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[Display omitted] • V-dopants were successfully incorporated into MIL-125 via solvothermal method. • V-doped TiO2@carbon was prepared by carbonizing the V-doped MIL-125. • V-doped TiO2@carbon showed much enhanced sodium storage performance. • V-doping of TiO2 enhanced the electronic/ionic transfer rate. Titanium dioxide (TiO 2) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO 2 via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal–organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO 2 with simultaneous carbon hybridization and controlled V-doping amount (denote as V x TiO 2 @C, where × represents the V/Ti molar ratio (R V/Ti)). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the V x TiO 2 @C. When used as an anode for SIBs, the V 0.1 TiO 2 @C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO 2 @C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V 0.1 TiO 2 @C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti3+ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V 0.1 TiO 2 @C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways. [ABSTRACT FROM AUTHOR]

Transition metal phosphides are emerging as potential anode materials for lithium‐ion batteries (LIBs) due to their high theoretical capacity and good thermal stability, but the severe volume changes during the charge/discharge process and low electrical conductivity have hampered their practical application. Herein, the facile synthesis of carbon‐coated CoP nanoparticles (CoP@C) with uniform spherical morphology is demonstrated through the solvothermal method followed by annealing and phosphating treatments, in which an interesting precursor, the Co–gluconate complex, is prepared as the Co/C sources. When used as the LIB anode, the CoP@C electrode displays excellent cycling stability with a reversible capacity of 483.4 mA h g−1 upon 1000 cycles at 0.5 A g−1. The superior lithium storage performance is attributed to the unique composite structure of CoP@C with the nanosized CoP particles wrapped into the carbon matrices, which can enhance the electrical conductivity, provide sufficient reaction sites, shorten the Li+ transport path, and buffer the volume changes of the electrode upon lithiation/delithiation. More importantly, the strategy of generating gluconate–metal complex as the metal‐ and carbon‐containing precursor can be widely applied in the synthesis of various functional materials for energy‐related applications. [ABSTRACT FROM AUTHOR]

Tin dioxide (SnO 2) has attracted extensive attention as an anode for lithium-ion batteries (LIBs) due to its high theoretical specific capacity, however, it suffers from the severe volume changes upon lithiation/delithiation cycling, thus leading to fast capacity fading. To overcome the drawbacks, we herein report a facile one-pot self-templating fabrication of Ti-doped SnO 2 @carbon nanotubes (Ti-SnO 2 @CNTs), via annealing the electrospun precursor nanofibers of tetrabutyl titanate (TBT), tetraethyl orthosilicate (TEOS), polyvinylidene difluoride (PVDF), polyvinylpyrrolidone (PVP), and stannous chloride (SnCl 2). Interestingly, the introduction of TBT or not can lead to the controlled fabrication of the tubular or solid fibrous structure. During the annealing process, the chemical reaction between PVDF, TEOS, and TBT in-situ leads to the formation of tubular structure, while the SnCl 2 converts into ultrafine SnO 2 nanoparticles, embedding into the PVP-derived N-doped carbon nanotubes. When employed as anode materials for LIBs, the Ti-SnO 2 @CNTs deliver high reversible capacities of 868.6/495.9 mAh g−1 at 0.2/1.0 A g−1 after 200/500 cycles, higher than those for the fibrous SnO 2 @CNFs counterpart (654.9/391.08 mAh g−1). The better lithium storage performance is related to the unique carbon nanotube structure and the Ti-doping, which bring improved electrical conductivity, enhanced structural stability, and shortened ion diffusion path. More importantly, we demonstrate the facile electrospinning fabrication of tubular nanostructured hybrid electrodes for high-performance energy storage applications. [Display omitted] • Ultrafine SnO 2 nanoparticles are uniformly embedded into PVP-derived N-doped carbon nanotubes though electrospinning and subsequent calcination. • Tubular structure was formed using TBT/TEOS-derivates as templates, HF released by PVDF as the etching agent. • The unique tubular structure and ultrafine SnO 2 nanoparticles synergistically contributed to enhanced pseudocapacitive behavior and shortened lithium diffusion path. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) is a promising anode for lithium‐ion batteries (LIBs) due to its long lifespan and high rate capability, arising from its excellent structural stability upon lithium intercalation‐deintercalation, but suffers from low conductivity and diffusivity. In contrast, germanium (Ge) possesses high specific theoretical capacity (1600 mA h g−1) as well as high electrical conductivity and high Li+ diffusivity, but the large volume changes upon cycling and the high price still impede its practical application. Herein, with the objective to overcome the drawbacks of TiO2‐based anode materials, Ge/TiO2@C nanotablets with a small amount of Ge content are successfully prepared by annealing C4H12GeO4/MIL‐125 mixtures in Ar/H2 atmosphere. Benefiting from the well‐dispersion of Ge nanoparticles within the TiO2@C matrices, the composites exhibit superior electrochemical performance when examined as a LIB anode material, delivering high reversible capacities of 502/258 mA h g−1 after 200/500 cycles at current densities of 200/500 mA g−1, respectively. Notably, the Ge/TiO2@C shows enhanced surface/pore features and demonstrates improved conductivity, lithium diffusion and specific capacities, owing to the introduction of Ge component. [ABSTRACT FROM AUTHOR]

