International Journal of Electrochemical Science
·
2023
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IF 1.5
Kai Xia,Rui Liang,Yi Luo,Anqiao Zheng,Guodong Jiang,Mingxia Fan,Jian Xiong,Songdong Yuan
A series of LiFe 0.7 Mn 0.3−x Mg x PO 4 /C (x = 0, 0.02, 0.05, and 0.08) cathode materials were synthesized by a high-temperature solid-phase method and characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests to determine the structural, morphological, and electrochemical properties of the synthesized materials. The experimental results showed that the small amount of Mg 2+ doping not only had no effect on the crystalline structure of the material but also significantly improved the electrochemical properties of the material. The LiFe 0.7 Mn 0.25 Mg 0.05 PO 4 /C material achieved specific discharge capacities of 163.2, 155.2, 149.1, and 142.0 mAh/g at 0.1C, 0.2C, 0.5C, and 1C, respectively, and a capacity retention rate of 98.6% after 50 cycles at 0.1C. It exhibited excellent rate performances and cycling stability. Electrochemical alternating-current impedance showed that the lithium-ion diffusion coefficient of the LiFe 0.7 Mn 0.25 Mg 0.05 PO 4 /C sample reached 1.19 × 10 −13 cm 2 /s, which was 4.1 times higher than that of the pre-modified sample. Combined with the cyclic voltammetry test results, it was found that the appropriate amount of Mg 2+ doping could reduce the impedance and polarization of the material as well as increase the conductivity and the lithium-ion diffusion rate, ultimately improving the electrochemical properties.
研究领域:
材料科学
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电化学
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DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2022
·Vol. 51
·期 7
·3896-3902
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IF 2.047
Cheng Jiawen,Qing Zhenjun,Wang Jin,Zhao Yun,Zhou Xin,Zou Huapeng,Li Haiyan,Li Yingxiang
In this paper, the traditional solid-phase reaction sintering process was used to synthesize Ca 1-x Mg x V 2 O 6 (x = 0.03, 0.06, 0.09, 0.12) ceramics under low-temperature conditions. The effects of partial replacement of Ca 2+ by Mg 2+ on the A-site on the crystalline type, sintering temperature, microstructure, densification, and microwave dielectric performances of Ca 1-x Mg x V 2 O 6 ceramic were studied. The only crystalline phase of CaV 2 O 6 was observed in the ceramics. The sintering densification and dielectric performances of the Ca 1-x Mg x V 2 O 6 ceramic show a trend of first increasing and then decreasing with the increase of Mg 2+ content. The addition of Mg ions can effectively increase the Q × f value of the Ca 1-x Mg x V 2 O 6 ceramics but cannot improve the τ f value. The Ca 0.91 Mg 0.09 V 2 O 6 ceramic sintered at 725°C displayed good microwave dielectric performances: ε r = 10.41, Q × f = 68524 GHz, and τ f = − 36.8 ppm/°C. The good dielectric properties of this ceramic can meet the development needs of 5G communication technologies.
研究领域:
材料科学
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电子工程
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DOI
高影响因子
Journal of Materials Chemistry C
·
2024
·
IF 5.7
Zhibin Ye,Ziwang Zhang,Nan Yang,Zhuo Li,Weijie Huang,Jianxin Shi
Artificial light sources have a significant impact on the cultivation of houseplants. In this work, a novel single-phase dual-emission phosphor, Ca18Na3Y(PO4)14:Eu2+,Mn2+ (CNYPO:Eu2+,Mn2+), was synthesized and the emission spectra were modulated by co-doping of Mg2+ to better match the absorption of plants. The occupancies of Eu2+, Mn2+ and Mg2+ are analyzed by using the data of bond length from XRD Rietveld refinements and the emission spectra. The energy transfer process from Eu2+ to Mn2+ is proved through the photoluminescence spectra and decay curves. Benefiting from the efficient energy transfer, two broadband emissions peaking at 500 and 650 nm can be achieved, which meets the requirements of plant growth, and the luminescence colour can be tuned from cyan to white and finally to red by changing the ratio of Mn2+ to Eu2+. The internal quantum efficiency of CNYPO:0.18Eu2+,0.18Mn2+ is 76.8% under 340 nm excitation. The introduction of Mg2+ can regulate the occupation sites of Eu2+ and the emission peak position, improve the responsiveness to the plant absorption spectra, and tune the luminescence colour to white. Finally, a white light-emitting diode (WLED) device fabricated using CNYPO:0.18Eu2+,0.18Mn2+,2.16Mg2+ on a 365 nm chip has a high colour rendering index of 89.0 and a low correlated colour temperature of 3580 K, indicating that the prepared phosphor has potential applications in plant lighting and WLEDs.
