogen atom. In comparison to non-substituted lithium pyrazolide, the BF 3 -addition led to a strong improvement of thermal and electrochemical stability, ionic conductivity, as well as better C-rate and cycling performance. Furthermore, the anodic stability of Al current collectors was investigated and compared to commercial lithium salts, namely LiPF 6 and lithium bis((trifluoromethyl)sulfonyl)imide (LiTFSI). Possible mechanisms that lead to the presented improvements are discussed. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A low-cost and scalable ultrasonic synthetic method to produce copper metal current collector with uniform nanopores on the surface is achieved for the first time. A layer of silicon active material was sputtered on the surface of as-prepared metal current collector (vs. metal lithium) as an innovative current collecting material for lithium ion battery. The assembled battery with this current collector showed an areal capacity of 2.2 mAh/cm 2 , comparable to that of commercially available lithium ion batteries. Due to the nano-porous structure of current collector, the silicon active material electrochemical capacity retention and cycling stability also improved significantly. [ABSTRACT FROM AUTHOR]

Layered Ni-rich Li[Ni 0.6 Mn 0.2 Co 0.2- x Sn x ]O 2 cathode active materials with x  = 0–0.05 are synthesized via a co-precipitation synthesis route and the effect of doping content on the structural behavior and electrochemical performance are investigated. All synthesized materials show a well-defined layered structure of the hexagonal α -NaFeO 2 phase (space group R 3 ¯ m ) analyzed by X-ray diffraction (XRD). Electrochemical Li-metal/cathode cell studies exhibit that a Sn-content of 1%–2% is beneficial regarding specific discharge capacity and cycle life (≥20%). Detailed electrochemical investigations of Li-metal and lithium ion cells with cathodes consisting of LiNi 0.6 Mn 0.2 Co 0.2 O 2 and LiNi 0.6 Mn 0.2 Co 0.18 Sn 0.02 O 2 are conducted. Post mortem analyses by means of ICP-OES and TXRF show beneficial effects of the Sn-doping with regard to a lower transition metal dissolution and a higher available Li content in the cathode active material. The thermal analyses (TGA, DSC, ARC) show a stabilizing effect of Sn-doping, which results from a lower mass loss and less heat evolution of the charged cathode active materials at elevated temperatures. [ABSTRACT FROM AUTHOR]

The homogeneous nano-CeO 2 coated on the LiNi 1/3 Co 1/3 Mn 1/3 O 2 powder like substrate was prepared via a novel hydrolytic precipitation reaction followed by the thoroughly baking at 450 °C. The chemical composite of nano-CeO 2 coating layer was spectroscopically examined by X-ray diffraction, field-emission scanning electron microscopy and X-ray photoelectron spectrometer. The electrochemical characterization of the resulting materials proclaim that nano-CeO 2 coating can drastically improve lithium storage performances. The optimum coating amount of CeO 2 is as high as 2 wt%, which rendered a discharge capacity of 148.9 mAh g −1 with 91.6% capacity retention ensuing as many as 100 cycles. In particular, the exothermic peak is vastly increased from 256.4 to 338.2 °C. The value is superior to its counterparts, LiNi 1/3 Co 1/3 Mn 1/3 O 2 . It paves a new avenue for developing high safety lithium batteries. [ABSTRACT FROM AUTHOR]

The Li 2 SiO 3 -graphene composite is successfully synthesized through an easy hydrothermal method. The structures and morphologies of the produced samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrum, Brunauer-Emmett-Teller formalism, scanning electron microscope, transmission electron microscope, and electrochemistry methods. The result shows a well crystalline of the Li 2 SiO 3 -GE composite. The existence of graphene doesn’t change the crystalline of Li 2 SiO 3 . In addition, the Li 2 SiO 3 compound with an average diameter of 20 nm can be seen on the surface of graphene with uniform distribution. After the composite with graphene, the composite displays large surface area which ensures the well electrochemistry of the composite. Finally, the Li 2 SiO 3 -graphene composite delivers a high initial capacity of 878.3 mAh g −1 at 1C as well as a high recovery capacity of 400 mAh g −1 after 200 cycles. When charged and discharged at high rate, the Li 2 SiO 3 -doping graphene composite still exhibits a high specific capacity of 748.3 mAh g −1 (at 2C, and 576 mAh g −1 at 5C) and well cycling performance. The well synthesized composite possesses well structure and well electrochemistry performance. [ABSTRACT FROM AUTHOR]

A liquid-phase mixing method is adopted to uniformly disperse the graphene nanosheets onto LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode for high-performance Li-ion batteries (LIBs). The electrochemical performance was characterized using a full pouch cells with state-of-the-art electrode areal loading (compared to half coin cells). The addition of graphene sheets (i.e., only 1 wt%) significantly improves the high rate capability for charging and discharging operation. For example, 6 times improvement in 5  C charging was achieved providing further insights in enabling extreme fast charging for LIBs. Other benefits include longer cycleability, lower internal resistance, and higher lithium ion diffusion coefficient, demonstrated by charge-discharge cycling tests and electrochemical impedance spectroscopy. Higher capacity retention of 88.2% and decreased internal resistance of ∼0.9 Ω are observed after 400 cycles. The diffusion coefficient of Li ions is 6.49 × 10 −8  cm 2  s −1 when charged to 4.2 V, which is approximately 1.37 times higher compared to the configuration with no graphene sheet (4.74 × 10 −8  cm 2  s −1 ). The improved performance is ascribed to a robust network among the active materials formed by graphene sheets, which serves as an extended current conductor and facilitates charge transfer, ionic reversibility, and ionic transportation. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) layers have been grown by spray-pyrolysis technique by using different spray pyrolysis deposition times (t sp ). AgNPs with ca. 80 nm mean diameter have been obtained for the lower t sp value, whereas as the spray-pyrolysis time value is increased, the Ag NPs diameters increased, reaching a AgNPs mean diameter of 190 nm for the highest t sp assayed value. X-ray diffraction patterns of the AgNPs layers samples exhibited a pure polycrystalline cubic silver phase, irrespective of the different t sp values. An optical visible light transmittance maximum of 60% at 550 nm has been observed for samples grown at t sp  = 5 s and 10 s. For higher t sp values this optical transmittance decreases. A semitransparent lithium ion battery (t sp  = 5 s) has been obtained, exhibiting an optical transmittance of about 49% at λ = 554 nm. Electrochemical measurements showed that the amount of lithium that reacted with the AgNPs layer was around 6 lithium/mol. By cycling a transparent Li/Ag-ITO single cell, good capacity retention was observed for the first ten cycles for which a high value of capacity is delivered: 706 A h kg −1 .When assembling this electrode in a full semitransparent battery, the electrochemical processes resulted to be reversible and the transparency preserved. [ABSTRACT FROM AUTHOR]

