Lithium-ion Storage Properties Research Articles

Study of binder effect on the lithium storage kinetics of copper phosphide nanotube anode

Copper phosphide (CP) stands out as a promising anode material for lithium-ion batteries due to its high theoretical capacity (1281 mAh g−1). However, the fast capacity decay of copper phosphide poses a significant challenge due to its huge volume change. Optimization of binder selection presents an effective way to harness the high lithium storage capacity of copper phosphide. In this study, copper phosphide nanotubes were synthesized using a hard template transformation method. The following investigation delved into the impact of different binders on the electrode structure and the lithium-ion storage performance of copper phosphide. Notably, employing polyacrylic acid (PAA) as a binder resulted in a stable capacity of 526.8 mAh g−1 over 400 cycles at 100 mA g−1 for the copper phosphide electrode. The remarkable lithium-ion storage property of the CP-PAA electrode is ascribed to the robust interaction between PAA and the P–O bond on the copper phosphide surface. This interaction not only mitigated volume expansion but also enhanced the kinetics of electrochemical reactions.

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500nm and yields the ≈5nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Consecutive engineering of anodic graphene supported cobalt monoxide composite and cathodic nanosized lithium cobalt oxide materials with improved lithium-ion storage performances

Downsizing the electrochemically active materials in both cathodic and anodic electrodes commonly brings about enhanced lithium-ion storage performances. It is particularly meaningful to explore simplified and effective strategies for exploiting nanosized electrode materials in the advanced lithium-ion batteries. In this work, the spontaneous reaction between few-layered graphene oxide (GO) and metallic cobalt (Co) foils in mild hydrothermal condition is for the first time employed to synthesize a reduced graphene oxide (RGO) supported nanosized cobalt monoxide (CoO) anode material (CoO@RGO). Furthermore, the CoO@RGO sample is converted to nanosized lithium cobalt oxide cathode material (LiCoO2, LCO) by taking the advantages of the self-templated effect. As a result, both the CoO@RGO anode and the LCO cathode exhibit inspiring lithium-ion storage properties. In half-cells, the CoO@RGO sample maintains a reversible capacity of 740.6 mAh·g−1 after 300 cycles at the current density of 1000 mA·g−1 while the LCO sample delivers a reversible capacity of 109.1 mAh·g−1 after 100 cycles at the current density of 100 mA·g−1. In the CoO@RGO//LCO full-cells, the CoO@RGO sample delivers a reversible capacity of 553.9 mAh·g−1 after 50 cycles at the current density of 200 mA·g−1. The reasons for superior electrochemical behaviors of the samples have been revealed, and the strategy in this work can be considered to be straightforward and effective for engineering both anode and cathode materials for lithium-ion batteries.

Lithium Iron Manganese Oxyfluoride High Energy Density Cathode

Ball-milling has also been used to add fluorine atoms into rock-salt structures to take advantage of fluorine’s high electronegativity to raise the working voltage of oxide materials to create high power and energy density cathodes. New composite structures of metal oxides and LiF synthesized using this method have been studied as conversion reactions. In this study, LiF-FeMnO3 composites are synthesized by the solid-state method after mechanochemical-ball milling 3 mol LiF, 1 mol FeO, and 1 mol MnO for 12 h. The synthesized composites are characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques as well as the electrochemical properties. The lithium ion storage property is evaluated by galvanostatic discharge/charge experiments. Initial discharge capacity of 418 mAh/g at 10 mA/g was obtained. The coulombic efficiency almost remains 100%, demonstrating good high-rate performance and good cyclability. The high electrochemical performance is attributed to unique lithium storage mechanism, including conversion and intercalation/de-intercalation mechanism. Small particle size also provides some benefits to lithium ion storage property. This mixture of 3LiF-FeMnO3 composites is a promising cathode material for lithium-ion batteries with high power and energy densities. Figure 1

Manganese, Fluorine, and Nitrogen Co-Doped Bronze Titanium Dioxide Nanotubes with Improved Lithium-Ion Storage Properties

