Dunaliella Salinas based Sn–carbon anode for high-performance Li-ion batteries

Long life, high capacity, environmental friendliness and good rate performance are the most important elements in the research of lithium ion batteries (LIBs). In this paper, Sn–carbon composite electrode materials are prepared using Dunaliella Salinas based carbon (amorphous carbon) as an amorphous carbon precursor combined with tin. Hence, an amorphous carbon template enwrapped by Sn particles forms a core–shell structure (Sn–carbon composite), the annealed Dunaliella Salinas based carbon makes up the carbon core, and Sn particles form the shell of the material. The components of the materials, microstructure and electrochemical properties of LIBs were characterized and tested. The results show that the prepared Sn–carbon composite electrode materials have high purity and combine with amorphous carbon uniformly. The Sn–carbon composite exhibits excellent performance as a LIB anode, its discharge capacities of the 1st, 2nd, and 4th cycles are 1777.39, 944.15 and 722.46 mA h g⁻¹ at a current density of 100 mA g⁻¹, and the capacity is 619.09 mA h g⁻¹ after stable cycling at a current density of 200 mA g⁻¹. The capacity continues to rise at a high current density of 1000 mA g⁻¹ and is 574.97 mA h g⁻¹ at its maximum, demonstrating the excellent performance of the electrode.

Long life, high capacity, environmental friendliness and good rate performance are the most important elements in the research of lithium ion batteries (LIBs).     

Effects of Al-dopant at Ni or Co sites in LiNi0.6Co0.3Ti0.1O2 on interlayer slabs (Li–O) and intralayer slabs (TM–O) and their influence on the electrochemical performance of cathode materials

In order to satisfy the energy demands of the electromobility market, further improvements in cathode materials are receiving much attention, especially high energy density cathode materials for Li-ion batteries (LIBs). In this work, the self-propagating combustion (SPC) method is use to synthesise undoped LiNi_0.6Co_0.3Ti_0.1O₂ (LNCT), novel nano-sized Al-doped LiNi_0.6Co_0.3−xAl_xTi_0.1O₂ (LCA) and LiNi_0.6−xCo_0.3Al_xTi_0.1O₂ (LNA) (x = 0.01) cathode materials. LNCT, LCA and LNA were annealed at 700 °C for 24 h. Following the synthesis, the phase, chemical structure and purity of the materials were analysed using X-ray diffraction (XRD). Based on the XRD results, all materials exhibit a single-phase structure with rhombohedral layered structure. Based on the HRTEM and EDX results, all samples exhibit polyhedral-like shapes, while the Al-doped samples display smaller crystallite sizes compared to the undoped sample. As for the electrochemical performances, the initially discharged capacity of LCA (238.6 mA h g⁻¹) is higher than that of LNA (214.7 mA h g⁻¹) and LNCT (150.5 mA h g⁻¹). However, LNA has a lower loss of capacity after the 50^th cycle compared to the LCA sample, which makes it a more excellent candidate for electrochemical applications. The main reason for the excellent electrochemical behaviour of LNA is due to lower cation mixing. Furthermore, Rietveld refinements reveal that the LNA sample has a longer atomic distance of Li–O and shorter TM–O in the cathode structure, which makes Li⁺ ion diffusion more efficient, leading to excellent electrochemical performance. These findings further proved the potential of the novel nano cathode material of LiNi_0.6−xCo_0.3Al_xTi_0.1O₂ (LNA) to replace the existing commercialized cathode materials for rechargeable Li-ion batteries.

Al substitute into Ni site increase Li–O and reduce M–O atomic distance lead to excellent cycleability with high energy density.     

Tuning composition of CuCo2S4–NiCo2S4 solid solutions via solvent-less pyrolysis of molecular precursors for efficient supercapacitance and water splitting