Lithium ion battery (LIB) waste contains significant valuable resources that could be recovered and reused to manufacture new products. This study aimed to develop an alternative process for extracting metals from LIB waste using acidic solutions generated by electrolysis for leaching. Results showed that solutions generated by electrolysis of 0.5 M NaCl at 8 V with graphite or mixed metal oxide (MMO) electrodes were weakly acidic and leach yields obtained under single stage (batch) leaching were poor (<10%). This was due to the highly acid-consuming nature of the battery waste. Multistage leaching with the graphite electrolyte solution improved leach yields overall, but the electrodes corroded over time. Though yields obtained with both electrolyte leach solutions were low when compared to the 4 M HCl control, there still remains potential to optimise the conditions for the generation of the acidic anolyte solution and the solubilisation of valuable metals from the LIB waste. A preliminary value proposition indicated that the process has the potential to be economically feasible if leach yields can be improved, especially based on the value of recoverable cobalt and lithium. [ABSTRACT FROM AUTHOR]

In this work, we select four types of substitute cations, Ti 4+ , Al 3+ , Mg 2+ and Zn 2+ , to compare their influence on LiNi 0.8 Co 0.1 Mn 0.1 O 2 . After modification, the average lengths of Ni O bonds are elongated with the turn of the Ti , Al , Mg , pristine and Zn-substituted, namely the bond energies are diminished with this sequence, according to their roughly inverse square relation. This tendency is also obeyed by oxygen defects, which induces the Ni Li exchanging and surface decomposition, and then exert the effect on electrochemical behavior of Ni-rich cathodes. Among the investigated samples, the Ti-modified sample, which possesses the highest Ni O bond energy, presents the best cyclic stability and rate capability, retaining 93.8% in the 200 th cycle and 155.1 mAh g −1 under 5C, which is ∼12% higher than the pristine sample. Our approaches illustrate the importance of Ni O network and provide a novel thought to further improve these promising cathodes. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) sandwich-like Si/Polyaniline/Graphene nanoarchitecture anode for lithium ion batteries (LIBs) is successfully fabricated through an easy approach. In this nanoarchitecture, the in-situ polymerized electronic conductive polyaniline (PAni) hydrogel, acting as “glue”, agglutinates tightly to both the silicon nanoparticles (SiNPs) and graphene sheets, forming efficient conductive networks with high elastic modulus and high tensile strength. This mechanically robust nanoarchitecture can endure the great volume change of silicon and retain structural stability during Li-ion insertion/extraction. The electrodes consisting of this 3D sandwich-like Si/Polyaniline/Graphene nanoarchitecture reveal excellent electrochemical performance. The progress made in this work provides an easy and scalable route for preparing Si-based anode materials with high performance for advanced LIBs. [ABSTRACT FROM AUTHOR]

The charge/discharge mechanism and electrochemical performance of Zn 3 V 3 O 8 as anode for Li-ion batteries are systematically studied. Theoretical calculation predicts that Zn 3 V 3 O 8 can act as a host for Li storage, and a possible diffusion way of Li-ions within the crystal structure is calculated via first principle methods. Experimentally, Zn 3 V 3 O 8 nanosheets with porous architecture are fabricated via a facile hydrothermal pretreatment and subsequent sintering. The Zn 3 V 3 O 8 shows superior electrochemical performance with graphite electric additive, exhibiting discharge/charge capacity of 541/537 mAh g −1 after 200 cycles at a specific current of 120 mA g −1 . The Li-storage mechanism is also studied via ex-situ XRD, and the maintenance of main diffraction peaks during lithiation/delithiation process suggests a possible intercalation/extraction mechanism of the Zn 3 V 3 O 8 . [ABSTRACT FROM AUTHOR]

Nowadays, exploiting electrode materials with high energy density and long cycling life is crucial for meeting the urgent requirement of ever-growing energy storage for EV/HEV. Herein, we introduced a simple synthetic route to prepare FeNi 2 S 4 QDs @C composites on a large scale. By means of suitable design, the ultra-small FeNi 2 S 4 quantum dots (QDs) were encapsulated in the carbon matrix, and the forming FeNi 2 S 4 QDs @C composites exhibit excellent electrochemical performances. When tested as anode materials for lithium ion battery, the high capacity of 920 mAhg −1 at 0.1 Ag -1 could be achieved. Except the high capacity, the FeNi 2 S 4 QDs @C composites present the enhancing cycling stability, which demonstrated more than 700 cycles with twice capacity of graphite and capacity retention of almost 100% could be achieved, compared to the capacity of second cycle. Detailed investigations of phase evolutions by XRD patterns and TEM indicate the phase segregation of FeS x and NiS y during the charge/discharge process. The conversion reactions between Fe/Ni and FeS x /NiS y took place in the carbon matrixes, which would hinder the aggregation and grow-up of nanoparticles, resulting in the structure stability. Hence, the ultra-small size, self-doping and stable structure led to the superior electrochemical properties. We believe that the FeNi 2 S 4 @C composites would be an alternative anode material for next generation lithium ion battery. [ABSTRACT FROM AUTHOR]

