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As a promising alternative as lithium‐ion anode, niobium dioxide appeals to researchers due to high theoretical capacity and good electron conductivity. However, rarely work about NbO2 based high performance anode is reported. Here, NbO2 nanoparticles emcoated in continuous carbon matrix is constructed through CO2/H2 coupling treatment. CO2 activation introduces unique carbon emcoating structure, which builds interconnected electron conductive network with low carbon content. Furthermore, crystallographic phase of NbO2 is enhanced during H2 treatment, which increases the lithium storage ability. Electrochemical performance of NbO2 anodes is significantly improved based on the carbon emcoating structure. A high reversible capacity of 391 mAh g−1 is retained after 350 cycles at 0.2 C. Additionally, at a current density of 1 A g−1, the reversible capacity reaches 139 mAh g−1. Compared with conventional NbO2/C nanohybrids, the lithium diffusion coefficient of carbon‐emcoated sample shows improvement of three orders of magnitude. Moreover, the in situ XRD investigation shows a reversible lithium insertion behaviour with a limited volume change. [ABSTRACT FROM AUTHOR]

Dual N‐doped TiO2/Si/C ternary nanohybrid has been successfully prepared via a facile solvothermal method. Polyethylene glycol (PEG) is applied to disperse TiO2 and silicon precursors. After polymerization with hexamethylene diisocyanate (HDI) and calcination, N‐doped TiO2 and carbon matrix are obtained. The contents of Si, TiO2 and C in N‐doped TiO2/Si/C are about 10 %, 72 % and 18 % respectively. N‐doped TiO2/Si/C shows an excellent electrochemical performance due to combined advantages of Si, TiO2 and C. The initial discharge/charge specific capacity of the N‐doped TiO2/Si/C is 658/548 mAh g−1 at a current of 0.1 A g−1 with a coulombic efficiency of 83 %. A reversible capacity of 538 mAh g−1 is achieved after 80 cycles. While at the high current of 5 A g1, the specific capacity of the N‐doped TiO2/Si/C can still reach 120 mAh g−1. Electrochemical impedance spectroscopy measurements prove the improved electric conductivity after N‐doping. [ABSTRACT FROM AUTHOR]

Binders play a crucial role in maintaining mechanical integrity of electrodes in lithium‐ion batteries. However, the conventional binders lack proper elasticity, and they are not suitable for high‐performance silicon anodes featuring huge volume change during cycling. Herein, a poly(siloxane imide) copolymer (PSI) has been designed, synthesized, and utilized as a binder for silicon‐based anodes. A rigidness/softness coupling mechanism is demonstrated by the PSI binder, which can accommodate volume expansion of the silicon anode upon lithiation. The electrochemical performance in terms of cyclic stability and rate capability can be effectively improved with the PSI binder as demonstrated by a silicon nanoparticle anode. [ABSTRACT FROM AUTHOR]

CuO based anodes hold a promise alternative to the commercial graphite due to their high reversible capacities, low cost, and environmental friendliness. However, drastic volume change, partial irreversibility, and poor electron conductivity yields compromised the electrochemical performance including reversible capacities, cyclic stability and rate performance. A facile scalable method is developed to synthesize CuO/C nanohybrid lithium‐ion battery anode. Copper nanoparticles are synthesized in situ using the amine based curing agent as both coordination ligand and reducing agent. The copper nanoparticles/amine based curing agent further reacts with the epoxy resin monomers, where the copper nanoparticles are incorporated into the thermosetting polymer network. Due to thermosetting nature of the epoxy polymer, agglomeration of the copper nanoparticles is effectively suppressed during the carbonization process, which are further converted to the CuO nanoparticles within the carbon matrix through heat treatment in air. Systematic structure and electrochemical performance characterizations are carefully studied. The results show that both the reversible capacities are effectively improved in comparision with the bare carbon sample. Moreover, excellent cyclic stability and high rate capability are also demonstrated by the CuO/C nanohybrid. [ABSTRACT FROM AUTHOR]

TiO 2 /SiO x /carbon nanohybrid consisting of super-small sized TiO 2 and SiO x nanoparticles is in situ formed within the in situ formed carbon matrix using difunctional methacrylate monomers as solvent and carbon source. The relative composition of TiO 2 and SiO x is systematically tuned by varying the feeding mass ratio of the precursors (TEOS/TTIP) and HF etching treatment after the carbonization process. The super-small sized TiO 2 and SiO x nanoparticles are well intermixed with each other and homogeneously dispersed throughout the carbon matrix, where a good control over crystallinity, morphology, and microstructure of the nanohybrids is achieved. Synergistic effects are demonstrated from both TiO 2 and SiO x regarding the increased reversible capacity from the SiO x phase and maintenance of good cyclic stability by the TiO 2 component when being used in lithium-ion batteries. A good balance is achieved in terms of reversible capacity, capacity retention, and rate performance in the TiO 2 /SiO 2 /C nanohybrid prepared with the TEOS/TTIP mass ratio of 1.0. The reversible capacities are improved by around two times compared to the SiO x free sample with a good capacity retention of 78 %, which exhibits good rate capability at the current densities up to 3350 mA g−1 as well. TiO 2 /SiO x /C nanohybrids with super-small sized TiO 2 and SiO x nanoparticles well intermixed with each other and homogeneously dispersed in the carbon matrix are prepared, where a good balance is achieved in terms of reversible capacity, capacity retention, and rate capability with the TiO 2 /SiO 2 /C nanohybrid prepared with the TEOS/TTIP mass ratio of 1.0. Image 1 [ABSTRACT FROM AUTHOR]

