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Your search keyword '"Ma, Zi-Feng"' showing total 22 results
Start Over Author "Ma, Zi-Feng" Journal acs applied materials & interfaces
22 results on '"Ma, Zi-Feng"'

16. Improved Cycling Performance of P2-Na0.67Ni0.33Mn0.67O2Based on Sn Substitution Combined with Polypyrrole Coating

Author

Yuan, Siqi, Qi, Jizhen, Jiang, Meidan, Cui, Guijia, Liao, Xiao-Zhen, Liu, Xi, Tan, Guoqiang, Wen, Wen, He, Yu-Shi, and Ma, Zi-Feng

Abstract

P2-Na0.67Ni0.33Mn0.67O2presents high working voltage with a theoretical capacity of 173 mAh g–1. However, the lattice oxygen on the particle surface participates in the redox reactions when the material is charged over 4.22 V. The resulting oxidized oxygen aggravates the electrolyte decomposition and transition metal dissolution, which cause severe capacity decay. The commonly reported cation substitution methods enhance the cycle stability by suppressing the high voltage plateau but lead to lower average working voltage and reduced capacity. Herein, we stabilized the lattice oxygen by a small amount of Sn substitution based on the strong Sn–O bond without sacrificing the high voltage performance and further protected the particle surface by polypyrrole (PPy) coating. The obtained Na0.67Ni0.33Mn0.63Sn0.04O2@PPy (3.3 wt %) composite showed excellent cycling stability with a reversible capacity of 137.6 (10) and 120.0 mAh g–1(100 mA g–1) with a capacity retention of 95% (10 mA g–1, 50 cycles) and 82.5% (100 mA g–1, 100 cycles), respectively. The present work indicates that slight Sn substitution combined with PPy coating could be an effective approach to achieving superior cycling stability for high-voltage layered transition metal oxides.

Published
2021
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22. Mg2+-Doping Constructed a Continuous and Homogeneous Cathode-Electrolyte Interphase Film on Na3.12Fe2.44(P2O7)2with Superior and Stable High-Temperature Performance for Sodium-Ion Storage

Author

Zhang, Yu, Zhang, Jianhua, Shao, Tong, Li, Xiaoqiang, Chen, Gaoyang, Liu, Haimei, and Ma, Zi-Feng

Abstract

Sodium-ion batteries (SIBs) are on the verge of achieving practical applications, and the key is to find suitable electrode materials. The polyanionic iron-based material Na3.12Fe2.44(P2O7)2(NFPO) possesses an open three-dimensional framework structure with good thermal stability and is regarded as an outstanding cathode material for SIBs. Nevertheless, its poor electrical conductivity, problems with erosion of electrolytes, and structural deterioration during cycling still need to be urgently addressed. Here, we first design a Mg2+-doped NFPO (NFPO-Mg) material with a dual-action effect. On the one hand, Mg2+improves the intrinsic conductivity of the NFPO material, and on the other hand, Mg2+promotes the formation of a homogeneous and stable cathode–electrolyte interphase film during the cycling process, which results in a superior rate performance and cycling stability. A capacity of 68.6 mAh g–1was achieved at 50C (1C = 117.4 mAh g–1), and a capacity retention of 79.1% was maintained after 3000 cycles at 20C. More impressively, NFPO-Mg exhibits outstanding high-temperature electrochemical performance, with a capacity retention of 95.3% after 400 cycles at 10C at 60 °C (much higher than the 54.2% for the NFPO). This paper explores an effective method for improving the electrochemical performance of cathode materials, which may prove instrumental in guiding the design of more high-performance cathode materials in the future.

Published
2022
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