Ni₃S₂ nanocrystals wrapped by thin carbon layer and anchored on the sheets of reduced graphene oxide (Ni₃S₂@C/RGO) have been synthesized by a spray-coagulation assisted hydrothermal method and combined with a calcination process. Cellulose, dissolved in Thiourea/NaOH aqueous solution is chosen as carbon sources and mixed with graphene oxide via a spray-coagulation method using graphene suspension as coagulation bath. The resulted cellulose/graphene suspension is utilized as solvent for dissolving of Ni(NO₃)₂ and then used as raw materials for hydrothermal preparation of the Ni₃S₂@C/RGO composites. The structure of the composites has been investigated and their electrochemical properties are evaluated as anode material for lithium-ion batteries. The Ni₃S₂@C/RGO sample exhibits increasing reversible capacities upon cycles and shows a superior rate performance as well. Such kinds of promising performance have been ascribed to the wrapping effect of carbon layer which confines the dislocation of the polycrystals formed upon cycles and the enhanced conductivity as the integration of RGO conductive substrate. Discharge capacities up to 850 and 630 mAh·g⁻¹ at current densities of 200 and 5000 mA·g⁻¹, respectively, are obtained. The evolution of electrochemical performance of the composites with structure variation of the encapsulated Ni₃S₂ nanocrystals has been revealed by ex-situ TEM and XRD measurements.

Aqueous zinc-ion batteries (AZIBs) have emerged as highly promising options for large-scale energy storage systems due to their cost-effectiveness, substantial energy capacity, and improved safety features. However, the Zn anode faces challenges such as self-corrosion and dendrite formation, which limit its practical use in AZIB applications. In this work, a simple blade-coating method was used to successfully coat poly (vinylidene fluoride–hexafluoro propylene) (PVDF-HFP) on the Zn anode. The coated Zn anode (P-Zn) displayed a stable cycling performance (700 h) at 1 mA cm⁻² current density in the symmetric cell. In addition, the full cell using MnO₂ as the cathode and P-Zn as the anode retained almost full capacity even after 1400 cycles at 2C, far outperforming the full cell using the unmodified Zn anode with only 50% capacity retention after 600 cycles. In situ optical observations of Zn deposition demonstrate that the special organic coating significantly enhances the uniform deposition of Zn²⁺, thus effectively mitigating corrosion and hydrogen evolution. Density Functional Theory (DFT) calculations show that the PVDF-HFP coating effectively narrows the adsorption energy gap between the P-Zn (002) and (101) planes, leading to the homogeneous deposition of Zn²⁺ with fewer Zn dendrites. A simple and feasible strategy for designing ultra-stable AZIBs by coating an organic protective layer on the Zn surface is provided by this work.

Two-dimensional molybdenum disulfide (MoS₂) is considered as a highly promising anode material for lithium-ion batteries (LIBs) due to its unique layer structure, large plane spacing, and high theoretical specific capacity; however, the overlap of MoS₂ nanosheets and inherently low electrical conductivity lead to rapid capacity decay, resulting in poor cycling stability and low multiplicative performance. This severely limits its practical application in LIBs. To overcome the above problems, composite fibers with a core//sheath structure have been designed and fabricated. The sheath moiety of MoS₂ nanosheets is uniformly anchored by the hydrothermal treatment of the axial of carbon nanofibers derived from an electrospinning method (CNFs//MoS₂). The quantity of the MoS₂ nanosheets on the CNFs substrates can be tuned by controlling the amount of utilized thiourea precursor. The influence of the MoS₂ nanosheets on the electrochemical properties of the composite fibers has been investigated. The synergistic effect between MoS₂ and carbon nanofibers can enhance their electrical conductivity and ionic reversibility as an anode for LIBs. The composite fibers deliver a high reversible capacity of 866.5 mA h g⁻¹ after 200 cycles at a current density of 0.5 A g⁻¹ and maintain a capacity of 703.3 mA h g⁻¹ after a long cycle of 500 charge–discharge processes at 1 A g⁻¹.

