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Effects of Triple Modification Of Sodium Hypophosphite on Structure and Electrochemical Performances of Lithium-Rich Manganese-Based Cathode materials

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SSRN 2022年

作者： Li, Heng Cao, Shuang Li, Zhi Wu, Chao Chen, Jiarui Guo, Xiaowei Chang, Baobao Wang, Xianyou National Base for International Science & Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage & Conversion School of Chemistry Xiangtan University Xiangtan411105 China School of Chemistry & Materials Engineering Xinxiang University Henan 453003 China Key Laboratory of Materials Processing Mold of Ministry of Education Zhengzhou University Henan 450001 China

Oxygen-anion charge compensation enables lithium-rich manganese-based cathode materials (LRMCs) to possess higher specific capacity than other conventional layered oxide cathode materials. However, irreversible oxygen redox makes LRMCs suffer from the oxygen loss, structure degradation and interfacial reactions, and thus resulting in low initial coulombic efficiency (ICE), poor cyclic stability and rate capacity. In order to suppress the irreversible anionic redox, herein Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) is triply modified with sodium hypophosphite (NaH2PO2) through interfacial reaction. The results show that optimum content of NaH2PO2 is 5 wt%, and the reducing gas PH3 produced by NaH2PO2 decomposition can react with the unstable surface oxygen and transition metal ions to form stable LiTMPO4 protection layer and generate oxygen vacancies, and in the same time Na+ can purposely be doped into the Li position of LMNCO. Accordingly, the electrochemical performance of the surface-treated LMNCO-NP 5% is distinctly improved. It has been found that LMNCO-NP 5% displays an ICE of 88.94%, which is much higher than untreated LMNCO (78.2%). Meanwhile, the capacity retentions of LMNCO-NP 5% at 1 C and 5 C after 100 cycles are 94.85% and 78.45%, respectively. Therefore, the triple modification strategy based on the formation of LiTMPO4 protection layer, generation of oxygen vacancies and Na+ ion surface doping can effectively inhibit the TMs migration and irreversible anionic redox, and thus promoting the electrochemical performances of LRMCs. © 2022, The Authors. All rights reserved.

关键词： Cathodes

Realization of blue-red dual-emission via energy transfer in Na 3 KMg 7 (PO 4 ) 6 : Eu 2+ , Mn 2+ phosphor for plant growth application

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Journal of Rare Earths 2024年

作者： Ruijie Ji Takatoshi Seto Yuhua Wang National and Local Joint Engineering Laboratory for Optical Conversion Materials and Technology School of Materials and Energy Lanzhou University Lanzhou 730000 China

A blue-red dual-emitting phosphor, Na 3 KMg 7 (PO 4 ) 6 : Eu 2+ , Mn 2+ was developed in this study. Eu 2+ acts as a sensitizer ion in Na 3 KMg 7 (PO 4 ) 6 : Mn 2+ , which significantly improves the undesirable luminous efficiency of Mn 2+ . The energy transfer between Eu 2+ and Mn 2+ significantly boosts both internal quantum efficiency (IQE) and external quantum efficiency (EQE) of the phosphor, achieving values of 72.5% and 42.6%, respectively. Additionally, the phosphor demonstrates exceptional thermal stability, at 150 °C, maintaining 71.49% of its initial emission intensity. The emission spectrum of the phosphor closely matches the chlorophyll’s absorption spectra, with similarities of 75.06% and 94.52%, respectively. This was further confirmed through a fabricated LED with a n-UV chip (395 nm). To further assess the potential for agritech applications, a light-conversion film incorporating the developed phosphor in PDMS glue was prepared. An outdoor cultivation trial with Chlorella showed that the algae's growth rate improves by 27.3% relative to a control group. These results reveal the significant potential of the Na 3 KMg 7 (PO 4 ) 6 : Eu 2+ , Mn 2+ phosphor for enhancing plant growth in practical applications.