In order to overcome the poor electrical conductivity of titania (TiO2) and silica (SiO2) anode materials for lithium ion batteries (LIBs), we herein report a facile preparation of integrated titania–silica–carbon (TSC) nanofibers via electrospinning and subsequent heat-treatment. Both titania and silica are successfully embedded into the conductive N-doped carbon nanofibers, and they synergistically reinforce the overall strength of the TSC nanofibers after annealing (Note that titania–carbon or silica–carbon nanofibers cannot be obtained under the same condition). When applied as an anode for LIBs, the TSC nanofiber electrode shows superior cycle stability (502 mAh/g at 100 mA/g after 300 cycles) and high rate capability (572, 518, 421, 334, and 232 mAh/g each after 10 cycles at 100, 200, 500, 1000 and 2000 mA/g, respectively). Our results demonstrate that integration of titania/silica into N-doped carbon nanofibers greatly enhances the electrode conductivity and the overall structural stability of the TSC nanofibers upon repeated lithiation/delithiation cycling. [ABSTRACT FROM AUTHOR]

[Display omitted] Tin dioxide (SnO 2) is a promising alternative material to graphite anode, but the large volume change induced electrode pulverization issue has limited its application in lithium-ion batteries (LIBs). In contrast, titanium dioxide (TiO 2) anode shows high structure stability upon lithium insertion/extraction, but with low specific capacity. To overcome their inherent disadvantages, combination of SnO 2 with TiO 2 and highly conductive carbon material is an effective way. Herein, we report a facile fabrication method of carbon-coated SnO 2 /TiO 2 nanowires (SnO 2 /TiO 2 @C) using tin titanate nanowires as precursor, which are prepared by reacting SnCl 2 ·2H 2 O with layered sodium titanate (Na 2 Ti 3 O 7) nanowires in the aqueous solution though the ion exchange between Sn2+ and Na+. After annealing under argon atmosphere, the hydrothermally carbon-coated tin-titanate nanowires decompose, forming a unique hybrid structure, where ultrafine SnO 2 nanoparticles are uniformly embedded within the TiO 2 substrate with carbon coating. Consequently, the SnO 2 /TiO 2 @C nanowires demonstrate excellent lithium storage capacity with high pseudocapacitance contribution, excellent reversible capacity, and long-term cycling stability (673.7/510.5 mAh/g at 0.5/1.0 A/g after 250/800 cycles), owing to the unique hybrid structure, as the well-dispersion of ultra-small SnO 2 within TiO 2 nanowire substrate with simultaneous carbon coating efficiently suppresses the volume changes of SnO 2 , provides abundant reactive sites for lithium storage, and enhances the electrical conductivity with shortened ion transport distance. [ABSTRACT FROM AUTHOR]

