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We studied the efficiency of different particle-sized sulfide solid electrolyte-based cathode composites. First, we prepared the Li7P2S8I solid electrolytes with different particle sizes through a high energy ball milling process and solution method. The structural details of the prepared solid electrolytes were studied by powder X-ray diffraction. The surface morphologies and particle size of the electrolytes were studied by field emission electron microscopy. The ionic conductivity of the prepared solid electrolytes was studied by the electrochemical impedance spectroscopy technique. Finally, we have prepared a LiNi0.8Co0.1Mn0.1O2 (NCM 811) based cathode composite and studied the electrochemical performance of the fabricated all-solid-state lithium batteries. The mixed particle-sized solid electrolyte-based cathode composite exhibited higher specific capacitance (127.2 mA h g−1) than the uniform-sized solid electrolyte-based cathode composite (117.1 mA h g−1). The electrochemical analysis confirmed that the sulfide solid electrolytes with mixed particle size exhibited better electrochemical performance.

Integration of P2 and O3 phases in Na0.5Fe0.5Mn0.5O2 cathode via Li-ion substitution is proposed to enhance its electrochemical performance for sodium-ion battery applications. The formation of P2 and the combination of P2/O3 intergrowth were confirmed by X-ray diffraction refinement, high resolution transmission electron microscopy and X-ray photoelectron microscopy analyses. Various content of lithium was used to find optimum P2+O3 combinations. The optimized Li-ion substituted Na0.5(Li0.10Fe0.45Mn0.45)O2 showed a high initial discharge capacity of 146.2 mAh g−1 with improved cycling stability, whereas the pristine Na0.5Fe0.5Mn0.5O2 initially delivered a discharge capacity of 127.0 mAh g−1. In addition, the combination of P2+O3 increased its average voltage, which is important for achieving high energy density sodium-ion batteries. Overall, the prepared Na0.5(Li0.10Fe0.45Mn0.45)O2 electrode exhibited the improved cycling performance in terms of reversible capacity and rate capability compared to pristine Na0.5Fe0.5Mn0.5O2 electrode material.

The development of anode materials with high capacity and good cycling stability is one of the state-of-the-art objectives in the field of rechargeable sodium-ion batteries. In this work, we synthesized high-capacity spinel Fe2GeO4 using a facile hydrothermal method followed by calcination and investigated its electrochemical performance as an anode material for sodium-ion batteries. The Fe2GeO4 material delivered a high initial discharge capacity of 448.1 mAh g−1, but it showed gradual capacity fading with a capacity retention of 67.4% after 50 cycles. Its high initial capacity originated from the high electrochemical activity of Fe caused by its multiple oxidation reactions. To enhance the cycling stability of the Fe2GeO4, carbon was coated onto the surface of Fe2GeO4 particles. The carbon-coated Fe2GeO4 (Fe2GeO4@C) exhibited an initial discharge capacity of 423.0 mAh g−1 with good capacity retention. The sodium-ion full cell was assembled with an Fe2GeO4@C anode and a NaCo0.5Fe0.5O2 cathode, and the results showed superior cycling performance, demonstrating that the Fe2GeO4@C can be used as a promising anode material for sodium-ion batteries.

Sodium-ion batteries (SIBs) are undoubtedly the most promising alternatives to lithium-ion batteries considering the natural abundance, distribution and cost of sodium resources. Still, SIBs face challenges in the development of suitable anode materials due to the large volume change during sodiation/de-sodiation, which results in inferior cycling stability. Herein, we synthesized a yolk–shell structured pyrrhotite (Fe1−xS)@N-doped carbon (FS@NC) through a solution-based method and investigated its electrochemical properties for use in SIBs as an anode material. The optimized yolk–shell structured FS@NC with distinctive voids and a core exhibited a high reversible capacity of 594 mA h g−1 over 100 cycles at 100 mA g−1, excellent rate capability and superior cycling performance compared to core–shell and pristine Fe1−xS materials. During the charge and discharge cycles, the synergistic effect of the porous core (Fe1−xS) with empty voids and a defective carbon shell configuration provided a large electrode/electrolyte contact area and shortened the diffusion path for electrons and sodium ions. It also mitigated the structural degradation by accommodating the volume change during continuous cycles, which was confirmed by ex situ SEM and TEM analyses. To demonstrate a practical application, we assembled a sodium-ion full cell with an O3-type NaCo0.5Fe0.5O2 cathode and a yolk–shell structured FS@NC anode, and the results showed superior energy storage performance.

