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In this paper, manganese is used as a medium to connect pyrolusite with lithium-ion batteries, which not only meets the needs of comprehensive utilization of global strategic mineral resources, but also maximizes the performance of lithium-ion batteries under the goal of global carbon neutralization and carbon peak. Firstly, the optimum experimental conditions for sulfuric acid roasting of pyrolusite were investigated by single factor experiment and orthogonal experiment: the roasting temperature was 650 °C, the roasting time was 4 h, the acid-to-ore ratio was 2:1, and the water-to-ore ratio was 0.6:1. The roasting temperature plays a major role. Then, LMF x P-C (x = 0, 1/4, 1/8, 1/12, 1/24) cathode materials were prepared by adding different mass Fe elements with manganese element purified from pyrolusite as manganese source. Its electrochemical analysis was carried out: the capacity retention rate of LMF 1/4 P–C cathode material is 92.54% after 500 cycles. After a total of 150 times of rate tests at different rates, the discharge specific capacity of LMF 1/4 P–C can still reach 148.5 mAh g−1. At the same time, the EIS results show that the values of R e and R ct of LMF 1/4 P–C cathode material are the smallest compared with other materials. Finally, the LMF x P-C cathode material was analyzed by first-principles, and the optimal Fe doping amount was theoretically predicted. The crystal structure, bonding and density of states of the LMF x P-C cathode material were calculated and discussed. The results show that when the Fe doping amount is 1/4, the LMF x P-C system has the highest conductivity and the best electrochemical performance. The calculation results are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The addition of 3,3,3‐trifluoropropyl acetate (TFPA) to electrolyte in a Li‐ion rechargeable battery (LIB) provides a means for increasing the discharge performance at low temperatures as a result of the formation of a superior solid electrolyte interphase (SEI) on the graphite anode. For instance, the addition of 2 wt% TFPA to the electrolyte significantly increased the cycle stability and the discharge capacities at low temperatures (‐10°C) even at current rates of 3 C. The SEI films formed on the graphite anodes were characterized by electrochemical and spectroscopic techniques and by computational analysis. Although the formation of LiF on the anode has been recognized, present research revealed that the decomposition of TFPA on the anode surface resulted in the formation of an SEI layer consisting predominantly of organic fluorides. This layer suppressed the decomposition of the electrolyte resulting in a decreased anode impedance and an increase in cycle stability and discharge capacity at low temperatures. [ABSTRACT FROM AUTHOR]

The incorporation of Carbon in Tin Oxide (SnO 2) nanocomposite (SnO 2 @C NCs) was synthesized successfully by hydrothermal method with sucrose and tin dichloride dihydrate (SnCl 2.2H 2 O) as precursor materials and was sintered at different temperatures. The as prepared SnO 2 -Carbon nanocomposites were characterized by various techniques such as X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) along with Energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Raman spectra, TGA and Electrochemical analyses. The controlled addition of Carbon in SnO 2 to exhibit enhanced electrochemical property was also studied. It was demonstrated that the Carbon derived from sucrose assisted anode showed the high reversible capacity of about 581 mAhg-1 indicating that the possibility of further increment in Li storage property. The initial discharge capacities of the samples heat treated at 400 °C, 450 °C and 500 °C were 1424.79, 1061.71 and 531.28 mAh g-1, exhibiting an increasing trend in capacity with increasing the Carbon content. The columbic efficiency of SnO 2 @C NCs attains more than 95%. The electrodes show a long cycling ability and high charge and discharge capacity due to the presence of carbon. [ABSTRACT FROM AUTHOR]

Abstract α-MoO 3 coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 electrode materials were obtained via a simple and effective wet chemical method. The results of X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM) and X-ray photoelectron spectroscopy (XPS) indicated that α-MoO 3 had been successfully coated on the surface of pristine materials. Charge-discharge measurements demonstrated that the α-MoO 3 thin layer could enhance the electrochemical performances. The initial coulombic efficiency improved from 75.7% to 89.6%, and the modified sample exhibited good cyclic performance of 87.0% at 100 mA g−1 after 100 cycles and 85.3% at 200 mA g−1 after 100 cycles with the excellent discharge properties. According to the analysis of electrochemical impedance spectroscopy (EIS) and cyclic voltammogram (CV), the largely enhanced electrochemical performance are mainly due to the restrain of the side reactions between electrode and electrolyte and the increased migration rate of Li+ between the electrode/electrolyte interface by α-MoO 3 film. Highlights • α-MoO 3 -coated sample shows significantly improved initial coulombic efficiency. • A Li+-free insertion host, α-MoO 3 , is coated on Li-rich Mn-based electrode material. • Superior cyclic performance and rate capability are obtained after Mo coating. • The mechanisms of Mo composites coating layer on improved performances are discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract Nanocomposites LiMn x Fe 1-x PO 4 /C (x = 1, 5/6, 2/3, 1/2) are synthesized by a sol-gel route combined with freeze drying. Fe2+ substituted samples coated by high-ordered carbon have the same olivine structure of LiMnPO 4 /C but reduced cell volumes. Fe2+ substituting greatly influences magnetic characteristics of LiMnPO 4 /C and slight amounts of Fe 2 P impurity in Fe2+ doped samples are verified by magnetic tests. Fe2+ substituted samples exhibit much better electrochemical properties. Among them, LiMn 1/2 Fe 1/2 PO 4 /C displays the best rate capacity and cyclic stability. Its initial discharge capacity reaches 140.1 mAh g−1 and remains at 132.5 mAh g−1 after 100 cycles at 2C, remarkably higher than those of LiMnPO 4 /C. The superior electrochemical performances are mainly attributed to small charge-transfer impedance, fast Li+ diffusion, residual carbon and existence of Fe 2 P with excellent electronic conductivity. Graphical abstract A T N peak of 47 K and a higher transition temperature are observed in χ−1(T) curve for LiMn 1/2 Fe 1/2 PO 4 /C. Moreover, non-linear behaviors in M (H, T) curves are presented at all testing temperatures. Two pairs of redox peaks in CV results with high symmetry separately match with those of LMP and LFP, indicating excellent electrochemical reversibility. Image 1 Highlights • LiMn x Fe 1-x PO 4 /C was synthesized via freeze drying assisted sol-gel method. • Magnetic tests were introduced to investigate microstructure differences and trace impurities. • Fe2+ substituted samples exhibit much better rate and cycle properties than LMP/C. [ABSTRACT FROM AUTHOR]

