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Replacing liquid electrolyte (LE) with gel polymer electrolyte (GPE) can significantly improve the safety and long-term stability of lithium-ion batteries. However, the traditional pure polymethyl methacrylate (PMMA)-based GPE after immersion in the electrolyte has the problem of poor mechanical properties and easy damage. In this article, PMMA was used as the matrix, and low-density polyethylene particles were mixed to prepare a kind of structure-enhanced and heat-resistant GPE by phase inversion method. The prepared GPE has high ionic conductivity at room temperature. It can slow down the temperature rise of the battery by reducing the ionic conductivity at high temperatures, thereby improving the safe application performance of the battery. In addition, the symmetrical battery made of this material can maintain ultra-low overvoltage and run stably for at least 800 h in the overpotential test when the current density is 1 mA cm−2. This study provides new insights for the preparation of high-temperature safety GPE. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials combined with carbonaceous materials have shown remarkable properties for boosting the performance of lithium-ion batteries (LIBs). Precise spatial modulation and accurate transmission characteristics of electronic conductivity require good contact between materials. Herein, the preparation of a molybdenum disulfide/polyacrylonitrile-derived carbon (MoS2/PDC) composite by heat treatment in argon atmosphere at 600 °C is presented. The polyacrylonitrile (PAN) and MoS2 are subjected to phase inversion preparation membrane and lignin-assisted exfoliation pretreatment, respectively. The MoS2 nanosheets can enter into the pore of PAN membrane and from C–S bonds during carbonization process, providing effective electron transport paths. Highly conductive carbonized PAN layer can act as an electron collector and provides the volume expansion space for MoS2. Cell tests indicate that the MoS2/PDC electrode exhibits an ultra-high lithium-ion storage capacity of 1354 mAh g−1 at a current density of 0.1 A g−1 and excellent cycling stability. With the advantages of low cost, green process and high electrochemical performance, the MoS2/PDC composite is a promising anode material of LIBs. [ABSTRACT FROM AUTHOR]

One kind of gel polymer electrolytes (GPE) with high performances based on polyacrylonitrile and green natural lignocellulose (LC) has been prepared. This as-prepared GPE exhibits excellent performance. When the proportion of LC reaches up to 60 wt%, the prepared composite membrane has a liquid electrolyte uptake of 673 wt% at room temperature, and the corresponding GPE-60 presents an ultrahigh lithium ion transference number of 0.84, high electrochemical stability and excellent specific capacity (143.90 mAh g−1 at 0.2 C at 90th cycle of LiFePO4||GPE-60||Li). These advantages prove that the GPE-60 has great potential for the application of lithium ion batteries. [ABSTRACT FROM AUTHOR]

A new gel polymer electrolyte (GPE) based on chitosan‐lignocellulose composites with a smooth and porous structure for applications in lithium‐ion batteries was prepared. The obtained GPE matrix and GPE show excellent comprehensive performances. The GPE matrix based on the composite containing 15 % chitosan (denoted CSLC‐15) had the best performance, with liquid electrolyte uptake of up to 749.1 wt %. The ionic conductivity for corresponding GPE is 2.89 mS cm−1 at room temperature, and the lithium ion transference number is 0.90. The GPE proved promising for use in lithium‐ion batteries, offering a large electrochemical window (4.8 V) and excellent interfacial compatibility (a stable impedance value of 227.97 Ω after 30 days). Moreover, the GPE shows excellent thermal and mechanical properties, and high C‐rates capability (163.13 mAh g−1, 152.53 mAh g−1, 144.27 mAh g−1, 128.45 mAh g−1, 156.12 mAh g−1, at 0.2 C, 0.5 C, 1.0 C, 2.0 C, 0.2 C, respectively) and cycle performance (161.99 mAh g−1 at the 99th cycle of 0.2 C), which proved its suitability of use in lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

A novel porous polymer membrane based on polyhedral oligomeric silsesquioxane (POSS) composite poly(acrylonitrile–maleic anhydride) (P(AN–MAH)) is prepared by phase inversion method, and corresponding P(AN–MAH) composite gel polymer electrolyte (GPE) is prepared by further absorbing the liquid electrolyte. The structure of the prepared POSS and P(AN–MAH), and the properties of the composite P(AN–MAH) membranes and GPEs are investigated. The results indicate that the introduction of POSS significantly reduces the crystallinity of P(AN–MAH), which gives the composite membrane and GPE excellent performance. Compared with pure P(AN–MAH)-based membrane and GPE, the composite membrane containing 5 wt% POSS exhibits the best porosity (69.9%) and electrolyte uptake (311.9 wt%), and the most excellent electrochemical performance is also presented by the corresponding GPE: enhanced ionic conductivity of 2.51 × 10−3 S cm−1 at room temperature; better compatibility with electrode; significantly increased lithium-ion transference number of 0.53; a remarkably widened electrochemical stability window of 5.6 V (vs. Li/Li+); a higher discharge specific capacity of 147 mAh g−1 with a Li/GPE-5%/LiFePO4 cell at 0.2 C. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are a typical representative of energy storage system with high storage capacity and good cycle stability. However, the low specific capacity can not meet the storage capacity requirements for new generation of electronic products, which have limited their practical application. Herein, CoF 2 nanoparticles loaded on carbon fiber cloth (CoF 2 @CFC) as a flexible composite material prepared without binder or conductive agent is introduced as a cathode for lithium-ion batteries, which exhibit a high specific capacity of 330 mA h g−1 at 100 mA g−1 and have a stable specific capacity of 100 mA h g−1 at 1 A g−1 even after 1000 cycles. In addition, the flexibility of CoF 2 @CFC creates an application potential in the field of flexible electronic devices and wearable electronics. Image 1 • The CoF 2 nanoparticles @carbon fiber cloth are fabricated by a facile hydrothermal synthesis. • The CoF 2 @CFC cathode possesses excellent flexibility. • The CoF 2 @CFC cathode shows high specific capacity and good cycling performance. [ABSTRACT FROM AUTHOR]

A novel gel polymer electrolyte (GPE) is prepared based on polyvinyl alcohol (PVA) composite lignocellulose (LC). In this work, mechanical strength of PVA composite LC membranes is significantly enhanced, which endows corresponding GPEs with application potential in lithium ion batteries (LIBs). Meanwhile, when the content of PVA is 5 wt.%, GPE presents high enough liquid electrolyte uptake (425 wt.%) and enough thermal stability. At room temperature, the ion conductivity is 3.92 × 10−3 S cm−1 and lithium ion transference number is up to 0.63. In addition, GPE exhibits electrochemical stability window at 5.2 V (vs. Li/Li+), good compatibility with electrode, excellent initial discharge specific capacity, C-rate and cycling performances. Image 1 • The LC/PVA film is prepared by a simple, low-cost, environment-friendly method. • The mechanical strength of LC/PVA films is dramatically enhanced. • Structure of LC/PVA film exhibits a positive impact on electrochemical stability. • GPE shows excellent capacity retention between 98 and 100% at 1.0 C after 150 cycles. [ABSTRACT FROM AUTHOR]