Mixed metal sulfides are increasingly being investigated because of their prospective applications for electrochemical energy storage and conversion. Their high electronic conductivity and high density of redox sites result in significant improvement of their electrochemical properties. Herein, the composition-dependent supercapacitive and water splitting performance of a series of Ni_(1−x)Cu_xCo₂S₄ (0.2 ≤ x ≤ 0.8) solid solutions prepared via solvent-less pyrolysis of a mixture of respective metal ethyl xanthate precursors is reported. The use of xanthate precursors resulted in the formation of surface clean nanomaterials at low-temperature. Their structural, compositional, and morphological features were examined by p-XRD, SEM, and EDX analyses. Both supercapacitive and electrocatalytic (HER, OER) properties of the synthesized materials significantly vary with composition (Ni/Cu molar content). However, the optimal composition depends on the application. The highest specific capacitance of 770 F g⁻¹ at a current density of 1 A g⁻¹ was achieved for Ni_0.6Cu_0.4Co₂S₄ (NCCS-2). This electrode exhibits capacitance retention (C_R) of 67% at 30 A g⁻¹, which is higher than that observed for pristine NiCo₂S₄ (838 F g⁻¹ at 1 A g⁻¹, 47% C_R at 30 A g⁻¹). On the contrary, Ni_0.4Cu_0.6Co₂S₄ (NCCS-3) exhibits the lowest overpotential of 124 mV to deliver a current density of 10 mA cm⁻². Finally, the best OER activity with an overpotential of 268 mV at 10 mA cm⁻² was displayed by Ni_0.8Cu_0.2Co₂S₄ (NCCS-1). The prepared electrodes exhibit high stability, as well as durability.

A multi-component CuCo₂S₄ and NiCo₂S₄ thiospinel solid solution is prepared over an entire range by a low-temperature solvent-less route. The synergistic effect from both thiospinels on water splitting and capacitance is studied.     

Design and synthesis of hierarchical NiO/Ni3V2O8 nanoplatelet arrays with enhanced lithium storage properties

Hierarchical NiO/Ni₃V₂O₈ nanoplatelet arrays (NPAs) grown on Ti foil were prepared as free-standing anodes for Li-ion batteries (LIBs) via a simple one-step hydrothermal approach followed by thermal treatment to enhance Li storage performance. Compared to the bare NiO, the fabricated NiO/Ni₃V₂O₈ NPAs exhibited significantly enhanced electrochemical performances with superior discharge capacity (1169.3 mA h g⁻¹ at 200 mA g⁻¹), excellent cycling stability (570.1 mA h g⁻¹ after 600 cycles at current density of 1000 mA g⁻¹) and remarkable rate capability (427.5 mA h g⁻¹ even at rate of 8000 mA g⁻¹). The excellent electrochemical performances of the NiO/Ni₃V₂O₈ NPAs were mainly attributed to their unique composition and hierarchical structural features, which not only could offer fast Li⁺ diffusion, high surface area and good electrolyte penetration, but also could withstand the volume change. The ex situ XRD analysis revealed that the charge/discharge mechanism of the NiO/Ni₃V₂O₈ NPAs included conversion and intercalation reaction. Such NiO/Ni₃V₂O₈ NPAs manifest great potential as anode materials for LIBs with the advantages of a facile, low-cost approach and outstanding electrochemical performances.

Hierarchical NiO/Ni₃V₂O₈ nanoplatelet arrays (NPAs) grown on Ti foil were prepared as free-standing anodes for Li-ion batteries (LIBs) via a simple one-step hydrothermal approach followed by thermal treatment to enhance Li storage performance.     

Preparation and lithium storage of core–shell honeycomb-like Co3O4@C microspheres

Core–shell honeycomb-like Co₃O₄@C microspheres were synthesized via a facile solvothermal method and subsequent annealing treatment under an argon atmosphere. Owing to the core–shell honeycomb-like structure, a long cycling life was achieved (a high reversible specific capacity of 318.9 mA h g⁻¹ was maintained at 5C after 1000 cycles). Benefiting from the coated carbon layers, excellent rate capability was realized (a reversible specific capacity as high as 332.6 mA h g⁻¹ was still retained at 10C). The design of core–shell honeycomb-like microspheres provides a new idea for the development of anode materials for high-performance lithium-ion batteries.

The reversible specific capacity of CSHCo₃O₄@C microspheres was as high as 332.6 mA h g⁻¹ at 10C, which was significantly higher than that of SCo₃O₄ microspheres (68.7 mA h g⁻¹).     