Abstract The need for a quick yet informative technique for diagnosing the lithium-ion batteries is escalating. Conventional impedance-based diagnosis methods are usually time-demanding for a complete electrochemical impedance spectroscopy measurement and involve complicated calculations to extract battery information, which therefore have limited applications in battery monitoring. In this study, we propose a multi-point impedance technique, involving impedance measurement on three characteristic frequency points and being able to separate ohmic, contact and solid electrolyte interphase resistances. The characteristic frequency points are calibrated using distribution of relaxation time method. This multi-point impedance technique holds potential for large-scale high-throughput battery monitoring and screening. Graphical abstract Image 1 Highlights • It requires impedance measurement at three frequency points only. • The three frequency points are calibrated using DRT analysis. • It can separate ohmic, contact and SEI resistances. • Utility in monitoring battery aging is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract Sn-based materials are one promising high-capacity anode material for lithium-ion batteries. The practical application of Sn-based materials is generally restricted by their significant capacity fading due to the volume expansion and structural changes during Sn alloying/dealloying process. In this work, Sn-SnO 2 hybrid nanoclusters are embedded into carbon nanotube network, forming a Sn-SnO 2 @CNT composite. The Sn-SnO 2 nanoclusters are consisted of interconnected Sn and SnO 2 nanocrystals, in which SnO 2 forms a beneficial environment for the alloying/dealloying of Sn. The ultrafine particle size of SnO 2 (<10 nm) also allows a highly reversible conversion reaction, contributing to high overall capacities. The Sn-SnO 2 nanoclusters are uniformly dispersed in CNT matrix, therefore providing abundant active sites for Li-ion storage. The CNT matrix functions in improving electrical conductivity, preventing Sn aggregation, and accommodating Sn volume change in prolonged cycles. As a result, the hybrid Sn-SnO 2 @CNT electrode shows excellent rate capability (1059 mAh g−1 at 1 A g−1 and 960 mAh g−1 at 5 A g−1, corresponding to 0.53 mAh cm−2 at 0.5 mA cm−2 and 0.48 mAh cm−2 at 2.5 mA cm−2) and outstanding cycling stability (86% capacity retention after 1000 cycles at 0.5 A g−1), making it an promising anode material for high-performance lithium-ion batteries. Highlights • Sn-SnO 2 hybrid nanoclusters are loaded onto conductive CNTs via facile methods. • Reversible alloying reactions are achieved in Sn with small mechanical crushing. • The Sn-SnO 2 @CNT composite delivered significantly increased performances. [ABSTRACT FROM AUTHOR]

Abstract Transition metal hydroxides are recently investigated due to its higher capacity than that of relative oxides for lithium storage in lithium ion batteries. Here, sheet-stacking Ni(OH) 2 /graphene compound is synthesized by a facile stirring solvothermal method. The as-prepared Ni(OH) 2 in the compound is proved to be β-Ni(OH) 2 and large BET specific surface area of 53.9 m2 g−1 is obtained with a total pore volume of 0.218 cm2 g−1. The graphene sheet in the sheet-stacking structure not only offers fast electronic transfer through carbon meshwork, but also serves as an efficient buffer to release the inner stress and stop the falling of the active material. Thus, high reversible discharge/charge capacity of 1132/1123 mAh g−1 can be obtained after 100 cycles at current density of 100 mA g−1. The rate capability is also improved. In addition, Ni(OH) 2 /graphene exhibits excellent cycle stability at high current density. Discharge/charge capacities of 702/691 and 592/587 mAh g−1 are obtained at 1.0 and 2.0 A g−1 after 200 cycles at room temperature. It distinctly reveals that such special sheet-stacking hydroxide/graphene compound obtained through stirring solvothermal reaction with enhanced cycle performance and rate capability will be a promising anode material for lithium ion battery. Highlights • Sheet-stacking Ni(OH) 2 /graphene is get via stirring solvothermal method. • β-Ni(OH) 2 /GO sheet is obtained with large surface area and pore volume. • Reversible capacity of 1132 mAh g−1 are obtained after 100 cycles at 0.1 A g−1. • Ni(OH) 2 /GO delivers 702 mAh g−1 at 1.0 A g−1 after 200 cycles. [ABSTRACT FROM AUTHOR]

Abstract Wide application of high capacity anode materials for Li ion batteries (LIBs) is hindered by their structural instability. Assembling graphene and high capacity nanostructures with tight interaction is highly desirable for obtaining high performance anode materials. Here, we report a novel hydrothermal synthesis of homogeneous graphene-wrapped MnO nanowires. MnCO 3 anchors formed by the redox reaction between graphene oxide (GO) and MnOOH have helped to assemble the core-shell structured nanowires. With an optimized graphene amount, the graphene-wrapped MnO nanowires exhibit high reversible capacities at a low voltage platform ∼1 V (1185 mAh g−1 at 50 mA g−1), excellent rate performance (884 mAh g−1 at 500 mA g−1 and 508 mAh g−1 at 3 A g−1), high initial coulombic efficiency (86.3%), and long-term cyclic stability (undiminished after 500 cycles at 1 A g−1). These remarkable electrochemical performances in LIBs are significantly associated with the special core-shell conductive framework. Our results show that the highly reactive groups in GO can be used to in-situ assemble graphene-coated nanostructures, and that the MnO-graphene core-shell nanowires are promising anode candidate for LIBs. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract The anode of Ge has attracted extensive attention due to its high theoretical capacity and energy density. A composite of hierarchically structural Ge encapsulated with nitrogen-doped carbon has been successfully synthesized by using a scalable method. Such a composite properly combines the two superiorities of hierarchically structural Ge and nitrogen-doped carbon, showing a superior electrochemical performance. Designed as an anode for lithium ion batteries, a high reversible capacity of 1067 mA h g−1 after 300 cycles at 1 A g−1, an outstanding rate capabilities of 1270 mA h g−1 at 0.1 A g−1 and 605 mA h g−1 at 20 A g−1 and a stably long-term capacity of 912 mA h g−1 after 600 cycles at 2 A g−1 were achieved. The hierarchically structural electrode could promote the diffusion of electrolyte into anode of Ge particles, and the nitrogen-doped carbon could strengthen the stability of structure and enhance electrical conductivity of the composite. This work could pave a new route for developing Ge-based anodes in next-generation lithium ion batteries and high-energy-storage devices. Graphical abstract Unlabelled Image Highlights • The composite was composed of hierarchically structural Ge encapsulated by N-doped carbon. • The synergistic effects between hierarchically structural Ge and N-doped carbon shell • The composite anode exhibited a high reversible capacity of 1064 mA h g−1 at 1 A g−1. • A capacity of 605 mA h g−1 can be remained even at a rate as high as 20 A g−1. [ABSTRACT FROM AUTHOR]

Abstract Li 4 Ti 5 O 12 as the well-known "zero strain" anode material for lithium ion batteries (LIBs) suffers from low intrinsic ionic and electronic conductivity. The strategy of lattice doping has been widely taken to relieve the intrinsic issues. But the roles of the dopants are poorly understood. Herein, we propose to modulate the crystal structure and improve the electrochemical performance of Li 4 Ti 5 O 12 by substituting Li and Ti with Ca and Sm, respectively. The roles of Ca and Sm on the crystal structure and electrochemical performances have been comprehensively investigated by means of X-ray diffraction (XRD), neutron diffraction (ND) and electrochemical analysis. The Rietveld refinement of ND data indicate that Ca and Sm prefer to take 8a site (tetrahedral site) and 16d site (octahedral site), respectively. Li 3.98 Ca 0.02 Ti 4.98 Sm 0.02 O 12 has the longer Li1-O bond and shorter Ti-O bond length which reduces Li+ migration barrier as well as enhances the structure stability. Ca-Sm co-doping also alleviates the electrode polarization and enhances the reversibility of oxidation and reduction. In compared to bare Li 4 Ti 5 O 12 and Li 3.95 Ca 0.05 Ti 4.95 Sm 0.05 O 12 , Li 3.98 Ca 0.02 Ti 4.98 Sm 0.02 O 12 electrode shows the lower charge transfer resistance, higher Li+ diffusion coefficient, better rate capability and cycling performance. The proposed insights on the roles of dopants are also instructive to design high performance electrode materials by lattice doping. Graphical abstract Image Highlights • Ca and Sm prefer to take 8a site and 16d site, respectively. • Ca-Sm co-doping expand Li1-O bond and shorten Ti-O bond length. • Ca-Sm co-doping alleviates the electrode polarization. • Li 3.98 Ca 0.02 Ti 4.98 Sm 0.02 O 12 shows lower charge transfer resistance and higher Li+ diffusion coefficient. • Li 3.98 Ca 0.02 Ti 4.98 Sm 0.02 O 12 has better rate capability and cycling performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Silicon is one of the most promising candidates for anodes of lithium ion batteries attributed to the highest theoretical specific capacity (4200 mAh/g). However, the conductivity and structural integrity during the lithiation-delithiation process are very poor, which seriously affect the actual electrochemical performance. To address these issues, we introduce graphene framework as both structural skeletons and conductive networks for silicon in this work. Through a facile freeze-drying approach, Si nanoparticles are successfully anchored on graphene sheets uniformly, and graphene form strong and conductive framework, which serves as mechanical support, electrical network, and buffer layer for Si, highly improving the structural integrity and conductivity. The electrochemical examinations indicate that the synthesized graphene-Si aerogels can deliver 104% specific capacity retention after cycled for 195 times at 0.8 A/g. Multi-walled carbon nanotubes are utilized to improve the rate property, and the resulting anode exhibits average specific capacities of 1415, 1209, 1057, 888, 781, and 646 mAh/g at charge/discharge rates of 0.05 C, 0.18 C, 0.2 C, 0.5 C, 1 C, and 2 C, respectively. Benefit from the facile synthesis and excellent cycling stability, it is expected that graphene-Si aerogels may play an important role in lithium ion battery. [ABSTRACT FROM AUTHOR]

