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Tuned tin chalcogenides rooted in hierarchical porous carbon (HPC) with N-carbon coating layers are prepared by thermal shock under various temperatures (denoted as HPC-SnS2-PAN-Various T). With the increase of annealing temperature, the morphology and phase structure of SnS2, as well as the cyclization degree of polyacrylonitrile (PAN), are significantly changed, which leads to the formation of rod-like SnS and ordered structure of conductive N-carbon layer. By combining HPC, N-carbon coating derived from the cyclization of PAN, with 1D SnS nanorods generated from structural phase transformation of SnS2, the optimized composite (HPC-SnS2-PAN-500) as anode for lithium ion batteries (LIBs) provides buffer space for volume changes during alloying/dealloying process, builds a highly conductive network as well as decreases irreversible capacity from solid electrolyte interphase and enhances the ion/electron transport. Attributed to the above merits from composition regulation and architecture modification by sulfur depletion and PAN cyclization, this target anode exhibits an extraordinary cycling stability with a high specific capacity of 652.5 mA h/g at 0.5 A/g after 900 cycles. It suggests that rod-like SnS embedded in HPC with cyclized PAN layers by thermal treatment approach renders a potential structural design of anode materials for LIBs.

Gas–solid interface engineered ultrahigh-pore-volume F-doped hierarchical porous hollow carbon nanospheres for high-sulfur-content Li–S batteries.

Tin sulfides have attracted great attention as promising anode materials for lithium-ion batteries due to their high theoretical specific capacity. However, the rapid capacity decay, resulting from...

Lithium sulfur batteries provide one of the most attractive opportunities for next generation energy storage devices benefiting from their particularly high energy density. However, the obstacle ma...

The graphene/mesocarbon microbead (MCMB) composite is assessed as an anode material with a high capacity for lithium-ion batteries. The composite electrode exhibits improved cycling stability and rate capability, delivering a high initial charge/discharge capacity of 421.4 mA·h/g/494.8 mA·h/g as well as an excellent capacity retention over 500 cycles at a current density of 40 mA/g. At a higher current density of 800 mA/g, the electrode still retains 35% of its initial capacity which exceeds the capacity retention of pure graphene or MCMB reference electrodes. Cyclic voltammetry and electrochemical impedance spectroscopy reveal that the composite electrode favors electrochemical kinetics as compared with graphene and MCMB separately. Superior electrochemical properties suggest a strong synergetic effect between highly conductive graphene and MCMB.

Nanocubic lithium titanate (Li4Ti5O12, N-LTO) has been synthesized by a modified solid-state reaction using H-titanate nanotubes as titanium source and lithium carbonate as lithium source. The as-prepared N-LTO was highly crystalline with size ranging from 50 nm to 200 nm. The electrochemical performance of the N-LTO was investigated and compared with commercial nanoscale lithium titanate (C-LTO). The N-LTO electrode showed an initial discharge capacity of 181.0 mAh g−1 at 0.5 C with capacity retention of 86.7% after 200 cycles. At a high rate of 10 C, the N-LTO electrode retained a high reversible capacity of 149.2 mAh g−1, considerably higher compared with the value of 117.1 mAh g−1 for C-LTO. The N-LTO electrode exhibited excellent long-term cycling stability with capacity retention of 82.6% at 5 C after 1000 cycles. A full cell of LiFePO4/N-LTO was tested, showing capacity retention of 78.7% at 1 C after 100 cycles.

Selenium–sulfur solid solutions show unique advantages beyond sulfur and selenium as cathode materials for lithium batteries. Herein, we propose a dual-confined SexSy-based cathode with a three-dimensional (3D) network structure where Se0.4S0.6 is first encapsulated in double-layered hollow carbon spheres (DLHCs) and embedded by 3D graphene-like material (3DG) shells. The dissolution of polysulfides/ polyselenides in the cathode is effectively inhibited through dual confinement from DLHCs and 3DG as well as chemical binding between sulfur and selenium. Benefiting from the indispensable advantages of Se0.4S0.6 and the uniquely designed host architecture, the 3DG-DLHC-Se0.4S0.6 cathode delivers a high reversible capacity of 627 mAh g−1 at 0.2 A g−1 after 200 cycles, good rate capability of 533 mAh g−1 at 2 A g−1, and outstanding long cycling stability over 500 cycles with Coulombic efficiency almost reaching 100%.

In this work, the V2O3 nanoparticles (NPs) with ultrathin carbon shells were synthesized by a facile solvothermal process. The V2O3 NPs were about 30 nm and contained a carbon shell of about 2 nm thick. The V2O3 NPs were homogeneously dispersed and loosely packed. When used as anode material, the V2O3 core-shell NPs showed a reversible capacity up to 525 mA h g−1 at 200 mA g−1 over 200 cycles with good cycle stability and rate capability. The excellent electrochemical performance promotes its practical application in lithium-ion batteries.