Cathode materials LiMn 0.5 Fe 0.5 PO 4 /C and LiMnPO 4 /C were synthesized by a high-energy ball-milling assisted sol-gel method. The LiMn 0.5 Fe 0.5 PO 4 consists of nanorods and nanoparticles homogeneously wrapped with highly ordering carbon. The increased Néel-temperature and decreased effective magnetic moment of LiMn 0.5 Fe 0.5 PO 4 /C revealed the microstructure differences from LiMnPO 4 /C. Meanwhile, tiny amount of ferromagnetic impurities is detected in LiMn 0.5 Fe 0.5 PO 4 /C by magnetic tests. The synergetic effects of Fe substitution and carbon coating remarkably improve rate capacity and cyclic stability of LiMn 0.5 Fe 0.5 PO 4 /C. This solid solution delivers initial discharge capacities of 128.6 mAh g −1 and 116.3 mAh g −1 and capacity retentions of 93.5% and 90.3% after 100 cycles at 1C and 2C respectively, significantly better than LiMnPO 4 /C. [ABSTRACT FROM AUTHOR]

Chromium nitride (CrN) synthesized by heating at 550 °C under a continuous stream of ammonia has been investigated as anode material for lithium electrochemistry. Due to its low lithium insertion potential, Cr is an attractive material for lithium–ion battery application, but the usual volume variation effect obstructs its practical use. In this study, different concentrations of carbon nanotubes doped with nitrogen (NCNTs) are combined with CrN to attain high electrochemical performance. The synthesized CrN/0.08%–NCNTs nanocomposite demonstrates network structure with 30–40 nm CrN nanoparticles anchored to specific sites on 40–60 nm diameter NCNTs. Upon electrochemical testing, CrN/0.08%–NCNTs nanocomposite displays a discharge capacity of 1172 mAh g −1 after 200 cycles with high coulombic efficiency (∼100%) and rate capability. The electrode can deliver a reversible capacity of 1042.9 mAh g −1 at 20 C. The n-type concentration, along with the conductive CNTs framework, mesoporous channels, appropriate surface area and buffering capability of CNTs, are together responsible for the excellent electrochemical performance. The electrochemical reaction mechanism of CrN with lithium is explored by investigating the structural changes using ex situ X-ray photoelectron spectroscopy, X-ray diffraction, selected area electron diffraction, and high-resolution transmission electron microscopy. The reversible conversion reaction of CrN into Cr metal and Li 3 N is revealed. [ABSTRACT FROM AUTHOR]

In lithium ion batteries anode material is very crucial. Exploring the high-performance anode materials remains a great challenge. Here, Ti 2 Nb 10 O 29 /Ag composite was obtained. Electrochemical measurements demonstrate that Ti 2 Nb 10 O 29 /Ag composite shows good electrochemical performance than pure Ti 2 Nb 10 O 29 , mostly due to enhanced electronic conductivity after Ag-coating. The specific capacities of Ti 2 Nb 10 O 29 /Ag composite can be as high as 253 and 173 mAh g −1 at 1 and 10C, respectively, and the specific capacity is 132 mAh g −1 at 20C. Moreover, the Ti 2 Nb 10 O 29 /Ag composite exhibited excellent cyclic stability, even after 500 cycles, its specific capacity at 10C still stabilized at a large value of 142 mAh g −1 , which was in sharp contrast to the corresponding values of pure Ti 2 Nb 10 O 29 (68 mAh g −1 ). The high electrochemical performance demonstrated that Ti 2 Nb 10 O 29 /Ag composite is highly promising anode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Pristine and yttrium-doped LiNi 0.5- x Y x Mn 1.5 O 4 spinel powders ( x = 0, 0.005, 0.01, 0.02, 0.04) were synthesized by a facile solid-state method. The effect of yttrium doping content on the electrochemical properties of LiNi 0.5- x Y x Mn 1.5 O 4 was investigated by using half-cells paired with lithium metal and full-cells paired with graphite. XRD and FT-IR analysis shows that the cation disordering degree (Mn 3+ content) first increase ( x ≤ 0.02) and then decrease with Y doping content and the Y doping can effectively inhibit the formation of Li x Ni 1- x O impurity phase. Electrochemical results show that in half-cells, the LiNi 0.5-x Y x Mn 1.5 O 4 cathode material with appropriate Y doping ( x = 0.01) exhibits optimal rate capability and cycling stability, due to higher phase purity, enlarged lattice parameter, higher disordering degree, higher structural stability by introducing Y O bond, lower charge transfer resistance and higher lithium ion diffusion coefficient, although the 0.2C discharge capacity is slightly lower than pristine LiNi 0.5 Mn 1.5 O 4 . Atomic Absorption Spectroscopy result shows that appropriate Y doping can effectively decrease the transition metal dissolution to certain extent, despite of higher Mn 3+ content. All above factors lead to the improved cycling performance of Y-doped electrode in half-cells paired with metallic Li at elevated temperature (55 °C) and in full-cells paired with graphite at room temperature. [ABSTRACT FROM AUTHOR]