Because of the unique crystal framework, bronze TiO2 (or TiO2(B)) is considered the prospective choice for high-performance lithium-ion battery anodes. Nevertheless, TiO2(B) requires efficient modification, e.g., suitable doping with other elements, to improve the electronic properties and enhance the stability upon insertion/extraction of guest ions. However, due to the metastability of TiO2(B), doping is challenging. Herein, for the first time, TiO2(B) co-doped with Mn, F, and N were synthesized through a successive method based on a hydrothermal technique. The prepared doped TiO2(B) consists of ultrathin nanotubes (outer diameter of 10 nm, wall thickness of 2–3 nm) and exhibits a highly porous structure (pore volume of up to 1 cm3 g−1) with a large specific surface area near 200 m2 g−1. The incorporation of Mn, F, and N into TiO2(B) expands its crystal lattice and modifies its electronic structure. The band gap of TiO2(B) narrows from 3.14 to 2.18 eV upon Mn- and N-doping and electronic conductivity improves more than 40 times. Doping with fluorine improves the thermal stability of TiO2(B) and prevents its temperature-induced transformation into anatase. It was found that the diffusivity of Li is about two times faster in doped TiO2(B). These properties make Mn, F, and N co-doped TiO2(B) nanotubes promising for application as high-performance anodes in advanced lithium-ion batteries. In particular, it possesses a good reversible capacity (231.5 mAh g−1 after 100 cycles at 70 mA g−1) and prominent rate capability (134 mAh g−1 at 1500 mA g−1) in the half-cell configuration. The (Mn, F, N)-doped TiO2(B) possesses a remarkable low-temperature Li storage performance, keeping 70% of capacity at −20 °C and demonstrating potentialities to be employed in full-cell configuration with LiMn2O4 cathode delivering a reversible capacity of 123 and 79 mAh g−1 at 35 and 1500 mA g−1, respectively, at a voltage of ~2.5 V. This research underlies that regulation of electronic and crystal structure is desired to uncover capabilities of nanoparticulate TiO2(B) for electrochemical energy storage and conversion.

Hollow nanostructured NiO particles as an efficient electrode material for lithium-ion energy storage properties.

This work has developed a straightforward approach to obtaining NiO hollow structures by using Li2O2 as an easily removable template. The easy availability and electrochemically active nature of NiO have attracted researchers' attention as an anode electrode for Li-ion storage applications, including Li-ion secondary batteries (LIBs) and for Li-ion hybrid supercapacitors (LiHSCs; which offer higher power densities than LIBs without compromising energy density). However, NiO usage has been limited to its low reaction reversibility, poor conductivity, and conversion reaction capability. Recently, hollow nanostructured materials have attracted attention as efficient battery materials due to their fascinating structural features. This study presents a modified Li2O2-assisted method to obtain porous open 3D architectures of NiO nanostructures. The resultant hollow structures are electrochemically studied as an anode for a LIB, exhibiting excellent stability over hundreds of cycles. The result is recognized as one of the finest among NiO anodes reported. Also, NiO hollow structures studied as anodes for LiHSC devices fabricated with activated carbon cathodes exhibit an outstanding comprehensive electrochemical performance which is better than the typical LIB and supercapacitors.

Synthesis of MAX Phase Nanofibers and Nanoflakes and the Resulting MXenes.

Layered ternary carbides and nitrides, also known as MAX phases, have attracted enormous attention for many applications, especially as precursors to produce 2D metal carbides and nitrides called MXenes. However, it is still challenging to tune and control the shape/morphology of MAX phase particles at the nanoscale, as they are typically manufactured as large grains using ceramic technology. Herein, nanostructured Ti-Al-C MAX phases with fine-tuned morphology of nanofibers and nanoflakes are prepared by using 1D and 2D carbon precursors at a synthesis temperature of 900°C. The nanostructured MAX phases are used as precursors to produce nanosized multilayered MXenes, with a considerably shorter etching time and a low reaction temperature. These nanosized MXenes exhibit good electrochemical lithium-ion storage properties and a pseudocapacitive electrochemical signature. The obtained Ti2 CTx MXene electrode can deliver delithiation capacity of 300 mAh g-1 at low rates and 100 mAh g-1 when the lithiation/delithiation cycle happens within 30 s. Availability of nanoscale MAX phases and MXene nanoflakes with small lateral size may open new opportunities for both classes of materials.