Abstract SnO 2 has attracted growing attention as a promising anode material for next generation of Lithium ion batteries because of its high theoretical capacity (1494 mAh g−1) and low working potential. However, the severe volume change during cycling remains one of the great challenges for its practical application. To overcome the obstacle, we propose to utilize the SnO 2 quantum dots loaded on the sulfur-doped reduced graphene oxides by one-pot synthesis. The SnO 2 quantum dots are uniformly dispersed on the sulfur-doped reduced graphene oxides and retain their tiny sizes during the electrochemical reaction, thus alleviate the volume expansion. Meanwhile, the sulfur-doped reduced graphene oxides introduces many defects and can benefit charge transfer and lithium ion diffusion in the electrode. With the synergetic effect between SnO 2 quantum dots and sulfur-doped reduced graphene oxides, the composite anode material can deliver a specific capacity of 897 mA h g−1 at 100 mA g−1 and maintain 88% of original capacity after over 500 cycles at 500 mA g−1, featuring large lithium ion storage capacity and high stability. Graphical abstract SnO 2 quantum dots anchored on 3D S-doped graphene were fabricated via a facile hydrothermal method, and the synergistic effect between the constituent parts ensured the hybrid structure with large lithium storage capacity and long cycle life. Image 1 Highlights • A facile in situ fabrication method is utilized to construct the nano-micro multi-scaled hybrid networks. • SnO 2 quantum dots can restrain the structure collapse during cycling process. • Sulfur-doping into graphene substrate leads to lower charge transfer impedance and faster lithium ion diffusion. • The synergistic effect between quantum dots and S-doped graphene provide high anode performance. [ABSTRACT FROM AUTHOR]

To improve the lithium storage capacity, electrochemical kinetics and stability of TiO 2 nanostructured electrode, a hybrid electrode of TiO 2 nanotubes coated with nitrogen-doped carbon (TiO 2 @NC) was rationally designed and prepared. With the unique coaxial nanotube structure, the porous TiO 2 nanotubes would offer short paths for Li + diffusion and numerous active sites, while the N-doped carbon matrix would prefer fast charge transportation and buffer the volume change of TiO 2 during lithiation/delithiation processes. In particular, a high reversible specific capacity of 480 mA h g −1 at a current density of 100 mA g −1 was achieved when evaluated as anodes for lithium ion batteries. The high capacity, outstanding cycling stability, and remarkable rate performance may attributed to its unique morphology and the synergetic effect of porous TiO 2 nanotube and conductive N-doped carbon nanoshell on the basis of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). [ABSTRACT FROM AUTHOR]

Abstract Ni-rich layered oxide (Ni-rich NCM) is a promising advanced cathode material for lithium-ion batteries (LIBs) because of its high specific capacity. However, the high Ni content in the layered structures is associated with poor surface stability, which in turn accelerates the capacity fading of the cell. To improve the interfacial stability of Ni-rich NCM cathode material, we propose poly(thiophene)-based artificial cathode-electrolyte interphase (CEI)-immobilized Ni-rich NCM cathode material, synthesized using a simple and convenient one-step spin-coating process. At room-temperature cycling, cells with thiophene-modified NCM811 cathodes exhibit improved cycling retention (>91.3%), compared those with bare NCM811 (84.2%). The effectiveness of the artificial CEI layer is evident during high-temperature cycling: cells with 36 kDa-NCM811 exhibit a specific capacity retention of 89.4%, whereas those with bare NCM811 exhibit a drastic decrease in the cycling retention capacity (55.1%) at 55 °C. XPS analyses reveal that the improved electrochemical performance of cells with cycled NCM811 cathodes is due to the surface stability of the cathode; the decomposed adducts in the recovered 36 kDa-NCM811 cathodes are less, whereas they are present in considerable amounts in the cycled NCM811 cathode. In addition, it is confirmed that the molecular weight of the polymer used for the artificial CEI-layer formation significantly affects the electrochemical performance of the cell; polymers with low molecular weights are preferred because P3HTs with low molecular weight have high crystallinity with a hard phase, particularly at high temperature, due to their low T g. Highlights • Thiophene-initiated artificial CEI layer is immobilized on Ni-rich NCM cathode. • Artificial CEI layer effectively suppresses electrolyte decomposition on electrode. • NCM modified by artificial CEI layer gives improved high temperature cycling. [ABSTRACT FROM AUTHOR]

Abstract LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode thin films were prepared on Pt-coated stainless steel (SS) substrates by radio-frequency magnetron sputtering. The layers were post-annealed at 500, 600 and 700 °C to study the impact of thermal treatment on the crystallization of the cathode material. As the annealing temperature increases, interdiffusion occurs between the substrate and the LNMO film, which degrades the electrochemical properties of the cathode film. In order to mitigate this problem, an In-Sn-O (ITO) interlayer was introduced between Pt and the SS substrate. The ITO film is electrochemically stable and acts as an effective diffusion barrier between the substrate and the LNMO layer, which results in improved electrochemical properties of the LNMO film for a lithium ion battery. [ABSTRACT FROM AUTHOR]

Resynthesized cathode active materials from the leaching solution of spent lithium ion batteries can contain a Cu impurity element, which is anode current collector. There is also a lack of consensus on the effects of Cu doping element/impurity in cathode active materials. We synthesize LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NCM) active materials with the addition of Cu. The effects of Cu on the electrochemical properties (initial charge/discharge capacity, rate capability, and cycleability) of NCM cathode are investigated under different experimental conditions such as cutoff voltage and temperature. Initial charge/discharge capacities gradually decrease and rate capability deteriorates with increasing the Cu content. The enhanced capacity retention of NCM with a certain range (∼1.5 mol%) of Cu content is obtained. A decline in the discharge capacity of the full cell, where graphite is adopted as anode active material, is more prominent than that of the half cell. Whereas the graphite anode before cycling contains no metal component on the surface, the surface composition on the graphite anode after cycling is dominated mostly by Cu, followed by Mn, with a negligible amount of Co and Ni. Cu in the NCM cathode dissolves and the dissolved Cu ions are deposited on the graphite surface, which would deteriorate the full cell performance. [ABSTRACT FROM AUTHOR]