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Improving Structure Stability of Single-Crystalline Ni-Rich Cathode at High-Voltage by Element Gradient Doping and Interfacial Modification

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SSRN 2024年

作者： Wang, Ruijuan Zhang, Yixu Li, Zhi Wu, Lei Chen, Jiarui Liu, Xiaolin Hu, Hui Cao, Shuang Ding, Hao Wei, Qiliang Wang, Xianyou National Base for International Science & Technology Cooperation of New Energy Equipment Energy Storage Materials and Devices National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage & Conversion School of Chemistry Xiangtan University Hunan411105 China Institute of Micro/Nano Materials and Devices Ningbo University of Technology Zhejiang Ningbo315211 China

Single-Crystalline (SC) Ni-Rich cathode materials for advanced lithium-ion batteries have attracted enormous interest because they can provide greater capacity retention and longer cyclic stability than their polycrystalline counterparts. However, the irreversible release of lattice oxygen and structural instability during high cut-off voltage operation greatly hinder their practical applications. Here, via a one-step calcination process, a combination strategy based on the uniform surface Li4TeO5 coating and bulk Te gradient doping is proposed to solve the above intrinsic instability issues of single-crystalline LiNi0.90Co0.05Mn0.05O2 (LTeO-1.0). The mechanical properties and modulating mechanisms of LTeO-1.0 are investigated by atomic force microscopy (AFM). It has been found that the Li4TeO5 coating layer with good ionic conductivity, not only enhances the surface Young’s modulus of LTeO-1.0 to reduce grain fragmentation but also suppresses parasitic reactions and the dissolution of transition metals. Concurrently, Te element gradient doping leads to the formation of robust Te-O bonds that effectively inhibit H2-H3 phase transformations and lattice oxygen release. Based on the synergistic effect, the LTeO-1.0 cathode material represents high cycling durability and superior rate performance at high voltages. This research provides an accessible approach to promote the application of SC Ni-rich cathode materials in lithium-ion batteries. © 2024, The Authors. All rights reserved.

关键词： Cathodes

Enhanced Quantum Efficiency via Co-Substitution in Red-Emitting Phosphor Sr2[MgAl5N7] : Eu2+for Advanced Spectroscopic Applications Including Laser Displays with Ultra-High Luminescence Saturation Threshold

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Angewandte Chemie 2024年第7期137卷

作者： Zebin Li Haoyang Wang Zhezhe Su Runtian Kang Takatoshi Seto Yuhua Wang National & local Joint Engineering Laboratory for Optical Conversion Materials and Technology School of Materials and Energy Lanzhou University 730000 Lanzhou China

In order to obtain novel and more efficient red light-emitting materials, a series of Sr 2 [Mg 1−x Li x Al 5−x Si x N 7 ] : 0.01Eu 2+ (SMAN-xLS, 0≤x≤0.5) red phosphors were devised and successfully synthesized via the high temperature solid state reaction and the effects of the co-substitution of [Mg−Al] 5+ by [Li−Si] 5+ on structural and luminescence properties is investigated in detail. A series of powder XRD data and Rietveld refinement indicate that [Li−Si] 5+ co-substitution can successfully enter the Sr 2 [MgAl 5 N 7 ] : 0.01Eu 2+ (SMAN) lattice. With the entry of [Li−Si] 5+ into the lattice, the substitution of Al 3+ by Si 4+ leads to the weakening of the nephelauxetic effect of the 5d level of Eu 2+ , which shifts the emission peak from 657 nm to 647 nm and reduces the excitation in the green region, i.e., lowers the absorption of green light. When the amount of [Li−Si] 5+ co-substitution is x =0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency (EQE), reflecting the luminescence intensity, is elevated by 49.6 %. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN-0.1LS can achieve an ultra-high luminescence saturation threshold of 52.22 W/mm 2 , which is remarkably superior to other existing red phosphors, a breakthrough performance that has enormous potential for application in high-power laser display light sources. Cathodoluminescence (CL) characterization and measurements attest to the favorable CL properties of SMAN-0.1LS. By measuring the pressure-dependent luminescence of SMAN-0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

关键词： nitride phosphor substitution photoluminescence thermal stability laser cathodoluminescence high pressure

Reducing the Charging Voltage of a Zn-Air Battery to 1.6 V Enabled by Redox Radical-Mediated Biomass Oxidation

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SSRN 2023年

作者： Li, Gangyong Long, Yating Li, Zhi Li, Siping Zheng, Yan He, Binhong Hu, Zongqian Zhou, Minjie Hou, Zhaohui Key Laboratory of Hunan Province for Advanced Carbon-based Functional Materials School of Chemistry and Chemical Engineering Hunan Institute of Science and Technology Yueyang414006 China National Base for International Science & Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage & Conversion School of Chemistry Xiangtan University Xiangtan411105 China Beijing Institute of Radiation Medicine Beijing100850 China

