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    Fabrication of a Stable and Highly Effective Anode Material for Li-Ion/Na-Ion Batteries Utilizing ZIF-12
    (Wiley-V C H Verlag Gmbh, 2024) Bugday, Nesrin; Wang, Haoji; Hong, Ningyun; Zhang, Baichao; Deng, Wentao; Zou, Guoqiang; Hou, Hongshuai
    Transition metal selenides (TMSs) are receiving considerable interest as improved anode materials for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) due to their considerable theoretical capacity and excellent redox reversibility. Herein, ZIF-12 (zeolitic imidazolate framework) structure is used for the synthesis of Cu2Se/Co3Se4@NPC anode material by pyrolysis of ZIF-12/Se mixture. When Cu2Se/Co3Se4@NPC composite is utilized as an anode electrode material in LIB and SIB half cells, the material demonstrates excellent electrochemical performance and remarkable cycle stability with retaining high capacities. In LIB and SIB half cells, the Cu2Se/Co3Se4@NPC anode material shows the ultralong lifespan at 2000 mAg-1, retaining a capacity of 543 mAhg-1 after 750 cycles, and retaining a capacity of 251 mAhg-1 after 200 cycles at 100 mAg-1, respectively. The porous structure of the Cu2Se/Co3Se4@NPC anode material can not only effectively tolerate the volume expansion of the electrode during discharging and charging, but also facilitate the penetration of electrolyte and efficiently prevents the clustering of active particles. In situ X-ray difraction (XRD) analysis results reveal the high potential of Cu2Se/Co3Se4@NPC composite in building efficient LIBs and SIBs due to reversible conversion reactions of Cu2Se/Co3Se4@NPC for lithium-ion and sodium-ion storage. The Cu2Se/Co3Se4@NPC material, which is synthesized from Cu@ZIF-12, utilizes the advantages of Cu and Co metal complexes to facilitate the storage of lithium and sodium ions. Defect-rich N-doped amorphous carbon (NPC) improves electrical conductivity, and the Cu2Se/Co3Se4@NPC composite material demonstrates remarkable cycle stability while retaining high capacities in LIB and SIB half cells. image
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    An in situ dual-modification strategy for O3-NaNi1/3Fe1/3Mn1/3O2 towards high-performance sodium-ion batteries
    (Royal Soc Chemistry, 2023) Hong, Ningyun; Li, Jianwei; Guo, Shihong; Han, Huawei; Wang, Haoji; Hu, Xinyu; Huang, Jiangnan
    O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM) is one of the most representative cathode materials with low cost and high capacity advantages. However, the sluggish diffusion kinetics and severe cathode-electrolyte interfacial reaction are serious roadblocks to commercialization. Hereby, a novel method of in situ V-modification is well-designed to play dual roles in reconstructing the crystal lattice and interface structure. Notably, the broadened layer spacing of O-Na-O and shortened TM-O bond are attributed to successful doping of V5+ into the bulk, accelerating the transmission of sodium ions and improving the structure stability. Concomitantly, the construction of a thin surface coating layer is beneficial for mitigating volume expansion and inhibiting structural degradation, which is validated by in situ X-ray diffraction coupled with the synchrotron X-ray absorption spectroscopy. Consequently, the rationally designed V-modified NFM cathode exhibits excellent cycling performances, exhibiting great capacity retention of 75.8% after 500 cycles at 2C in a half cell, and 85.6% capacity retention is observed after 150 cycles at 1C in the full cell. This work provides new insights into the development of O3-type layered oxide cathodes toward long-cycle life applications for large-scale energy storage systems.
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    Manipulating Local Chemistry and Coherent Structures for High-Rate and Long-Life Sodium-Ion Battery Cathodes
    (Amer Chemical Soc, 2024) Wang, Haoji; Chen, Hongyi; Mei, Yu; Gao, Jinqiang; Ni, Lianshan; Hong, Ningyun; Zhang, Baichao
    Layered sodium transition-metal (TM) oxides generally suffer from severe capacity decay and poor rate performance during cycling, especially at a high state of charge (SoC). Herein, an insight into failure mechanisms within high-voltage layered cathodes is unveiled, while a two-in-one tactic of charge localization and coherent structures is devised to improve structural integrity and Na+ transport kinetics, elucidated by density functional theory calculations. Elevated Jahn-Teller [Mn3+O6] concentration on the particle surface during sodiation, coupled with intense interlayer repulsion and adverse oxygen instability, leads to irreversible damage to the near-surface structure, as demonstrated by X-ray absorption spectroscopy and in situ characterization techniques. It is further validated that the structural skeleton is substantially strengthened through the electronic structure modulation surrounding oxygen. Furthermore, optimized Na+ diffusion is effectively attainable via regulating intergrown structures, successfully achieved by the Zn2+ inducer. Greatly, good redox reversibility with an initial Coulombic efficiency of 92.6%, impressive rate capability (86.5 mAh g(-1) with 70.4% retention at 10C), and enhanced cycling stability (71.6% retention after 300 cycles at 5C) are exhibited in the P2/O3 biphasic cathode. It is believed that a profound comprehension of layered oxides will herald fresh perspectives to develop high-voltage cathode materials for sodium-ion batteries.
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    Post-Substitution Modulated Robust Sodium Layered Oxides
    (Wiley-V C H Verlag Gmbh, 2023) Gao, Xu; Wang, Haoji; Liu, Huanqing; Hong, Ningyun; Zhu, Fangjun; Ga, Jinqiang; Song, Bai
    Sodium layered oxides feature in high capacity and diverse composition, however, are plagued by various issues including limited kinetics and interfacial instability with residual alkali. Conventional substitution/doping and heterogeneous coating are promising to tackle the problems of bulk and surface, respectively, but normally insufficient to address both. Herein, a post-substitution strategy is proposed to modify primary sodium-layered-oxide particles that can simultaneously deal with bulk and surficial issues. As a typical example, post Ti-substitution for O3-NaNi1/3Fe1/3Mn1/3O2 is successfully performed by adjusting thermodynamic driving force, resulting in depth-controllable Ti infusion from surface to bulk, as proved by energy dispersive spectroscopy maps collected at the cross-section. Residual alkali species are efficiently diminished and benefited from the surface-to-bulk osmotic reaction, significantly improving Coulombic efficiency. Moreover, remarkable enhancements in reversible capacity (135 mAh g(-1) at C/10), rate capability (74% retention at 5 C), and long-term cycling stability (80% retention after 300 cycles at 2 C) are achieved by manipulating gradient-like Ti distribution in a primary particle that brings with increased kinetics and strengthened interfacial stability, surpassing those given by rough heterotic coating and homogeneous Ti-substitution. Such post-substitution is expected to provide a universal strategy to modify primary layered-oxide particles for developing advanced cathode materials of SIBs.