Li₂TiSiO₅ is a ‘zero-strain’ anode material with a large theoretical capacity, appropriate operation potential, and good cyclability. However, its low electronic conductivity negatively affects its practical capacity and rate performance. Herein, we improve the electrochemical performance of Li₂TiSiO₅ by carbon-coating and nanosizing dual modifications, and further explore its lithium-storage and ‘zero-strain’ mechanisms by in-situ XRD. Within 0.2–3.0 V, the carbon-coated Li₂TiSiO₅ nanowires deliver a large reversible capacity of 257 mAh g⁻¹, high rate performance with a 5000 mA g⁻¹ vs. 50 mA g⁻¹ capacity ratio of 71.6%, and excellent cyclability with 90.0% capacity retention at 5000 mA g⁻¹ over 4000 cycles. The special crystal structure of Li₂TiSiO₅ with electrochemical active TiO₆ octahedra surrounded by inactive SiO₄ and LiO₆ polyhedra can effectively strengthen the volume-buffering capability, resulting in the ‘zero-strain’ behaviour with a tiny lattice-volume change of only 0.41%. Therefore, this dual-modified Li₂TiSiO₅ material has great practicability for high-performance lithium storage.

Niobates are very promising anode materials for Li⁺-storage rooted in their good safety and high capacities. However, the exploration of niobate anode materials is still insufficient. In this work, we explore ~1 wt% carbon-coated CuNb₁₃O₃₃ microparticles (C-CuNb₁₃O₃₃) with a stable shear ReO₃ structure as a new anode material to store Li⁺. C-CuNb₁₃O₃₃ delivers a safe operation potential (~1.54 V), high reversible capacity of 244 mAh g⁻¹, and high initial-cycle Coulombic efficiency of 90.4% at 0.1C. Its fast Li⁺ transport is systematically confirmed through galvanostatic intermittent titration technique and cyclic voltammetry, which reveal an ultra-high average Li⁺ diffusion coefficient (~5 × 10^–11 cm² s⁻¹), significantly contributing to its excellent rate capability with capacity retention of 69.4%/59.9% at 10C/20C relative to 0.5C. An in-situ XRD test is performed to analyze crystal-structural evolutions of C-CuNb₁₃O₃₃ during lithiation/delithiation, demonstrating its intercalation-type Li⁺-storage mechanism with small unit-cell-volume variations, which results in its capacity retention of 86.2%/92.3% at 10C/20C after 3000 cycles. These comprehensively good electrochemical properties indicate that C-CuNb₁₃O₃₃ is a practical anode material for high-performance energy-storage applications.

To improve the performance and overcome the processing difficulties of La_0.99Ca_0.01NbO₄ proton-conducting ceramic oxide, external and internal strategies were used, respectively, to modify La_0.99Ca_0.01NbO₄ with NiO. The external strategy refers to the use of the NiO as a sintering aid. The NiO was added to the synthesized La_0.99Ca_0.01NbO₄ powder as a secondary phase, which is the traditional way of using the NiO sintering aid. The internal strategy refers to the use of NiO as a dopant for the La_0.99Ca_0.01NbO₄. Both strategies improve the sinterability and conductivity, but the effect of internal doping is more significant in enhancing both grain growth and conductivity, making it more desirable for practical applications. Subsequently, the influences of different concentrations of NiO were compared to explore the optimal ratio of the NiO as the dopant. It was found that the sample with 1 or 2 wt.% NiO had similar performance, while with 5 wt.%, NiO doping content hampered the grain growth. In addition, the inhomogeneous distribution of the element in the high-NiO content sample was found to be detrimental to the electrochemical performance, suggesting that the moderate doping strategy is suitable for La_0.99Ca_0.01NbO₄ proton-conducting electrolyte with improved performance. Furthermore, first-principle calculations indicate the origin of the enhanced performance of the internally modified sample, as it lowers both oxygen formation energy and hydration energy compared with the un-modified one, facilitating proton migration.