Rechargeable aqueous Zn-air batteries (ZABs) are receiving intense interest as a future energy storage technology because of their high energy density, inherent safety, and low-cost. However, the sluggish oxygen evolution reaction kinetics results in high voltage polarization and low energy efficiency of a ZAB. Herein we show that the addition of a redox radical, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), and a biomass, glucose, into the electrolyte, reduces the charging voltage of a ZAB to ~1.6 V with a high energy efficiency of ~70%, and achieves biomass valorization in a rechargeable aqueous ZAB. On charging, TEMPO is oxidized to TEMPO+ at the cathode surface;TEMPO+ in turn catalyzes the oxidation of glucose to generate the value-added derivatives, which results in the regeneration of TEMPO. The ZABs with TEMPO and glucose exhibit long-term charging/discharging cycles over 400 h. This work offers a promising pathway for developing novel ZABs with high energy efficiency and expanding the synthesis of biomass chemicals. © 2023, The Authors. All rights reserved.

关键词： Biomass

Construction and Regulation of a Perovskite-Type Sulfur Reduction Catalyst Based on Oxygen Vacancy engineering for Advanced Lithium-Sulfur Batteries

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SSRN 2024年

作者： Huang, Xuelin Zeng, Peng Lu, Yunfeng Yang, Juan Chen, Manfang Liu, Hong Wang, Xianyou National Base for International Science & Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage & Conversion School of Chemistry Xiangtan University Xiangtan411105 China Key Laboratory for Theoretical Organic Chemistry and Functional Molecules Ministry of Education Hunan University of Science and Technology Xiangtan411201 China

Lithium-sulfur batteries are considered as a promising energy storage solution due to their considerably high theoretical capacity of 1675 mAh g-1 and high energy density of 2600 Wh kg-1. Nevertheless, the lithium-sulfur batteries in commercial application is facing some challenges such as the shuttle effect. In this paper, the perovskite-type La2Ti2O7-x with oxygen defect is developed and applied as an advanced catalyst in lithium-sulfur batteries. It is found that La2Ti2O7-x with oxygen defects can not only strengthen the chemical binding between the metal sites and LiPSs, but also provide additional adsorption and catalytic sites. The as-prepared La2Ti2O7-x/S cathodes exhibit a high initial discharge specific capacity of 1047 mAh g-1 at 1 C (1 C=1675 mA g-1), and a capacity decay rate of merely 0.089% per cycle after 500 cycles. Therefore, this study demonstrates a significant approach to producing high-performance lithium-sulfur batteries using perovskite transition metal oxides as high efficiency electrocatalyst. © 2024, The Authors. All rights reserved.

关键词： Transition metals

(INVITED)KRbAl 2 B 2 O 7 : Eu 2+ : A new blue-emitting luminescent material with good thermal stability

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optical materials: X 2022年 13卷

作者： Hang Chen Yuhua Wang China Gansu Province Engineering Laboratory for Optical Functional Materials National& Local Joint Engineering Laboratory for Optical Conversion Materials and Technology School of Materials and Energy Lanzhou University Lanzhou 730000 China

Exploring new efficient phosphor for lighting has always been a worthwhile and necessary work. Herein, we develop a new blue-emitting luminescent material KRbAl 2 B 2 O 7 :Eu 2+ through the solid-state method. Under n-UV excitation, this phosphor can emit blue light peaking at 450 nm with FWHM about 55 nm. It owns a broad excitation spectrum covering from 250 nm to 425 nm. Two luminescent centers were identified through the analysis of crystal structure and decay times. Furthermore, the phosphor shows high thermal stability and the emission intensity remains about 81% at 425 K of that at room temperature. The thermal quenching is mainly attributed to the increase of non-radiative transition and thermally activated phonon-assisted tunneling effect at high temperature. By employing as-prepared material as blue phosphor, the fabricated white LED device can emit white light with high CRI (Ra = 85.6) and low CCT (4236 K). These results illustrate that the possibility of KRbAl 2 B 2 O 7 as a blue-emitting phosphor for practical application.