研究领域:
材料科学
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光学工程
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农业科学
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DOI
高影响因子
Nano Research
·
2021
·Vol. 15
·期 4
·3143-3149
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IF 8.897
Huang Ruling,Xue Qing,Lin Jiao,Zhang XiXue,Zhou Jiahui,Wu Feng,Li Li,Chen Renjie
Layered Mn-based oxides are one of the promising cathode materials for potassium-ion batteries (KIBs) owing to their high theoretical capacities, abundant material supply, and simple synthesis method. However, the structural deterioration resulting from the Jahn-Teller effect of Mn ions hinders their further development in KIBs. Herein, a novel Mn-based layered oxide, K 0.54 Mn 0.78 Mg 0.22 O 2 , is successfully designed and fabricated as KIBs cathode for the first time. It delivers smooth charging/discharging curves with high specific capacity of 132.4 mA·g −1 at 20 mA·g −1 and good high-rate cycling stability with a capacity retention of 84% over 100 cycles at 200 mA·g −1 . Combining in-situ X-ray diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy (XPS) analysis, the storage of K-ions by K 0.54 Mn 0.78 Mg 0.22 O 2 is revealed to be a solid-solution processes with reversible slip of the crystal lattice. The studies suggest that the rational doping of inactive Mg 2+ can effectively suppress the Jahn-Teller effect and provide outstanding structure stability. This work deepens the understanding of the structural evolution of Mn-based layered materials doped with inactive materials during de/potassiation processes.
研究领域:
材料科学
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电化学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ziqian Meng,Jiadong Hou,Chufei Cheng,Bei Ren,Yang Miao,Weihua Ji
To create thermal barrier coatings (TBCs) with superior thermal characteristics and high-temperature stability, understanding the microscopic process of heat transfer in high-entropy solid solutions is crucial. In this study, novel (Zr 0.2(1-x) Ce 0.2(1-x) Pr 0.2(1-x) Y 0.2(1-x) Ho 0.2(1-x) Mg x )O 2-δ single-phase high-entropy fluorite-structured oxides with varying Mg elemental contents were successfully synthesized at 1600 °C. Given the unique ionic radius and valence nature of Mg 2+ , the effects of varying the Mg doping amount on the thermophysical properties and microstructures were explored. Furthermore, the mechanism influencing high-temperature thermal conductivity was studied at the microscopic scale using first-principles calculations to clarify the nature of the thermal conductivity behavior. On one hand, an increase in oxygen vacancies leads to an enhancement of the lattice distortion degree and phonon scattering level. On the other hand, divalent Mg 2+ activates the lattice via unequal substitutions, thereby reducing the thermal conductivity. The experimental and simulation results revealed that as Mg doping increases, the content of oxygen vacancies significantly increases, the degree of lattice distortion increases, phonon scattering is enhanced (19.54–21.37 THz), high-temperature thermal conductivity progressively decreases (1.91-1.20 w·m −1 ·K −1 ), and the coefficient of thermal expansion progressively increases (11.70 × 10 −6 -12.31 × 10 −6 K −1 ). These results offer a novel approach for designing doped high-entropy strategies that can satisfy the performance requirements of TBCs.