Synthesis of a MnS/NixSy composite with nanoparticles coated on hexagonal sheet structures as an advanced electrode material for asymmetric supercapacitors

Herein, a facile hydrothermal method was designed to synthesize a novel structure of micro-flowers decorated with nanoparticles. The micro-flower structure consists of enormous cross-linked flat hexagonal nanosheets with sufficient internal space, providing fluent ionic channels and enduring volume change in the electrochemical storage process. As expected, the MnS/Ni_xS_y (NMS) electrode exhibits a relatively high specific capacitance of 1073.81 F g⁻¹ (at 1 A g⁻¹) and a good cycling stability with 82.14% retention after 2500 cycles (at 10 A g⁻¹). Furthermore, the assembled asymmetric supercapacitor achieves a high energy density of 46.04 W h kg⁻¹ (at a power density of 850 W kg⁻¹) and exhibits excellent cycling stability with 89.47% retention after 10 000 cycles. The remarkable electrochemical behavior corroborates that NMS can serve as an advanced electrode material.

A MnS/Ni_xS_y composite with nanoparticles coated on hexagonal sheets was successfully synthesized and exhibited enhanced performance.     

Zinc vacancy modulated quaternary metallic oxynitride GeZn1.7ON1.8: as a high-performance anode for lithium-ion storage

The development of alternative anode materials to achieve high lithium-ion storage performance is crucial for the next-generation lithium-ion batteries (LIBs). In this study, a new anode material, Zn-defected GeZn_1.7ON_1.8 (GeZn_1.7−xON_1.8), was rationally designed and successfully synthesized by a simple ammoniation and acid etching method. The introduced zinc vacancy can increase the capacity by more than 100%, originating from the additional space for the lithium-ion insertion. This GeZn_1.7−xON_1.8 particle anode delivers a high capacity (868 mA h g⁻¹ at 0.1 A g⁻¹ after 200 cycles) and ultralong cyclic stability (2000 cycles at 1.0 A g⁻¹ with a maintained capacity of 458.6 mA h g⁻¹). Electrochemical kinetic analysis corroborates the enhanced pseudocapacitive contribution and lithium-ion reaction kinetics in the GeZn_1.7−xON_1.8 particle anode. Furthermore, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses at different electrochemical reaction states confirm the reversible intercalation lithium-ion storage mechanism of this GeZn_1.7−xON_1.8 particle anode. This study offers a new vision toward designing high-performance quaternary metallic oxynitride-based materials for large-scale energy storage applications.

Zn-defected GeZn_1.7ON_1.8 (GeZn_1.7−xON_1.8) was successfully synthesized by a simple ammoniation and acid etching method. This well-designed Zn cation-deficient GeZn_1.7−xON_1.8 anode shows enhanced lithium-ion storage performance.     

Characterization of NaxLi0.67+yNi0.33Mn0.67O2 as a positive electrode material for lithium-ion batteries

The relationship between the charge–discharge properties and crystal structure of Na_xLi_0.67+yNi_0.33Mn_0.67O₂ (0.010 ≤ x ≤ 0.013, 0.16 ≤ y ≤ 0.20) has been investigated. Li/Na_xLi_0.67+yNi_0.33Mn_0.67O₂ cells exhibit gradually sloping initial charge and discharge voltage–capacity curves. The initial charge capacity increased from 171 mA h g⁻¹ for thermally-treated Na_0.15Li_0.51Ni_0.33Mn_0.67O₂ to 226 mA h g⁻¹ for Na_0.010Li_0.83Ni_0.33Mn_0.67O₂ with an increase in the Li content. The initial maximum discharge capacity was 252 mA h g⁻¹ in the case of Na_0.010Li_0.83Ni_0.33Mn_0.67O₂ between 4.8 and 2.0 V at a fixed current density of 15 mA g⁻¹ (0.06C) at 25 °C. The predominance of the spinel phase leads to the high initial discharge capacity of Na_0.010Li_0.83Ni_0.33Mn_0.67O₂. This study shows that chemical lithiation using LiI is effective to improve the electrochemical properties.

The relationship between the charge–discharge properties and crystal structure of Na_xLi_0.67+yNi_0.33Mn_0.67O₂ (0.010 ≤ x ≤ 0.013, 0.16 ≤ y ≤ 0.20) has been investigated.     

Synthesis and electrochemical performance of NaV3O8 nanobelts for Li/Na-ion batteries and aqueous zinc-ion batteries

NaV₃O₈ nanobelts were successfully synthesized for Li/Na-ion batteries and rechargeable aqueous zinc-ion batteries (ZIBs) by a facile hydrothermal reaction and subsequent thermal transformation. Compared to the electrochemical performance of LIBs and NIBs, NaV₃O₈ nanobelt cathode materials in ZIBs have shown excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹ and good cycle stability with a capacity retention of 94% over 500 cycles at 5 A g⁻¹. The good diffusion coefficients and high surface capacity of NaV₃O₈ nanobelts in ZIBs were in favor of fast Zn²⁺ intercalation and long-term cycle stability.