Li- and Na-transition metal fluorosulfate materials (AFeSO 4 F, A = Li, Na) are proposed as highly promising novel cathode materials for Li- and Na-ion batteries. In this study, the electrochemical performance and elastic properties of AFe 1- x M x SO 4 F (A = Li, Na; M = Co, Ni, Mg; x = 0, 0.5, 1) are investigated from the view of first-principles calculations. The computational results reveal that the substitutions of Fe by Ni, Co and Mg enhance the intercalation voltage of the fluorosulphate materials. The density of states analysis shows that transition metal-doping AFeSO 4 F, especially for Ni doping case, could achieve better electronic conductivity in comparison with the pure phase and Mg-doped AFeSO 4 F. Further bader charges calculations give a confirmation that the Fe and Co in AFe 0.5 Co 0.5 SO 4 F play significant role in the charge transfer during delithiated or desodiated progresses, but the relatively inert character of Ni and Mg is discovered in AFe 0.5 Ni 0.5 SO 4 F and AFe 0.5 Mg 0.5 SO 4 F. LiFeSO 4 F and NaFeSO 4 F are found to be ductile from the exploration of elastic constants, whereas their delithiated and desodiated configurations have brittle character. In addition, Young’s Modulus ( E ), and Poisson's Ratio ( ν ) for LiFeSO 4 F, NaFeSO 4 F and 50% metal-doped AFe 1- x M x SO 4 F (A = Li, Na; M = Co, Ni, Mg) are also presented to explore the hardness, bond characteristic and stability against shear. [ABSTRACT FROM AUTHOR]

Electrochemical method for recovering cobalt and manganese from electrode materials of spent lithium ion batteries was studied. Electrochemical leaching of cobalt and manganese from electrode material was optimized by varying different process parameters such as time, acid concentration and current density. Both cobalt and manganese could effectively be leached out at a current density of 400 A/m 2 in 3 h using 2 M sulphuric acid. In the subsequent study, the metallic cobalt and electrolytic manganese dioxides was recovered from the leach liquor at 200 A/m 2 , pH 2–2.5 and 90 °C after removing aluminum. The commercial feasibility of the study was tested in pilot scale. Overall recovery of Co, Cu and Mn was above 96%, 97% and 99%, respectively. [ABSTRACT FROM AUTHOR]

LiCoO 2 (LCO) has been functionally modified by mixed lithium ion and electron conducting LiAlPO 3.93 F 1.07 (LAPF) for the first time. Due to the unique coating layer with accepted Li-ion diffusion rate and electronic conductivity, the LAPF-coated LCO exhibits outstanding rate capability and cycle stability in the voltage range of 2.75–4.55 V. This material delivered a specific capacity of 206 mAh·g − 1 up to 0.5C rate and the capacity retention was 91.7% after 50 cycles, which is a remarkable improvement comparing with uncoated LCO (34.8%). It also exhibited superior rate capability with a discharge capacity of 161.4 mAh·g − 1 at 4C. The functionalized LAPF coating technique is an efficient approach to improve the electrochemical performance of LCO and can also be referred for other layered oxide cathode materials. [ABSTRACT FROM AUTHOR]

Designing heteroatom doped metal oxides and modifying them with carbonaceous materials can grant metal oxides with good Li + storage performance because of the improved structure stability and enhanced electric conductivity. Herein, monodispersed Cr-doped SnO 2 quantum dots fixed by graphene nanosheets and carbon layers (C/Cr-SnO 2 /G) were successfully assembled, which showed excellent cyclic stability, high reversible capacity and remarkable rate capability for Li + storage. According to the characteristics results, 3.8 wt% Cr were uniformly incorporated into SnO 2 lattice in form of Cr 3 + , resulting the decrease of SnO 2 diameters. The C/Cr-SnO 2 /G electrodes displayed an excellent reversible capacity of 672 mA h g − 1 after 200 cycles at 100 mA g − 1 without apparent capacity fading throughout the test, and still retained a stable specific capacity of 296 mA h g − 1 even at 5 A g − 1 . The enhanced electrochemical performances of C/Cr-SnO 2 /G can be related to incorporation of Cr into lattice of SnO 2 and the double structure protections by graphene nanosheets and carbon layers, which can easily obtain quantum dots structure, increase the conductivity, and keep the structure stability. [ABSTRACT FROM AUTHOR]

In this work a novel pulse combustion reactor method for preparation of Li-ion cathode materials is introduced. Its advantages and potential challenges are demonstrated on two widely studied cathode materials, LiFePO 4 /C and Li-rich NMC. By exploiting the nature of efficiency of pulse combustion we have successfully established a slightly reductive or oxidative environment necessary for synthesis. As a whole, the proposed method is fast, environmentally friendly and easy to scale. An important advantage of the proposed method is that it preferentially yields small-sized powders (in the nanometric range) at a fast production rate of 2 s. A potential disadvantage is the relatively high degree of disorder of synthesized active material which however can be removed using a post-annealing step. This additional step allows a further tuning of materials morphology as shown and commented in some detail. [ABSTRACT FROM AUTHOR]