Pomegranate-like Sn-Ni nanoalloys@N-doped carbon nanocomposites as high-performance anode materials for Li-ion and Na-ion batteries

Tin-based alloy materials are one of the most promising anodes with high intrinsic electrical conductivity and superior capacity for lithium-ion batteries (LIBs) /sodium-ion batteries (SIBs). However, they are confronted with the obstacle of large volume dilatation and structural collapse during the insertion/deinsertion reactions of Li+/Na+. In this study, the three-dimensional (3D) pomegranate-like Sn-Ni nanoalloys@N-doped carbon nanocomposites are successfully synthesized. They deliver high discharge/charge capacities at 0.05 A g−1 (1117/846.4 mAh g−1 for LIBs; 539.4/319.7 mAh g−1 for SIBs) and exceptional cycling stability (330.7 mAh g−1 after 1000 cycles at 2.0 A g−1 for LIBs). These features may be attributed to the buffer effect of volume expansion by the unique 3D pomegranate-like architecture and the synergy effect between Sn-Ni nanoalloys and N-doped carbon for enhanced electrical conductivity. The electrochemical kinetics analyses of the Sn-Ni@NC electrode are performed to reveal the superior lithium-ion storage property. This work aims to design a kind of tin-based anode materials with superior electrochemical performances for LIBs and SIBs.

Tunable oxygen-vacancy mediated NiCo2O4 microspheres coupled by holey graphene framework with superior lithium-ion storage properties

Homogeneous NiCo2O4 (NCO) microspheres encapsulated by holey graphene framework (HGF) are synthesized by using solvothermal and further annealing approaches, respectively. By tuning the solvothermal conditions involved in the synthesis process, the specific oxygen vacancies induced into NCO microspheres with different ratios can be researched comprehensively. Thus, lower (NCO/HGF-1) and higher (NCO/HGF-2) oxygen vacancy forms of hybrid NCO/HGF microspheres are prepared, respectively. Specifically, those hybrid NCO/HGF microspheres exhibit a uniformly spherical structure along with the average particle size around 600 nm. Meanwhile, the inner NCO kernels are covered by the superficial HGF layers. More importantly, those NCO/HGF electrodes show excellent reversibly specific discharging capacity for lithium-ion batteries (LIBs) (554.71 mAh g−1 and 591.84 mAh g−1 for NCO/HGF-1 electrodes and NCO/HGF-2 electrodes at 2 A g−1, respectively) and relatively higher Li+ diffusion coefficient (9.76*10−12 cm2 s−1 for NCO/HGF-1 electrodes and 5.53*10−12 cm2 s−1 for NCO/HGF-2 electrodes, respectively). The superior electrochemical properties of the hybrid NCO/HGF electrodes can be explained to the specific holes in HGF layers facilitating Li+ transport and the oxygen vacancies in NCO enhancing electronic conductivity. The result is further verified by the density functional theory (DFT) analysis. This work presents a new strategy and promising potential of electrodes preparation for metal-ion batteries.

Camphene-derived hollow and porous nanofibers decorated with hollow NiO nanospheres and graphitic carbon as anodes for efficient lithium-ion storage

A synthesis strategy for hollow and porous nanofibers comprising hollow NiO (H-NiO) nanospheres formed via nanoscale Kirkendall diffusion and supported over a porous graphitic carbon matrix (H-NiO@HNFs) is reported herein to enable the fabrication of advanced anodes for stable lithium-ion batteries (LIBs). The H-NiO@HNFs comprising 1D longitudinal hollow channels ensured efficient diffusion of charged species via effective electrolyte percolation besides providing sufficient space to accommodate the large volume variations during repeated cycling. The hollow NiO nanospheres acted as chemical sites for lithiation and delithiation. Additionally, the H-NiO@HNFs exhibited improved lithium-ion storage properties, such as reasonable rate capability, stable prolonged cyclability at a high current density (1.0 A g-1), and a high lithium-ion diffusion coefficient, primarily owing to their enhanced structural integrity compared to that of filled NiO nanofibers (F-NiO NFs). This facile synthesis approach could broaden the current understanding of 1D hollow nanostructures decorated with conventional hollow metal-oxide nanoparticles for various applications.