关键词： KRbAl 2 B 2 O 7 Blue-emitting White LED Photoluminescence

Enhanced Energy Storage Performance of Nico-Ldh Nanosheets Decorated on Biomass-Derived Carbon Microtubes from Natural Poplar Catkins for Advanced Hybrid Supercapacitors

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SSRN 2024年

作者： Li, Wei Qian, Guo Guanjie, Ren Zhuokun, Li Jiachang, Li Hongwei, Yue Tingting, Li Li, Pinjiang Lou, Xiaojie Key Laboratory of Micro-Nano Materials for Energy Storage and Conversion of Henan Province Institute of Surface Micro and Nano Materials College of Chemical and Materials Engineering Xuchang University Henan461000 China Key Laboratory for Special Functional Materials of Ministry of Education National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology School of Nanoscience and Materials Engineering Collaborative Innovation Center of Nano Functional Materials and Applications Henan University Kaifeng475004 China Henan Joint International Research Laboratory of Nanomaterials for Energy China Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi’an710049 China Shaanxi Normal University China

Nickel-cobalt layered double hydroxides (NiCo-LDHs) are promising electrode materials for hybrid supercapacitors (HSCs) due to their high theoretical charge storage capacity and excellent reversibility. However, their practical application is limited by low electrical conductivity and a tendency to agglomerate, which suppress their electrochemical performance. To address these challenges, NiCo-LDH NSs/CMT-PC composite electrode material is synthesized via a hydrothermal method. This composite integrates NiCo-LDH nanosheets (NiCo-LDH NSs) as a coating and carbon micro-tubes derived from poplar catkins (CMT-PC) with a high specific surface area as the framework. In a three-electrode system, the NiCo-LDH NSs/CMT-PC electrode demonstrated a specific capacity of 228.4 mAh g-1 (1644.5 F g-1, 822.2 C g-1) at a current density of 1 A g-1, and maintained a specific capacity of 101.7 mAh g-1 (732.2 F g-1, 366.1 C g-1) even at 30 A g-1. After 5000 cycles, the material exhibited excellent stability, retaining 96.5% of its capacity, with a decrease from 193.6 mAh g-1 to 186.9 mAh g-1. To explore its practical application in HSCs, we assembled NiCo-LDH NSs/CMT-PC//AC HSCs, using the NiCo-LDH NSs/CMT-PC as the positive electrode and activated carbon (AC) as the negative electrode. The assembled device exhibited a specific capacity of 88.3 mAh g-1 at 1 A g-1 and an energy density of 72.2 Wh kg-1 at a power density of 508.6 W kg-1. Impressively, after 9000 cycles at 3 A g-1, the specific capacity increased from 64.2 mAh g-1 to 66.5 mAh g-1, demonstrating exceptional cycling stability and suitability for practical applications. © 2024, The Authors. All rights reserved.

关键词： Nanosheets

Nasicon-Type V-Doped Ca0.5ti2 (Po4)3/C Nanofibers for Fast and Stable Potassium Storage

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SSRN 2022年

作者： Liu, Li Yang, Jianping Dai, Jing Su, Die Ren, Qiaochu Liu, Guangzhan Luo, Qi Luo, Junwei Liu, Shaoxiong Hai, Hu National Base for International Science & Technology Cooperation National Local Joint Engineering Laboratory for Key materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage and Conversion School of Chemistry Xiangtan University Xiangtan411105 China Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization school of Chemistry and Chemical Engineering Chongqing University ShaZhengjie174 Chongqing400044 China

Potassium ion batteries (PIBs) are considered as the next-generation energy storage devices owing to the relatively low cost and the plentiful reserves. In addition, the redox potential of K+/K is comparable to that of Li+/Li. When it comes to the negative electrode, NASICON type materials draw much attention owing to their robust structure and high ionic mobility. Herein, vanadium doped Ca0.5Ti2 (PO4)3/C nanofibers are prepared by means of electrospinning and post-annealing, and vanadium is doped into the matrix in order to boost the ionic/electronic conductivities. When assembled as PIBs half cells, it delivers a high capacity of 131 mAh g-1 at 5 A g-1, which performs best in analogues. Furthermore, it provides a stable capacity of 112 mAh g-1 after 1000 cycles at 1 A g-1. This finding indicates that V-doped Ca0.5Ti2 (PO4)3/C nanofibers have the potential to be an attractive anode choice for PIBs. © 2022, The Authors. All rights reserved.

关键词： Nanofibers