Compared to the electrochemical performance for LIBs and NIBs, NaV₃O₈ nanobelts electrode for ZIBs shows excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹, good rate performance and cycle performance.     

Hydrothermal-template synthesis and electrochemical properties of Co3O4/nitrogen-doped hemisphere-porous graphene composites with 3D heterogeneous structure

Despite the high capacity of Co₃O₄ employed in lithium-ion battery anodes, the reduced conductivity and grievous volume change of Co₃O₄ during long cycling of insertion/extraction of lithium-ions remain a challenge. Herein, an optimized nanocomposite, Co₃O₄/nitrogen-doped hemisphere-porous graphene composite (Co₃O₄/N-HPGC), is synthesized by a facile hydrothermal-template approach with polystyrene (PS) microspheres as a template. The characterization results demonstrate that Co₃O₄ nanoparticles are densely anchored onto graphene layers, nitrogen elements are successfully introduced by carbamide and the nanocomposites maintain the hemispherical porous structure. As an anode material for lithium-ion batteries, the composite material not only maintains a relatively high lithium storage capacity (the first discharge specific capacity can reach 2696 mA h g⁻¹), but also shows significantly improved rate performance (1188 mA h g⁻¹ at 0.1 A g⁻¹, 344 mA h g⁻¹ at 5 A g⁻¹) and enhanced cycling stability (683 mA h g⁻¹ after 500 cycles at 1 A g⁻¹). The enhanced electrochemical properties of Co₃O₄/N-HPGC nanocomposites can be ascribed to the synergistic effects of Co₃O₄ nanoparticles, novel hierarchical structure with hemisphere-pores and nitrogen-containing functional groups of the nanomaterials. Therefore, the developed strategy can be extended as a universal and scalable approach for integrating various metal oxides into graphene-based materials for energy storage and conversion applications.

The Co₃O₄/N-HPGC nanocomposites synthesized by a hydrothermal-template approach with polystyrene microspheres as the template possess excellent electrochemical performance.     

Co9S8@carbon nanofiber as the high-performance anode for potassium-ion storage

Thanks to their intrinsic merits of low cost and natural abundance, potassium-ion batteries have drawn intense interest and are regarded as a possible replacement for lithium-ion batteries. The larger radius of potassium, however, provides slow mobility, which normally leads to sluggish diffusion of host materials and eventual expansion of volume, typically resulting in electrode failure. To address these issues, we design and synthesize an effective micro-structure with Co₉S₈ nanoparticles segregated in carbon fiber utilizing a concise electrospinning process. The anode delivers a high K⁺ storage capacity of 721 mA h g⁻¹ at 0.1 A g⁻¹ and a remarkable rate performance of 360 mA h g⁻¹ at a high current density of 3 A g⁻¹. A small charge-transfer resistance and a high pseudocapacitive contribution that benefit fast potassium ion migration are indicated by quantitative analysis. The outstanding electrochemical performance can be attributed to the distinct architecture design facilitating high active electrode–electrolyte area and fast kinetics as well as controlled volume expansion.

Co₉S₈@carbon nanofibers with boosted highly active electrode–electrolyte area, fast kinetics and controlled volume expansion show an excellent cycling and rate performance in potassium ion batteries.     

Off-stoichiometric Na3−3xV2+x(PO4)3/C nanocomposites as cathode materials for high-performance sodium-ion batteries prepared by high-energy ball milling

Na₃V₂(PO₄)₃ (NVP) is regarded as a promising cathode material for sustainable energy storage applications. Here we present an efficient method to synthesize off-stoichiometric Na_3−3xV_2+x(PO₄)₃/C (x = 0–0.10) nanocomposites with excellent high-rate and long-life performance for sodium-ion batteries by high-energy ball milling. It is found that Na_3−3xV_2+x(PO₄)₃/C nanocomposites with x = 0.05 (NVP-0.05) exhibit the most excellent performance. When cycled at a rate of 1C in the range of 2.3–3.9 V, the initial discharge capacity of NVP-0.05 is 112.4 mA h g⁻¹, which is about 96% of its theoretical value (117.6 mA h g⁻¹). Even at 20C, it still delivers a discharge capacity of 92.3 mA h g⁻¹ (79% of the theoretical capacity). The specific capacity of NVP-0.05 is as high as 100.7 mA h g⁻¹ after 500 cycles at 5C, which maintains 95% of its initial value (106 mA h g⁻¹). The significantly improved electrochemical performance of NVP-0.05 is attributed to the decrease of internal resistance and increase of the Na⁺ ion diffusion coefficient.

