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Suppressed Internal Intrinsic Stress Engineering in High-Performance Ni-Rich Cathode Via Multi layered In Situ Coating Structure

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Energy & Environmental Materials 2024年第2期7卷 58-66页

作者： Jiachao Yang Yunjiao Li xiaoming xi Junchao Zheng Jian Yu Zhenjiang He School of Metallurgy and Environment Central South UniversityChangsha 410083China Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083China Changsha Research Institute of Mining and Metallurgy Changsha 410083China Ningbo Ronbay New Energy Technol Co Ltd Tanjialing East Rd 39Ningbo 315400China

LiNi_(x)Co_(y)Al_(z)O_(2)(NCA)cathode materials are drawing widespread attention,but the huge gap between the ideal and present cyclic stability still hinders their further commercial application,especially for the Ni-rich LiNi_(x)Co_(y)Al_(z)O_(2)(x>0.8,x+y+z=1)cathode material,which is owing to the structural degradation and particles'intrinsic *** tackle the problems,Li_(0.5)La_(2)Al_(0.5)O_(4)in situ coated and Mn compensating doped multilayer LiNi_(0.82)Co_(0.14)Al_(0.04)O_(2)was *** refinement indicates that La-Mn co-modifying could realize appropriate Li/Ni disorder *** results and in situ XRD patterns reveal that the LLAO coating layer could effectively restrain crack in secondary particles benefited from the suppressed internal *** further improves as NCA-LM2 has superior mechanical *** SEM,TEM,XPS tests indicate that the cycled cathode with LLAO-Mn modification displays a more complete morphology and less side reaction with *** was used to further investigate cathode-electrolyte interface which was reflected by gas ***-LM2 releases less CO_(2)than NCA-P indexing on a more stable *** modified material presents outstanding capacity retention of 96.2%after 100 cycles in the voltage range of 3.0-4.4 V at 1C,13%higher than that of the pristine and 80.8%at 1 C after 300 *** excellent electrochemical performance could be attributed to the fact that the high chemically stable coating layer of Li_(0.5)La_(2)Al_(0.5)O_(4)(LLAO)could enhance the interface and the Mn doping layer could suppress the influence of the lattice mismatch and *** believe that it can be a useful strategy for the modification of Ni-rich cathode material and other advanced functional material.

关键词： compensating doped in situ coating multilayer material Ni-rich cathode materials suppressed internal strain

Difficulty-aware prior-guided hierarchical network for adaptive segmentation of breast tumors

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Science China(Information Sciences) 2023年第2期66卷 127-141页

作者： Sumaira HUSSAIN xiaoming xi Inam ULLAH Syeda Wajiha NAIM Kashif SHAHEED Cuihuan TIAN Yilong YIN School of Software Engineering Shandong University Department of Computer Science Sindh Madressatul Islam University School of Computer Science and Technology Shandong Jianzhu University School of Computer Science and Engineering South China University of Technology School of Medicine Shandong University Health Management Center Qilu Hospital of Shandong University

Breast tumor segmentation is vital to tumor detection at the early stages. Deep learning methods are typically used in automatic tumor segmentation tasks. However, in existing methods, the difference between pixels is disregarded, and the union network architecture is used to segment all pixels; these methods involve a tradeoff between accuracy and efficiency. A novel, difficulty-aware, prior-guided hierarchical network for the adaptive segmentation of breast tumors is presented herein. A difficulty prior learning module is proposed to learn the pixel’s difficulty prior to guild adaptive segmentation in the proposed network. To achieve a more accurate segmentation of hard pixels, a hard pixel processing unit is presented to learn more discriminative features for hard pixels. Experiments are conducted based on three datasets. The experimental results show that the proposed methods outperform traditional deep learning methods and achieve a balance between accuracy and efficiency.

关键词： breast tumor ultrasound image segmentation deep neural network difficulty-awareness

Structural self-reconstruction strategy empowering Ni-rich layered cathodes with low-strain for superior cyclabilities

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Nano Research 2023年第4期16卷 4950-4960页

作者： Zhouliang Tan Yunjiao Li xiaoming xi Shijie Jiang xiaohui Li xingjie Shen Panpan Zhang Zhenjiang He School of Metallurgy and Environment Central South UniversityChangsha 410083China Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083China Changsha Research Institute of Mining and Metallurgy Changsha 410083China Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000China

The key to hindering the commercial application of Ni-rich layered cathode is its severe structural and interface degradation during the undesired phase transition(hexagonal to hexagonal(H2→H3)),degenerating from the build-up of mechanical strain and undesired parasitic ***,a perovskite Li_(0.35)La_(0.55)TiO_(3)(LLTO)layer is built onto Ni-rich cathodes crystal to induce layered@spinel@perovskite heterostructure to solve the root cause of capacity *** exploration based on structure characterizations,in situ X-ray diffraction techniques,and first-principles calculations demonstrate that such a unique heterostructure not only can improve the ability of the host structure to withstand the mechanical strain but also provides fast diffusion channels for lithium ions as well as provides a protective barrier against electrolyte ***,the LLTO modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)cathode manifests an unexpected cyclability with an extremely high-capacity retention of≈94.6%after 100 cycles,which is superior to the pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(79.8%).Furthermore,this modified electrode also shows significantly enhanced cycling stability even withstanding a high cut-off voltage of 4.6 *** surface self-reconstruction strategy provides deep insight into the structure/interface engineering to synergistically stabilize structure stability and regulate the physicochemical properties of Ni-rich cathodes,which will also unlock a new perspective of surface interface engineering for layered cathode materials.

