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Unraveling the degradation mechanism of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) at the high cut-off voltage for lithium ion batteries

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Journal of Energy Chemistry 2023年第2期77卷 428-437,I0011页

作者： Liming Wang Qingmei Su Bin Han Weihao Shi Gaohui Du Yunting Wang Huayv Li Lin Gu Wenqi Zhao Shukai Ding Miao Zhang Yongzhen Yang Bingshe Xu School of Materials Science&Engineering Shaanxi University of Science and TechnologyXi’an 710021ShaanxiChina Materials Institute of Atomic and Molecular Science Shaanxi University of Science and TechnologyXi’an 710021ShaanxiChina School of Materials Science&Engineering Tsinghua UniversityBeijing 100084China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan 030032ShanxiChina Key Laboratory of Interface Science and Engineering in Advanced Materials Taiyuan University of TechnologyTaiyuan 030024ShanxiChina

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy densities at high operation voltage.However,the capacity fading under high operation voltage still restricts the practical application.Herein,the capacity degradation mechanism of NCM811 at atomic-scale is studied in detail under various cut-off voltages using aberration-corrected scanning transmission electron microscopy(STEM).It is observed that the crystal structure of NCM811 evolution from a layered structure to a rock-salt phase is directly accompanied by serious intergranular cracks under 4.9 V,which is distinguished from the generally accepted structure evolution of layered,disordered layered,defect rock salt and rock salt phases,also observed under 4.3 and 4.7 V.The electron energy loss spectroscopy analysis also confirms the reduction of Ni and Co from the surface to the bulk,not the previously reported only Li/Ni interlayer mixing.The degradation mechanism of NCM811 at a high cut-off voltage of4.9 V is attributed to the formation of intergranular cracks induced by defects,the direct formation of the rock salt phase,and the accompanied reduction of Ni^(2+)and Co^(2+)phases from the surface to the bulk.

关键词： Ni-rich layered cathode Electrochemical performance degradation mechanism Crack Atomic scale

degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation

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Journal of Environmental Sciences 2007年第12期19卷 1430-1435页

作者： CHANG Shuang-jun LIU Yu-cun College of Chemical Engineering and Environment North University of China Taiyuan 030051 China

The 2,4,6-trinitrotoluene （TNT） is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation （SCWO） to treat TNT contaminated wastewater was studied in this article, The TNT concentration in wastewater was measured by high-performance liquid chromatograph （HPLC） and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently in the presence of oxygen. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increased. At 550℃, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occured in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO included toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously when TNT was oxidized by SCWO.

关键词： supercritical water oxidation TNT degradation mechanism wastewater treatment

Structural evolution of layered oxide cathodes for spent Li-ion batteries:degradation mechanism and repair strategy

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SusMat 2023年第3期3卷 362-378页

作者： Shan Jin Jianquan Liang Deying Mu Tianning Lin Yuyang Tian Jian Zhang YueWang Meng Chen Qingmo Shi Changsong Dai MIIT Key Laboratory of CriticalMaterials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbinChina State Grid Heilongjiang Electric Power Co. Ltd.Electric Power Research InstituteHarbinChina Dongying Cospower Technology Co. Ltd.DongyingChina

Sustainable development has long been recognized as one of the most critical issues in today’s energy and environment-conscious society.It has never been more urgent to recycle and reuse the end-of-life cathode materials.Here,this work systematically investigates the structure-critical degradation mechanism of polycrystalline LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)(NCM),combining experimental characterization and DFT simulations.Targeting the key degradation factors,a synergistic repair strategy based on deep mechanochemical activation and heat treatment was successfully proposed to direct regenerate the degradedNCMmaterial.Studies indicate the induction and promotion of synergistic repair technique on the reconstruction of particlemorphology,the recovery of the chemical composition and crystal structure,and the favorable transformation of the impurities phase in the failed materials.In particular,the synergistic repair process induces a gradient distribution of LiF and further enables partial fluorine doping into the NCM surface,forming abundant oxygen vacancies and increasing the content of highly reactive Ni2+.Benefiting from the comprehensive treatment for the multi-scale and multi-form degradation behaviors,the repaired material exhibits a capacity of 176.8 mA h g^(-1)at 0.1 C,which is comparable to the corresponding commercial material(172.8 mA h g^(-1)).The satisfactory capacity of the recovered cathode proves that it is an effective direct renovating strategy.