Na₃V₂(PO₄)₃ (NVP) is regarded as a promising cathode material for sustainable energy storage applications.     

UIO-66-NH2-derived mesoporous carbon used as a high-performance anode for the potassium-ion battery

As potassium is abundant and has an electronic potential similar to lithium''s, potassium-ion batteries (KIBs) are considered as prospective alternatives to lithium-ion batteries (LIBs). However, the much larger radius of the K ion poses challenges for the potassiation and depotassiation processes when the typical graphite-based anode is used, resulting in poor electrochemical performance. Thus, there is an urgent need to develop novel anode materials that are suitable for K ions. Herein, we develop a porous carbon material with high surface area derived from UIO-66-NH₂ metal–organic frameworks as an anode material instead of a graphite-based anode. The material is prepared using a double-solvent diffusion-pyrolysis method, which increased mesopore volume and average pore size, and to a certain extent, slightly improved the nitrogen content of the production. The material exhibits a high capacity as well as excellent rate performance and cycling stability. A potassium battery with our porous carbon as the anode delivers a high reversible capacity of 346 mA h g⁻¹ at 100 mA g⁻¹ (compared to 279 mA h g⁻¹ with a graphite-based anode), and 214 mA h g⁻¹ at a discharge rate of up to 2 A g⁻¹. After 800 cycles, the capacity is still 187 mA h g⁻¹ at 0.1 A g⁻¹. Qualitative and quantitative kinetics analyses demonstrated that the battery''s high K storage performance was principally dominated by a surface-driven capacitive mechanism, and the potassiation and depotassiation processes may have occurred on the surface of the porous carbon instead of in the interlayer space, as is the case with a graphite anode. This work may provide a basis for developing other carbonaceous materials to use in KIBs.

The N-doped mesoporous carbon material prepared by a double-solvent diffusion pyrolysis method with UIO-66-NH₂ as a precursor can deliver a high reversible capacity of 346 mA h g⁻¹ at 100 mA g⁻¹ when used as an anode for non-aqueous KIBs.     

Facile synthesis of mesoporous NixCo9−xS8 hollow spheres for high-performance supercapacitors and aqueous Ni/Co–Zn batteries

Porous micro/nanostructure electrode materials have always contributed to outstanding electrochemical energy storage performances. Co₉S₈ is an ideal model electrode material with high theoretical specific capacity due to its intrinsic two crystallographic sites of cobalt ions. In order to improve the conductivity and specific capacitance of Co₉S₈, nickel ions were introduced to tune the electronic structure of Co₉S₈. The morphology design of the mesoporous hollow sphere structure guarantees cycle stability and ion diffusion. In this work, Ni_xCo_9−xS₈ mesoporous hollow spheres were synthesized via a facile partial ion-exchange of Co₉S₈ mesoporous hollow spheres without using a template, boosting the capacitance to 1300 F g⁻¹ at the current density of 1 A g⁻¹. Compared with the pure Co₉S₈ and Ni-Co₉S₈-30%, Ni-Co₉S₈-60% exhibited the best supercapacitor performance, which was ascribed to the maximum Ni ion doping with morphology and structure retention, enhanced conductivity and stabilization of Co³⁺ in the structure. Therefore, Ni/Co–Zn batteries were fabricated by using a Zn plate as the anode and Ni-Co₉S₈-60% as the cathode, which deliver a high energy density of 256.5 W h kg⁻¹ at the power density of 1.69 kW kg⁻¹. Furthermore, the Ni/Co–Zn batteries exhibit a stable cycling after 3000 repeated cycles with capacitance retention of 69% at 4 A g⁻¹. This encouranging result might provide a new perspective to optimize Co₉S₈-based electrodes with superior supercapacitor and Ni/Co–Zn battery performances.

Mesoporous NiCo₉S₈-0.6 hollow spheres as a high-performance supercapacitor and aqueous Ni/Co–Zn battery.     