关键词： Ni-rich layered oxides cathode structural self-reconstruction phase transition mechanical strain first-principal calculation

External-to-internal synergistic strategy to enable multi-scale stabilization of LiCoO_(2)at high-voltage

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Journal of Energy Chemistry 2023年第1期76卷 516-527,I0013页

作者： Shuaipeng Hao Yunjiao Li Jiachao Yang Shan Wang Zhouliang Tan xiaoming xi Zhenjiang He Panpan Zhang School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of Mining and Metallurgy Changsha 410083HunanChina Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

High-voltage LiCoO_(2)(LCO)offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,LiCoO_(2)is subject to serious structural and interfacial degradation above voltages>4.55 V(***/Li^(+)).Herein,an in-situ Li_(6.25)La_(3)Zr_(2)A_(l0.25)O_(12)(LLZAO)layer is constructed on the LCO surface to achieve operating voltage at 4.6 *** detailed characterizations(ex-situ XRD,ex-situ Raman,DFT,etc.)reveal that the LLZAO layer greatly enhances Li+conductivity attributed to the ionconducting layer on the surface/interface,and closely combines with LiCoO_(2)particle to ensure stable cathode/electrolyte interface,thus suppressing the highly reactive Co^(4+)and O^(-)triggered surface side reactions at ***,the introduction of La^(3+)/Zr^(4+)/Al^(3+)with a larger ionic radius(La^(3+)/Zr^(4+)are larger than Co^(3+))and weaker electronegativity(La/Zr/Al are weaker than Co)into Co^(3+)sites readjusts the electron cloud density between Co–O–Li,which reinforces the Co–O bond and widens the band-center gap of Co 3d and O 2p,thus restraining the detrimental phase transition(from H3 to H1-3 phase)and the formation of Co_(3)O_(4)spinel phase(attributed to lattice oxygen release),subsequently alleviating the particle cracking and structural collapse during repeated Li^(+)de/***,after 100 cycles at 3.0–4.6 V,LCO@1.0LLZAO exhibits a superior discharge capacity of 188.5 m A h g^(-1),with a capacity retention of 85.1%.The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage.

关键词： LLZAO layer High-voltage LiCoO_(2) Irreversible phase transition Band-center gap Lattice oxygen release

Towards high-power mid-IR light source tunable from 3.8 to 4.5 µm by HBr-filled hollow-core silica fibres

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Light(Science & Applications) 2022年第1期11卷 101-113页

作者： Zhiyue Zhou Zefeng Wang Wei Huang Yulong Cui Hao Li Meng Wang xiaoming xi Shoufei Gao Yingying Wang College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China State Key Laboratory of Pulsed Power Laser Technology Changsha 410073China Hunan Provincial Key Laboratory of High Energy Laser Technology Changsha 410073China Institute of Photonics Technology Jinan UniversityGuangzhou 511443China

Fibre lasers operating at the mid-IR have attracted enormous interest due to the plethora of applications in defence,security,medicine,and so ***,no continuous-wave(CW)fibre lasers beyond 4μm based on rare-earth-doped fibres have been demonstrated thus ***,we report efficient mid-IR laser emission from HBr-filled silica hollow-core fibres(HCFs)for the first *** pumping with a self-developed thulium-doped fibre amplifier seeded by several diode lasers over the range of 1940–1983 nm,narrow linewidth mid-IR emission from 3810 to 4496 nm has been achieved with a maximum laser power of about 500 mW and a slope efficiency of approximately 18%.To the best of our knowledge,the wavelength of 4496 nm with strong absorption in silica-based fibres is the longest emission wavelength from a CW fibre laser,and the span of 686 nm is also the largest tuning range achieved to date for any CW fibre *** further reducing the HCF transmission loss,increasing the pump power,improving the coupling efficiency,and optimizing the fibre length together with the pressure,the laser efficiency and output power are expected to increase *** work opens new opportunities for broadly tunable high-power mid-IR fibre lasers,especially beyond 4μm.