Intercalation of lithium ions into the electrodes of lithium ion batteries is affected by the stress of active materials, leading to energy dissipation and stress dependent voltage hysteresis. A reaction-diffusion-stress coupling model is established to investigate the stress effects under galvanostatic and potentiostatic operations. It is found from simulations that the stress hysteresis contributes to the voltage hysteresis and leads to the energy dissipation. In addition, the stress induced voltage hysteresis is small in low rate galvanostatic operations but extraordinarily significant in high rate cases. In potentiostatic operations, the stresses and stress induced overpotentials increase to a peak value very soon after the operation commences and decays all the left time. Therefore, a combined charge-discharge operation is suggested, i.e., first the galvanostatic one and then the potentiostatic one. This combined operation can not only avoid the extreme stress during operations so as to prevent electrodes from failure but also reduce the voltage hysteresis and energy dissipation due to stress effects. [ABSTRACT FROM AUTHOR]

Abstract The V 4 P 7 phase is synthesized by a facile high energy mechanical milling (HEMM) using vanadium (V) and red phosphorus (P), and its electrochemical properties and reaction mechanism as an anode for lithium ion batteries (LIBs) are investigated. As-synthesized 100 nm-sized V 4 P 7 nanopowder electrode shows the insertion reaction during lithiation/delithiation by forming the amorphous Li-V-P ternary phase and delivers the high discharge and charge capacities of 1035 and 882 mA h g-1, respectively, with a high Coulombic efficiency of 85% at the current density of 100 mA g−1. In addition, V 4 P 7 nanopowder is encapsulated with the conformal carbon layer, which is achieved through polymerization of dopamine and subsequent carbonization. As-fabricated core-shell V 4 P 7 @C nanocomposite electrode exhibits the much improved high rate capability and long cycle stability, delivering a high capacity of 388 mA h g-1 after 200 cycles at a high current density of 1 A g−1, which is attributed to high electrical conductivity, high Li+ ion mobility, and structural stability to restrict the aggregation and pulverization of active materials. Graphical abstract Image 1 Highlights • V 4 P 7 is synthesized by a high energy mechanical milling as an anode for LIBs. • V 4 P 7 shows insertion reaction during lithiation by forming amorphous Li-V-P phase. • V 4 P 7 electrode delivers the high discharge capacity of 1035 mA h g-1 at 100 mA g−1. • V 4 P 7 @C shows the enhanced rate capability and high rate long-term cycle stability. [ABSTRACT FROM AUTHOR]

The organic-inorganic multilayer thin film composed of SiO x (nonstoichiometric silicon suboxides) and PI (polyimide) has been synthesized by a hybrid sputtering system combining reactive RF sputtering and pulsed laser deposition. SiO x /PI thin films were deposited on a copper foil to investigate its electrochemical properties. The chemical composition of as-deposited SiO x /PI coatings was measured by a FE-EPMA. The overall multilayered structure was observed by a Scanning Electron Microscopy. The SiO x /PI multilayer thin film anode with proper architecture control exhibits higher columbic efficiency during 1st charge/discharge cycle and better capacity retention as compared to pure SiO x thin film anode. The fracture toughness of SiO x /PI multilayer thin film anode is measured via nanoindentation and be compared to the pure SiO x thin film anode. The results show that the multilayer structure reveals a higher fracture toughness, which leads to a better structure stability during the charge/discharge cycling. [ABSTRACT FROM AUTHOR]

Porous CoP 3 @PPy microcubes are synthesized from the cubic Co 3 [Co(CN) 6 ] 2 precursors followed by PPy coating. When used as anode material for lithium ion batteries, a large specific capacity of 1310 mAh g −1 can be obtained for CoP 3 @PPy composite at 100 mA g −1 , and retains 650 mAh g −1 after 220 cycles at 500 mA g −1 . Even at high current density of 4000 mA g −1 , the CoP 3 @PPy composite still maintains a reversible capacity as high as 800 mAh g −1 . When matched with LiFePO 4 for full battery, a high capacity of 540 mAh g −1 can be obtained at 100 mA g −1 after 100 cycles. The improved lithium storage performance of CoP 3 @PPy is ascribed to the unique porous structure of CoP 3 microcubes and the homogeneous PPy buffer/conducting layers, which can alleviate the giant volume changes and facilitate fast charge transfer during the lithiation/delithiation process. [ABSTRACT FROM AUTHOR]

To address the issues of sluggish electronic transport and large volume variation of Fe 2 O 3 anode nanomaterials caused by repeated Li + insertion/extraction, herein we engineer an erythrocyte-like Fe 2 O 3 with thin mesoporous carbon into yolk-shell architectures, in which the erythrocyte-like Fe 2 O 3 is well confined inside the thin mesoporous carbon. In this design, the erythrocyte-like Fe 2 O 3 cores with high specific capacity together with the permeable thin carbon shells could not only greatly facilitate the fast diffusion for both ion and electron but also retain a thin and stable solid electrolyte interface (SEI) layer on its surface, resulting in excellent rate capability and cycling stability. Meanwhile, the hollow cavity between carbon shell and Fe 2 O 3 core provides extra free space for Fe 2 O 3 expansion, thus preserving the structural integrity. By virtue of their advantageous structural features, the elegant void-containing mesoporous carbon-encapsulated erythrocyte-like Fe 2 O 3 electrodes exhibit superior performance including large capacity, high rate capability and long cycle stability. More importantly, when coupled with commercial LiCoO 2 cathode, the assembled Li-ion full cell demonstrates a high reversible capacity of 615 mA h g −1 after 100 cycles at 1C with capacity retention of 83.4% as well as outstanding rate capability (675 mA h g −1 at 4C with capacity retention of 83% from 0.2C to 4C), demonstrating significant potential for future practical applications. [ABSTRACT FROM AUTHOR]

Graphene like graphite (GLG) samples containing various amounts of oxygen are prepared from the thermal reduction of graphite oxide (GO) and are used as anodes of lithium ion battery. The oxygen/carbon (O/C) ratios in GLG varied from 0 to 0.08, depending on the thermal reduction temperature, oxygen gas pressure during heat treatment and degree of oxidation of the starting GO. The cell voltage during discharge almost linearly increases below 1 V independent of the oxygen contents in them. The discharge capacity of GLG above 1 V increases with the increase in the oxygen content with a slope of lithium/oxygen ratio of 3 at lower O/C ratios. Then the slope becomes smaller and the discharge capacity reaches 673 mAhg −1 for GLG with O/C = 0.08. When GLG is treated with hydrogen gas, considerable amounts of oxygen atoms are substituted by hydrogen ones. The discharge capacity of the resulting GLG samples is larger than that expected form their oxygen contents and coulombic efficiency is slightly improved up to 59%. Introduction of oxygen atoms within carbon layers results in the large increase in the interlayer spacing during charging, which leads to accommodation of large amounts of lithium ions. [ABSTRACT FROM AUTHOR]