CN(CH2)2Si(CH3)(OCH2CH2OCH3)2 (BNS) is used as electrolyte solvent to improve the safety for LiNi1/3Co1/3Mn1/3O2 (NCM)/graphite battery. BNS increases the thermal stability of the carbonate-based electrolyte with (de) lithiated cathode/anode and the electrochemical stability of coin cells. By using an optimal BNS-based electrolyte formula, 13 Ah NCM/graphite prismatic cell achieves 95.8% retain of capacity at 2 C/3 C (charge/discharge) rate after 600 cycles. Meanwhile, 13 Ah prismatic cell exhibits improved safety performance in the nail penetration test.

Selenium disulfide (SeS2) exhibits attractive advantages beyond naked selenium and sulfur as an electroactive material for lithium storage. Herein, a three-dimensional (3D) interconnected, sulfur-doped mesoporous carbon (ISMC) with a sulfur content of 9.3 wt% has been prepared by a simple in-situ constructing strategy to confine SeS2 for lithium batteries. The sulfur doping enhances the conductivity of the carbon matrix and inhibits the diffusion of polysulfides and polyselenides, while the 3D mesoporous network facilitates fast electron and ion transport. Benefiting from the synergy between sulfur doping and 3D network architecture, the SeS2@ISMC composite displays a high reversible capacity of 486 mAh g−1 after 200 cycles at 0.5 A g−1 and outstanding rate capability of 465 mAh g−1 at 4 A g−1.

Polyvinyl alcohol grafted poly (acrylic acid) (PVA-g-PAA) is synthesized through graft polymerization of acrylic acid (AA) onto PVA backbone via a free radical reaction. PVA-g-PAA is used as a water-soluble binder for silicon (Si) anodes in lithium-ion batteries (LIBs). The enhanced adhesion strength, excellent flexibility and high electrolyte uptake after grafting reaction render PVA-g-PAA a robust binder for Si anodes. Compared to linear PVA, PAA and CMC, optimal Si-PVA-g-10PAA electrode exhibits better cycle stability, higher Coulombic efficiency and more excellent rate capability, possessing a high electrical conductivity, low SEI/charge transfer resistance and fast lithium-ion diffusion coefficient. PVA-g-PAA binder not only maintains the electrode's mechanical and electrical integrity, facilitates a favorable electrochemical kinetics, but also assists in forming a stable SEI layer on Si surface upon long-term cycling. Such a strategy sheds light on the design of novel polymer binders for practical applications of high-capacity active materials with great volume change.

N-cyanoethyl polyethylenimine (CN-PEI) is synthesized by modifying polyethylenimine (PEI) with acrylonitrile through a Michael addition reaction. Depending on cyanoethylation level, CN-PEI can be obtained as a form of solution, micro-emulsion or emulsion in water. CN-PEI micro-emulsion is investigated as water-soluble binder for the application of lithium iron phosphate (LFP) cathode in lithium-ion batteries. CN-PEI binder not only maintains the outstanding dispersion capability of PEI but also exhibits an excellent adhesion strength and higher ionic conductivity because of the introduction of polar cyano groups. As a result, CN-PEI binder can effectively maintain the mechanical integrity and decrease the polarization of LFP electrode during the operation of the battery. LFP electrode with CN-PEI binder exhibits good cycle stability and enhanced rate performance delivering a capacity of 99.6% at a rate of 0.5 C after 100 cycles and a high discharge capacity of 102.4 mAh g−1 at 5 C.

Poly (3, 4-ethylenedioxythiophene): tosylate (PEDOT: Tos) is synthesized by chemical oxidative polymerization with polyvinylpyrrolidone (PVP) as stabilizer in organic solvent. The effects of different molecular weight and additive amount of PVP stabilizer, various volume ratios of propylene carbonate (PC) to ethanol in organic system, different oxidative agents and various polymerization temperature/time on as-prepared PEDOT dispersion are taken into consideration and investigated systematically. Fourier transform infrared spectroscopy (FT-IR), film-forming property and electrical conductivity are studied and compared among different reaction conditions. The optimal polymerization scenario is to prepare PEDOT particles with 2 wt.% PVP (M.w. = 58,000) stabilizer and Fe2(SO4)3 oxidant at 80 °C for 24 h in organic system of PC and ethanol (volume ratio = 1: 3). Optimal PEDOT with PVP possesses more homogeneous particle size, better particle-particle connectivity in film and higher electrical conductivity (1.67*10−2 s cm−1) than that of PEDOT without PVP (5.2*10−4 s cm−1) and commercial organic PEDOT (4.7*10−4 s cm−1). The morphology and elemental composition of PEDOT particles with PVP are also investigated and compared with that of commercial organic PEDOT and aqueous PEDOT/PSS dispersion.

