Advanced Optical Materials
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2024
·Vol. 12
·期 19
·2400250
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IF 8
Wenyu Tang,Yuanjing Wang,Yayun Zhou,Chuang Zhang,Zhen Chen,Fanquan He,Enhai Song,Qinyuan Zhang
Mn 4+ -activated red-light fluorides are widely used in high-quality displays, due to the narrow-spectral emission. However, achieving exceptional chromaticity coordinates and appropriate quantum efficiency (QE) at the same time is a great challenge. Herein, a Li substitution strategy is proposed for enhancing QE and improving the thermal stability of red-light Mn 4+ -activated Cs 2 NaGaF 6 (CNGF). The external quantum efficiency (EQE) of optimal Cs 2 NaGaF 6 : Mn 4+ , Li + (CNGF: Mn 4+ , Li + ) is improved from 15.79% to 33.61% and thermal stability increases from 68.4% to 85.5% (intensity at 150 °C relative to room temperature). EQE enhancement mechanism on the strategy is explored that Li substitution increases the local structural distortion of Mn 4+ for relieving the parity forbidden, and promotes Mn 4+ doping in the host lattice, which provides new insights for improving the QE of Mn 4+ non-equivalent doped fluorides. Moreover, with exceptional chromaticity coordinates of (0.7029, 0.2970), optimal sample CNGF: 4.8 mol% Mn 4+ ,0.9 mol% Li + can be used to fabricate white light-emitting diode (w-LED) backlight, which obtains wide color gamut of 110.68% National Television Standards Committee (NTSC) and high luminous efficacy of 110.57 lm W −1 , indicating that CNGF: Mn 4+ , Li + is a promising candidate for the next generation of wide gamut and efficient displays.
研究领域:
材料科学
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光学工程
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显示技术
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DOI
高影响因子
Journal of Physical Chemistry C
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2016
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IF 4.509
Zheng-Yao Li,Jicheng Zhang,Rui Gao,Heng Zhang,Lirong Zheng,Zhongbo Hu,Xiangfeng Liu
The effects of Li substitution for Ti on the structure and electrochemical performances of Co-free Na0.67Mn0.55Ni0.25Ti0.2–xLixO2 (x = 0, 0.1, 0.2) layered cathode materials for sodium ion batteries have been comprehensively investigated. X-ray diffraction and Rietveld refinement results demonstrate that Li mainly occupies TM (TM = transition metal) sites in the crystal structure to maintain the P2 structure majority and a small amount of Li atoms enter Na sites to generate some O3 phase. The discharge voltage, reversible capacity, rate capability, cycling performance, and Coulombic efficiency all have been improved by Li substitution, which can be largely attributed to the integration of P2 and O3. Li substitution also raises the average discharge voltage from 2.6 to 3.1 V. Na0.67Mn0.55Ni0.25Li0.2O2 (L02) can deliver an initial capacity of about 158 mA h g–1 at 0.05C (12 mA g–1) in comparison with the Li-free sample (147 mA h g–1). Even at the high rates of 480 (2C), 1200 (5C), and 1920 (8C) mA g–1, L02 can also display ca. 93, 65, and 38 mA h g–1 discharge capacities, respectively. The rate capability is higher than what is reported in the previous Li-substituted cathode materials. In addition, Li substitution in transition-metal sites generates more defects to maintain the charge neutrality, which enhances the electronic conductivity and also has a positive effect on the Na ion diffusion coefficient. The electronic conductivity and Na ion diffusion coefficient have been enhanced by 122% and 29%, respectively, with the substitution of Li for Ti. Our results also show that the oxidation peaks become sharper with increasing Li content, which indicates the feasibility of Na ion intercalation/deintercalation in the integrated P2/O3 phase. This study also offers some new insights into designing high-performance cathode materials for sodium ion batteries.
研究领域:
材料科学
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能源存储与转换
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DOI
高影响因子
INORGANIC CHEMISTRY
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2021
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IF 5.165
Wenfeng Zhou,Qing Zhang,Wen-Dong Yao,Huaiguo Xue,Sheng-Ping Guo
One of the key scientific issues for exploration of novel infrared nonlinear optical (NLO) crystals is to obtain ones with good hybrid NLO behaviors. Herein, we report four diamond-like Ag-based sulfides via stepwise Li substitution of Ag in Ag2ZnSnS4, including Ag2ZnSnS4 (1), (Li1.22Ag0.78)ZnSnS4 (2), (Li1.58Ag0.42)ZnSnS4 (3), and Li2ZnSnS4 (4). With the increase of Li content, the sulfide’s noncentrosymmetric crystal structure changes from tetragonal I42m for 1, to orthorhombic Pmn21 for 2 and 3, and to monoclinic Pn for 4. Accordingly, their NLO responses are improved along with the increase of Li content, viz. from non-NLO-active for 1, to non-phase-matchable for 2 and 3, and to phase-matchable for 4. Their optical band gaps also increase regularly. The relationship between their chemical compositions, crystal structures, and NLO activities is investigated by means of chemical structural analysis and theoretical calculation. This work offers a new systematic case for designing promising NLO-active compounds via rarely adopted cation’s stepwise partial substitution and understanding the chemical composition–structure–NLO property relationship.
研究领域:
材料科学
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化学
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DOI
PubMed
高影响因子
JOURNAL OF POWER SOURCES
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2024
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IF 8.1
Peilin Ran,Xiaoqing Li,Kang Wu,Na Li,Kesheng Gao,Chenzhang Gu,Jinkui Zhao,Enyue Zhao,Zhimin Wu,Fangwei Wang
Cobalt-free Lithium-rich layered oxides (LRLOs) are promising cathodes for low-cost and high-energy-density Li-ion batteries. However, their remarkable capacity comes with challenges including structural degradation, irreversible oxygen release and sluggish kinetics. Herein, we conduct a one-step dual-modified strategy by yttrium doping and Li 3 PO 4 surface modification. Combining density-functional theory calculations with in-situ X-ray diffraction and in-situ differential electrochemical mass spectrometry, the Y 3+ doping and Li 3 PO 4 nano coating modified LRLOs is demonstrated has an excellent structural stability with enhanced Li⁺ diffusion kinetics and stabilized oxygen lattice. Excellent rate performance and thermal stability are achieved: high discharge specific capacity of 221 mAh·g −1 at room temperature (96.5 % at 1 C after 100 cycles) and incredible discharge specific capacity of 210 mAh·g −1 at 55 °C (91.8 % at 2 C after 100 cycles). This work resolves the safety and stability issues and provides a feasible strategy for Co-free LRLOs.
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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DOI
高影响因子
危险品化学品经营许可证（带存储）