The olivine polymorph LiCoPO 4 was synthesized by solvothermal and a subsequent annealing process. Carbon free, ex-situ carbon coated and in-situ carbon coated materials were prepared. With the addition of citric acid in the solvothermal reaction, a carbon layer was coated via an in-situ approach. To systematically compare the different carbon coating routes, the structure and morphology of the LiCoPO 4 materials were investigated by XRD, Raman, and SEM. HAADF-STEM combined with EDX was applied to analyze the homogeneity of the carbon layer and corresponding antisite defects. Electrochemical properties were analyzed by half-cells measuring cyclic-voltammograms, charge/discharge cycling behavior stability and rate-capability. It was found that the in-situ carbon coated LiCoPO 4 /C exhibited a superior electrochemical performance due to the relatively uniform and complete surface-layer formation. As a result, an appropriate carbon layer improves the electronic and ionic transport properties, ensures fast electron-transfer kinetics at the electrode particle surfaces and suppresses unwanted side reactions with the electrolyte. [ABSTRACT FROM AUTHOR]

Waste antibiotics into the natural environment are the large challenges to the environmental protection and the human health, and the unreasonable disposal of the expired antibiotics is a major pollution source. Herein, to achieve the innocent treatment and the resource recovery, the expired tetracycline was tried to be reutilized as the electrode active material in lithium ion battery (LIB) for the first time. The micro-structure and element component of the expired tetracycline were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the corresponding electrochemical performances were also investigated by galvanostatic charge/discharge and cyclic voltammetry (CV). To be satisfactory, the expired-tetracycline-based electrode delivered the initial specific discharge capacity of 371.6 mAh/g and the reversible specific capacity of 304.1 mAh/g after 200 cycles. The decent results will not only offer an effective strategy to recycle the expired tetracycline, but also shed a new light on the cyclic economy and the sustainable development. [ABSTRACT FROM AUTHOR]

A series of two-dimensional ternary selenides, [NH 4 ] 2 [Ga 2 Sn 2 Se 8 ] (1), [NH 4 ] 2 [In 2 Ge 2 Se 8 ] (2), [NH 4 ] 2 [In 2 Sn 2 Se 8 ] (3), [NH 4 ] 2 [Ga 2 Ge 2 Se 8 ] (4), have been solvothermally synthesized and characterized by single crystal X-ray diffraction, energy dispersive X-ray (EDX) spectroscopy, solid-state UV–Vis diffuse reflectance spectroscopy, and thermogravimetric analyses. The solid-state optical absorption spectra indicated that these compounds were semiconductors with band gaps of 1.71 eV for 1, 1.95 eV for 2, 1.85 eV for 3, and 1.83 eV for 4. In addition, compound 2 was employed as an anode material for lithium ion battery application, which exhibited a high specific capacity of 479 mA h g −1 over 200 cycles at a current density of 200 mA g −1 , and an excellent rate capability of 425.2 mA h g −1 at a current density of 1000 mA g −1 . Our results suggest that crystalline chalcogenides could be an alternative anode material for high performance LIBs application. [ABSTRACT FROM AUTHOR]

In this work, N-doped biomass derived porous carbon (NSBDC) has been prepared utilizing low-cost agricultural waste--sugarcane bagasse as the prototype, and needle-like PANI as the dopant. NSBDC possesses a special 3D interconnected framework structure, superior hierarchical pores and suitable heteroatom doping level, which benefits a large number of applications on ion storage and high-rate ion transfer. Typically, the NSBDC exhibits the high specific capacitance (298 F g −1 at 1 A g −1 ) and rate capability (58.7% capacitance retention at 20 A g −1 ), as well as the high cycle stability (5.5% loss over 5000 cycles) in three-electrode systems. A two-electrode asymmetric system has been fabricated employing NSBDC and the precursor of NSBDC (sugarcane bagasse derived carbon/PANI composite) as the negative and positive electrodes, respectively, and an energy density as high as 49.4 Wh kg −1 is verified in this asymmetric system. A NSBDC-based whole symmetric supercapacitors has also been assembled, and it can easily light a 1.5 V bulb due to its high energy density (27.7 Wh kg −1 ). In addition, for expanding the application areas of NSBDC, it is also applied to lithium ion battery, and a high reversible capacity of 1148 mAh g −1 at 0.1 A g −1 is confirmed. Even at 5 A g −1 , NSBDC can still deliver a high reversible capacity of 357 mAh g −1 after 200 cycles, indicating its superior lithium storage capability. [ABSTRACT FROM AUTHOR]

Derivates of metal-organic frameworks are promising materials of self-supported Li ion battery anodes due to the good dispersion of active materials, conductive scaffold, and mass transport channels in them. However, the discontinuous growth and poor adherence of metal-organic framework films on substrates hamper their development in self-supported electrodes. In the present study, cobalt-based metal-organic frameworks are anchored on Ti nanowire arrays through an electrochemically assistant method, and then the metal-organic framework films are pyrolyzed to carbon-containing, porous, self-supported anodes of Li ion battery anodes. Scanning electron microscope images indicate that, a layer cobaltosic oxide polyhedrons inserted by the nanowires are obtained with the controllable in-situ synthesis. Thanks to the good dispersion and adherence of cobaltosic oxide polyhedrons on Ti substrates, the self-supported anodes exhibit remarkable rate capability and durability. They possess a capacity of 300 mAh g −1 at a rate current of 20 A g −1 , and maintain 2000 charge/discharge cycles without obvious decay. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NRC/Si composite is prepared through a facile self-assembly process. • NRC/Si composite possesses a two-dimensional structure. • Rich-nitrogen doping improves the electronic conductivity of the composites. • NRC/Si anode exhibits high reversible capacity and excellent rate capability. Abstract The two-dimensional (2D) carbon material shows great superiority in improving the electrochemical performance of silicon-based anode for lithium ion batteries. We synthesize a nitrogen-rich carbon/silicon composite (NRC/Si) with a graphene-like structure by an amino-carboxyl self-assembly of the citric acid, melamine and Si-NH 2. The NRC/Si composite with a two-dimensional structure can effectively buffer the volume change of silicon material during cycling. Moreover, the rich-nitrogen doping improves the electronic conductivity and facilitates the charge transfer during charge and discharge process. The NRC/Si as anode material for lithium ion batteries shows good cycle stability and rate capability, delivering a reversible capacity of 1000 mA h g−1 after 300 cycles at 2 A g−1 and 572 mA h g−1 even at 5 A g−1, respectively. In addition, the synthesis method of the NRC/Si composite is cost-effective, environmentally friendly and industrially scalable, which makes it very promising to obtain the high-performance anode materials in lithium ion batteries. [ABSTRACT FROM AUTHOR]

A kind of novel three-dimensional SnS 2 array was fabricated by an ethylenediamine (EDA) assisting low-temperature solvothermal method. It was observed that as-obtained SnS 2 array was composed of numerous SnS 2 nanosheets with the thickness of about 22 nm. When used as lithium ion batteries (LIBs) anode, the SnS 2 array displayed remarkable capacities on rate and cycling performances, delivering the rates with reversible capacities of 763.3, 658.6, 593.6, 554.4 and 450.3 mAh g −1 at the current densities of 0.2, 0.5, 1, 2 and 5 A g −1 , respectively. Moreover, the satisfactory cycling performance was also disclosed, remaining capacity of 547.8 mAh g −1 after 100th cycle at 0.2 A g −1 , better than some reported pure SnS 2 nanostructures. Based on the characterization and experimental results, the reasons of such superior electrochemical performances were determined and elaborated. It means that the SnS 2 array possesses promising potential on the renewable energy field. [ABSTRACT FROM AUTHOR]