A novel molybdenum disulfide/carbon (MoS2/C) nanocomposite is synthesized by a simple hydrothermal method using glucose as a carbon source and Pluronic F127 as promoting agent in presence of MoS2 nanoparticles and followed by carbonization. Pluronic F127 is used as an essential agent which inhibits the spontaneous formation of carbon microspheres during the hydrothermal reaction. The composite electrode exhibits excellent cycling stability and rate capability, delivering a reversible capacity of 882.6 mA h g−1 at a current density of 50 mA g−1 and a capacity retention of 82.8% after 100 cycles at a current density of 100 mA g−1. At a higher current density of 300/500 mA g−1, it still retains a capacity of 603.6/461.6 mA h g−1 respectively, as compared to 295.6/228.4 mA h g−1 for the pristine MoS2 electrode. The composite shows favorable electrochemical kinetics compared with pristine MoS2 due to the incorporation of homogenous conductive carbon layer and its nanostructured morphology.

The development of solid state electrolytes is considered as an effective approach to build safer lithium-ion batteries by replacing the conventional liquid electrolytes. However, the solid state electrolytes face continuous challenges to improve their ionic conductivities and mechanical properties. Herein, we report the synthesis of novel polymer electrolytes based on cross-linked polyacrylonitrile-polyethylenimine (PAN-PEI) nanofiber membranes infiltrated with in-situ gelated electrolytes using tripropylene glycol diacrylate as crosslinking agent in the organic carbonate-based liquid electrolytes. The PAN-PEI nanofiber membranes with different mass ratios of PAN/PEI prepared by electrospinning method are constructed with entangled nanofibers of an average diameter of ~600 nm. The optimized PAN-PEI based electrolyte has a high ionic conductivity up to 3.39 mS cm−1 at room-temperature and decent tensile strength of 9.36 MPa. Linear sweep voltammetry shows that the polymer electrolyte also has a wide electrochemical window of 5.4 V (vs. Li/Li+). This polymer electrolyte exhibits excellent cycling stability even in the high energy density of LiNi0.8Co0.1Mn0.1O2/Graphite, delivering an initial discharge capacity of 175 mAh g−1 at 0.5 C with a capacity retention of 91.4% after 200 cycles.

Nitrogen and sulfur co-doped hierarchical porous carbon (N,S-HPC) is synthesized by using polyaniline and poly(3,4-ethylenedioxythiophene) as doping sources and polytetrafluoroethylene as the silica template removal agent for lithium-sulfur batteries. N,S-HPC shows the interconnected hierarchical porous network, which enables sulfur to be uniformly dispersed in the carbon matrix thus accelerating the transport of electrons and lithium ions. The S@N,S-HPC composite cathode exhibits a high capacity utilization of 1106 mA h/g at 0.2 C, together with excellent rate capacity of 600 mA h/g at 2 C, and also superior cycle life over 500 cycles with a capacity decay of 0.08 % per cycle at 1 C. The outstanding electrochemical performances for S@N,S-HPC cathode are mainly ascribed to the hierarchical porous structure of carbon and N/S co-doping, which offers sufficient interface for the deposition of solid discharge products and impedes the diffusion of polysulfides due to both physical confinement and chemical interaction by porous carbon matrix and N/S atoms.

High voltage LiNi0.5Mn1.5O4 cathode material was prepared by two steps solid-state method with additive PEG dispersant. XRD, SEM, XPS and electrochemical tests have been carried out, and the results show that the PEG can promote the pyrolysis of MnO2 and limit the impurities formation. The secondary particle can also be effectively restrained in the pre-calcination of MnO2 and NiO, and the effect can be last to the final product. The capacity from Mn3+/Mn4+ couple was reduced and the whole capacity can reach 140.7 mAh g−1 with the retention rate of 81.33% after 100 cycles at 0.2C. Meanwhile, the product has better rate performance and surface stability than those prepared by traditional two-step solid-state method.

Xanthan Gum (XG) is systematically investigated and employed as water soluble binder for LiFePO4 (LFP) cathode in Li-ion batteries. XG binder exhibits good thermal stability and processes abundant functional groups such as carboxyl and hydroxyl, displaying a better adhesion strength of 0.085 N cm−1 than sodium carboxymethyl cellulose (CMC, 0.050 N cm−1), but inferior to polyvinylidene difluoride (PVDF, 0.170 N cm−1). The Rheology test reveals that the viscosity of LFP slurry prepared with XG binder is higher than that of PVDF, resulting in a better dispersion of LFP and carbon black particles. The electrochemical performances of LFP-XG electrode are investigated and compared with those of aqueous CMC and conventional PVDF binder. LFP-XG displays better cycle stability and rate performance than PVDF, comparable to CMC, which retains 55.3% capacity of C/5 at 5 C as compared to PVDF (34.8%) and CMC (57.8%). Cyclic voltammetry (CV) shows that LFP-XG has smaller redox polarization and faster lithium diffusion rate than PVDF while electrochemical impedance spectroscopy (EIS) measurement at specified intervals reveals its more favorable electrochemical kinetics than that with PVDF, similar to CMC, thus better rate capability. Scanning electron microscopy (SEM) displays that LFP-XG has a more homogenous distribution of LFP and conductive carbon black particles with XG before cycling and better maintains its structure integrity after 100 cycles than that of PVDF. Furthermore, LFP-XG is observed to process a high ionic conductivity supported by dQ/dV profiles.