A systematic study to reveal the relationship between the surface oxygen-containing functionalities of sub-10-nm GNRs and their electrochemical properties for lithium-ion batteries has been presented. Sub-10-nm GNRs with controlled oxygen-containing groups were synthesized by a green and scalable intercalation-assisted unzipping SWCNTs. Detailed materials characterizations including TEM, XRD, Raman and XPS indicate that KNO 3 could be an effective intercalation agent to facilitate the SWCNT unzipping by reducing the strong Van der Waals force attraction of bundled SWCNT. The levels of surface functionalities of sub-10-nm GNR were tuned by carefully controlling the KMnO 4 concentration during the unzipping process. The electrochemical analysis suggests that the as-produced sub-10-nm GNR with 31.4 atomic percent (atom %) oxygen-containing functional groups showed the highest capacity of 490.4 mAh g −1 after 100 cycles. This work proposed that sub-10-nm GNRs with appropriate oxygen-functional groups can be a promising electrode material for high performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Zero-dimensional quantum dots (QDs) are desired to enhance electrochemical response in energy storage. Here, we successfully synthesize well-dispersed and ultrafine TiO 2 -QDs, which are in situ embedded into the three-dimensional porous graphene-like networks (denoted as TiO 2 -QDs-3D GNs) via a simple low-temperature mixed solvothermal method, aiming at a fast electrochemistry with high-efficient electron and ion transport for lithium ion battery (LIB) anodes. By combining the advantages of the porous 3D GNs and ultrafine TiO 2 -QDs, the as-prepared TiO 2 -QDs-3D GNs hybrid electrode exhibits a high reversible capacity of 219 mA h g −1 after 100 cycles at 0.1 A g −1 , accompanied with an ultrahigh-rate capability of 121 mA h g −1 and a super-long lifespan of 3000 cycles with ∼82.0% capacity retention at 10 A g −1 . Detailed electrochemical analysis reveals that the superior rate capability and cycle performance are the main results of the integrated intercalation-based and interfacial lithium storage as well as the 3D fast electron/ion transfer of materials, which is attributed to the ultra-small size and high surface-to-volume ratio of TiO 2 -QDs as well as the 3D conducting networks of the integrated hybrid electrode. This study demonstrates the distinct advantages of our material design strategy, making it promising for the fast and ultralong-life anodes in LIBs. [ABSTRACT FROM AUTHOR]

We fabricated all-solid-state thin film batteries based on well-aligned slanted LiCoO 2 nanowires by glancing angle deposition, as a facile template-free method in order to increase the electrochemically active site, i.e. , the contact area between the solid electrolyte and the electrode. A highly porous thin film composed of well-separated slanted LiCoO 2 nanowires not only facilitates the penetration of solid electrolyte phase into the cathode, but also alleviates the thermally and mechanically induced stresses during post-annealing and electrochemical cycling. The all-solid-state thin film battery based on the well-aligned slanted LiCoO 2 nanowires, whose contact area between electrolyte and electrode was three times as high as that of a dense thin film, could provide additional migration pathways for lithium ion diffusion due to the enlarged reaction sites. This resulted in enhanced electrochemical kinetics, thereby leading to better rate capability and long-term cyclic stability as compared to the dense LiCoO 2 thin film. [ABSTRACT FROM AUTHOR]

Recently, layered transition metal chalcogenides (LTMCs) have attracted great attention as anode materials for lithium ion batteries (LIBs). However, the volume expansion and structure instability of LTMCs during the lithiation and delithiation process still remains challenging. Herein, we report NbSe 3 nanobelts wrapped by reduced-graphene oxide (NbSe 3 @rGO) utilized as buffer layers with enhanced electrochemical performance. The X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were used to probe features of the NbSe 3 @rGO. The NbSe 3 @rGO nanobelts as anode exhibit a discharge capacity of 300 mAh/g at the current density of 100 mAh/g after 250 cycles, several times higher than pure NbSe 3 nanobelts. The improved electrochemical performance of NbSe 3 @rGO is attributed to a buffer effect from the rGO, cushioning the volume-change-induced strain effect on the structure of NbSe 3 nanobelts during cycling. [ABSTRACT FROM AUTHOR]

The composite of Co 3 O 4 , Co and graphitized carbon is synthesized by carbonization and cobalt-catalyzed-graphitization of carboxymethyl chitosan, followed by low-temperature thermal oxidation. At the high temperature, the Co(+2) is reduced to metallic Co and the produced Co acts as a catalyst for the graphitization of the pyrolytic carbon. The low-temperature oxidation is conducted to selectively oxidize Co to Co 3 O 4 while the carbon remains unreacted. The structure analysis indicates that three crystal phases (graphite, metallic Co, Co 3 O 4 ) accompanied with amorphous carbon are co-existed in the composite. Morphological results demonstrate that a lot of graphite grains around the Co element are distributed in the carbon. The electrochemical testing results indicate that the composite shows good electrochemical performance. It delivers a reversible capacity of 843 mAh g −1 at low current density, and remains 88.9% after 60 cycles at 200 mA g −1 . Even performed at 1 A g −1 , it also exhibits 493 mAh g −1 . The performance improvement is mainly due to the high capacity of Co 3 O 4 , high conductivity of graphitic carbon and metallic cobalt, the porous structure offering enough ion transport pathways and relieving the strain during cycling. [ABSTRACT FROM AUTHOR]

As a high-capacity hydrogen storage material, MgH 2 also shows specific advantages for LIB anode. In this work, MgH 2 and MgH 2 -C films were prepared by magnetron sputtering and hydrogenation treatment, and their microstructural and electrochemical properties were investigated. Through the conversion reaction of MgH 2 with lithium (MgH 2 + 2Li + → Mg + 2LiH), the reversible lithium storage was achieved in the MgH 2 and MgH 2 -C films. The MgH 2 film delivers the initial discharge capacity of 313.9 μAh cm −2 (∼2956 mAh g −1 ), the discharge and charge capacities related to the conversion process are respectively 150.0 μAh cm −2 (∼1412 mAh g −1 ) and 55.0 μAh cm −2 (∼518 mAh g -1 ), with the inefficiency of 63.3%. The GITT measurement determined the equilibrium potential of this conversion reaction to be 0.55 V vs. Li/Li + , and the voltage hysteresis between discharge and charge is only 10 mV vs. Li/Li + . In comparison with the MgH 2 film, the MgH 2 -C film has smaller crystallite size, lower polarization effect and structural stability, but exhibiting lower capacity and equally poor cyclic performance. The poor cycle life of MgH 2 -C film electrode is due to the large irreversibility of conversion reaction of MgH 2 , instead of structural damage of film electrode during cycling. [ABSTRACT FROM AUTHOR]