Novel hierarchical microspheres of aggregated silicon nanoparticles (p‐Si microsphere) with nanometre gaps have been synthesized through reverse microemulsion in combination with a modified magnesiothermic reduction approach using silica (∼200 nm) as the precursor. The hierarchical porous structure of p‐Si microspheres is composed of abundant intergranular gaps (100–200 nm) in the interconnected nanosized Si particles, along with ultrafine Si nanosized grains (∼5 nm) and intragranular voids formed in interconnected nanosized Si particles. The hierarchical microspheres of aggregated Si nanoparticles possess a high specific surface area of 136 m2 g−1 and can achieve a high tap density of 0.3 g cm−3. Such a novel microstructure with a large surface area and void gaps between interconnected Si nanoparticles can accommodate the volume change of Si during the lithium ion (Li+) alloying/dealloying process. Meanwhile, the mesoporous structure facilitates Li+ penetration into the nano‐Si grain interface, significantly shortening the Li+ diffusion pathway as well as enhancing the heterogeneous reaction sites. Such hierarchical microspherical Si anodes demonstrated excellent cycling stability, delivering reversible capacity of 845 mAh g−1 after 200 cycles at 0.2 A g−1 and rate performance with a high reversible capacity of 681 mAh g−1 at 1 A g−1 with 97 % of initial capacity retention. Mind the gap: Novel micron sized porous Si spheres are synthesized controllably by a reverse microemulsion technique in combination with a modified magnesiothermic reduction approach. The spheres exhibit a unique hierarchical structure and stable electrochemical performance. [ABSTRACT FROM AUTHOR]

A novel non-woven fabric supported polymer membrane based on poly(methyl methacrylate-polyhedral oligomeric silsesquioxane) (P(MMA-POSS)) copolymer is prepared by phase inversion method. The difficulty in preparing PMMA membrane by phase inversion method is solved. Further, the P(MMA-POSS) based gel polymer electrolyte (GPE) is prepared by absorbing liquid electrolyte. The morphology structure and properties of the P(MMA-POSS) membrane and electrochemical performance of P(MMA-POSS) GPE are investigated. The results of the analysis exhibit that the P(MMA-POSS) membrane possesses a significant pore structure, and P(MMA-POSS) membrane containing 10 wt% POSS in polymerization presents the optimal electrolyte uptake of 275 wt%. Compared with pure PMMA GPE without introducing POSS, the excellent electrochemical performances of P(MMA-POSS) GPE are demonstrated: a higher ionic conductivity of 3.41 mS cm −1 at room temperature, a wider electrochemical stability window of 5.01 V (vs. Li/Li + ), the excellent interface compatibility with anode and a satisfactory lithium ion transference number of 0.49. The lithium ion battery with the P(MMA-POSS) GPE also exhibits a higher charge-discharge capacity of 151.9 mAh g −1 at 0.2 C, and a capacity retention rate of 99.8% at 0.5 C is confirmed after 100 cycles. [ABSTRACT FROM AUTHOR]

Abstract A polymer matrix of poly(acrylonitrile-maleic anhydride) (P(AN-MAH)) is used to prepare a novel porous membranes by phase inversion. The membranes are immersed into liquid electrolyte to form gel polymer electrolyte (GPE) used in lithium ion batteries (LIBs). The results indicate that P(AN-MAH) is successfully synthesized and the membrane of P(AN-MAH) copolymer with adding mass ratios of AN: MAH = 4:1 exhibits superior pore structure and better thermal stability compared with that of pure PAN membrane, which endows the corresponding GPE with excellent comprehensive performances: the considerable ionic conductivity (3.03 × 10−3 S cm−1 at room temperature), fine compatibility between GPE and electrode, eminent lithium transference number (t Li + = 0.57), and high enough electrochemical stability potential (up to 5.4 V (vs. Li/Li+)). Accordingly, in constant current charging/discharging cycle, the prepared battery for the GPE also presents excellent initial discharge capacity, C-rate and cycling performances. Highlights • P(AN-MAH) is used as gel polymer electrolyte for the first time. • P(AN-MAH) based membrane is prepared by phase inversion. • The poor compatibility of PAN based GPE is significantly improved. • The lithium ion transference number of PAN based GPE is obviously increased. • Polymerization of MAH enhances the thermal stability to PAN matrix. [ABSTRACT FROM AUTHOR]

A kind of organic-inorganic nanocomposite of methacrylisobutyl-polyhedral oligomeric silsesquioxane (MA-POSS) is synthesized and the nanocomposite as the modified filler is introduced into polymethyl methacrylate (PMMA) matrix to prepare gel polymer electrolyte (GPE) membrane used in lithium ion battery (LIB) through phase inversion method combined with liquid electrolyte adsorption. The results reflect that compared to the solvent evaporation technique, the electrochemical performances of the GPE corresponding to the membrane prepared by phase inversion method are more outstanding. Besides, the membrane also shows good mechanical strength. Compared to the GPE based on pure PMMA matrix, the comprehensive performances of the modified GPE are also enhanced a lot and the GPE with the mass of 10% MA-POSS exhibits the most favorable properties. The excellent performances are shown as follows: the ionic conductivity reaches to 2.77 × 10 −3  S cm −1  at room temperature; the lithium ion transfer number is up to 0.40; the GPE is electrochemical stable below 5.5 V (vs. Li/Li + ); the compatibility between GPE and lithium anode is satisfying and the ionic conductivity obeys the Arrhenius behavior. [ABSTRACT FROM AUTHOR]

A biodegradable composite polymer membrane is fabricated by synthesizing polyvinylpyrrolidone (PVP) on the matrix of lignin, and then the corresponding gel polymer electrolyte (LP-GPE) is further prepared by absorbing the liquid electrolyte. The morphology, mechanical property, and thermal stability of the composite lignin-PVP membrane and the electrochemical properties of LP-GPE are investigated. The results of the investigation present that the mechanical property of the membrane is remarkable improved (670%) and the composite membrane exhibits a better thermal security. For electrochemical properties, a high ionic conductivity of 2.52 × 10−3 S cm−1 at room temperature, excellent lithium-ion transference number of 0.56, and outstanding electrochemical stability of LP-GPE are confirmed. Moreover, the C-rate performance and capacity retention based on Li/LP-GPE/LiFePO4 cell are superior to that of the commercial Celgard 2730 cell. Consequently, all these results demonstrate that LP-GPE can be applied as a novel electrolyte for lithium ion battery with high-performance, low-cost, and environment-friendly properties.ᅟ [ABSTRACT FROM AUTHOR]