A novel core–shell structured Si/S-doped-carbon composite with buffering voids (Si/v-SC), was prepared by a facile hydrothermal method using glucose as carbon source and simultaneously chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of Si@SiO2 nanoparticles, and followed by carbonization and removal of the SiO2 layer. The results showed that the Si nanoparticles were embedded in the S-doped-carbon buffer space to form a core–shell structure. Compared to the Si/carbon composite (Si/v-C) without S-doping in carbon layer, the Si/v-SC composite electrode showed improved cycling and rate performance, exhibiting a reversible capacity of 664 mA h g−1 over 300 cycles at the current of 0.4 A g−1 and a high capacity of 537 mA h g−1 even at 10 A g−1. The effects of S-doping on the properties of carbon material were further investigated. XRD and Raman test revealed that the S-doping increased the interspace of carbon crystal face, and improved the amorphous structure of carbon and thus the initial coulombic efficiency.

A water-soluble conductive composite binder consisting of carboxymethyl chitosan (CCTS) as a binder and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a conduction-promoting agent is reported for the LiFePO 4 (LFP) cathode in Li-ion batteries. The introduction of conductive PEDOT:PSS as a conductive composite binder facilitates the formation of homogeneous and continuous conducting bridges throughout the electrode and raises the compaction density of the electrode sheet by decreasing the amounts of the commonly used conducting agent of acetylene black. The optimized replacement ratios of acetylene black with PEDOT:PSS (acetylene black/PEDOT:PSS = 1:1, by weight) are obtained by measuring electrical conductivity, peel strength and compaction density of the electrode sheets. The LFP half-cell with the optimized conductive binder exhibits better cycling and rate performance and more favorable electrochemical kinetics than that using only acetylene black conducting agent. The pilot application of PEDOT:PSS/CCTS binder in 10 Ah CCTS-LFP prismatic cell exhibits a comparable cycling performance, retaining 89.7% of capacity at 1 C/2 C (charge/discharge) rate as compared with 90% for commercial PVDF-LFP over 1000 cycles, and better rate capability than that of commercial PVDF-LFP, retaining 98% capacity of 1 C at 7 C rate as compared with 95.4% for PVDF-LFP.

Structural hierarchy of porous carbon has been a key role in the sulfur hosts for lithium sulfur (Li-S) batteries. Herein, coral-like hierarchical porous carbon (HPC) is developed by a dual alkaline activation process. The production of HPC is inexpensive and scalable, which gives a great promise as sulfur host for the future application of Li-S batteries. Moreover, the as-prepared material achieves an admirable interconnected conductive network, hierarchical pore size distribution and notably high pore volume. This architecture contributes to ultrafast ion diffusion, rapid mass transport, robust electrode configuration as well as effective physical adsorption for soluble polysulfide, thus enabling a favorable scaffold for Li-S battery cathodes with high sulfur utilization and exceptionally electrochemical stability. As a consequence, the HPC based sulfur cathode manifests high areal capacity of 7.5mAh/cm2 with a high sulfur loading and superb cycling stability over 500 cycles with lower sulfur loading. The classification of alkali significantly affects on the hierarchical porosity of the resultant carbon. And the correlation between the pore size distribution and electrochemical performance is revealed. This work offers a hierarchical material engineering of a sulfur host material for restricting the mobile polysulfide moieties, thus achieving a high efficiency and stable Li-S battery.

Silicon oxycarbonitride (SiOCN) composites with different carbon contents were synthesized by pyrolysis of precursors generated from aldimine condensation of 3-aminopropyltriethoxysilane (APTES) with different aldehydes and simultaneous hydrolysis of APTES. Both SiOCN-1 and SiOCN-5 composites, derived from formaldehyde and glutaraldehyde respectively, display similar bulky structure composed by aggregated nanospheres with a diameter of 70–100 nm. SiOCN-5 has a higher carbon content of 30.4% than 15.9% for SiOCN-1, while a lower specific surface area of 38.2 m2 g−1 than 76.0 m2 g−1 for SiOCN-1. SiOCN/S cathodes with sulfur loading of 1.2–1.5 mg cm−2 were fabricated using SiOCN as sulfur host on different current collector of aluminum foil (AL) or carbon paper (CP). When using aluminum foil as current collector, SiOCN-5/S-AL cathode exhibits better electrochemical performance than SiOCN-1/S-AL, primarily due to the higher electrical conductivity of SiOCN-5 comparing with SiOCN-1. When using porous carbon paper as current collector, SiOCN-5/S-CP cathode shows the best cycling performance with a discharge capacity of 648.9 mA h g−1 at 0.2C after 100 cycles. Even at a high rate of 1C, SiOCN-5/S-CP also exhibits an excellent cycling stability, delivering a reversible discharge capacity of 374.5 mA h g−1 after 500 cycles with a capacity retention of 73.0%.