研究领域:
材料科学
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热力学工程
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DOI
高影响因子
ACS Applied Energy Materials
·
2025
·
IF 5.5
Ketai Ren,Jinkai Qiu,Honglai Liu,Hongfang Song,Quan Li,Jingkun Li
Fluorophosphate Na3V2(PO4)2F3 (NVPF) is considered a promising cathode material for sodium-ion batteries, while its specific capacity is still insufficient compared to that of cathodes of lithium-ion batteries. Activating the third Na+ effectively increases the specific capacity of NVPF. However, the accompanied irreversible phase transition deteriorates the cycling stability. In this study, we synthesized sodium-rich Na3.5V1.5Mg0.5(PO4)2F3 (NVMPF) through doping low-valence Mg2+ with a high content, which introduces an extra 0.5 Na+ in the crystal lattice. The extra 0.5 Na+ remains in the lattice of NVMPF, acting as “pillars” to suppress the irreversible phase transition after the third Na+ is extracted by activating the V5+/4+ redox couple at a high voltage. Thus, NVMPF achieves a specific discharge capacity of 170 mAh g–1 between 1.0 and 4.7 V while maintaining the tetragonal structure of NVMPF. This work offers insightful guidelines to achieve the full utilization of three Na+ with enhanced cycling stability.
研究领域:
材料科学
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电化学
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DOI
高影响因子
JOURNAL OF POWER SOURCES
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2024
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IF 8.1
Shuting Zhao,Wentao Qi,Chao Yang,Rui Ling
Na 3 V 2 (PO 4 ) 3 has received a lot of attention as a prospective cathode for sodium-ion batteries (SIBs) owing to its strong 3D wide-open architecture for Na + transport. However, the practical application is still hampered by its poor electronic conductivity and weak Na + diffusion kinetics . In this paper, a novel Mg 2+ -doped Na 3 V 2 (PO 4 ) 3 flower-like cathode (Na 3+x V 2-x Mg x (PO 4 ) 3 /C, x = 0, 0.02, 0.04, 0.06) with abundant mesoporous has been synthesized by a convenient template-assisted sol-gel method. Mg 2+ doping successfully triggers V 4+ /V 5+ reversible redox with improved voltage plateau and reversible capacity. The hierarchical mesoporous structure combined with carbon layers is beneficial to the fast transport of Na + and e − , which guarantee improved kinetic properties and enhanced conductivity. Attributed to these competitive advantages, significantly improved electrochemical properties of Na 3.04 V 1.96 Mg 0.04 (PO 4 ) 3 /C (NVMP-4) are acquired, including extremely high specific capacity (123.8 mAh g −1 at 1C), excellent rate performance (73.8 mAh·g −1 at 100C) and exceptionally stable energy output with 89.1 % capacity retention after 3000 cycles at 20C. Additionally, when assembled with a hard carbon anode (HC), NVMP-4||HC provides an exceptional energy density of 216.9 Wh kg −1 at 0.2C. By enhancing nanostructure and rational surface engineering, this project offers fresh perspectives for creating superior electrodes, increasing the energy density of SIBs.