Alloy-/conversion-type metal oxides usually exhibit high theoretical lithium storage capacities but suffer from the large volume change induced electrode pulverization and the poor electric conductivity, which limit their practical applications. Hybrid/mixed metal oxides with different working mechanisms/potentials can display advantageous synergistic enhancement effect if delicate structure engineering is performed. Herein, atomically hybridized SnO 2 /Co 3 O 4 nanocomposites with amorphous nature are successfully cast onto the porous N -doped carbon (denoted as NC) nanoflakes through facile pyrolysis of the tin (II) 2-ethylhexanoate (C 16 H 30 O 4 Sn) and cobalt (II) 2-ethylhexanoate (C 16 H 30 O 4 Co) mixture within NC nanoflakes in air at 300 °C for 1 h. The Sn/Co atomic ratio and the loading amount of SnO 2 /Co 3 O 4 can be readily controlled, whose effect on lithium storage are investigated as anodes for lithium ion batteries (LIBs). Notably, SnO 2 /Co 3 O 4 @NC (R Sn/Co = 1.25) nanoflakes exhibit the most excellent lithium storage properties, delivering a reversible capacity of 1450.3 mA h g−1 after 300 cycles at 200 mA g−1, which is much higher than that of the single metal oxide SnO 2 @NC and Co 3 O 4 @NC electrodes. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2) has been considered as a promising anode material for alkaline ion batteries (AIBs), yet the low electrical conductivity and sluggish reaction kinetics have restricted its practical applications, while rational structure design can significantly overcome these drawbacks. Herein, we report a one-step fabrication of ultrafine anatase TiO 2 nanoparticles within holely carbon nanofibers (denoted as A-TiO 2 @HCNFs) via a facile electrospinning method and subsequent annealing treatment. The chemical reaction between TEOS (Si(OC 2 H 5) 4) and PVDF ((CH 2 CF 2) n) in the precursor induces the generation of numerous holes (via 4HF + SiO 2 = SiF 4 ↑+ 2 H 2 O) during the carbonization process by annealing in Ar at 800 °C, leading to the formation of holely structure and the suppression of the anatase-to-rutile phase transformation. When employed as anode materials for AIBs, the A-TiO 2 @HCNFs exhibit a high sodium storage capacity of 206.8 mAh g−1 at 1.0 A g−1 after 500 cycles and a superior rate performance of 188.4 mAh g−1 at 5.0 A g−1, and a lithium storage capacity is 354.0/233.9 mAh g−1 at 0.2/1.0 A g−1 after 100/500 cycles with an excellent rate performance of 145.6 mAh g−1 at 5.0 A g−1. The superior electrochemical performance is related to the unique structure with integration of ultrafine anatase TiO 2 nanoparticles and holely carbon nanofibers, which bring many advantages including improved electrical conductivity, sufficient reaction sites and robust structure stability. [Display omitted] • Template-free one-pot hole generation within carbon nanofibers is realized through chemical reaction between TEOS and PVDF. • Ultrafine anatase TiO 2 nanoparticles were produced and uniformly distributed within the holely carbon nanofibers. • The anatase TiO 2 nanoparticles within holely carbon nanofibers demonstrate excellent sodium and lithium storage performances. [ABSTRACT FROM AUTHOR]

[Display omitted] TiNb 2 O 7 (TNO) as a promising candidate anode for lithium-ion batteries (LIBs) shows obvious advantages in terms of specific capacity and safety, but which undergoes the intrinsic poor electrical and ionic conductivity. Herein, we propose a simple synthesis strategy of mesoporous TNO via a polymeric surfactant-mediated evaporation-induced sol-gel method, using polyvinylpyrrolidone (PVP) with different molecular weights (average Mw: 10000/58000/1300000) as the regulating agent, which greatly affects the lithium storage performance of the as-prepared TNO. The optimized TNO (i.e., PVP of 58000) delivers a high reversible capacity of 303.1 mAh/g at 1 C, with a retention rate of 73.4% (222.5 mAh/g) after 300 cycles. Even at 5 C, a high reversible capacity of 185.6 mAh/g can be achieved, with a retention rate of 72.3% after 1000 cycles. The superior lithium storage behavior is attributed to the fine mesoporous framework consisting of interconnected TNO nanocrystallites with high specific surface area and high mesoporosity, which greatly increases the active sites, improves the Li+ diffusion kinetics and alleviates volume fluctuation induced by the repetitive Li+ insertion-extraction processes. [ABSTRACT FROM AUTHOR]