s Arabic gum grafted poly (acrylic acid) (GA-g-PAA) is prepared through a free radical graft polymerization of acrylic acid onto Arabic gum. Crosslinkable aqueous binder is developed by combining GA-g-PAA and branched polyols (pentaerythrotol, PER; triethanolamine, TEOA) as crosslinking agent for Si anodes of lithium-ion batteries. The aqueous composite binder undergoes crosslinking at about 110 °C to form robust crosslinked networks, matching well with the processing temperature of the electrode sheet in industry. GA-g-PAA/PER binder displays higher adhesion strength than GA-g-PAA and GA-g-PAA/TEOA. The Si electrode with GA-g-PAA/PER exhibits a slightly better cycling stability at 0.2C for 100 cycles, better rate capability than GA-g-PAA and GA-g-PAA/TEOA. At a high rate of 1C, Si electrode with GA-g-PAA/P delivers a higher specific capacity of 1968.1 mAhg−1 with a better capacity retention of 57.5% when compared with those with GA-g-PAA and GA-g-PAA/T binder.

Oligo(ethylene oxide)-functionalized trialkoxysilanes can be used as novel electrolytes for high-voltage cathode, such as LiCoO2 (4.35 V) and Li1.2Ni0.2Mn0.6O2 (4.6 V); however, they are not well compatible with graphite anode. In this study, a synergistic solid electrolyte interphase (SEI) film-forming effect between [3-[2-(2-methoxyethoxy)ethoxy]propyl]-trimethoxysilane (TMSM2) and propylene carbonate (PC) on graphite electrode was investigated. Excellent SEI film-forming capability and cycling performance was observed in graphite/Li cells using the electrolyte of 1 M LiPF6 in the binary solvent of TMSM2 and PC, with the PC content in the range of 10–30 vol.%. Meanwhile, the graphite/Li cells delivered higher specific capacity and better capacity retention in the electrolyte of 1 M LiPF6 in TMSM2 and PC (TMSM2:PC = 9:1, by vol.), compared with those in the electrolyte of 1 M LiPF6 in TMSM2 and EC (TMSM2:EC = 9:1, by vol.). The synergistic SEI film-forming properties of TMSM2 and PC on the surface of graphite anode was characterized by electrolyte solution structure analysis through Raman spectroscopy and surface analysis detected by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analysis.

To improve corrosion resistance of magnesium alloy AZ91D, y-Mercaptopropyltrimethoxysilane (MPTS) was assembled on the surface of micro-arc oxidation (MAO) treated magnesium alloy by self-assembly membrane (SAM) technique. The surface morphology and chemical components of the MAO/SAM composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The corrosion resistance of samples was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy and total immersion tests in a 3.5 wt % NaCl solution. The measured EIS data were simulated by an equivalent circuit. Also the molecular dynamic simulation was used to study the adsorption behavior at the molecular level. The results showed that the surface of magnesium alloy was well covered by the MAO/SAM composite coatings with a better corrosion resistance. Chemical adsorption was formed between the organic molecules and the surface of the MAO coating. The approach presented here afforded an effective alternative for surface modification of magnesium-based materials to meet the many aspects of the application requirements.

CdS nanoparticles with high uniformity have been synthesized through a new liquid–liquid approach, using dimethyl sulfoxide and the mixture of oleyl amine and oleic acid as separate solvents, more convenient inorganic cadmium salt as cadmium source, and sulfur powder as sulfur source. The process can be conducted under mild conditions. It is found that the initial Cd/S molar ratio of precursor plays important role in controlling particle size. Higher concentration of sulfur precursor results in the larger particle size. The obtained colloidal CdS nanocrystals show obvious absorption and fluorescence in visible light region. When using methylene blue as degradation agent, the obtained CdS nanoparticles exhibit high photocatalytic ability.

Driven by intriguingly high energy density up to 2600 Wh/kg, lithium sulfur (Li-S) battery is considered as one of the most promising energy storage devices compared with conventional lithium ion battery. The main obstructions plaguing Li-S batteries associated with the electrical resistivity of sulfur/lithium sulfides, the dissolution of polysulfides in ether-based electrolyte and the large volume variation, result in poor cycling performance and rate capability. Here, we develop a polymer optimized cathode that is polydopamine layer coated on the surface of sulfur loaded hierarchical porous graphitic carbon composites (HPGC-S-PD) by a simple in-situ polymerization method toward the highly suppressed shuttle effect, thus the significantly improved cell performance. Attributed to the superiorities of the structure engineering including the strengthened polysulfide trapping, accelerated ionic conductivity and stable electrode construction, this cathode can deliver an excellent cycling performance over 700 cycles at 1 C, a high areal capacity of 7.25 mAh/cm2 with raised sulfur loading as high as 5.15 mg/cm2. Meanwhile, the obtained cathode can work well with a lower E/S ratio compared with the non-coated cell, which suggests the immense possibility for yielding a practically Li-S battery with high energy density based on this electrode architecture. Strikingly, the pouch cell with optimized cathode material can realize an energy density of 272 Wh/kg after 40 cycles at 0.1 C. This rational design of sulfur cathode combining HPGC with polymer coating by a scalable strategy provides a comprehensive understanding of the structural engineering for sulfur cathodes in pursuit of practically high performance Li-S batteries.