A novel porous membrane, based on a polymer matrix of poly(acrylonitrile-polyhedral oligomeric silsesquioxane) (P(AN-POSS)), is prepared by phase inversion process, and the corresponding gel polymer electrolyte (GPE) is further fabricated by immersing the porous membrane into liquid organic electrolyte. The thermal stability and structure of prepared POSS and polymers are investigated. The research indicates that the P(AN-POSS) membrane with copolymerization content of 8 wt% POSS exhibits the better pore structure and superior electrolyte uptake compared with pure PAN membrane, which endows the corresponding GPE with remarkable comprehensive performances: the maximum ionic conductivity value of 6.06 × 10 −3 S cm −1 at ambient temperature, the sufficiently stable interface compatibility between GPE and electrode, the excellent lithium ion transference number of 0.59 and the higher electrochemical stability potential of 5.7 V (vs. Li/Li + ). At 0.2 C, the GPE with 8 wt% POSS in polymerization based lithium ion battery shows a satisfactory discharge capacity of 148 mAh g −1 and improved capacity retention of 93.7% after 80 cycles. [ABSTRACT FROM AUTHOR]

One novel cage kind of polyhedral ligomeric silsesquioxane (POSS), for modification application of gel polymer electrolyte (GPE) in lithium ion batteries (LIBs), was successfully synthesized via a facile two-step reaction under simple conditions. In four kinds of GPE with different filling amount of POSS, GPE-8 with 8 wt.% POSS content expresses the highest ionic conductivity up to the level of 10 S cm at 30 °C. The comprehensive investigation indicates that GPE-8 is thermally stable before 100 °C, electrochemical stability window (ESW) is identified as 5.0 V, and the compatibility of electrolyte with lithium electrode and the charging-discharging cycling property of the assembled cell is satisfying. [ABSTRACT FROM AUTHOR]

Tin dioxide (SnO2) is recognized as one of the most promising anode materials for lithium-ion batteries. However, the large volume changes of pure SnO2 anodes during Li+ insertion/extraction inevitably result in rapid capacity decay. Herein, the fabrication of microsized, porous SnO2/Sn/carbon (p-SnO2/Sn/C) composites by a straightforward one-step hydrothermal process with triblock copolymer Pluronic F-127 as templating agent and subsequent carbonization is reported. In this composite structure, SnO2/Sn nanoparticles (≈5 nm) are uniformly embedded in an ordered porous carbon matrix to form an interpenetrating framework structure. The ordered porous carbon matrix not only offers three-dimensional channels for extraction/insertion of Li+ during cycling, but also buffers severe volume changes of the SnO2/Sn nanoparticles. Furthermore, the composite structure also ensures formation of stable solid electrolyte interface films as compared with isolated SnO2/Sn nanoparticles, which efficiently improves the electrochemical stability of the active materials. Thus, the p-SnO2/Sn/C anode delivers a high reversible capacity of 1016.2 mAh g−1 at 100 mA g−1 after 100 cycles and has remarkable long-term cycle stability (a charge capacity of 710 mAh g−1 even after 600 cycles at 1000 mA g−1). [ABSTRACT FROM AUTHOR]

Organic redox-active materials are investigation hotspots for lithium ion storage due to their structural diversity and tunability. A large number of researches have focused on the organic materials of benzene para-substitution type. There are little investigations on benzene ortho-substitution type organic materials. Benzene ortho-substitution redox molecules are generally considered to be too close to the functional group to fully react, and conjugated structure is not as stable as that of para-substitution. However, we reported dilithium phthalate (Li 2 PA) anode active material for lithium ion battery. Interestingly, Li 2 PA anode has an excess capacity and reaches four-electrons reaction, and the lithium ions storage mechanism is explored: not only the two adjacent conjugated carbonyls can fully react, but also the rearranged benzene ring can accept two Li + ions. Li 2 PA anode has a high specific capacity of 674 mA h g−1 at 60 mA g−1, with 91.7% capacity retention after 125 cycles (cycled for 4 months). Furthermore, it achieves high-rate capability, holding the specific capacity of 110 mA h g−1 at 4000 mA g−1. This research shows that Li 2 PA can be used as organic active material for anode, opening up new possibility for organic anode development. • Dilithium phthalate is first used in lithium ion battery. • Dilithium phthalate anode performances exceed reported dilithium terephthalate. • Crystalline state of dilithium phthalate changes to amorphous state during cycles. [ABSTRACT FROM AUTHOR]

Porous V2O5 nanotubes, hierarchical V2O5 nanofibers, and single-crystalline V2O5 nanobelts were controllably synthesized by using a simple electrospinning technique and subsequent annealing. The mechanism for the formation of these controllable structures was investigated. When tested as the cathode materials in lithium-ion batteries (LIBs), the as-formed V2O5 nanostructures exhibited a highly reversible capacity, excellent cycling performance, and good rate capacity. In particular, the porous V2O5 nanotubes provided short distances for Li+-ion diffusion and large electrode-electrolyte contact areas for high Li+-ion flux across the interface; Moreover, these nanotubes delivered a high power density of 40.2 kW kg−1 whilst the energy density remained as high as 201 W h kg−1, which, as one of the highest values measured on V2O5-based cathode materials, could bridge the performance gap between batteries and supercapacitors. Moreover, to the best of our knowledge, this is the first preparation of single-crystalline V2O5 nanobelts by using electrospinning techniques. Interestingly, the beneficial crystal orientation provided improved cycling stability for lithium intercalation. These results demonstrate that further improvement or optimization of electrochemical performance in transition-metal-oxide-based electrode materials could be realized by the design of 1D nanostructures with unique morphologies. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-coated LiFePO4 (C-LFP) composites incorporated with electrochemically-active conducting polymer polyaniline (PANI) are fabricated via a self-assembly process. Inorganic acids HCl, H2SO4 and H3PO4 are used as dopants for PANI. The C-LFP/PANI composites are characterized by thermogravimetric analysis, scanning electron microscopy, electrochemical impedance spectroscopy, Raman spectra and four-probe resistivity measurements. Our results show that a remarkable improvement in capacity and rate capability can be achieved in the C-LFP/PANI composite cathodes doped with HCl and H3PO4. The C-LFP/PANI-HCl composite exhibits the best electrochemical performance, which gives a ca. 15% capacity enhancement at 0.2C and 40% enhancement at 5C compared to the parent C-LFP. The mechanism for the enhancement has been discussed. [Copyright &y& Elsevier]