关键词： cathode material degradation mechanism impurity phase transformation spent lithium-ion batteries synergistic repair strategy

Preparation of Perovskite Solar Cells in the Air:degradation mechanism and Prospects on Large-Area Fabrication

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Chinese Journal of Chemistry 2023年第5期41卷 599-617页

作者： Shuaishuai Guo Kaikai Liu Li Rao Xiaotian Hu Yiwang Chen School of Physics and Materials Nanchang University999 Xuefu AvenueNanchangJiangxi 330031China College of Chemistry and Chemical Engineering/Institute of Polymers and Energy Chemistry Nanchang University999 Xuefu Avenue NanchangJiangxi330031China Peking University Yangtze Delta Institute of Optoelectronics NantongJiangsu 226010China National Engineering Research Centerfor Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministryof Education Jiangxi Normal University99 Ziyang VenueNanchangJiangxi 330022China

The preparation of perovskite solar cells(PsCs)in the air environment has attracted the attention of numerous experimenters due to its low preparation cost and the possibility of commercialization.Although the power conversion efficiency(PCE)of PSCs has increased rapidly and exceeded 25%,which is comparable to commercial polysilicon solar cells,most certified or reported high-efficiency perovskite solar cells are still confined to glove boxes or relatively small active areas in the air environment due to moisture,oxygen,high temperature,and ultraviolet(UV)factors.In this review.

关键词： Perovskite solar cells degradation mechanism Fabrication in the air Stability strategy Large-area fabrication Thin films Photooxidation

Performance degradation mechanism of lithium compounds ceramic fuel cell with GDC as electrolyte

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Carbon Resources Conversion 2023年第3期6卷 238-244页

作者： Kai Wei Rui Zhang Gang Chen Zhuo Chen Ruixin Dai Xiaohong Lv Shujiang Geng School of Metallurgy Northeastern UniversityShenyang 110819China Liaoning Key Laboratory for Metallurgical Sensor and Technology Northeastern UniversityShenyang 110819China

The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.

关键词： Ceramic fuel cell Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2) degradation mechanism Lithium compound molten salt Dynamic migration

Simultaneous acceleration of sulfur reduction and oxidation on bifunctional electrocatalytic electrodes for quasi-solid-state Zn–S batteries

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Science China Chemistry 2024年第5期67卷 1531-1538页

作者： Mingli Wang Hong Zhang Tianhang Ding Fangjun Wu Lin Fu Bin Song Pengfei Cao Ke Lu Institutes of Physical Science and Information Technology School of Materials Science and EngineeringKey Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationAnhui UniversityHefei 230601China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China School of Chemistry and Chemical Engineering Harbin Institute of TechnologyHarbin 150001China School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China Institute of Functional Nano&Soft Materials(FUNSOM) Soochow UniversitySuzhou 215123China State Key Lab of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

The incomplete sulfur reduction and high ZnS re-oxidation energy barrier along with severe side reactions during the battery cycling compromise the practical application of Zn–S electrochemistry. Herein, a bifunctional electrocatalytic sulfur matrix that simultaneously accelerates the sulfur reduction and ZnS oxidation is proposed to realize a highly-efficient Zn–S cell. It is revealed that the N-heteroatom hotspots are more favorable for facilitating the conversion of S to ZnS while the CoO nanocrystal substantially lowers the ZnS activation energy barrier thereby suppressing the formation of disproportionation species(e.g.,SO_(4)^(2-)) and accumulation of inactive ZnS. Accordingly, the Co O anchored on the N-doped carbon-supported sulfur cathode delivers a high Zn^(2+)storage capacity of 1,172 m Ahg^(-1)and outstanding cycling stability with a capacity retention of 71.6% after500 cycles with a high average Coulombic efficiency of 97.8%. Simultaneously, the stable cycling of solid-state Zn–S pouch cells with an energy density of 585 Whkg^(-1)sulfuris also demonstrated. Moreover, the postmortem analysis reveals that the degradation of Zn–S cells is mainly attributed to the limited reversibility of Zn anodes rather than the ZnS decomposition and/or accumulation. The approach to the bidirectional catalysis manipulated the sulfur redox provides a new perspective to realize the theoretical potentials of Zn–S cells.

关键词： Zn–S battery bifunctional catalysts solid-state battery sulfur redox degradation mechanism

Development of MoS_(2)-stainless steel catalyst by 3D printing for efficient destruction of organics via peroxymonosulfate activation

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Journal of Environmental Sciences 2024年第1期135卷 108-117页

作者： Yufeng Liu Jianhui Xu Xin Fu Pengxu Wang Dan Li Yunfei Zhang Shenggui Chen Chunhui Zhang Peng Liu School of Environment and Civil Engineering Dongguan University of TechnologyDongguan 523808China School of Art and Design Guangzhou Panyu PolytechnicGuangzhou 511483China Dongguan Institute of Science and Technology Innovation Dongguan University of TechnologyDongguan 523808China School of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China