Nanostructured sulfur cathode with a multiple core-shelled structure, featured with the spherical double-layered hollow carbon/sulfur composite (DLHC/S) coated with a conductive layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), is designed and synthesized for lithium-sulfur batteries. Transmission electron microscope images of DLHC/S single nanoparticle show that the sulfur aggregates predominantly in the interior space between the two carbon shells by using a vacuum infiltration process. The electric conductivity of DLHC/S@PEDOT:PSS increases over 5 times as comparing to DLHC/S without PEDOT:PSS coating. The composite cathode exhibits a high reversible capacity of 1089 mAh g−1 at 0.2C and superior rate capacity of 510 mAh g−1 even at 4 C, and also remarkable cycling stability with a capacity decay of 0.097% per cycle after 500 cycles at 1 C. The excellent electrochemical performances for DLHC/S@PEDOT:PSS cathode are primarily attributed to the engineering of the unique multiple core-shell structure of DLHC/S@PEDOT:PSS, which inhibits the sulfur dissolution into the electrolyte and the polysulfide shuttle effect, together with the conductivity enhancement due to PEDOT:PSS coating.

Main obstacles from the shuttle effect and slow conversion rate of soluble polysulfide compromise the sulfur utilization and cycling life for lithium sulfur (Li-S) batteries. In pursuit of a practically viable high performance Li-S battery, a separator configuration (CoS2 /HPGC/interlayer) as efficient polysulfide trapping barrier is reported. This configuration endows great advantages, particularly enhanced conductivity, promoted polysulfide trapping capability, accelerated sulfur electrochemistry, when using the functional interlayer for Li-S cells. Attributed to the above merits, such cell shows excellent cyclability, with a capacity of 846 mAh g-1 after 250 cycles corresponding to a high capacity retention of 80.2% at 0.2 C, and 519 mAh g-1 after 500 cycles at 1C (1C = 1675 mA g-1 ). In addition, the optimized separator exhibits a high initial areal capacity of 4.293 mAh cm-2 at 0.1C. Moreover, with CoS2 /HPGC/interlayer, the sulfur cell enables a low self-discharge rate with a very high capacity retention of 97.1%. This work presents a structural engineering of the separator toward suppressing the dissolution of soluble Li2 Sn moieties and simultaneously promoting the sulfur conversion kinetics, thus achieving durable and high capacity Li-S batteries.

A novel aminoakyldisiloxane compound, (3-(N,N-dimethylamino)diethoxypropyl) pentamethyldisiloxane (DSON), is reported as an effective electrolyte additive for improving the electrochemical performances of high energy density power batteries of nickel-rich LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite. The NCM622/graphite cells using DSON addition in the carbonate-based reference electrolyte exhibit enhanced electrochemical performances, especially high temperature performances including long cycle life and high temperature storage. The pouch cell (1 Ah) with 0.2 wt% DSON retained a capacity of 88% as compared with 84% for that without DSON in electrolyte after 200 cycles at 45 °C. The mechanism investigation reveals that DSON acts as a film-forming additive for constructing uniform conductive cathode electrolyte interphase (CEI) layer upon NCM622 particles, which suppresses the internal cracks and prohibits the irreversible phase transformation of NCM622. DSON also serves as an effective water/acid scavenger and inhibits the hydrolysis of LiPF6, thus effectively blocking the occurrence of side reactions and the dissolution of transition metal ions from cathode. Therefore, NCM622 cathode sheet maintains a better integrity surface morphology after 100 cycles. This work demonstrates that aminoakyldisiloxane is promising for practical use as effective electrolyte additive for high energy density power batteries of nickel-rich NCM/graphite.

Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g−1 at 0.2 A g−1, together with outstanding rate capability of 619 mAh g−1 at 2 A g−1 and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy-based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries.

Novel nanostructured silicon composites, Si/Poly(3,4-ethylenedioxythiophene) nanowire network (Si/PNW) and Si/(S-doped-carbon nanowire network) (Si/S-CNW), are prepared by a soft-template polymerization of 3,4-ethylenedioxythiophene (EDOT) using sodium dodecyl sulfate (SDS) as surfactant with the presence of Si nanoparticles and a subsequent carbonization of Si/PNW, respectively. The presence of Si nanoparticles in the soft-template polymerization of EDOT plays a critical role in the formation of PEDOT nanowire network instead of 1D nanowire. After the carbonization of PEDOT, the S-doped-carbon nanowire network matrix shows higher electrical conductivity than PNW counterpart, which facilitates to construct robust conductive bridges between Si nanoparticles and provide large electrode/electrolyte interfaces for rapid charge transfer reactions. Thus, Si/S-CNW composite exhibits excellent cycling stability and rate capability as anode material, retaining a specific capacity of 820 mAh g−1 after 400 cycles with a very small capacity fade of 0.09% per cycle.