As one of the most prospective candidates for next-generation rechargeable batteries, lithium-sulfur (Li-S) batteries currently still encounter great challenges associated with the low conductivity, severe shuttle effects, and sluggish redox kinetics. Herein, a self-supported sulfur host is fabricated by an in-situ growth of MoO 2 /MoS 2 nano-sheets on a carbon cloth (CC). First, carbon cloth serves as a good template for the morphology-controlled synthesis of nanostructured materials, which not only alleviates the agglomeration of MoO 2 /MoS 2 , but also enhances the flexibility and mechanical strengthen of the hybrid architecture as a free-standing host. Second, the polysulfide-trapping ability can be greatly enhanced by both physical and chemical adsorption from the MoO 2 /MoS 2 -anchored carbon cloth. Moreover, the partially sulfurized MoO 2 /MoS 2 nano-sheets integrate the benefits of conductive MoO 2 and sulfiphilic MoS 2 , thus facilitating fast charge transfer and redox kinetics of polysulfide conversion. As a result, these attributes enable the host to hold a high sulfur loading (up to 7.6 mg cm−2), which exceeds most of the reported carbon cloth-related cathode work in the literature. Additionally, the Li-S cells can achieve a high peak capacity of 1350 mA h g−1, excellent rate capability (C/20 - 2C rate), impressive areal capacity (up to 6.3 mA h cm−2), and a high capacity retention of 85% after 100 cycles. Image, graphical abstract [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium ion capacitors (LICs) are a new generation of energy storage devices that combine the super energy storage capability of lithium ion batteries with the satisfactory power density of supercapacitors. The development of high-performance LICs still faces great challenges due to the unbalanced reaction kinetics at the anode and cathode. Therefore, it is an inevitable need to enhance the electron/ion transfer capability of the anode materials. In this paper, to obtain a superior-rate and high-capacity Ni 3 S 2 -based anode, highly conductive Ti 3 C 2 T x MXene sheets were introduced to sever as the carrier of Ni 3 S 2 nanoparticles and simultaneously an amorphous carbon layer which coats onto the surface of Ni 3 S 2 nanoparticles was in-situ generated by the carbonization of dopamine reactant. The as-synthesized Ni 3 S 2 /Ti 3 C 2 T x /C composite exhibits a high specific surface area (112.6 m2/g) because of the addition of Ti 3 C 2 T x that can reduce the aggregation of Ni 3 S 2 nanoparticles and the in-situ generated amorphous carbon layer that can suppress the growth of Ni 3 S 2 nanoparticles. The Ni 3 S 2 /Ti 3 C 2 T x /C anode possesses a remarkable reversible discharge specific capacity (626.0 mAh/g under 0.2 A/g current density), which increases to 1150.8 mAh/g after 400-cycle charge/discharge measurement at the same measurement condition indicating eminent cyclability, along with superior rate capability. To construct a superior-performance LIC device, a sterculiae lychnophorae derived porous carbon (SLPC) cathode with an average discharge specific capacity of 73.4 mAh/g@0.1A/g was prepared. The Ni 3 S 2 /Ti 3 C 2 T x /C//SLPC LIC device with optimal cathode/anode mass ratio has a satisfactory energy density ranging from 32.8 to 119.1 Wh kg−1 at the corresponding power density of 8799.4 to 157.5 W kg−1, together with a prominent capacity retention (95.5 %@1 A/g after 10,000 cycles). [ABSTRACT FROM AUTHOR]

A novel composite porous membrane is obtained by phase inversion using the prepared poly(acrylonitrile-N-vinylpyrrolidone) (P(AN-NVP)) as a polymer matrix, which absorbs liquid electrolyte to form the corresponding P(AN-NVP) based gel polymer electrolyte (GPE). A large number of test methods are used to characterize the overall performances of P(AN-NVP) membranes. These results show that when AN and NVP are copolymerized at a mass ratio of 6:1, the prepared P(AN-NVP) copolymer film possesses membrane structure that riching in three-dimensional interpenetrating micropores, and has lower crystallinity and satisfactory mechanical properties compared with that of pure PAN membrane, which greatly promotes the electrochemical performances of the corresponding GPE: the supreme liquid electrolyte uptake of 876.67 wt% and higher ion conductivity of 4.54 × 10−3 S cm−1 at room temperature, a significantly enhanced lithium ion transference number of 0.55, a broader electrochemical stability window of 5.11 V (vs. Li/Li+) and relatively stable interfacial compatibility. The higher charge-discharge capacity of 114.8 mAh g−1 at 0.2C, and the great capacity retention of 95.4% at 0.5C after 70 cycles with the coulomb efficiency of 98%. In addition, the GPE-6-1 based lithium ion battery exhibits excellent cycle performance and a weak voltage hysteresis of 5.8 mV over a 600 h Li plating/stripping process at current density of 0.5 mA cm−2 and capacity of 0.5 mAh cm−2. Image 1 • P(AN-NVP) copolymer is first applied as the matrix for gel polymer electrolyte. • The introduction of NVP effectively reduces the crystallinity of the PAN matrix. • A membrane of P(AN-NVP) with excellent pore structure can be harvested by the phase inversion method. • NVP significantly enhances the electrochemical performances of P(AN-NVP) copolymer. [ABSTRACT FROM AUTHOR]