Mesopore-dominant nitrogen-doped carbon with a large defect degree and high conductivity via inherent hydroxyapatite-induced self-activation for lithium-ion batteries

In this study, N-doped mesopore-dominant carbon (NMC) materials were prepared using bio-waste tortoise shells as a carbon source via a one-step self-activation process. With intrinsic hydroxyapatites (HAPs) as natural templates to fulfill the synchronous carbonization and activation of the precursor, this highly efficient and time-saving method provides N-doped carbon materials that represent a large mesopore volume proportion of 74.59%, a high conductivity of 4382 m S⁻¹, as well as larger defects, as demonstrated by Raman and XRD studies. These features make the NMC exhibit a high reversible lithium-storage capacity of 970 mA h g⁻¹ at 0.1 A g⁻¹, a strong rate capability of 818 mA h g⁻¹ at 2 A g⁻¹, and a good capacity of 831 mA h g⁻¹ after 500 cycles at 1 A g⁻¹. This study provides a highly efficient and feasible method to prepare renewable biomass-derived carbons as advanced electrode materials for the application of energy storage.

A hydroxyapatite-induced self-activation method has been used to prepare nitrogen-doped mesopore-dominant carbon. The carbon has abundant macro/mesopores, high conductivity, and favorable defects and exhibited high-performance in LIBs.     

Surface phosphation of 3D mesoporous NiCo2O4 nanowire arrays as bifunctional anodes for lithium and sodium ion batteries

A novel surface phosphate strategy was adopted to dramatically improve the charge transport, ion diffusion, electroactive sites, and cycle stability of mesoporous NiCo₂O₄ nanowire arrays (NWAs), drastically boosting their electrochemical properties. Consequently, the as-prepared phosphated NiCo₂O₄ NWA (P-NiCo₂O₄ NWA) electrode achieved excellent energy storage performance as a bifunctional anode material for both lithium ion batteries (LIBs) and sodium ion batteries (SIBs). When evaluated as an anode for LIBs, this P-NiCo₂O₄ NWA electrode showed a high reversible capacity up to 1156 mA h g⁻¹ for 1500 cycles at 200 mA g⁻¹ without appreciable capacity attenuation, while in SIBs, the electrode could also deliver an admirable initial capacity as high as 687 mA h g⁻¹ and maintained 83.5% of this after 500 cycles at the same current density. Most important, when the current density increased from 100 to 1000 mA g⁻¹, the capacity retention was about 63% in LIBs and 54% in SIBs. This work may shed light on the engineering of efficient electrodes for multifunctional flexible energy storage device applications.

A novel surface phosphate strategy was adopted to dramatically improve the charge transport, ion diffusion, electroactive sites, and cycle stability of mesoporous NiCo₂O₄ nanowire arrays (NWAs), drastically boosting their electrochemical properties.     

Self-supporting V2O5 nanofiber-based electrodes for magnesium–lithium-ion hybrid batteries

The increasing demand for high energy, sustainable and safer rechargeable electrochemical storage systems for portable devices and electric vehicles can be satisfied by the use of hybrid batteries. Hybrid batteries, such as magnesium–lithium-ion batteries (MLIBs), using a dual-salt electrolyte take advantage of both the fast Li⁺ intercalation kinetics of lithium-ion batteries (LIBs) and the dendrite-free anode reactions. Here we report the utilization of a binder-free and self-supporting V₂O₅ nanofiber-based cathode for MLIBs. The V₂O₅ cathode has a high operating voltage of ∼1.5 V vs. Mg/Mg²⁺ and achieves storage capacities of up to 386 mA h g⁻¹, accompanied by an energy density of 280 W h kg⁻¹. Additionally, a good cycling stability at 200 mA g⁻¹ over 500 cycles is reached. The structural integrity of the V₂O₅ cathode is preserved upon cycling. This work demonstrates the suitability of the V₂O₅ cathode for MLIBs to overcome the limitations of LIBs and MIBs and to meet the future demands of advanced electrochemical storage systems.

This work shows the feasibility of a self-supporting V₂O₅ nanofiber-based cathode for magnesium–lithium-ion batteries reaching an energy density of 280 W h kg⁻¹.     