Herein,a novel MoS_(2)-stainless steel composite material was first synthetized via a 3D printing method(3DP MoS_(2)-SS)for peroxymonosulfate(PMS)activation and organics degradation.Compared with MoS_(2)-SS powder/PMS system(0.37 g/(m^(2)/min)),4.3-fold higher k_(FLO)/S_(BET)value was obtained in 3DP MoS_(2)-SS/PMS system(1.60 g/(m^(2)/min),resulting from the superior utilization of active sites.We observed that 3DP MoS_(2)-SS significantly outperformed the 3DP SS due to the enhanced electron transfer rate and increased active sites.Moreover,Mo^(4+)facilitated the Fe^(2+)/Fe^(3+)cycle,resulting in the rapid degradation of florfenicol(FLO).Quenching experiments and electron paramagnetic resonance spectra indicated that·OH,SO_(4)·^(-),O_(2)·^(-)and^(1)O_(2)were involved in the degradation of FLO.The effect of influencing factors on the degradation of FLO were evaluated,and the optimized degradation efficiency of 98.69%was achieved at 1 mM PMS and pH of 3.0.Six degradation products were detected by UPLC/MS analyses and several possible degradation pathways were proposed to be the cleavage of C-N bonds,dechlorination,hydrolysis,defluorination and hydroxylation.In addition,3DP MoS_(2)-SS/PMS system also demonstrated superior degradation performance for 2-chlorophenol,acetaminophen,ibuprofen and carbamazepine.This study provided deep insights into the MoS_(2)-SS catalyst prepared by 3DP technology for PMS activation and FLO-polluted water treatment.

关键词： 3D printing Stainless steel MoS_(2) Peroxymonosulfate activation degradation mechanism

degradation mechanism of two-dimensional electron gas density in high Al-content AlGaN/GaN heterostructures

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Chinese Physics B 2009年第7期18卷 2998-3001页

作者：张进成郑鹏天张娟许志豪郝跃 Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

This paper finds that the two-dimensional electron gas density in high Al-content A1GaN/GaN heterostructures exhibits an obvious time-dependent degradation after the epitaxial growth. The degradation mechanism was investigated in depth using Hall effect measurements,high resolution x-ray diffraction,scanning electron microscopy,x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy.The results reveal that the formation of surface oxide is the main reason for the degradation,and the surface oxidation always occurs within the surface hexagonal defects for high Al-content AlGaN/GaN heterostructures.

关键词： degradation mechanism two-dimensional electron gas AlGaN/GaN heterostructures,surface oxidation

Investigation into charge carrier dynamics in organic light-emitting diodes

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Nano Research Energy 2024年第2期3卷 39-46页

作者： Dong-Guang Zheng Hyeon-Dong Lee Gyeong Won Lee Dong-Soo Shin Jeongwon Kim Jong-In Shim Zhiqun Lin Tae-Woo Lee Dong Ha Kim Information Engineering College Hangzhou Dianzi UniversityHangzhou 311305China Department of Materials Science and Engineering Seoul National University1 Gwanak-roGwanak-guSeoul 08826Republic of Korea Department of Photonics and Nanoelectronics Hanyang University ERICA55 Hanyangdeahak-roSangnok-guAnsanGyeonggi 15588Republic of Korea Department of Chemistry and Nanoscience Ewha Womans University52Ewhayeodae-gilSeodaemun-guSeoul 03760Republic of Korea Department of Chemical and Biomolecular Engineering National University of Singapore4 Engineering Drive 4Singapore 117585Singapore School of Chemical and Biological Engineering Institute of Engineering ResearchResearch Institute of Advanced MaterialsSoft FoundrySeoul National University1 Gwanak-roGwanak-guSeoul 08826Republic of Korea Basic Sciences Research Institute(Priority Research Institute) Ewha Womans UniversitySeoul 03760Republic of Korea Nanobio∙Energy Materials Center(National Research Facilities and Equipment Center) Ewha Womans UniversitySeoul 03760Republic of Korea

Organic light-emitting diodes(OLEDs)have demonstrated remarkable advancements in both device lifetime and luminous efficiency.However,insufficient operation lifetime due to device degradation remains a major hurdle,especially for brighter devices.Understanding the degradation mechanisms of OLEDs due to the degradation of functional materials and the formation of defects in device architectures continues to be a significant challenge.Herein,we evaluate the degradation characteristics by scrutinizing the electrical and optical properties,as well as analyzing the charge carrier dynamics in pristine and aged states of phosphorescent OLEDs(PhOLEDs).We show that degradation mechanisms in PhOLEDs can be elucidated in terms of the ideality factors of current and luminance in pristine and aged device states.The consistent shifts in distinct ideality factors across various states points out that the device degradation is attributed to the deterioration of the guest material,i.***.green-light-emitting phosphorescent material.Conversely,the incongruity in ideality factor changes between the two states indicates that the degradation results from the deterioration of non-light-emitting material.Subsequent characterization experiments provide further evidence that this degradation is primarily attributed to the deterioration of CBP-host material.The thorough understanding of degradation mechanisms established in this study can contribute to realizing the highly reliable PhOLEDs with a long lifetime.

关键词： organic light-emitting diodes ideality factor carrier transport processes degradation mechanism