Silicon is the one of the most promising anode material alternatives for next-generation lithium-ion batteries. However, the low electronic conductivity, unstable formation of solid electrolyte interphase, and the extremely high volume expansion (up to 300%) which results in pulverization of Si and rapid fading of its capacity have been identified as primary reasons for hindering its application. In this work, we put forward to introduce dual carbonaceous materials synergetic protection to overcome the drawbacks of the silicon anode. The silicon nanoparticle was coated by pyrolysed carbon, and meanwhile anchored on the surface of reduced graphene oxide, to form a self-standing film composite (C@Si/rGO). The C@Si/rGO film electrode displays high flexibility and an ordered porous structure, which could not only buffer the Si nanoparticle expansion during lithiation/delithiation processes, but also provides the channels for fast electron transfer and lithium ion transport. Therefore, the self-standing C@Si/rGO film electrode shows a high reversible capacity of 1002 mAh g−1 over 100 cycles and exhibits much better rate capability, validating it as a promising anode for constructing high performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Spent lithium-ion batteries rich in transition metals are highly potential to catalyze the biomass pyrolysis process. This research provided insight into the performance and mechanism of ex - situ catalytic upgrading of biomass pyrolysis volatiles over the thermally pyrolyzed spent Ni–Co–Mn ternary batteries (PyNCM) for the first time. The results showed that the PyNCM exhibited high catalytic activities for the secondary decompositions of pyrolysis volatiles, resulting in 12.6% reduction on bio-oil yield and 57.5% promotion on syngas productivity. The magnetic Ni and Co compounds in PyNCM were primarily responsible for the enhanced volatile deoxygenations, and the maximum H 2 yield reached 2.66 mmol g−1 biomass. Two levels of synergistic catalysis were identified: (1) the synergy among the transition metals established multiple active centers to promote the H 2 selectivity; (2) the non-magnetic graphite and lithium could probably improve the dispersion and surface oxygen vacancies of nickel and cobalt to further enhance the catalytic activity. [Display omitted] • Concentrations of O-species were notably reduced by 31.7% with PyNCM. • The catalysis of PyNCM could be enhanced via raising the reforming temperature. • Maximum CO and H 2 yields achieved 4.02 and 2.66 mmol g−1 biomass at 650 °C. • Magnetic Ni and Co were primarily responsible for the catalytic activity. • Two levels of synergistic effects were identified within the PyNCM constituents. [ABSTRACT FROM AUTHOR]

MnO is a promising anode material for LIBs due to its low cost and high theoretical capacity, but large volume changes and low conductivity limit its application. To improve its conductivity and electron transport rate, we fabricated mesoporous MnO/C hollow microtube through a hydrodynamic force-induced rapid assembly in T-type microchannel reactor followed with a sintering process. The as-synthesized mesoporous MnO/C hollow microtube is consist of MnO nanograins with abundant porous reaction sites embedding uniformly on carbon layers to form a hollow tubular-like structure. When used this mesoporous MnO/C hollow microtube as an anode material of LIBs, it can deliver a high reversible capacity of 845 mAh·g−1 after 100 cycles at 1.5 A g−1 and a capacity of 699 mAh·g−1 at 3.75 A g−1, exhibiting good rate capability and cycle stability. The temperature-dependence electrochemical impedance spectra showed that the mesoporous hollow microtube structure can decrease the barrier energy for jumping through the SEI film, the intercalation reaction and the diffusion of Li+ in the bulk of the solid. The improved performances can be attributed to the unique mesoporous hollow-tubular structure, which enhances the structural stability, improves the electrical conductivity and fasten electrode reaction kinetics. [ABSTRACT FROM AUTHOR]

Silicon(Si)/graphene composite has been regarded as one of the most promising candidates for next generation anode materials with high power and energy density in lithium ion batteries. Introduction of graphene in Si anodes could improve the electronic conductivity, suppress the severe volume expansion of Si, and facilitate the formation of stable solid electrolyte interphase, etc. However, traditionally mechanical mixing of Si and graphene cannot realize uniform distribution of Si particles on the graphene sheets, which would largely weaken the effectiveness of the graphene in the composite. In this work, nano-Si/reduced graphene oxide porous composite (p Si/rGO) has been fabricated by a facile electrostatic self-assembly approach via using SiO 2 as the sacrificial template. Compared with the simply mechanically mixed nano-Si and rGO (Si/rGO), the nano-Si particles could be more uniformly dispersed among the rGO sheets in the p Si/rGO, which significantly increases its electronic conductivity. Moreover, the drastic volume expansion of nano-Si during repeated lithiation/delithiation cycles also has been effectively accommodated by the large number of pores left after removing the SiO 2 template in the composite. Thus, the p Si/rGO presented largely enhanced electrochemical performances, showing a high reversible capacity up to 1849 mA h g −1 at 0.2 A g −1 with good capacity retention, and high rate capability (535 mA h g −1 at 2 A g −1 ). [ABSTRACT FROM AUTHOR]

As a promising anode candidate for lithium-ion batteries (LIBs), SnO 2 -based material has been extensively investigated. However, its practical application is still hindered due to the inherent drawbacks of poor conductivity, severe volume expansion, and unavoidable agglomeration of active material during repeated discharge/charge process as well as formation of unstable solid electrolyte interface (SEI) layer. In this paper, the SnO 2 @carbon nanotube/reduced graphene oxide (SnO 2 @CNT/RGO) composite is rationally designed and fabricated, in which nano SnO 2 nanoparticles (NPs, ~6 nm) are anchored onto three-dimensional (3D) conductive CNTs/RGO skeleton by first assembling SnO 2 onto CNT and then entangling SnO 2 @CNT nanofibers in 3D graphene networks. The synergistic effect of CNT and RGO significantly increase the conductivity and prevent aggregation of active material. In addition, the mesopores structure constructed by CNT and RGO can accommodate the volume change of SnO 2 NPs and form more stable SEI layer during repeated discharge/charge process. Therefore, the SnO 2 @CNT/RGO electrode exhibits not only more stable cycle performance but also more superior rate capacity. The discharge/charge specific capacity at 0.2 A g −1 is 1032/1022 mAh g −1 after 100 cycles. Even at high current density of 2.0 A g −1 , it still maintains the discharge/charge capacity of 586/578 mAh g −1 after 200 cycles. [ABSTRACT FROM AUTHOR]

In this paper, we design a novel one dimensional and coaxial polyaniline@tin dioxide@multi-wall carbon nanotube (PANI@SnO 2 @MWCNT) composite as advanced conductive additive free anode material for the lithium ion battery. The SnO 2 nanoparticles (∼5 nm) are firstly fixed on the conductive MWCNT skeleton by self-assembling the nano-sized SnO 2 particles on the surface of MWCNT with the assist of surfactant P123 then followed by in-situ coating a flexible layer of PANI with excellent electron and lithium ion conductivity. The one dimensional and coaxial PANI@SnO 2 @MWCNT can effectively accommodate the volume expansion of SnO 2 nanoparticles during lithiating and delithiating via the wrapping of the flexible coating layer of PANI and the buffer of the one dimensional MWCNT. Moreover, the electronic and lithium ionic conductivities of the composite are also obviously improved by the synergistic action between the PANI and MWCNT. As a result, the PANI@SnO 2 @MWCNT composite exhibits an excellent rate capacity and stable cycling performance even without the adding of the conductive additive. [ABSTRACT FROM AUTHOR]