One-dimensional π-d conjugated coordination polymer with double redox-active centers for all-organic symmetric lithium-ion batteries

The development of new π-d conjugated metal coordination polymers (CCPs) provides broad prospects for exploring a new generation of energy storage materials. Here, we report the synthesis, characterization and lithium-ion storage properties of carbonyl-containing π-d CCPs, which use tetraaminobenzoquinone (TABQ) as the organic ligand and M2+ (M = Co, Ni, and Cu) as the metal ligands. Among them, Ni-TABQ shows the higher conductivity and best electrochemical performance, when used as a cathode material in lithium-ion batteries (LIBs), it delivers a high initial discharge specific capacity of 318.7 mAhg-1 at 50 mA g−1 and good rate performance (even 237.2 mAhg-1 at 2 Ag-1). The reason for the superior performance of Ni-TABQ as well as its lithium-ion storage mechanism is verified by density functional theory (DFT) and spectroscopic characterization. Encouragingly, Ni-TABQ can be served as both cathode and anode materials to construct high-performance all-organic symmetric LIBs, which delivers high energy density up to 142 Wh kg−1 with stable cyclability for 100 cycles at 200 mA g−1. More importantly, the flexible all-organic pouch LIBs assembled by Ni-TABQ also show stable electrochemical properties under different bending states, demonstrating its great potential in the field of flexible wearable devices. These research results will highlight the vigorous application of π-d CCPs in LIBs and provide new insights for the rational design of similar advanced electrode materials in other energy storage systems.

Controllable synthesis of nitrogen-containing core-shell carbon spheres with a gap for enhanced lithium-ions storage

Carbon nanospheres from phenolic resin are considered as one of the most hopeful carbon-based materials for lithium storage due to the controllable size, adjustable structure, and easy fabrications. However, the lithium-ion storage properties of as-prepared carbon spheres were suppressed by the inaccessible interior sites and low heteroatom content. Here, 3-Aminophenol-Formaldehyde resin@Polystyrene@ Polypyrrole core/interlayer/shell nanospheres were designed as precursors to prepare nitrogen-containing carbon spheres. With the appropriate amount of polystyrene interlayer, carbon spheres with a gap were formed, which shown an enhanced reversible discharge capacity of 536.9 mAh g−1 after 1600 cycles at 2 A g−1. The superior electrochemical performance can be mainly ascribed to the introduction a gap between core and shell, which have made interior sites accessible. High nitrogen content and elegant nanostructure are also the main factors to improve Lithium-ions storage performance.

A facile synthesis of raspberry-shaped Fe3O4 nanoaggregate and its magnetic and lithium-ion storage properties

Raspberry-shaped aggregates of Fe3O4 nanoparticles are synthesized via a facile hydrazine reduction method with high purity and good yield. The size of the Fe3O4 nanoparticles is in the range of 20–50 nm, which joins together to form raspberry-shaped secondary aggregates. In the absence of hydrazine, only Fe2O3 nanoparticles are formed. The Fe3O4 shows superparamagnetic behavior along with the coercivity and saturation magnetization value of 480 Oe and 41 emu/g at 5 K. The Fe3O4 aggregates show good lithium-ion storage capability with a combination of multi-walled carbon nanotubes. The electrode maintains a high reversible capacity of 662 mAhg−1 after 100 cycles at 50 mAg−1. Therefore, this can be a promising material for magnetic and lithium-ion battery applications.

Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

• Self-formed template method is developed to prepare Sn/N-doped porous C composite. • N-doped C introduces more defects and low lithium-ion diffusion energy barrier. • The Sn/NPC electrode achieves excellent lithium-ion storage properties. • A Sn/NPC||LiCoO 2 full cell is assembled to expound the real application. • The alloying/dealloying reaction mechanism is detailly investigated by in-situ XRD. To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process, a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon (Sn/NPC) by pyrolysis of a mixture of disodium stannous citrate and urea. The vital point of this strategy is the formation of Na 2 CO 3 templates during pyrolysis. This self-formed Na 2 CO 3 acts as porous templates to support the formation of NPC. The obtained NPC provides good electronic conductivity, ample defects, and more active sites. Serving as anode for Li-ion batteries, the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g. Especially, a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g. Additionally, a full cell coupled with LiCoO 2 as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g. In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms. Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity, and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability. Climbing image nudged elastic band method reveals low Li + diffusion energy barrier in presence of N atoms, which accounts for the terrific electrochemical properties of Sn/NPC electrode.