Particle morphology structure design combined with surface modification has been applied to improve the electrochemical properties of lithium rich layered oxides. Hollow spherical lithium rich layered Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 oxides with different shell thickness are synthesized by co-precipitation followed by calcination. The morphology and interior structure have been investigated by SEM and cross section, and their electrochemical properties have been evaluated to identify an appropriate shell thickness. Furthermore, a Zr compound coating layer has been applied to modify the interface between corrosive electrolyte and hollow spherical particles with an appropriate shell thickness. The Electrochemical impedance spectroscopy shows hollow spherical structure and Zr compound coating layer both can modificate the electronic and ionic transmission capacities and inhibit their deterioration during charge-discharge process at the same time. The HRTEM tests indicate that hollow spherical structure and Zr compound coating layer can dramatically suppress Mn dissolution in electrolyte and make the crystal structure more stable during the electrode process. Therefore, a surface modification combine with the hollow spherical structure (with an appropriate shell thickness) can effectively enhance these electrochemical properties of lithium ion layered oxides. [ABSTRACT FROM AUTHOR]

New self-supported poly(vinylidene fluoride)/poly (vinyl chloride-co-vinyl acetate) (PVdF/P(VC-VAc)) blended polymer membranes are prepared via a phase inversion method, and then their electrochemical performances, immersed in the liquid electrolyte as the polymer electrolyte for lithium-ion batteries (LIBs), are evaluated. The Fourier transform infrared spectroscopy analysis, the differential scanning calorimeter test and the X-ray diffraction measurement demonstrate that homogeneous PVdF/P(VC-VAc) polymer composites can form at all blend compositions and the crystallinity degree of the blended polymers decreases as the P(VC-VAc) content increases. Specifically, when the proportion of PVdF/P(VC-VAc) is 70:30 (wt%), membranes with a rich surface and internal porous structure can be acquired. The ionic conductivity of the polymer electrolyte achieves a maximum value of 3.57 mS cm-1 at room temperature, and favourable electrochemical performances of LIBs can be obtained. LiNi0.5Mn1.5O4/Li cells with the as-prepared polymer electrolyte exhibit a higher initial discharge capacity of 131.0 mAh g-1 and superior cycle stability with a capacity retention of 96.1% at 0.2 C after 200 cycles compared to cells based on pure PVdF and P(VC-VAc) membranes. This can be attributed to the superior compatibility of the electrolyte with the electrodes. The results also indicate this electrolyte has promising applications in high-voltage LIBs. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/Mn 3 O 4 (RGO/Mn 3 O 4 ) nanocomposites were synthesized via a cost-effective approach, and their microstructural and morphological features were investigated. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results revealed that the Mn 3 O 4 nanoparticles were crystallized with particle size 50–100 nm while the size of the Mn 3 O 4 particles in RGO/Mn 3 O 4 composites decreased to 30–50 nm, suggesting that RGO promoted the dispersion of Mn 3 O 4 particles. We tested the electrochemical behavior of the RGO/Mn 3 O 4 composites for supercapacitor and Li-ion battery. And it was found that they exhibited an excellent discharge specific capacitance of about 194.8 F/g at 1.0 A/g with 90% capacity retention even after 1000 cycles in supercapacitor, and an initial discharge capacity of about 1813 mAh/g at 0.1 A/g with outstanding cycling stability in Li-ion battery. [ABSTRACT FROM AUTHOR]

Polypyrrole-coated Bi 2 O 3 @CMK-3 nanocomposite is prepared by nanocasting technique and chemical polymerization method. Bi 2 O 3 nanoparticles are dispersed into CMK-3 matrix, and polypyrrole is coated onto the surface of Bi 2 O 3 @CMK-3. Polypyrrole-coated Bi 2 O 3 @CMK-3 nanocomposite as an anode material for lithium-ion batteries has an outstanding power capability (321 mAh g −1 at a current rate of 6 A g −1 ) and a significantly improved cycling ability (380 mAh g −1 after 1000 cycles at a current rate of 5 A g −1 ). The greatly enhanced electrochemical performance of polypyrrole-coated Bi 2 O 3 @CMK-3 nanocomposite is associated with the synergistic effect of highly conductive CMK-3, polypyrrole layer and Bi 2 O 3 nanoparticles. Such a configuration inhibits the aggregation of Bi 2 O 3 nanoparticles and preserves the structure integrity of electrode material, in addition to highly improving the electrical conductivity and maintaining the stable structure of solid electrolyte interface film. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of silicon-based anode material, the silicon/carbonized polydopamine/graphene (Si/PDAC/rGo) was prepared via pre-coating process in which graphene oxide was added and subsequent annealing process. The silicon particles with polydopamine (PDA) layer was encapsulated by graphene sheets due to interaction between the amine groups on PDA and the oxygen-containing groups on graphene oxide (GO), so the aggregation of silicon particles was hindered. The X-ray photoelectron spectroscopy (XPS) results present that most of the oxygen-containing groups were removed and the carbon layer contained nitrogen element. The initial coulombic efficiencies of Si/PDAC/rGo were 83.8%, 84.3%, 83.1% at 0.1, 0.3, 0.5 A g −1 , respectively. The cycle and rate performance of Si/PDAC/rGo was also enhanced ascribed to the synergistic buffer effects of carbonized polydopamine layer and graphene sheets. [ABSTRACT FROM AUTHOR]