Accurate diagnosis of lithium ion battery state-of-health (SOH) is of significant value for many applications, to improve performance, extend life and increase safety. However, in-situ or in-operando diagnosis of SOH often requires robust models. There are many models available however these often require expensive-to-measure ex-situ parameters and/or contain unmeasurable parameters that were fitted/assumed. In this work, we have developed a new empirically parameterised physics-informed equivalent circuit model. Its modular construction and low-cost parametrisation requirements allow end users to parameterise cells quickly and easily. The model is accurate to 19.6 mV for dynamic loads without any global fitting/optimisation, only that of the individual elements. The consequences of various degradation mechanisms are simulated, and the impact of a degraded cell on pack performance is explored, validated by comparison with experiment. Results show that an aged cell in a parallel pack does not have a noticeable effect on the available capacity of other cells in the pack. The model shows that cells perform better when electrodes are more porous towards the separator and have a uniform particle size distribution, validated by comparison with published data. The model is provided with this publication for readers to use. [ABSTRACT FROM AUTHOR]

Si is a promising anode material for lithium-ion batteries, but suffers from sophisticated engineering structures and complex fabrication processes that pose challenges for commercial application. Herein, a ternary Si/graphite/pyrolytic carbon (SiGC) anode material with a structure of crystal core and amorphous shell using low-cost raw materials is developed. In this ternary SiGC composite, Si component exists as nanoparticles and is spread on the surface of the core graphite flakes while the sucrose-derived pyrolytic carbon further covers the graphite/Si components as the amorphous shell. With this structure, Si together with the graphite contributes to the high specific capacity of this Si ternary material. Also the graphite serves as the supporting and conducting matrix and the amorphous shell carbon could accommodate the volume change effect of Si, reinforces the integrity of the composite architecture, and prevents the graphite and Si from direct exposing to the electrolyte. The optimized ternary SiGC composite displays high reversible specific capacity of 818 mAh g −1 at 0.1 A g −1 , initial Coulombic efficiency (CE) over 80%, and excellent cycling stability at 0.5 A g −1 with 83.6% capacity retention (∼610 mAh g −1 ) after 300 cycles. [ABSTRACT FROM AUTHOR]

Silicon is an ideal candidate anode material for Li-ion batteries (LIBs). However, it suffers from rapid capacity fading due to large volume expansion upon lithium insertion. Herein, we design and fabricate highly stable carbon coated porous Mg 2 Si intermetallic anode material using facile mechano-thermal technique followed by carbon coating using thermal vapour deposition (TVD), toluene as carbon source. The electrode exhibits an excellent first reversible capacity of 726 mAh g −1 at a rate of 100 mA g −1 . More importantly, the electrode demonstrates high rate capability (380 mAh g −1 at high rate of 2 A g −1 ) as well as high cycle stability, with capacity retentions of 65% over 500 cycles. These improvements are attributable to both Mg supporting medium and the uniform carbon coating, which can effectively increase the conductivity and electronic contact of the active material and protects large volume alterations during the electrochemical cycling process. [ABSTRACT FROM AUTHOR]

The rapid capacity fading induced by volumetric changes is the main issue that hinders the widespread application of silicon anode materials. Thus, double-shelled silicon composite materials where lithium silicate was located between an Nb 2 O 5 coating layer and a silicon active core were configured to overcome the chemical compatibility issues related to silicon and oxides. The proposed composites were prepared via a facile co-precipitation method combined with calcination. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis demonstrated that a transition layer of lithium silicate was constructed successfully, which effectively hindered the thermal inter-diffusion between the silicon and oxide coating layers during heat treatment. The electrochemical performance of the double-shelled silicon composites was enhanced dramatically with a retained specific capacity of 1030 mAh g −1 after 200 cycles at a current density of 200 mA g −1 compared with 598 mAh g −1 for a core-shell Si@Nb 2 O 5 composite that lacked the interface. The lithium silicate transition layer was shown to play an important role in maintaining the high electrochemical stability. [ABSTRACT FROM AUTHOR]

In this work, a novel CoO/CoFe 2 O 4 bi-component nanorod coated with S-doped carbon nanospheres shell (CO/CFO@SC Nr) composites have been synthesized through one in-situ polymerization and subsequent annealing treatment. The S-doped carbon shell, special structure and synergistic effect between CoO and CoFe 2 O 4 significantly enhance the electrochemical performance of the CoO/CoFe 2 O 4 anode material. CO/CFO@SC Nr composites present an impressive capacity of 511.3 mAh g −1 after 700 cycles when tested at a high current density of 2000 mA g −1 . In addition, this is the first time that polythiophene is used as sulfur and carbon source to synthesis transition metal oxide (TMO) @S-doped carbon core-shell composites. This work illuminates a new preparation way for fabrication other TMO@S-doped carbon core-shell materials for lithium-ion batteries and other energy storage devices. [ABSTRACT FROM AUTHOR]

Supermolecular complexation with cyclodextrins by non-covalent host-guest interaction is used for various applications. In this work, we fabricated the freestanding and flexible core-shell MnO/carbon nanofiber (CNF) composite thin films by host-guest interaction and high-voltage electrospining technique. The as-prepared composite thin film with dual carbon layer nanofibers showed smaller MnO particle size, lower electron-transfer resistance, and faster lithium ion migration, which were attributed to intermolecular non-covalent assembling behavior among polyacrylonitrile (PAN), β-cyclodextrin (β-CD) and Mn ion. As expected, the composite film as anode in Li-ion battery showed impressive performance: a high reversible capacity (∼1025 mAh g −1 at ∼0.1 A g −1 ), excellent rate capability (∼376 mAh g −1 at ∼5 A g −1 ), and superior cyclability (∼844 mAh g −1 at the current density of ∼1 A g −1 after 800 cycles). Such outstanding electrochemical performance endows the MCNFs composites with great potential as anode material for LIBs. [ABSTRACT FROM AUTHOR]

We report a comprehensive and systematic study on the preparation and characterization of carbonaceous materials that are obtained from five different sustainable precursor materials and petroleum coke as reference material, particularly focusing on the correlation between the structural transformation of the precursors into carbons in dependence of heat treatment temperature (HTT) and their corresponding electrochemical characteristics as anode material in lithium ion batteries. The carbons were carbonized and graphitized in 200 °C steps, covering a broad temperature range from 800 °C to 2800 °C. So far, such a systematic synthesis approach has not been reported in literature. For biomass-derived carbons, we found a heterogeneous (discontinuous) graphitization process, i.e. a transformation from the amorphous to the graphitic phase via the turbostratic phase. A general trend was observed for the discharge capacity, i.e. a decrease of capacity from 800 °C to ≈1800–2000 °C, followed by an increase of capacity for temperatures >2000 °C. An increase of the 1 st cyle Coulombic efficiency was found and could be directly correlated to the decrease of the “non-basal plane” surface area upon HTT. In addition, we found that the voltage efficiency and energy efficiency of the different carbons also increase with rising treatment temperatures. [ABSTRACT FROM AUTHOR]

The intercalation and aging induced volume changes of lithium-ion battery electrodes lead to significant mechanical pressure or volume changes on cell and module level. As the correlation between electrochemical and mechanical performance of lithium ion batteries at nano and macro scale requires a comprehensive and multidisciplinary approach, physical modeling accounting for chemical and mechanical phenomena during operation is very useful for the battery design. Since the introduced fully-coupled physical model requires proper parameterization, this work also focuses on identifying appropriate mathematical representation of compressibility as well as the ionic transport in the porous electrodes and the separator. The ionic transport is characterized by electrochemical impedance spectroscopy (EIS) using symmetric pouch cells comprising LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) cathode, graphite anode and polyethylene separator. The EIS measurements are carried out at various mechanical loads. The observed decrease of the ionic conductivity reveals a significant transport limitation at high pressures. The experimentally obtained data are applied as input to the electrochemical-mechanical model of a prismatic 10 Ah cell. Our computational approach accounts intercalation induced electrode expansion, stress generation caused by mechanical boundaries, compression of the electrodes and the separator, outer expansion of the cell and finally the influence of the ionic transport within the electrolyte. [ABSTRACT FROM AUTHOR]