关键词： tunable power amplifier

Designing and evaluating assessment and learning in adaptive learning systems

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语言测试与评价 2022年第1期 94-115,119,120页

作者： xi xiaoming Hong Kong Examinations and Assessment Authority

The recent emergence of adaptive language learning systems calls for conceptual work to guide the design of assessment and learning in an adaptive *** adaptive learning might have been touted as a universal cure for learning problems,many adaptive language learning systems fall short of educators’expectations,partly due to a lack of standards and best practices in this *** fill this gap,this paper proposes some major considerations in designing a high-quality assessment and learning experience in adaptive learning and ways to evaluate an adaptive learning *** architecture of adaptive learning is decomposed,with a chain of inferences supporting the overall efficacy of an adaptive learning system presented,including user property representation,user property estimation,content representation,user interaction representation,and user interaction impact.A detailed analysis of key validity issues is provided for each inference,which motivates the major considerations in designing and evaluating assessment and *** paper first provides an overview of different types of assessment used in adaptive learning and an analysis of the assessment approach,priorities,and design considerations of each to optimize its use in adaptive *** it proposes a framework for evaluating different aspects of an adaptive learning *** special connections are made to models,techniques,designs,and technologies specific to language learning and assessment,bringing more relevance to adaptive language learning *** establishing some guidelines on key aspects to evaluate and how to evaluate them,the work intends to bring more rigor to the field of adaptive language learning systems.

关键词： assessment adaptive learning evaluation framework efficacy validity

A novelty strategy induced pinning effect and defect structure in Ni-rich layered cathodes towards boosting its electrochemical performance

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Journal of Energy Chemistry 2022年第9期31卷 570-580,I0016页

作者： Zhouliang Tan Yunjiao Li xiaoming xi Shijie Jiang xiaohui Li xingjie Shen Panpan Zhang Zhenjiang He Junchao Zheng School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of Mining and Metallurgy Changsha 410083HunanChina Office of Laboratory and Equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

Layered Ni-rich transition metal oxide is treated as the most promising alternative cathode due to their high-capacity and flexible ***,the severe lattice strain and slow Li-ion migration kinetics severely restrict their practical ***,a novelty strategy induced pinning effect and defect structure in layered Ni-rich transition metal oxide cathodes is proposed via a facile cation(iron ion)/anion(polyanion)co-doping ***,the effects of pinning effect and defect structure on element valence state,crystal structure,morphology,lattice strain,and electrochemical performance during lithiation/delithiation are systematically *** detailed characterizations(soft X-ray absorption spectroscopy(sXAS),in-situ X-ray diffraction(XRD),etc.)and density functional theory(DFT)calculation demonstrate that the pinning effects built-in LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)materials by the dual-site occupation of iron ions on lithium and transition metal sites effectively alleviate the abrupt lattice strain caused by an unfavorable phase transition and the subsequent induction of defect structures in the Li layer can greatly reduce the lithium-ion diffusion ***,the modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)exhibits a high-capacity of 206.5 mAh g^(-1)and remarkably enhanced capacity retention of 93.9%after 100 cycles,far superior to~14.1%of the pristine ***,an excellent discharge capacity of 180.1 mAh g^(-1)at 10 C rate is maintained,illustrating its remarkable rate *** work reports a pinning effect and defect engineering method to suppress the lattice strain and alleviate lithium-ion kinetic barriers in the Ni-rich layered cathodes,providing a roadmap for understanding the fundamental mechanism of an intrinsic activity modulation and structural design of layered cathode materials.

关键词： Ni-rich layered cathode Pinning effect Defect structure Lattice strain Lithium-ion kinetic

Automated scoring and feedback systems： Where are we and where are we heading？

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英语考试研究 2011年第2期 51-57页

作者： xiaoming xi Educational Testing Service USA

Difficulty-aware bi-network with spatial attention constrained graph for axillary lymph node segmentation

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Science China(Information Sciences) 2022年第9期65卷 74-85页

作者： Qing XU xiaoming xi xianjing MENG Zheyun QIN xiushan NIE Yongjian WU Dongsheng ZHOU Yi QU Chenglong LI Yilong YIN School of Software Shandong University School of Computer Science and Technology Shandong Jianzhu University School of Computer Science and Technology Shandong University of Finance and Economics Shandong Provinvial Qianfoshan Hospital The First Hospital Affiliated with Shandong First Medical University Department of Geriatrics Qilu Hospital of Shandong University

Axillary lymph node(ALN) segmentation in ultrasound images is important for the diagnosis and treatment of breast cancer. Recently, deep learning methods for automatic medical image segmentation have improved significantly. However, two problems arise.(1) A unified model is often employed to segment all images without considering the difficulty diversity.(2) The relationship between elements in the learned class probability map is disregarded. To address these two issues, we propose a novel difficulty-aware binetwork with a spatial attention constrained graph. First, a difficulty grading module(DGM) is developed to learn the difficulty grade of input images. Based on the difficulty grade of images, a novel bi-network architecture is proposed to segment the image adaptively using different branches. In complex branches,a novel spatial attention module(SAM) and graph-based energy with spatial attention constraint are proposed. The learned spatial attention map can provide additional discriminative information. Moreover,the graph-based segmentation framework can capture the relationship between pixels, further improving the segmentation performance for complex images. We conducted an experiment on our ultrasound database using 216 cases. The overall dice similarity coefficient, Jaccard coefficient, volumetric overlap error, and false positive rate are 83.41%, 74.4%, 12.02%, and 13.36% for ALN segmentation, respectively. The comparison results demonstrated that the proposed method outperforms other deep learning methods.

关键词： ultrasound image axillary lymph nodes segmentation difficulty-aware segmentation graph with spatial attention