Cyanoethylated carboxymethyl chitosan (CN-CCTS) has been synthesized through a straightforward cyanoethylation reaction by reacting CCTS with acrylonitrile in NaOH aqueous solution. CN-CCTS shows improved adhesion strength of 0.047 N/cm as compared with 0.013 N/cm for CCTS after introducing cyanoethyl group in the chemical structure of CCTS. The electrochemical performances of LiFePO 4 electrode with CN-CCTS binder have been investigated and compared with those using water soluble sodium carboxymethyl cellulose (CMC) and non-aqueous polyvinylidene difluoride (PVDF) binder. LiFePO 4 electrode with CN-CCTS exhibits better cycling stability and rate capability, retaining 56.3% capacity of C/5 at 5C rate as compared with 48.4% and 32.8% for CMC and PVDF, respectively. Cyclic voltammetry and electrochemical impedance spectroscopy measurement reveal that LiFePO 4 electrode with CN-CCTS has a more favorable electrochemical kinetics than that with CMC and PVDF, thus better rate capability.

A simple and easily operating strategy, in-situ anion-exchange method, has been developed for synthesis of AgCl/AgVO 3 heterojunctions. Cube-shaped AgCl nanoparticles of approximately 50–100 nm were closely attached to the surface of AgVO 3 nanoribbons. The content of AgCl in heterojunctions could be controlled by adjusting the NaCl concentration in the ion-exchange reaction solution. The photocatalytic efficiency of AgCl/AgVO 3 heterojunctions was far higher than that of pure AgVO 3 nanoribbons through degradation of methyl orange solution. This approach is a general method and can be extended to the synthesis of a variety of other AgVO 3 heterojunctions.

The polyacrylic latex (LA132) was firstly reported as a water-soluble binder for LiNi1/3Co1/3Mn1/3O2 (NCM) cathode in Li-ion battery. The electrochemical performances of NCM cathode with LA132 binder were investigated and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and commercial non-aqueous polyvinylidene difluoride (PVDF). NCM cathode with LA132 binder exhibited a much higher specific capacity of 146 mAh g−1 and capacity retention of 96.4 % after 100 cycles as compared with 122 mAh g−1/88 % and 121 mAh g−1/75% for the NCM electrode with CMC and PVDF, respectively. In addition, NCM cathode with LA132 binder exhibited better rate capability than that of CMC and PVDF, e.g., retaining 34.3 % capacity of C/5 at 5 C rate as compared with 28.5 and 10.9 % for CMC and PVDF, respectively.

The formation mechanism of LiTi2O4, prepared by a carbon thermal reduction reaction using Li2CO3 and TiO2 (anatase) as starting materials and acetylene black as a reducing agent, was investigated by in situ variable temperature X-ray diffraction and thermal gravimetric analysis/differential scanning calorimetry system. It was found that the cooling rate significantly impacts on obtaining pure phase LiTi2O4 sample after forming LiTi2O4 product during the carbon thermal reduction reaction. LiTi2O4 has excellent cycling stability, remaining a specific capacity of 126.6/111.9 mA h g−1 with a capacity fade of 5.1%/3.1% at 0.5C/1C rate after 200 cycles.

Dimethyl-2-methoxylethoxyl-3-nitrilepropylsilane (SN1) is miscible with the commercial carbonate electrolyte and used as co-solvent to form hybrid electrolyte with a content up to 30 vol%. By using such hybrid electrolyte, the LiCoO2/graphite full cell exhibits good cyclic stability and rate capability at an upper cutoff voltage of 4.4 V, showing an initial specific capacity of 154 mA h/g and 92.9% capacity retention after 150 cycles at 0.5 C rate. When the rate is increased to 1 and 1.5 C, the cell still retains a specific capacity of 143 and 133 mA h/g, respectively. The results of scanning electron microscopy, fourier transform infrared and electrochemical impedance spectroscopy show that SN1 as a co-solvent reduces the decomposition of the electrolyte and suppresses the polarization growth of the cell over cycling which facilitates Li+ diffusion and electron transportation at electrode/electrolyte interface.

Carboxymethyl chitosan (C-CTS) was firstly reported as a water soluble binder for LiFePO 4 cathode in Li-ion batteries. The electrochemical performances of LiFePO 4 cathode with C-CTS binder was investigated and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and the commercial non-aqueous polyvinylidene difluoride (PVDF). LiFePO 4 cathode with C-CTS exhibited a comparable cycling performance, but better rate capability than that of CMC and PVDF, retaining 65% capacity of C/5 at 5 C rate as compared with 55.9% and 39.4% for CMC and PVDF, respectively. In addition, LiFePO 4 cathode with C-CTS exhibited excellent cycling performance at 60 °C, retaining 91.8%/62.1% capacity after 80 cycles at 1 C/10 C, respectively.