Super‐small sized TiO2 nanoparticles are in situ co‐composited with carbon and nickel nanoparticles in a facile scalable way, using difunctional methacrylate monomers as solvent and carbon source. Good control over crystallinity, morphology, and dispersion of the nanohybrid is achieved because of the thermosetting nature of the resin polymer. The effects of the nickel nanoparticle on the composition, crystallographic phase, structure, morphology, tap density, specific surface area, and electrochemical performance as both lithium‐ion and sodium‐ion battery anodes are systematically investigated. It is found that the incorporation of the in situ formed nickel nanoparticles with certain content effectively enhances the electrochemical performance including reversible capacities, cyclic stability and rate performance as both lithium‐ion and sodium‐ion battery anodes. The experimental I‐V profiles at different temperatures and theoretical calculations reveal that the charge carriers are accumulated in the amorphous carbon regions, which act as scattering centers to the carriers and lower the carrier mobility for the composite. With increasing nickel content, the mobility of the charge carriers is significantly increased, while the number of the charge carriers maintains almost constant. The nickel nanoparticles provide extra pathways for the accumulated charge, leading to reduced scatterings among the charge carriers and enhanced charge‐carrier transportation. [ABSTRACT FROM AUTHOR]

A novel electrochemically compatible, high-voltage, and nonflammable electrolyte has been prepared based on a fluorinated ether with no flash point, that is, 1,1,1,3,3,3-hexafluoroisopropyl methyl ether (HFPM). Our experimental results demonstrate that this F-electrolyte is not only totally nonflammable in fire burning tests, but it also exhibits a remarkably high anodic stability of at least 5.5 V (vs. Li+/Li). In particular, this F-electrolyte has good compatibility with graphite anodes. Mesocarbon microbeads/LiNi0.5Mn1.5O4 18650 batteries made with this F-electrolyte display an excellent cycling stability with 82 % capacity retention after 200 cycles at a high cutoff voltage of 4.9 V, confirming their potential as high-voltage lithium-ion batteries with enhanced safety and longevity. [ABSTRACT FROM AUTHOR]

Abstract Silicon (Si) is regarded as one of the most promising lithium-ion battery anodes to replace commercial graphite due to its exceptional theoretical capacity, appropriate voltage profile, environmental friendliness and natural abundance. It is crucial to develop effective strategies to improve the cyclic performance of the Si anodes. A new concept to synthesize Si/carbon composite with three dimensional (3D) hierarchical macro-/mesoporous structure is reported. Stöber silica (SiO 2) particles are used as templating agent and precursor for Si simultaneously. Unlike conventional work reported previously, here the silica particles are composited with carbon matrix before magnesiothermic reduction. Difunctional methacrylate monomers are used as solvent and carbon source coupled with a fast, environmental friendly and energy saving photo polymerization to prepare the SiO 2 /C composite. Based on a self-templating mechanism during the magnesiothermic reduction process, 3D hierarchical macro-/mesoporous Si is formed in situ within the carbon matrix. Compared to the Si/carbon composite composed of micro-sized Si and bare macro-/mesoporous Si, the cyclic performance is significantly improved with a reasonable mass loading density. Good rate performance is exhibited comparable to the bare porous Si. The hierarchical macro-/mesoporous structure within the carbon matrix helps to retain the porous Si structure, which effectively improves the electrochemical performance. Graphical abstract Self-templating synthesis of Si/C lithium-ion battery anode with 3D hierarchical macro-/mesoporous Si network encapsulated within the carbon matrix is achieved via a magnesiothermic reduction of SiO 2 /carbon composite, whose cyclic performance is significantly improved compared to the bare porous Si and Si/C composite with micrometer sized Si particles. Image 1 Highlights • Si/carbon was fabricated by magnesiothermic reduction of the silica/carbon composite. • Macro-/mesoporous silicon was encapsulated by carbon via a self-templating process. • Improved cyclic stability and rate performance was exhibited due to unique structure. [ABSTRACT FROM AUTHOR]