FeCO 3 with the morphology of microspheres and rice-like were successfully fabricated by a facile mixed solvothermal method by using urea and ammonium bicarbonate as precipitants, respectively. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of the samples were investigated by battery testing system. The influences of different precipitants on its structure, morphology and the electrochemical properties were also discussed. The results showed that the diameter of FeCO 3 microspheres (FCO-1) was 8–10 μm by using urea as precipitant, while the size of FeCO 3 rice-like (FCO-2) by using ammonium bicarbonate as precipitant was 0.5–1.0 μm. When used as an anode material for lithium ion batteries, FCO-1 and FCO-2 delivered the initial specific discharge capacities of 1563.54 and 1518.09 mAh g −1 at the current density of 100 mA g −1 in the voltage range of 0.01–3 V and remained its reversible value of 854.65 and 1019.47 mAh g −1 over 100 cycles, respectively. The FCO-2 still possessed a considerable capacity of 890.23 mAh g −1 at a high current density of 500 mA g −1 . Therefore, FCO-2 synthesized through using ammonium bicarbonate as precipitant could be a potential anode candidate for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Temperature dependent fabrication of NiCr 2 O 4 is studied and the application of the as-prepared NiCr 2 O 4 in both half-cell with Li metal anode and full-cell with LiFePO 4 cathode are assessed. When mixing with natural graphite (NG), the NiCr 2 O 4 obtained at 550 °C can deliver initial charge and discharge capacities of 795 and 1275.5 mAh g −1 at a specific current of 150 mA g −1 , maintaining of 939 and 955 mAh g −1 after 140 cycles. In contrast, after 140 cycles at the same specific current, the NiCr 2 O 4 obtained at 450 °C and 650 °C can maintain charge/discharge capacities of 800/814 and 523/528 mAh g −1 , respectively. When matching with a LiFePO 4 cathode, The NiCr 2 O 4 /NG (obtained at 550 °C) electrode delivers initial discharge capacity of 285 mAh g −1 , which maintains of 106 mAh g −1 after 50 cycles at a specific current of 100 mA g −1 . [ABSTRACT FROM AUTHOR]

Within the academic and industrial communities there has been an increasing desire to better understand the sustainability of producing vehicles that contain embedded electrochemical energy storage. Underpinning a number of studies that evaluate different circular economy strategies for the electric vehicle (EV) or Hybrid electric vehicle (HEV) battery system are implicit assumptions about the retained capacity or State of Health (SOH) of the battery. International standards and best-practice guides exist that address the performance evaluation of both EV and HEV battery systems. However, a common theme is that the test duration can be excessive and last for a number of hours. The aim of this research is to assess whether energy capacity measurements of Li-ion cells can be accelerated; reducing the test duration to a value that may facilitate further EOL options. Experimental results are presented that highlight it is possible to significantly reduce the duration of the battery characterization test by 70–90% while still retaining levels of measurement accuracy for retained energy capacity in the order of 1% for cell temperatures equal to 25 °C. Even at elevated temperatures of 40 °C, the peak measurement error was found to be only 3%. Based on these experimental results, a simple cost-function is formulated to highlight the flexibility of the proposed test framework. This approach would allow different organizations to prioritize the relative importance of test accuracy verses experimental test time when grading used Li-ion cells for different end-of-life (EOL) applications. [ABSTRACT FROM AUTHOR]

Hierarchical CuCl with high economic value added (EVA) was successfully recycled with 85% recovery from the acid Cu printed circuit board (Cu-PCB) waste etchant via facile liquid chemical reduction. The micro-structure and morphology of the recycled hierarchical CuCl were systematically characterized in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Furthermore, the corresponding electrochemical performances as lithium ion battery (LIB) anode were also investigated in terms of galvanostatic charge/discharge, cyclic voltammetry (CV) and AC impedance. As expected, the recycled CuCl displayed a hierarchical tripod-like structure and large specific surface area of 21.2 m 2 /g. As the anode in LIB, the reversible discharge capacity was about 201.4 mAh/g even after 100 cycles, implying the satisfactory cycle performance. Clearly, the satisfactory results may open a new avenue to develop the sustainable industry, which is very important in terms of both the resource recovery and the environmental protection. [ABSTRACT FROM AUTHOR]

We unravel the role of flake dimensionality on the lithiation/de-lithiation processes and electrochemical performance of anodes based on few-(FLG) and multi-layer graphene (MLG) flakes prepared by liquid phase exfoliation (LPE) of pristine graphite. The flakes are sorted by lateral size (from 380 to 75 nm) and thickness from 20 (MLG) to 2 nm (FLG) exploiting a sedimentation-based separation in centrifugal field and, finally, deposited onto Cu disks for the realization of four binder-free anodes. The electrochemical results show that decreasing lateral size and thickness leads to an increase of the initial specific capacity from ≈590 to ≈1270mAhg −1 . However, an increasing irreversible capacity is also associated to the reduction of flakes’ size. We find, in addition, that the preferential Li ions storage by adsorption rather than intercalation in small lateral size (<100 nm) FLG flakes has a detrimental effect on the average de-lithiation voltage, resulting on low voltage efficiency of these anodes. We believe that the results reported in this work, provide the guidelines for the practical exploitation of graphene-based electrodes. [ABSTRACT FROM AUTHOR]

Core-shell nano-ring α-Fe 2 O 3 @Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe 2 O 3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe 2 O 3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe 2 O 3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g −1 and retains 920/897 mAh g −1 after 200 cycles at 500 mA g −1 (0.5C). Even at 2000 mA g −1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g −1 , and still maintains 630/610 mAh g −1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe 2 O 3 @Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe 2 O 3 and facilitate the transportation of electrons and Li + ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe 2 O 3 @Carbon changing to flower-like networks during lithiation/de-lithiation has been reported. [ABSTRACT FROM AUTHOR]

Micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres are prepared by applying Ostwald ripening and Kirkendall effect to the spray pyrolysis process. The Co-C composite powders uniformly dispersed with different sizes of metallic Co nanocrystals are formed by reduction of the cobalt oxide-carbon composite powders prepared using spray pyrolysis. Subsequent oxidation of the Co-C composite powders with filled structures forms the micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres. The mean sizes of the Co 3 O 4 hollow nanospheres oxidized from Co-C composite powders formed at reduction temperatures of 400, 600, and 800 °C are 37, 55, and 73 nm, respectively. The discharge capacities of the Co 3 O 4 powders formed from the Co-C composite powders reduced at temperatures of 400, 600, and 800 °C for the 300 th cycle are 644, 702, and 660 mA h g −1 , respectively, and their capacity retentions calculated from the second cycle are 81, 86, and 84%, respectively. The porous-structured Co 3 O 4 powders formed from the Co-C composite powders reduced at 800 °C show slightly better rate performance than those of the other two samples. [ABSTRACT FROM AUTHOR]

Ionic liquids are often named solvents of the future because of flexibility in design. This statement has given credence that ionic liquids should simply replace the problematic electrolytes of lithium batteries. As a result, the promising potentials of ionic liquids in electrochemical systems are somehow obscured by inappropriate expectations. We summarize recent advancements in this field, especially, ionic liquids as standalone electrolytes, additives, plasticizers in gel polymer electrolytes, and binders; and attempt to shed light on the future pathway of this area of research. Ionic liquids are not dilute media to serve as pure solvents in electrochemical systems where mobility of ions is the priority; instead, they can contribute to the ionic conductivity of various components in a battery system. Owing to the enormous possibilities of ionic liquids, it is not merely a matter of choice. Ionic liquids can be used to design novel types of electrolytes for a new generation of lithium batteries. A promising possibility, which is still at a very early stage, is supercooled ionic liquid crystals for fast ion diffusion through the guided channels of a liquid-like medium. This, of course, will be a breakthrough in the realm of electrochemistry, far beyond lithium battery field, when materialized. [ABSTRACT FROM AUTHOR]

Cubic MnCO 3 @C composite was first synthesized using one-pot hydrothermal method. The prepared cubic MnCO 3 @C presented a homogeneous core-shell structure, which was composed of cubic MnCO 3 as core, a mixture of amorphous carbon and MnCO 3 as shell, and a separating interlayer. Compared to pure MnCO 3 , core-shell structured MnCO 3 @C exhibited better cycling stability, rate performance and recovery capability. It delivered a reversible capacity of 1020 mAh g −1 which was 94.7% of the initial capacity, and a recovery capacity of 862 mAh g −1 after 80 cycles under current density from 100 mA g −1 to 10000 mA g −1 . The superior electrochemical performance of MnCO 3 @C could be attributed to the improved electronic conductivity and suppressed particle aggregation during the conversion reaction. Voltage profile and cyclic voltammetry test results showed active material transformation in both anode materials during the cycling process. Furthermore, the infrared spectra at different discharge/charge states showed that the conversion reactions of MnCO 3 included not only the transition from MnCO 3 to Mn, but also a further reaction from Li 2 CO 3 to Li 2 O. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of Mg-birnessite (Mg x MnO 2 ) with different crystallite sizes, prepared though low temperature precipitation and ion exchange was demonstrated. The influence of crystallite size on electrochemical performance of Mg-birnessite was studied for the first time, where material with smaller crystallite size was demonstrated to have enhanced capacity and rate capability in Li ion, Na ion, and Mg ion based electrolytes. Cation diffusion using GITT type testing demonstrated the ion diffusion coefficient of Mg 2+ was ∼10× lower compared with Li + and Na + . This work illustrates that tuning of inorganic materials properties can lead to significant enhancement of electrochemical performance in lithium, sodium as well as magnesium based batteries for materials such as Mg-birnessite and provides a deliberate approach to improve electrochemical performance. [ABSTRACT FROM AUTHOR]

MoO 2 has gained renewed attention as a safe oxide anode host material for lithium ion insertion because of its high gravimetric/volumetric capacity and highly stable cycling behavior. However, these recent results are completely contrary to previous reports. To confirm that MoO 2 is an appropriate anode material as well as further understand lithium ion reactions when inserted into MoO 2 , we combine electrochemical characterization of MoO 2 electrodes and ex situ X-ray diffraction analysis with first principle calculations. Theoretical capacity of the MoO 2 electrode (∼209 mAh g −1 ) and stable capacity retention up to 100 cycles are simultaneously attained using a proper particle size and type of binder. Ex situ XRD analysis with first principle calculations of the phase transformation of MoO 2 electrodes shows that MoO 2 undergoes reversible structural changes upon lithiation and subsequent delithiation, clearly demonstrating that nanostructured MoO 2 can be used as an anode material for highly reliable lithium ion batteries. [ABSTRACT FROM AUTHOR]

Lithium ion batteries (LIBs) for high performance require separators with auspicious reliability and safety. Keeping LIBs reliability and safety in view, microporous polyacrylonitrile (PAN)/polyurethane (PU) nonwoven composite separator have been developed by electrospinning technique. The physical, electrochemical and thermal properties of the PAN/PU separator were characterized. Improved ionic conductivity up to 2.07 S cm −1 , high mechanical strength (10.38 MPa) and good anodic stability up to 5.10 V are key outcomes of resultant membranes. Additionally, high thermal stability displaying only 4% dimensional change after 0.5 h long exposure to 170 °C in an oven, which could be valuable addition towards the safety of LIBs. Comparing to commercialized polypropylene based separators, resulting membranes offered improved internal short-circuit protection function, offering better rate capability and enhanced capacity retention under same observation conditions. These fascinating characteristics endow these renewable composite nonwovens as promising separators for high power LIBs battery. [ABSTRACT FROM AUTHOR]