In order to suppress the undesired interfacial reactions between the LTO and electrolyte, the LTO was coated with a chemically stable and electrochemically inert compound of YPO 4 via a facile chemical co-precipitation approach. The results indicated that the YPO 4 coating process did not change the crystal structure of LTO and an amorphous YPO4 coating layer existed on the surface of LTO. The YPO 4 coating layer could suppress the undesired interfacial reactions of LTO. Moreover, the appropriate amount of YPO 4 coating layer was also favourable to improve the rate capability and cyclic stability of the LTO. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO 2 ) based materials are considered promising anodes for high-energy lithium ion batteries (LIBs). However, significant challenges including low initial coulombic efficiency, poor cycling stability and low rate capability are still hindering their practical applications. Effectively constructing a conductive material structure plays a vital role in improving the electrochemical performance of tin based composite anodes for LIBs. In this work, we utilize carbon nanotube-graphene nanosheet with 3D conductive framework to fabricate a SnO 2 /carbon nanotube-graphene nanosheet (SnO 2 /CNT-GN) aerogel composite, in which a small amount of carbon nanotube is introduced to increase the electronic transportation by interconnecting the independent porous graphene structure. In addition, the synergistic interplay between high mechanical property of CNT and flexibility of graphene significantly enhance the stability of SnO 2 /CNT-GN composite. As a result, the SnO 2 /CNT-GN composite exhibit a very decent cycling stability, retaining a stable specific capacity of 809 mAh g −1 (87% capacity retention) after 100 cycles at 0.2 A g −1 , as well as an excellent rate capability, delivering 787 mAh g −1 even at a high current density of 5A g −1 . [ABSTRACT FROM AUTHOR]

The commercial Li 4 Ti 5 O 12 (LTO) is successfully modified by SrF 2 via a low temperature coprecipitation process. The results indicate that Sr 2+ and F − do not co-dope into the bulk phase of the LTO, but instead form a SrF 2 coating layer on the surface of the LTO. The suitable SrF 2 buffer layer could cover the catalytic active sites of the LTO and suppress the electrolyte reduction decomposition on the surface of the LTO, which means that the SrF 2 modification is favorable to suppress gas generation of the LIBs using LTO as anode material during charge/discharge cycles and storage. Moreover, according to optimized the amount of SrF 2 , the 2 wt% of SrF 2 in the SrF 2 modified LTO composites exhibits the best rate capability and an excellent cyclic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • DES was firstly employed to recycle and regenerate waste graphite from spent LIBs. • The impurities in spent graphite were removed efficiently by DES leaching. • DRG exhibited a rather high specific capacity of 449.4 mAh/g for 1st cycle at 0.1C. • The regeneration mechanism of graphite during the DES leaching process was revealed. • The proposed DES treatment had significant economic and environmental benefits. Recovery of graphite from spent lithium-ion batteries (LIBs) as new anode materials in the LIBs after regeneration can not only promote the recycling of spent LIBs, but also help to alleviate its environmental risks. However, the removal of the impurities in spent graphite is unsatisfying and its electrochemical performance need to be further improved when using conventional regeneration methods (such as acid treatment). Herein, we proposed a novel deep eutectic solvent (DES) leaching method to recover and regenerate waste graphite from spent LIBs under mild condition. The result showed that DES leaching could not only effectively remove the impurities in spent graphite, but also restore its crystal structure and morphology. The regenerated graphite obtained by DES treatment (DRG) exhibited a high specific capacity of 449.4 mAh/g for the first cycle at 0.1C and 285.4 mA h/g even after 500 cycles at 1C. In addition, the retention rate and coulombic efficiency of DRG were as high as 96.0 % and 100 %, respectively. These results demonstrated the excellent electrochemical performance of DRG, which was even comparable to that of commercial graphite. The regeneration mechanism of the proposed method was also elucidated. The organic binder was dissolved in DES by forming hydrogen bonds (O H...F and C H...Cl−). The Li coordination complex formed between SEI film and DES contributed to the dissolution of SEI film, and the residual electrolytes were removed based on the similarity-intermiscibility theory. This study provides a facile and green method to accomplish the closed-loop utilization of spent graphite in spent LIBs. [ABSTRACT FROM AUTHOR]

A novel Li 3 V 2 (PO 4 ) 3 composite modified with Fe-doping followed by C+SiO 2 hybrid layer coating (LVFP/C-Si) is successfully synthesized via an ultrasonic-assisted solid-state method, and characterized by XRD, XPS, TEM, galvanostatic charge/discharge measurements, CV and EIS. This LVFP/C-Si electrode shows a significantly improved electrochemical performance. It presents an initial discharge capacity as high as 170.8 mA h g −1 at 1 C, and even delivers an excellent initial capacity of 153.6 mA h g −1 with capacity retention of 82.3% after 100 cycles at 5 C. The results demonstrate that this novel modification with doping followed by hybrid layer coating is an ideal design to obtain both high capacity and long cycle performance for Li 3 V 2 (PO 4 ) 3 and other polyanion cathode materials in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Nano tin dioxide-carbon (SnO 2 /C) composites prepared by various carbon materials, such as carbon nanotubes, porous carbon, and graphene, have attracted extensive attention in wide fields. However, undesirable concerns of nanoparticles, including in higher surface area, low tap density, and self-agglomeration, greatly restricted their large-scale practical applications. In this study, novel porous micron-SnO 2 /C (p-SnO 2 /C) composites are scalable prepared by a simple hydrothermal approach using glucose as a carbon source and Pluronic F127 as a pore forming agent/soft template. The SnO 2 nanoparticles were homogeneously dispersed in micron carbon spheres by assembly with F127/glucose. The continuous three-dimensional porous carbon networks have effectively provided strain relaxation for SnO 2 volume expansion/shrinkage during lithium insertion/extraction. In addition, the carbon matrix could largely minimize the direct exposure of SnO 2 to the electrolyte, thus ensure formation of stable solid electrolyte interface films. Moreover, the porous structure could also create efficient channels for the fast transport of lithium ions. As a consequence, the p-SnO 2 /C composites exhibit stable cycle performance, such as a high capacity retention of over 96% for 100 cycles at a current density of 200 mA g −1 and a long cycle life up to 800 times at a higher current density of 1000 mA g −1 . [ABSTRACT FROM AUTHOR]