Cobalt vanadates have been demonstrated as superior anode candidates for lithium ion batteries (LIBs) owing to their unique advantages, such as superb specific capacity, low operating potential, and excellent cycling stability. Among the cobalt vanadates, Co 3 V 2 O 8 manifests tremendous potential of commercialization because of their controllable particle size and morphology. In this study, we readily synthesized both hollow and solid Co 3 V 2 O 8 micro-pencils and thoroughly compared their electrochemical properties. Employed as anode for LIBs, the hollow Co 3 V 2 O 8 exhibited much higher initial specific capacity than the solid ones (∼1200 mAhg −1 vs. ∼680 mAhg −1 ). When tested at 1000 mAg −1 , the hollow Co 3 V 2 O 8 displayed superior reversible capacity over the solid ones (∼650 mAhg −1 vs. ∼450 mAhg −1 after 300 cycles), benefiting from the hollow architecture. Moreover, the hollow micro-pencils showed better rate performance, with outstanding stability and capacity loss when higher current density was applied. The comparative study demonstrated the hollow Co 3 V 2 O 8 is more efficient than the solid ones for LIB anodes. Based on the comparison on pure micro-pencils, further approach (e.g. graphene coating) can be exploited for superior performance towards ultimate application in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Two electrochemical reactions are possible in regard to Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 (0.5Li 2 MnO 3 −0.5LiNi 0.33 Mn 0.33 Co 0.33 O 2 ), viz, Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like reactions. The open circuit potential (OCP) and changes in crystal structure during the charge-discharge process of Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 were investigated to clarify the mechanism responsible for the two reactions. Li 2 MnO 3 and LiNi 0.33 Mn 0.33 Co 0.33 O 2 were separately prepared for the investigation, and the OCPs and crystal structures in these cathodes were measured and then compared with those for Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . The results obtained using X-ray diffraction (XRD) indicated that two phases existed in Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . The changes in crystal structure of the two phases during the charge-discharge process were similar to those in Li 2 MnO 3 and LiNi 0.33 Mn 0.33 Co 0.33 O 2 . This indicated that two phases, viz, Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like, existed in Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . Li 2 MnO 3 -like, LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like, and Li 2 MnO 3 -like phases were found to contribute mainly to electrochemical reactions in the low, middle, and high state of charge (SOC) ranges during the charge process from the results obtained using XRD and electrochemical measurements carried out on Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . In contrast, the Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like phases mainly contributed to electrochemical reactions in the low and high SOC ranges during the discharge process. Furthermore, the high polarization and potential decay during the charge-discharge cycling of Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 were mainly attributed to the Li 2 MnO 3 -like phase. [ABSTRACT FROM AUTHOR]

Iron fluorides based on conversion chemistry are developed as alternative cathode materials for Li-ion batteries due to their high capacity, also suffering from some drawbacks, such as poor electrical conductivity and structural instability. In order to improve the electrochemical performance of iron fluoride, in this work, we focus on the enhancement of the lithium extraction capability of FeF 3 by introducing extra C@LiF additive. FeF 3 /C@LiF composites are fabricated by high energy ball milling. Due to the compact connection between LiF and conductive carbon in FeF 3 /C@LiF composites, LiF can not only act as high-active reactant for lithium extraction process, but also provide active sites for subsequent charge/discharge reaction. Electrochemical study results suggest that a suitable content of LiF enables FeF 3 /C@LiF composite to deliver a satisfactory electrochemical performance, which retain a capacity of 229 mAh g − 1 at a current rate of 40 mA g − 1 after 50 cycles (10% higher than that of FeF 3 /C composite). [ABSTRACT FROM AUTHOR]

Bulk graphite is widely used in today's Li-ion batteries as an anode material due to its high cycling stability. However, graphite's low capacity and rate capability prevent its application in high power density batteries. Here, a nanostructured carbon, consisting of vertical carbon nanotubes on few-layer graphene, has been synthesized and tested as an anode material for high capacity Li-ion batteries. In this synthesis, a simple hydrothermal method was used to assemble homogeneous distributed Fe 2 O 3 nanoparticles on few-layer graphene based on van der Waals interaction, and these were then used as a catalyst to grow carbon nanotubes further by means of a chemical vapor deposition method. The electrochemical properties of the nanocomposites were measured. A reversible capacity of 525 mAh g −1 after 1000 cycles at 500 mA g −1 with Coulombic efficiency in excess of 98% was accomplished. Voids between vertical carbon nanotubes provide a short diffusion path for both electron and Li-ion, and the defects in carbon nanotubes provide more storage sites for lithium. Three kinds of nanocomposites with different carbon nanotube diameters were synthesized and characterized. The influence of the carbon nanotube diameter and morphology on the lithium storage properties of these nanocomposites was also studied. [ABSTRACT FROM AUTHOR]

Here, we designed a facile solvothermal method to prepare Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 hollow microspheres with considerable uniformity and monodispersity. In this method, lithium ions and transition metal carbonate have been simultaneously precipitated in the ethanol-polyethylene glycol mixed solvent system to form carbonate precursors, which subsequently transform into self-assembled hollow microspheres by a heat treatment. As cathode material for lithium ion batteries, its unique structure makes for sufficient contact between electrode and electrolyte to provide more reaction sites and shorter paths for Li + transportation, contributing to remarkable cycling stability and excellent rate capability with improved electrochemical kinetics properties. Specifically, Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 hollow microspheres achieve a high initial discharge capacity of 287 mAh g −1 at 0.1 C and 234 mAh g −1 at 1 C, with capacity retentions of 85.7% and 81.3% after 100 cycles, respectively. Besides, it exhibits a high rate capacity of 150 mAh g −1 even at 5 C. Moreover, the present synthesis method could also provide an effective and promising strategy for the preparation of high energy density cathode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The carbon nanotubes (CNTs) branched on three-dimensional (3D) macroporous, nitrogen-incorporated reduced graphene oxide (NG)/iron oxide (CNT/NG-Fe) hybrid architectures have been prepared via an ice templating and microwave synthesis. Compared with the pristine RGO, the CNTs can be more readily and uniformly grown on the 3D NG surfaces due to the good electronic conductivity by N-type configurations. As demonstrated by the electrochemical performances, the discharge capacity of the 3D CNT/NG-Fe is 1208 mAh g −1 at 50 mA g −1 which is greater than 890 and 820 mAh g −1 of the CNT/G-Fe and NG. When the rate increases from 100 to 1000 mAh g −1 , the capacity retention reaches 52% of initial capacity corresponding to the discharge capacity of 947 mAh g −1 . After 130 cycles at 100 mA g −1 , the capacity gradually increases to 1020 mAh g −1 with the Coulombic efficiency of >98.5%. The enhanced capacity, rate capability and cyclic stability of the CNT/NG-Fe are associated with the doping effect of N-configuration and unique hierarchical structure consisting of the dense CNT branches on 3D macroporous continuity. [ABSTRACT FROM AUTHOR]

