ChemNanoMat
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2025
·Vol. 11
·期 7
·e202500102
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IF 2.6
Yuanchao Li,Shixing Han,Pengchao Liang,Xiaokun Shang,Qi Li,Jingjing Ma,Songlin Wang,Li Yang,Guangri Xu
The Na x MnO 2 ( x < 0.44) material with a T-type tunnel phase shows excellent cycling performance, but low initial specific capacity. The Na x MnO 2 ( x > 0.6) with P2-type phase exhibits high initial specific capacity, yet poor cycling performance. Layer-tunnel hybrid materials has served as cathode materials for sodium-ion batteries (SIBs) due to the integration of high specific capacity and superior cycling performance. Herein, sodium manganite composites is synthesized with tunnel phase containing a small amount of P2-type layered phase in Na 0.44 MnO 2 materials using citric acid as the dispersant. The citric acid can promote the transition of the T-P2 phase and contribute to the uniform distribution of elements. The as-prepared Na 0.44 MnO 2 with layered-tunnel hybrid phase exhibits the best overall electrochemical performances with a capacity retention of 68% after 300 cycles at 1 C and an initial discharge capacity of 143.7 mA h g −1 , due to combination of the advantages of layered and tunnel structure. This work provides a new strategy for synthesizing transition metal oxides with hybrid phase as the cathode of advanced SIBs.
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DOI
高影响因子
Batteries & Supercaps
·
2025
·Vol. 8
·期 9
·e202500029
·
IF 4.7
Wenchong Ding,Zhongqiang Ye,Zhifeng Huang,Hai Hu,Li Liu
As the cathode material of sodium-ion battery, sodium manganese oxide has attracted considerable critical attention due to its abundant resources and low cost. However, due to the disproportionation of manganese, sodium manganese oxide often suffers from significant capacity degradation and low rate performance, which hinders its practical application. Here, the electrochemical performance of Na 0.44 MnO 2 is significantly improved by an appropriate amount of B doping. The Na 0.44 Mn 0.95 B 0.05 O 2 shows outstanding rate capability and excellent cycle performance, which could deliver a capacity of 61.0 mAh g −1 at 60 C and a capacity retention of 84.7% for 400 cycles at 30 C. B doping could effectively improve the electronic/ionic conductivity of Na 0.44 MnO 2 , which has been demonstrated. Graphical B-doped tunnel-type Na 0.44 MnO 2 is synthesized using the sol–gel method. The introduction of B expanded the lattice spacing of tunnel-type Na 0.44 MnO 2 , reduced the resistance for Na-ion transport within the tunnels, and enhanced the material's conductivity. Na 0.44 Mn 0.95 B 0.05 O 2 demonstrates a capacity of 61 mAh g −1 at a high current density of 60 C, showing excellent rate performance.
研究领域:
材料科学
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电化学
·
储能
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DOI
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2020
·
IF 3.442
Fanpei Gu,Tianjiao Sun,Xiaolin Yao,Miao Shui,Jie Shu
Here, A kind of carbon nanotubes (CNT) wrapping Na 0·44 MnO 2 has been synthesized via a high-temperature solid state method and showed better electro-chemical performance in 1 M Na 2 SO 4 aqueous solution as cathode material for aqueous sodium ion batteries . This rod-like nano-composite exhibited a first charge capacity of 70.1 mA h·g −1 with the reversible capacity retention of about 63.4% after 300 cycles at a current density of 50 mA g −1 . It can also remain reversible specific capacity of 53.1, 44.7, 34.8, and 19.7 mA h·g −1 at the current density of 1 C, 2 C, 5 C and 10 C, respectively. The Na + migration mechanism and kinetics of Na 0·44 MnO 2 are fully investigated by molecular dynamics (MD) and the density functional theory (DFT). A SQS-8 quasi-random structure is used to model the structure of the material. The results show that Na + is highly vigorous and propagates 1D along the c-axis. A minimum of 0.081 eV and 0.51 eV is required for Na + to travel through the large S -shaped tunnel and the small tunnel, respectively.
研究领域:
材料科学
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电化学
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能源存储
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纳米技术
·
计算物理
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DOI
高影响因子
ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Bi Fu,Yong Su,Junxi Yu,Shuhong Xie,Jiangyu Li
Sodium-ion battery (SIB) is one of the most promising alternatives to partly substitute for lithium-ion batteries (LIBs), yet the large radius of Na + leads to substantial volume change during sodiation/desodiation processes, resulting in inferior electrochemical performance. Na 0.44 MnO 2 (NMO) possesses S-shaped Na + diffusion pathway that can accommodate insertion/deinsertion of large Na + , though the poor electronic conductivity of NMO limits its ionic transport kinetics. Herein, single crystalline NMO nanorods (NRs) were synthesized, and their electronic conductivity was enhanced by one order of magnitude using reduced graphene oxide (rGO), as quantified by local conductive atomic force microcopy (c-AFM) measurement. When used as a cathode material for SIBs, NMO/rGO nanocomposite exhibits reversible specific capacities of 124mAh/g at 0.2C after 200 cycles and 70.8mAh/g at 15C, which are significantly enhanced over control cathode made of pure NMO NRs. Through detailed electrochemical impedance spectroscopy (EIS) analysis, it was found that NMO/rGO nanocomposite exhibits much reduced Warburg factor, resulting in enhanced Na + diffusion at each discharging voltage platform. This suggests that the enhanced electronic conductivity helps Na + insertion/deinsertion, resulting in improved electrochemical performance, and these insights help us understand how electronic conductivity improves ionic transport kinetics in SIBs.
研究领域:
材料科学
·
电化学
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DOI
高影响因子
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