[Display omitted] • The activation energy with these catalysts ranged from 79.00 to 83.90 kJ/mol. • Both PyNCM and PyLCO facilitated the production of hydrocarbon compounds in bio-oils. • The content and yield of H 2 increased by 1.6 times and 5.5 times respectively with PyNCM. • PyNCM exhibited better catalytic effect for bio-oil and syngas upgrading than PyLCO. • A catalytic pyrolysis mechanism of biomass with PyNCM and PyLCO was proposed. Thermal treatment is an efficient method to recycle spent lithium-ion batteries and the thermal treatment products are rich in valuable metals with catalytic activity such as Co and Ni. Therefore, the feasibility of using the thermal treatment products (PyNCM and PyLCO) of spent ternary lithium batteries (NCM) and lithium cobalt oxide batteries (LCO) as the cheap catalysts for biomass (wheat straw) pyrolysis was explored in this study. The catalytic effect of the typical components of PyNCM and PyLCO (Ni, Co, NiO and CoO) on the biomass pyrolysis process was also investigated for comparison purposes. The results showed that PyNCM and PyLCO could promote the devolatilization process of wheat straw. The Second order model could well describe the catalytic pyrolysis process of wheat straw based on the Coats-Redfern method, and the obtained activation energy was in the range of 79.00 kJ/mol to 83.90 kJ/mol. The PyNCM and PyLCO had good catalytic activity for enhancing the cracking of bio-oil to produce more gaseous products (syngas), especially for PyNCM, whose gas yield increased significantly from 15.70% to 22.26%. As for bio-oil compositions, the PyNCM and PyLCO both promoted the formation of hydrocarbon compounds and reduce the oxygen content of the obtained bio-oils. The increase of the hydrocarbon content was mainly attributed to the NiO and CoO components in PyNCM and PyLCO. In addition, both PyNCM and PyLCO increased the content and yield of H 2 in the syngas. Especially for PyNCM, the content and yield of H 2 increased 1.6 times and 5.5 times respectively compared with direct pyrolysis of wheat straw without catalyst. The mechanism of biomass catalytic pyrolysis in the presence of PyLCO and PyNCM was proposed and discussed. The catalytic effect of PyNCM on wheat straw pyrolysis was more distinct than that of PyLCO, which might be attributed to the positive synergistic effect of Ni and Co compounds in PyNCM. This study demonstrated that the thermal treatment products of spent lithium-ion batteries could be used as efficient catalysts for biomass pyrolysis products upgrading. [ABSTRACT FROM AUTHOR]

This study presents the preparation and electrochemical performance of cobalt-doped Li 2 FeSiO 4 /C (Co-doped LFS/C) composite by using a solid-state reaction assisted with refluxing process. The Co-doped LFS/C composite delivers a higher discharge capacity of 142.5 mAh g −1 at 3.0 C even after 100 cycles compared with pristine LFS/C. A clear feature of cobalt-doping in Li 2 FeSiO 4 has been specified by X-ray powder diffraction, X-ray photoelectron spectroscopy coupled with Ar-ion sputtering, X-ray absorption spectroscopy, and positron annihilation lifetime spectroscopy. It is confirmed that Co has been successfully doped into the lattice of LFS, and Co-doping does not change the monoclinic structure of LFS and the oxidation state of Fe. Positron annihilation lifetime spectroscopy analysis further demonstrates that Co-doping increases the defect concentration and the electronic conductivity of LFS. The results clarify the nature of cobalt-doping in LFS and are helpful for understanding the enhancement mechanism of the electrochemical performance of LFS and other cathode materials. [ABSTRACT FROM AUTHOR]

A series of Li 2 Fe 1- x V x SiO 4 /C ( x = 0.00, 0.03, 0.05 and 0.07) composites have been synthesized via a refluxing-assisted solid-state reaction. XRD results confirm the monoclinic structure with space group P2 1 for Li 2 Fe 1- x V x SiO 4 /C compounds. TEM and Raman spectroscopy demonstrate V-doping can increase the graphitization degree of residual carbon. XPS confirms that V-incorporation does not change the divalent state of Fe, and the oxidation state of V in V-doped Li 2 FeSiO 4 /C is +3. Combined Ar-ion sputtering with XPS, it is found that V has been successfully doped into the crystal lattice of Li 2 FeSiO 4 . Electrochemical tests show that LFS/C-5 V delivers the highest initial discharge capacity of 220.4 mAh g −1 and the biggest Li-ion diffusion coefficient of 1.60 × 10 −11 cm 2 s −1 . In addition, the density functional theory (DFT) calculations predict that V-doping decreases the electronic band gap of Li 2 FeSiO 4 , thus leads to significant improvement in the electrical conductivity of Li 2 FeSiO 4 . The enhanced electrochemical performance can be attributed to the increased electronic conductivity, the decreased charge transfer impedance, and the improved Li-ion diffusion coefficient. Our results clarified the nature of V doping into Li 2 FeSiO 4 and demonstrated that V-doping is a promising approach to improve the electrochemical performance of Li 2 FeSiO 4 . [ABSTRACT FROM AUTHOR]

Highlights: [•] Zn is employed as dopant in LiNi0.5Mn1.5O4. [•] The effects of Zn doping on structure and performance are investigated. [•] LiZn0.08Ni0.42Mn1.5O4 shows excellent rate capability and cyclic performance. [•] The mechanism of performance improvement by Zn doping is examined. [ABSTRACT FROM AUTHOR]

Highlights: [•] LVP/C is successfully prepared by a novel refluxing-assisted solid-state reaction. [•] The LVP/C composite contains much lower carbon than that prepared by hydrothermal method. [•] The LVP/C exhibits more uniform morphology and a smaller size. [•] The LVP/C shows a desirable electrochemical performance. [Copyright &y& Elsevier]

Highlights: [•] Nano-Li2FeSiO4/C/MWCNTs composite was successfully synthesized via a citric acid-based sol–gel method. [•] High conducting network were attained for Li2FeSiO4/C/MWCNTs. [•] The Li2FeSiO4/C/MWCNTs electrode can extract more than 1mol Li+ at 0.1C. [•] The as-prepared Li2FeSiO4/C/MWCNTs electrode displays a remarkably enhanced high-rate performance and cycling stability. [Copyright &y& Elsevier]

Highlights: [•] A polymer-assisted sol–gel method is developed to fabricate porous nanoscaled LiMn2O4. [•] Porous nanoscaled LiMn2O4 cathode exhibits superior rate capability and excellent cyclability. [•] Morphology, Li+ diffusion coefficient and Mn dissolution are examined to explain the high performance. [Copyright &y& Elsevier]

Abstract: Hollow porous submicron-sized ZnMn2O4 spheres have been successfully prepared using self-made MnCO3 spheres as template. The morphology and structure evolution of the hollow porous ZnMn2O4 spheres are well examined to achieve optimal electrochemical performance. The SEM image shows that the ZnMn2O4 sample is composed of hollow porous submicron spheres (0.5–1.0μm) formed by nanosized particles with diameters of 25–50nm. The 600°C-sintered sample exhibits the best electrochemical performance. At a current density of 100mAg−1, the discharge capacity is as high as 1260mAhg−1 for the first cycle and retains stably at 599mAhg−1 after 40 cycles. Even at 1000mAg−1, the average specific capacity is still 450mAhg−1. The excellent electrochemical performance can be attributed to its unique feature of hollow porous structure, which may not only buffer the volume variation during discharge/charge process with hollow interior, but also facilitate the electrolyte penetration and thus shorten the transport length of Li+ ions. [Copyright &y& Elsevier]