A novel Si/porous-C composite with buffering voids was prepared by the co-assembly of phenol-formaldehyde resin, SiO 2 and Si nanoparticles, followed by a carbonizing process and subsequent removal of SiO 2 template. Si nanoparticle was coated with a layer of porous carbon shell with rationally designed void in between which provides the accommodating space for the volume change of Si over cycling. The as-prepared composite electrode exhibited good electrochemical performances as an anode material in lithium-ion cells, showing a stable reversible capacity of 980 mAh g −1 over 80 cycles with small capacity fade of 0.17%/cycle and high rate capability (721 mAh g −1 at 2000 mA g −1 ).

Micro/nano-structured SnS2 was prepared by a hydrothermal method using biomolecular l-cysteine and SnCl4·5H2O as sulfur source and tin source, respectively. The electrochemical performances of SnS2 electrodes were investigated using water-soluble binders of carboxymethyl chitosan (C-chitosan) and chitosan lactate, and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and non-aqueous polyvinylidene difluoride (PVDF). SnS2 electrode using the water-soluble binders (C-chitosan, chitosan lactate, and CMC) showed higher initial coulombic efficiency, larger reversible capacity, and better rate capabilities than that of PVDF. In addition, SnS2 electrode using C-chitosan binder exhibited somewhat worse cycling stability, but better rate capability at a high rate of 5C than CMC.

{3-[2-(2-methoxyethoxy) ethoxy]-propyl} triethoxysilane (TESM2) was synthesized and used as an electrolyte additive to improve the performances of lithium-ion batteries (LIBs). The electrochemical properties of the electrolyte (1 mol/L lithium hexafluorophosphate (LiPF6)/ethylene carbonate (EC):diethylene carbonate (DEC):dimethyl carbonate (DMC), 1: 1: 1) with different contents of TESM2 were characterized by ionic conductivity measurement, galvanostatic charge/discharge test of graphite/Li half cells, and electrochemical impedance spectroscopy. Both the cycling performances and C-rate capabilities of graphite/Li half cells were significantly improved with an optimized content of 15% TESM2 in the electrolyte. The graphite/Li half cell delivered a very high specific capacity of 370 mAh/g at 0.2C rate without any capacity loss for 60 cycles, and retained a capacity of 292 mAh/g at 2C rate. The solid electrolyte interphase (SEI) film on the surface of the graphite anode was investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), indicating that TESM2 was effectively involved in the formation of SEI film on the surface of graphite.

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) counter electrodes, doped with polyethylene glycol (PEG) and acetylene black as binding and conductivity promoting agent, were prepared by a simple mixing method for dye-sensitized solar cell. The electrochemical properties of the electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves. Using PEG dopant, the electrocatalytic activity of PEDOT:PSS electrode was much improved, and further improved by adding a small amount of conducting acetylene black (0.2 wt%). The DSSC cells, using the PEDOT:PSS electrode with PEG (5 wt%) dopant and the composite electrode with PEG (5 wt%)/acetylene black, exhibited an energy conversion efficiency of 3.57 and 4.39 %, comparable with 4.50 % of the commonly used Pt electrode under the same experimental conditions. These results demonstrate that PEG-modified PEDOT:PSS counter electrode is promising to replace the expensive Pt for low cost DSSC, especially to meet the large-scale fabrication demands.

A novel porous Si/S-doped carbon composite was prepared by a magnesiothermic reaction of mesoporous SiO2, subsequently coating with a sulfur-containing polymer-poly(3,4-ethylene dioxythiophene), and a post-carbonization process. The as-prepared Si composite was homogeneously coated with disordered S-doped carbon with 2.6 wt.% S in the composite and retained a high surface area of 58.8 m2 g−1. The Si/S-doped carbon composite exhibited superior electrochemical performance and long cycle life as an anode material in lithium ion cells, showing a stable reversible capacity of 450 mAh g−1 even at a high current rate of 6,000 mA g−1.

Nano-Si/(multi-wall carbon nanotube) (Si/MWCNT) composite paper was prepared as flexible electrode for lithium ion batteries by a simple filtration method using sodium carboxymethyl cellulose (CMC) as a dispersing/binding agent, followed by a thermal sintering process. Scanning electron microscopy (SEM) showed that nanosized Si particles were dispersed homogeneously and intertwined by the MWCNT throughout the whole paper electrode. After thermal sintering, Si/MWCNT paper electrode exhibited a significantly improved flexibility with a high Si content of 35.6 wt% as compared with before sintering, and retained a specific capacity of 942 mAh g −1 after 30 cycles with a capacity fade of 0.46%/cycle.