Functionalized graphite oxide films are synthesized by using (NH 4 ) 2 SO 4 during self-assembly process of graphite oxide in water. Instead of stacking layer by layer, graphite oxide films with three-dimensional (3D) structure are obtained due to strong hydration of ions from (NH 4 ) 2 SO 4 . After low temperature treatment (400 °C) of the self-assembly films, (NH 4 ) 2 SO 4 decomposes and N-doped films are obtained, the films can be used directly as anodes for lithium ion batteries. According to electrochemical test, the 3D self-assembly films exhibit enhanced lithium ion storage performances such as initial coulombic efficiency and specific capacity due to 3D structure and N atoms. Further studies show that owing to low chemical activities of graphitic structure in air, low temperature treatment (400 °C) under different atmospheres (N 2 or air) has little effect on structures and electrochemical performances of 3D self-assembly films, which is meaningful for producing the films on a large scale in the future. [ABSTRACT FROM AUTHOR]

The double shell SnO 2 @amorphous TiO 2 spheres were obtained by morphology-controlled method in this work. The structure and morphology of double shell SnO 2 @amorphous TiO 2 were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier infrared spectrometer (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). The electrochemical performance of SnO 2 @amorphous TiO 2 as anode materials for lithium ion battery were further analyzed by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The results demonstrate that SnO 2 @amorphous TiO 2 has inner diameter 300 nm, and the thickness of SnO 2 shell is about 15 nm. The cycling performance of composites is stable benefited from the reasonable structure designing as well as the amorphous state of TiO 2 . The electrochemical performance including cyclability, the rate capability and charge transfer kinetics of SnO 2 @amorphous TiO 2 is further enhanced by calcining at a higher temperature because the adsorbed water and hydroxyl groups (H 2 O/OH − ) was removed from the surface of amorphous TiO 2 . The charging and discharging capacity of SnO 2 @amorphous TiO 2 can be 334 mAh·g − 1 and 326 mAh·g − 1 respectively after 50 times cycle at a current density of 100 mA·g − 1 . The double shell SnO 2 @amorphous TiO 2 spheres can be a very promising anode material for lithium ion battery. [ABSTRACT FROM AUTHOR]

Molybdenum doping is introduced to improve the electrochemical performance of lithium-rich manganese-based cathode material. X-ray diffraction (XRD) results illustrate that the crystallographic parameters a , c and lattice volume V become larger with the increase of Mo content. The scanning electron microscope (SEM) shows that the molybdenum substitution increases the crystallinity of the primary particles. When evaluated as cathode material, the as-prepared Li[Li 0.2 Mn 0.54- x /3 Ni 0.13- x /3 Co 0.13- x /3 Mo x ]O 2 ( x = 0.007) delivers a discharge capacity of 155.5 mA h g −1 at 5 C (1 C = 250 mA g −1 ) and exhibits the capacity retention of 81.8% at 1 C after 200 cycles. The results of cyclic voltammetry (CV) and electronic impedance spectroscopy (EIS) tests reflect that the molybdenum substitution is able to significantly reduce the electrode polarization and lower the charge-transfer resistance. Within appropriate amount of Mo doping, the lithium ion diffusion coefficient of the material can reach to 8.92 × 10 –15 cm 2 s −1 , which is ~ 30 times higher than that of pristine materials (2.65 × 10 –16 cm 2 s −1 ). [ABSTRACT FROM AUTHOR]

Li 2 Fe 1-x Ti x SiO 4 /C cathode materials are designed and realized by a facile sol-gel method. The effects of various Ti doping amounts on the microstructure and electrochemical performance of Li 2 FeSiO 4 /C are investigated comprehensively. X-ray powder diffraction result confirms the crystal structure of Li 2 Fe 1-x Ti x SiO 4 /C to be monoclinic Li 2 FeSiO 4 with minor decrease in the unit cell volume. X-ray photoelectron spectroscopy shows that Ti does successfully dope into the crystal structure of Li 2 FeSiO 4 . Galvonostatic charge-discharge experiments are used to study the electrochemical performance of Ti-doped Li 2 FeSiO 4 /C as a lithium-ion batteries cathode material. As results, Li 2 Fe 0.98 Ti 0.02 SiO 4 /C exhibits the best electrochemical performance with the discharge capacity of 102.8 and 91.1 mAh g −1 even at 5 and 10 C (1 C = 165 mA g −1 ) high rate after 1000 cycles. Additionally, the electrochemical kinetic performance of Li 2 Fe 1-x Ti x SiO 4 /C is further determined by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic intermittent titration technique. The results indicate that the enhanced electrochemical performance can be attributed to the effect of Ti doping, which not only enhances the structural stability, but also improves the kinetic properties of Li 2 FeSiO 4 /C. [ABSTRACT FROM AUTHOR]

A joint chemical reactor system referred to as an ultrasonic-intensified micro-impinging jetting reactor (UIJR), which possesses the feature of fast micro-mixing, was proposed and has been employed for rapid preparation of FePO 4 particles that are amalgamated by nanoscale primary crystals. As one of the important precursors for the fabrication of lithium iron phosphate cathode, the properties of FePO 4 nano particles significantly affect the performance of the lithium iron phosphate cathode. Thus, the effects of joint use of impinging stream and ultrasonic irradiation on the formation of mesoporous structure of FePO 4 nano precursor particles and the electrochemical properties of amalgamated LiFePO 4 /C have been investigated. Additionally, the effects of the reactant concentration ( C = 0.5, 1.0 and 1.5 mol L −1 ), and volumetric flow rate ( V = 17.15, 51.44, and 85.74 mL min −1 ) on synthesis of FePO 4 ·2H 2 O nucleus have been studied when the impinging jetting reactor (IJR) and UIJR are to operate in nonsubmerged mode. It was affirmed from the experiments that the FePO 4 nano precursor particles prepared using UIJR have well-formed mesoporous structures with the primary crystal size of 44.6 nm, an average pore size of 15.2 nm, and a specific surface area of 134.54 m 2 g −1 when the reactant concentration and volumetric flow rate are 1.0 mol L −1 and 85.74 mL min −1 respectively. The amalgamated LiFePO 4 /C composites can deliver good electrochemical performance with discharge capacities of 156.7 mA h g −1 at 0.1 C, and exhibit 138.0 mA h g −1 after 100 cycles at 0.5 C, which is 95.3% of the initial discharge capacity. [ABSTRACT FROM AUTHOR]

A Ni-Co-Al ternary oxide precursor with a trigonal structure, which can be used to synthesize LiNiCoAlO cathode material, was prepared by calcining Ni-Co-Al composite oxalates formed by using a facile chemical approach. The LiNiCoAlO cathode material calcined at a temperature as low as 650 °C had acceptable electrochemical performance with an initial discharge capacity of 183.9 mAh g. The sample prepared at 750 °C possessed the highest initial discharge capacity of 196.0 mAh g, while the sample calcined at 700 °C showed the optimal capacity retention (89.9%) after 100 cycles under 1 C. To prepare a pure LiNiCoAlO phase by a conventional solid-state reaction, the calcination temperature should exceed 750 °C, and the highest initial discharge capacity was only 185.4 mAh g. We suggest that the ternary oxide precursor with trigonal structure accelerates lithiation and, therefore, promotes the generation of LiNiCoAlO with high crystallinity at a lower temperature. This study provides a facile way to synthesize layered cathode material with good electrochemical performance at a lower calcination temperature. [ABSTRACT FROM AUTHOR]