We develop a new solution synthesis strategy for producing high ionic-conducting sulfide solid electrolyte using ethylenediamine (EDA) solvent. Here, we follow three simple steps: dissolve the precursor in ethylenediamine solvent to form the clear solution, then removing a solvent at 180 °C followed by heat treatment. The prepared Li5.5PS4.5Cl1.5 electrolyte demonstrated the high ionic conductivity of 2.87 mS cm−1 at 25 °C. Further, fabricated solid battery using optimized electrolyte exhibited a high initial discharge capacity of 175.7 mAh g−1 at 0.1 C rate. Moreover, the synthesis technique is a convenient and quick process, thus facilitating mass production of solid electrolytes.

Ternary nanocomposite of Co2GeO4/r-GO@C is synthesized by single step hydrothermal method followed by calcination. The XRD analysis reveals the formation of cubic structured Co2GeO4 and their corresponding functional groups identified through Raman analysis. The TEM analysis assures that uniform distribution of Co2GeO4 nanoparticles on the r-GO layers. The Galvanostatic charge-discharge (GCD) curve demonstrates that the initial discharge capacity of pristine Co2GeO4, Co2GeO4/r-GO and Co2GeO4/r-GO@C composite is 1400, 1284 and 1594mAhg-1 at 50mAg-1, respectively. The cycling stability curve shows the specific capacity of 609, 970 and 1180mAhg-1 for pristine, Co2GeO4/r-GO and Co2GeO4/r-GO@C composite, respectively over 15 cycles. The ternary composite of Co2GeO4/r-GO@C delivers the discharge capacity of 323mAhg-1 at high current density of 1Ag-1 over 500 cycles with capacity retention of 71%. The rate capability curve indicates that Co2GeO4/r-GO@C composite shows the better rate capability.

Sodium-ion batteries have gained an intense attention as a promising alternate for Li-ion batteries due to their low cost, and abundant availability. To meet high energy density requirements, developing a high voltage cathode with ultra-long cycle life is of great importance. Na3V2(PO4)2F3 (NVPF) features a high working voltage, fast sodium-ion diffusion channels, and small volume change during the cycling process. However, the practical performance of NVPF cathode is currently hindered by poor Na+ ion diffusion at high voltage, low cycle life, and limited rate behavior. Herein, we evaluate the effect of synthesis conditions in sol–gel technique, binders (PVDF, PAI and CMC), and electrolytes (ether, and ester based solvents) to overcome the diffusion limitation in high voltage NVPF cathode. Benefiting from the synergistic effect of CMC binder, and DEGME electrolyte, and reduced graphene oxide composite, NVPF effectively overcome the potential barrier during Na+ ion insertion/extraction at high voltage. NVPF with CMC binder and DEGDME electrolyte displayed a high Na+ ion diffusion kinetics, low cell resistance, and delivered an excellent electrochemical performance. NVPF delivered a high coulombic efficiency (92%), long cycle life (10,000 cycles), and an excellent rate performance (50 C), outperforming the conventional PVDF binder, and carbonate based electrolytes. Furthermore, the full-cell constructed by NVPF cathode, and Na3V2(PO4)3 anode delivered an capacity retention. The current study provides new insights for overcoming the kinetic barrier during sodium ion storage in high voltage cathode that could direct the research development towards high energy sodium-ion batteries.