研究领域:
材料科学
·
电化学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Zuizhi Lu,Hua Fan,Yingjun Ou,Mianhong Chen,Ye Yang,Linawa Shen,Liya Zhou,Xiaotong He,Jiansheng Zhao,Peican Chen
Recently, near-infrared (NIR) light-emitting diodes (LED) have attracted much research attention globally. To advance this technology, NIR phosphors with high efficiency, thermal stability, and broad bands are required. In this work, we modified ZnGa 2 O4:Cr 3+ phosphor with Mg 2+ ions. Results show that this method improves the luminescence intensity of ZnGa 2 O4:Cr 3+ phosphor, and the emission wavelength of the sample can be changed by doping different Mg 2+ concentrations. This method also improved the thermal stability of the samples. The quantum yield of Mg-modified ZnGa 2 O 4 :Cr 3+ phosphors reached 87.12%, and the white LED fabricated with Zn 0.4 Mg 0.6 Ga 2 O 4 :0.01Cr 3+ phosphor and commercial Y 3 Al 5 O 12 :Ce 3+ phosphor demonstrated good performance. The NIR-LED fabricated with Zn 0.4 Mg 0.6 Ga 2 O 4 :0.01Cr 3+ phosphor achieved a photoelectric conversion efficiency of 7.17%. The lines on the surface of an orange taken by a NIR camera reveal that phosphor can be used in night vision lighting. Meanwhile, the distribution of blood vessels in the human palm highlights the promising biological applications of the Zn 0.4 Mg 0.6 Ga 2 O 4 :0.01Cr 3+ phosphor.
研究领域:
材料科学
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光学工程
·
生物医学工程
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DOI
高影响因子
Laser & Photonics Reviews
·
2025
·
IF 10
Yang Tang,Qingyu Xie,Xuanming Zhang,Jiwei Ma,Hao Xie,Yongfeng Liu,Liang Zhao,Dongdong Yan,Xiaoyu Wang,Weixiang Ye
Cs 3 Cu 2 Cl 5 nanocrystals (NCs) have emerged as promising optoelectronic materials owing to their efficient self-trapped exciton (STE) emission. However, their limited environmental stability has significantly constrained their application in light-emitting diodes (LEDs). In this work, a facile ambient-air synthesis strategy is developed for Mg 2 ⁺-doped Cs 3 Cu 2 Cl 5 NCs that simultaneously addresses both stability and emission efficiency challenges. Remarkably, optimal Mg 2 ⁺ doping (20%) enhances the photoluminescence quantum yield (PLQY) from 28.69% to 59.3%. Comprehensive theoretical investigations through density of states (DOS) calculations and ab initio molecular dynamics (AIMD) simulations demonstrate that Mg 2 ⁺ doping induces bandgap narrowing for enhanced radiative recombination while reinforcing the crystal lattice stability. When integrated with a UV LED chip, the optimized NCs enable the fabrication of high-performance green LEDs exhibiting outstanding luminance (17 281 cd m − 2 ) and excellent color stability (CIE coordinates: 0.354, 0.518). This study provides not only a practical synthetic approach for stable copper halide NCs but also valuable insights for designing efficient STE emitters for optoelectronic applications.
研究领域:
材料科学
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光学工程
·
理论计算
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 27
·12199-12208
·
IF 2.7
Shaowei Wang,Zesen Gao,Futing Sun,Yan Yang,Lang Tao,Yunluo Wang,Zhiqian Yu,Jianghua Wu,Jingshan Hou,Zhanqiang Liu,Hucheng Song,Haijie Chen
Safety concerns associated with lithium batteries suggest the development of solid-state batteries as a promising variant. In this work, we doped a lithium boracite (Li4B7O12Cl) with Mg2+ to modify the Li+ sites and observed significant improvement in ionic conductivity by two orders of magnitude (from 3.03 × 10−7 S cm−1 to 2.81 × 10−5 S cm−1 at room temperature). We attribute the enhanced ion conductivity to the artificially induced Li vacancies resulting from Mg doping. The as-fabricated symmetrical battery (Li|Li3.6Mg0.2B7O12Cl|Li) exhibited good cycling performance with a stable voltage output even after 60 hours of cycling. The battery showed a coulombic efficiency retention of ∼99.7% after the cycling test. Our work demonstrates that Li4B7O12Cl is a superior solid electrolyte for solid-state batteries and the introduction of Li vacancies can be an efficient approach to greatly improve the ionic conductivity of other electrolytes.
研究领域:
材料科学
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电化学
·
电池技术
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DOI
高影响因子
危险品化学品经营许可证（带存储）