Comparison of electrochemical performance of LiNi1−xCoxO2 cathode materials synthesized from coated (1−x)Ni(OH)2@xCo(OH)2 and doped Ni1−xCox(OH)2 precursors

LiNi_1−xCo_xO₂ cathode materials were successfully synthesized from coated (1−x)Ni(OH)₂@xCo(OH)₂ and doped Ni_1−xCo_x(OH)₂ precursors, and the effects of the Co site and content in the precursor and final cathode material on the structure, morphology, and electrochemical performance of the cathodes were investigated using X-ray diffraction, scanning electron microscopy, and charge–discharge tests. The electrochemical performance of the materials prepared from the coated precursor was generally better than that of the materials prepared from the doped precursor. However, with increasing Co content, the performance difference gradually decreased. Among the as-prepared samples, the sample coated with 12 mol% Co delivered an excellent reversible capacity of 213.8 mA h g⁻¹ at 0.1C and the highest capacity retention of 88.5% after 100 cycles at 0.2C in the voltage range of 2.75–4.3 V. High-performance LiNi_1−xCo_xO₂ materials were successfully synthesized, and our findings clearly reveal the differences in the electrochemical properties of the materials prepared from the two different precursors with increasing Co content, thereby providing a valuable reference for the synthesis of high-performance Ni-rich layered cathode materials for Li-ion batteries.

The effects of Co site and content on electrochemical performance of LiNi_1−xCo_xO₂ cathodes materials were investigated.     

Rigid TiO2−x coated mesoporous hollow Si nanospheres with high structure stability for lithium-ion battery anodes

Rigid oxygen-deficient TiO_2−x coated mesoporous hollow Si nanospheres with a mechanically and electrically robust structure have been constructed through a facile method for high-performance Li-ion battery anodes. The mesoporous hollow structure provides enough inner void space for the expansion of Si. The oxygen-deficient TiO_2−x coating has functions in three aspects: (1) avoiding direct contact between Si and the electrolyte; (2) suppressing the outward expansion of the mesoporous hollow Si nanospheres; (3) improving the conductivity of the composite. The combined effect leads to high interfacial stability and structural integrity of both the material nanoparticles and the whole electrode. By virtue of the rational design, the composite yields a high reversible specific capacity of 1750.4 mA h g⁻¹ at 0.2 A g⁻¹, an excellent cycling stability of 1303.1 mA h g⁻¹ at 2 A g⁻¹ with 84.5% capacity retention after 500 cycles, and a high rate capability of 907.6 mA h g⁻¹ even at 4 A g⁻¹.

A conductive TiO_2−x shell suppresses the outward expansion of Si to maintain high interfacial stability and structural integrity.     

Electrochemical studies of a high voltage Na4Co3(PO4)2P2O7–MWCNT composite through a selected stable electrolyte

Cathode materials that operate at high voltages are required to realize the commercialization of high-energy-density sodium-ion batteries. In this study, we prepared different composites of sodium cobalt mixed-phosphate with multiwalled carbon nanotubes (Na₄Co₃(PO₄)₂P₂O₇–MWCNTs) by the sol–gel synthesis technique. The crystal structure and microstructure were characterized by using PXRD, TGA, Raman spectroscopy, SEM and TEM. The electrochemical properties of the Na₄Co₃(PO₄)₂P₂O₇–20 wt% MWCNT composite were explored using two different electrolytes. The composite electrode exhibited excellent cyclability and rate capabilities with the electrolyte composed of 1 M sodium hexafluorophosphate in ethylene carbonate:dimethyl carbonate (EC:DMC). The composite electrode delivered stable discharge capacities of 80 mA h g⁻¹ and 78 mA h g⁻¹ at room and elevated (55 °C) temperatures, respectively. The average discharge voltage was around 4.45 V versus Na⁺/Na, which corresponded to the Co^2+/3+ redox couple. The feasibility of the Na₄Co₃(PO₄)₂P₂O₇ cathode for sodium-ion batteries has been confirmed in real time using a full cell configuration vs. NaTi₂(PO₄)₃–20 wt% MWCNT, and it delivers an initial discharge capacity of 78 mA h g⁻¹ at 0.2C rate.

Na₄Co₃(PO₄)₂P₂O₇–MWCNT composites in 1 M NaPF₆ in EC:DMC electrolytes deliver stable discharge capacities of 80 mA h g⁻¹ and 78 mA h g⁻¹ at normal and elevated temperatures, respectively. In a full cell configuration vs. NaTi₂(PO₄)₃–MWCNT, they deliver an initial discharge capacity of 78 mA h g⁻¹ at 0.2C rate.