Graphene-wrapped MnCO3/Mn3O4 nanocomposite as an advanced anode material for lithium-ion batteries: Synergistic effect and electrochemical performances

• A novel MnCO3/Mn3O4 nanocomposite wrapped by rGO is facilely prepared. • The graphene-wrapped MnCO3/Mn3O4 nanocomposite exhibits superior electrochemical performance as anodes for LIBs. • The synergistic effect of MnCO3/Mn3O4 nanocomposite leads to lower charge transfer resistance and inhibits the occurrence and propagation of cracks. • The surface-covered rGO improves interfacial lithium storage performance. Developing new electrode materials with a high specific capacity for excellent lithium-ion storage properties is very desirable. The MnCO 3 /Mn 3 O 4 nanoparticles with uniform size (about 50 nm) and shape which are wrapped with graphene have been successfully synthesized via the one-step method for anode material of lithium-ion batteries. The as-prepared graphene-wrapped MnCO 3 /Mn 3 O 4 nanocomposite exhibits remarkable electrochemical performance, including high reversible specific capacity, outstanding cycling stability, and excellent rate capability in comparison with the bare MnCO 3 and MnCO 3 /Mn 3 O 4 nanocomposite. This is because the synergistic effect of MnCO 3 and Mn 3 O 4 nanoparticles and graphene nanosheets act as both electron conductors and volume buffer layers. From the scanning electron microscopy (SEM) analysis, we confirmed that the morphology and structure of the composite are preserved after 200 cycles. This further confirms that graphene-wrapped MnCO 3 /Mn 3 O 4 nanocomposite acts as a stable template for reversible lithium-ion intercalation/deintercalation.

Iron vacancies engineering of Fe x C@NC hybrids toward enhanced lithium-ion storage properties

Defect engineering have profound influence on the energy storage properties of electrode hybrids by adjusting their intrinsic electronic characteristics. For iron carbide based materials, however, the effect of defect (especially cation vacancies) toward their electrochemical performance are still unclear. Herein, the feasible and scalable synthesis of Fe x C@NC with 3D honeycomb-like carbon architecture and abundant Fe vacancies via template etching is reported. Such structure enable outstanding lithium-ion storage properties owing to hierarchical pores, improved intrinsic electrochemical activity, as well as the introduction of more active sites. As a result, the Fe x C@NC-2 presents a high reversible specific capacity of 1079 mAh g−1 after 1000 cycles. Moreover, an excellent cycling stability can be achieved via maintaining a high-capacity retention (689 mAh g−1, 98.4%) over 1000 cycles at 5 A g−1. This study provides a feasible strategy for developing high-performance hybrids with hierarchical pore and rich defects structures.

A unique two-phase heterostructure with cubic NiSe2 and orthorhombic NiSe2 for enhanced lithium ion storage and electrocatalysis.

Two-phase heterostructures have received tremendous attention in energy-related fields as high-performance electrode materials. However, heterogeneous interfaces are usually constructed by introducing foreign elements, which disturbs the investigation of the intrinsic effect of the two-phase heterostructure. Herein, unique heterostructures constructed with orthorhombic NiSe2 and cubic NiSe2 phases are developed, which are embedded in in situ formed porous carbon from metal-organic frameworks (MOFs) (O/C-NiSe2@C). Precisely-controlled selenylation of MOFs is crucial for the formation of the O/C-NiSe2 heterostructure. The heterogeneous interfaces with lattice dislocations and charge distribution are conducive to the high-speed transfer of electrons and ions during electrochemical processes, so as to improve the electrochemical reaction kinetics for lithium-ion storage and the hydrogen evolution reaction (HER). When used as the anode of lithium-ion batteries (LIBs), O/C-NiSe2@C shows a superior electrochemical performance to the counterparts with only the cubic phase (C-NiSe2@C), in view of the cycling performance (719.3 mA h g-1 at 0.1 A g-1 for 100 cycles; 456.3 mA h g-1 at 1 A g-1 for 1000 cycles) and rate capabilities (344.8 mA h g-1 at 4 A g-1). Furthermore, O/C-NiSe2@C also exhibits better HER properties than C-NiSe2@C, that is, much lower overpotentials of 154 mV and 205 mV in 0.5 M H2SO4 and 1 M KOH, respectively, at 10 mA cm-2, a smaller Tafel slope as well as stable electrocatalytic activities for 2000 cycles/10 h. Preliminary observations indicate that the unique orthorhombic/cubic two-phase heterostructure could significantly improve the electrochemical performance of NiSe2 without additional modifications such as doping, suggesting the O/C-NiSe2 heterostructure as a promising bifunctional electrode for energy conversion and storage applications.