Abstract Metallic lithium, with super high theoretical specific capacity, enjoys great potential as an anode for rechargeable batteries. However, safety issues caused by lithium dendrite growth as well as limited cycling life restrict its practical application. Herein we validate that the application of a new dual-salt electrolyte composed of Lithium difluorophosphate (LiPO 2 F 2) and lithium bis(fluorosulfony)imide (LiFSI) in the same proportion enables the improved long-term cycling performance along with high coulombic efficiency for lithium metal batteries. With 1 M LiPO 2 F 2 and 1 M LiFSI in 1,2-dimethoxyethane as the electrolyte, a Li/Cu cell can be cycled at 1 mA for more than 300 cycles with a deposited capacity of 1.0 mAh. It also displays that a homogeneous and dendrite free solid electrolyte interphase layer is generated on the Cu electrode, which can be ascribed to the favorable stability of LiPO 2 F 2 and high ionic conductivity of LiFSI. These results deliver perceptions for the advancement of high-performance lithium metal anode. Highlights • A dual-salt electrolyte composed of LiPO 2 F 2 and LiFSI is proposed for LMBs. • The electrolyte shows high ionic conductivity and wide electrochemical windows. • Improved cyclic stability and high coulombic efficiency have been achieved. • Low voltage polarization and dendrite-free SEI layer have been observed. [ABSTRACT FROM AUTHOR]

Pre-lithiation technology is essential to improve the initial coulombic efficiency (ICE) and cycling stability of high SiO x content cells. Different amounts of pre-lithiation significantly affect the electrochemical performance of cells. In this study, three groups of LiNi 0.8 Co 0.1 Mn 0.1 O 2 || SiO x /Graphite pouch cells (SiO x , 45 wt%) with different pre-lithiation amounts are fabricated using an electrochemical pre-lithium method. The effects of pre-lithiation amounts on the capacity and cycling stability are comprehensively investigated by non-destructive tests and post-mortem analysis. The results show that increasing the amounts of pre-lithiation can substantially improve the capacity of the cells, but may also accelerate their aging. Further studies reveal that the cycling stability of SiOx/Graphite anode is strongly affected by the amounts of pre-lithiation, whereas the effect on the cathode is negligible. Moreover, titration gas chromatography (TGC) experiments are used to quantify the lithium loss in SiO x /Graphite anode. The accelerated formation of SEI and trapped lithiated active materials as well as lithium dendrites caused by over-lithiation at SiO x /Graphite anode are responsible for the rapid degradation of pouch cells with high pre-lithiation amounts. This work demonstrates the complex relationship between pre-lithiation amounts and electrochemical performance, which needs to be carefully measured in SiO x -based cells. [Display omitted] • NCM811||SiO x /Graphite pouch cells with different pre-lithiation amounts are evaluated. • Both ICE and cycle stability is greatly influenced by the pre-lithiation amount. • The amounts of pre-lithiation have little effect on the aging of the cathode. • High pre-lithiation amounts can accelerate anode aging. • Titration gas chromatography is used to quantify the lithium loss in anode. [ABSTRACT FROM AUTHOR]

Abundant and low-cost sodium, iron,and titanium have great potentialsto act as raw materials for large-scale power sources. Here we reportthe synthesis of novel orthorhombic Nax[FeTi]O4(x= 1 and 4/3) anode materialsby a solid-state reaction method and their electrochemical behaviorsin sodium-ion batteries. These materials are able to reversibly insertadditional Na+ions and show very good cycling stabilities.In particular, the Na4/3[FeTi]O4material candeliver a high reversible capacity of 120 mA h g–1at 0.1 C, and cyclic voltammetry (CV) investigation proves thatthere is no phase transformation during testing cycles. The Na[FeTi]O4material exhibits an even higher initial charge capacityof 181 mA h g–1at 0.1 C, and in situX-ray diffraction (XRD) results indicate that Na+ionsbehave in topotactic insertion and extraction manners inside thismaterial. Meanwhile, gas evolutions during the initial redox processare analyzed by an operandomass spectrometry technique.The result suggests that the Na[FeTi]O4material exhibitsan enhanced safety. [ABSTRACT FROM AUTHOR]

Silicon is a promising anode material for lithium-ion batteries (LIBs) because of its impressive theoretical capacity. However, it undergoes severe volume changes in the lithiated state thus limiting its development in LIBs. Herein, a cross-linked dextrin binder is created through in-situ thermal cross-linking of dextrin and the inorganic cross-linker sodium tetraborate decahydrate, which is a cost-effective, "greener" water-soluble binder. This binder can significantly strengthen the adhesion between Si electrode and copper current collector, which is almost three times more effective in adhesion than commercially available CMC binder. Meanwhile, the cross-linked dextrin binder also has superior mechanical properties and is able to well mitigate the huge volume changes upon cycling, consequently achieving an excellent cycling stability and superior rate capability. It is believed that this aqueous binder has the potential to utilize in silicon anodes for high-energy-density LIBs, as well as providing a new idea in the design of binders for other electrode materials which suffer from volume change during cycling. [Display omitted] • Dextrin is a natural bio-derivative with low cost and sustainable characteristics. • The dextrin binder shows superior mechanical properties of the Si anode. • The binder improves the electrochemical performance of Si anode significantly. [ABSTRACT FROM AUTHOR]