Abstract: Ti-incorporated LiFe1−x Ti x PO4 (0≤ x ≤0.2) samples have been prepared via a two-step solid-state reaction route. The samples have systematically been investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge/discharge measurements. The incorporation of Ti in LiFePO4 significantly enhances the electrochemical performance; the carbon-coated LiFe0.9Ti0.1PO4 sample shows the best performance. It is confirmed that LiFe1−x Ti x PO4 with x ≤0.05 are of single phase while those with 0.07≤ x ≤0.2 contain impurity phases: LiTi2(PO4)3 and TiP2O7. The impurities influence not only the electronic conductivity, but also the total specific capacity. Appropriate amount of titanium incorporation is favorable for the improvement in electrochemical performance. [Copyright &y& Elsevier]

Abstract: LiFe0.8Mn0.2PO4/C composites are synthesized via solid state reaction promoted by wet ball milling. Synthesis conditions are optimized to obtain desirable crystallization, morphology, particle size and specific surface area. Our experiments show that the LiFe0.8Mn0.2PO4/C sample sintered at 600°C exhibits the best performance with initial discharge capacities of 160mAhg−1 at 0.1C, 133mAhg−1 at 5C and 122mAhg−1 at 10C. At 5C, the cathode exhibits an excellent cyclability over 100 cycles, and the average specific energy density is as high as 414Whkg−1. We attribute the superior performance to well crystallization, uniform morphology, small particle size and high specific surface area. Our results indicate that partial substitution of Mn ions for Fe ions can significantly improve rate capability and energy density in LiFePO4. LiFe0.8Mn0.2PO4 should be identified as highly promising cathode material with high energy density. [Copyright &y& Elsevier]

Abstract: Mn3O4 nanocomposite with multi-walled carbon nanotubes (MWCNTs) has been successfully fabricated via a simple solvothermal route assisted by sodium acetate. Mn3O4 nanocrystals are uniformly anchored on MWCNTs. As anode material for lithium-ion batteries, the nanocomposite exhibits excellent cycling stability and rate capability. It delivers an initial reversible capacity of 1380mAhg−1 at a current density of 100mAg−1, and retains the capacity to 592mAhg−1 after 50 cycles. Even at 1000mAg−1, the capacity is still 387mAhg−1 after 35 cycles. The superior performance is ascribed to the unique architecture with short diffusion length for lithium ions and effective conductive network for electron transport. [Copyright &y& Elsevier]

Abstract: Nonstoichiometry and Na incorporation are designed to attain controllable impurity phases Li4P2O7 and Li3PO4 in LiFePO4. The effects of Li4P2O7 and Li3PO4 on structure and electrochemical performance have been investigated. Both Li4P2O7 and Li3PO4 impurities are observed in (Fe, P)-deficient LiFe0.9P0.95O4−δ . With Na+ incorporation, Li4P2O7 phase disappears while Li3PO4 content increases. Proved by X-ray photoelectron spectroscopy, nonstoichiometry and Na-incorporation do not change the chemical state of Fe(II). Our experiments indicate that Li4P2O7 and Li3PO4 show different effects on the electrochemical performance. Li4P2O7 leads to degradation of cyclability, whereas a small amount of Li3PO4 is beneficial for the improvement in capacity and rate capability. The 1% Na-doped LiFe0.9P0.95O4−δ composite exhibits the best electrochemical performance. We ascribe the improvement to the structural stabilization caused by the existence of Li3PO4. [Copyright &y& Elsevier]

Abstract: SnO2-based composite coaxial nanocables with multi-walled carbon nanotube (MWCNT) and polypyrrole (PPy), SnO2@MWCNT@SnO2@PPy have been successfully synthesized via a simple one-pot chemical route. Such a novel nanostructure can not only provide a high conductivity, but also effectively suppress mechanical stress and prevent aggregation of SnO2 nanoparticles, leading to the improvement in the electrochemical utilization and cycling stability of SnO2 during Li-storage reaction. As anode materials, the as-obtained coaxial nanocables show a reversible capacity as high as 600mAh g−1 and a coulombic efficiency close to 100%, which is potential for practical application in lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: Na+ and Cl− co-doped LiFePO4/C composites were prepared via a simple solid state reaction. The structure, valence state and electrochemical performance were carefully investigated. Rietveld refinement on X-ray diffractions reveals that Na+ and Cl− have successfully been introduced into the lattice of LiFePO4. X-ray photoelectron spectroscopy proves that the co-doping of Na+ and Cl− does not change the chemical state of Fe(II). Experimental results further show that the co-doping contributes to induce the lattice distortion, modify the particle morphology, and increase the electronic conductivity. Considerably enhanced capacity, coulombic efficiency and rate capability were obtained in the co-doped LiFePO4. The specific capacities are 157mAhg−1 at 0.2C, 115mAhg−1 at 10C and 98mAhg−1 at 20C for the (Na+, Cl−) co-doped LiFePO4/C cathode material. The improvement can be ascribed to the enhanced electronic conductivity and electrode kinetics due to the micro-structural modification promoted by co-doping. [Copyright &y& Elsevier]

Abstract: A simple and efficient strategy was employed to enhance high-rate performance for carbon-coated LiFePO4 (C-LFP) by incorporating with conducting polymer polyaniline (PANI). C-LFP was synthesized via a solid state reaction whereas PANI was formed in situ by chemical oxidative polymerization of aniline with ammonium persulfate as an oxidizer to achieve the C-LFP/PANI composites. Specific capacities as high as 165mAhg−1 at 0.2C, 133mAhg−1 at 7C and 123mAhg−1 at 10C were obtained in C-LFP/7wt.% PANI composite. Moreover, the composite exhibits remarkably improved cyclability as compared with the parent C-LFP. The mechanism has been carefully investigated for the improvement in the electrochemical performance. Experimental results show that the charge transfer impedance decreases significantly and the cathode surface becomes much smooth over cycling with modification of conductive PANI. The incorporated PANI can work not only as an additional host for Li+-ion insertion/extraction, but also as a binder to modify the electrode surface and a container for electrolyte to penetrate into C-LFP particles. [Copyright &y& Elsevier]