A truncated octahedron metal-organic framework derived TiO2@C@MoS2 composite with superior lithium-ion storage properties

Metal-organic frameworks (MOFs), as 3D porous precursors, have demonstrated great potential as electrode materials for lithium storage on account of high specific area and tunable structure. To enhance the intrinsic performance and endow MOFs with versatility, constructing distinctive morphology of MOFs while maintaining their porous structure to satisfy various application is highly desirable. Herein, we successfully developed a facile strategy for rationally designing and synthesizing the morphology of MOFs from circular plate shape to truncated octahedron gem shape via regulating the ratio of Pluronic F127 to terephthalic acid. In addition, the as-prepared Pluronic F127-regulated Ti-based MOFs (F-MIL-125-Ti) sacrifice as precursor to derive 3D mesoporous titanium dioxide (TiO 2 ) and as template for in situ growth of molybdenum disulfide (MoS 2 ) nanosheets to prepare a truncated octahedron TiO 2 @C@MoS 2 hierarchical composite. As expected, the distinctive 3D hierarchical TiO 2 @C@MoS 2 electrode exhibits superb rate capability (775 mAh g −1 at 5 C) and outstanding cycling stability (822 mAh g −1 after 1000 cycles at 1 C), which is benefiting from the 3D mesoporous TiO 2 and synergies between TiO 2 and MoS 2 nanosheets. This work develops new insight to design novel and controllable morphology MOFs-derived materials for application of energy storage devices. We fabricated 3D hierarchical MOF-derived TiO 2 @C@MoS 2 composite with unique truncated octahedron morphology for the first time. The as-prepared composite exhibits superb specific capacity and cycling stability as Li-ion battery anode material. • The morphology evolution of metal-organic frameworks via different additive dosage. • The synergy effects between nanosheets and truncated octahedron materials. • The hierarchical porous composite electrode with enhanced electrochemical performance. • TiO 2 @C@MoS 2 delivered 1180 mAh g −1 at 0.1 C.

Designed graphite with an activated edge for fast-charging lithium-ion storage properties.

Graphite with an activated edge is carefully designed via a controllable solution treatment and sintering process. The simultaneous existence of extra active sites and expanded layers at the edge enable it to exhibit excellent fast-charging performance in a half-cell and full-cell set-up. This work highlights an overall understanding of polarization and the optimum structure for a fast-charging anode.

An insight into the sodium-ion and lithium-ion storage properties of CuS/graphitic carbon nitride nanocomposite.

Metal sulfides are gaining prominence as conversion anode materials for lithium/sodium ion batteries due to their higher specific capacities but suffers from low stability and reversibility issues. In this work, the electrochemical properties of CuS anode material has been successfully enhanced by its composite formation using graphitic carbon nitride (g-C3N4). The CuS nanoparticles are distributed evenly in the exfoliated g-C3N4 matrix rendering higher electronic conductivity and space for volume alterations during the repeated discharge/charge cycles. The 0.8CuS:0.2g-C3N4 composite when used as an anode for lithium ion coin cell exhibits a reversible capacity of 478.4 mA h g−1 at a current rate of 2.0 A g−1 after a run of 1000 cycles which is better than that reported for CuS composites with any other carbon-based matrix. The performance is equally impressive when 0.8CuS:0.2g-C3N4 composite is used as an anode in a sodium ion coin cell and a reversible capacity of 408 mA h g−1 is obtained at a current rate of 2.0 A g−1 after a run of 800 cycles. A sodium ion full cell with NVP cathode and 0.8CuS:0.2g-C3N4 composite anode has been fabricated and cycled for 100 runs at a current rate of 0.1 A g−1. It can be inferred that the g-C3N4 matrix improves the ion transfer properties, alleviates the volume alteration happening in the anode during the discharge/charge process and also helps in preventing the leaching of polysulfides generated during the electrochemical process.