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Pr doped single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)cathode enables high rate capability and cycle stability for lithium ion batteries

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Journal of Materiomics 2023年第1期9卷 82-89页

作者： Xiaopei Zhu Han Yu Lina Cheng Feifei Xu Zilu Wang Li-Zhen Fan Key Laboratory of new Energy materials and Technologies Institute of Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China tianjin guoan mengguli new materials science&technology limit corporation Tianjin301811China Beijing mengguli new materials science&technology Co. LtdBeijing102200China

The massive application of single crystal(SC)ternary cathode material LiNi_(1-x-y)Mn_(x)Co_(y)O_(2)is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+diffusion and structural instability.Herein,Pr^(3+),a large radius ion is introduced to single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)to enhance Li^(+)conductivity and structural stability.With 0.4%Pr doping,the Li(Ni_(0.5)Mn_(0.3)Co_(0.2))_(0.996)Pr_(0.004)O_(2)cathode displays a capacity retention of 79.72%at 10 C,and a 98.17%capacity retention after 50 cycles at 25°C and 96.3%capacity retention after 50 cycles at 55°C within a 3.0–4.5 V voltage window.Electrochemical impedance spectroscopy confirms that the Pr doping can effectively lower the charge-transfer resistance and facilitate the transportation of Li^(+)on the surface of LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2).The Direct current internal resistance result implies that the structure of the Pr-doped cathode particles is more stable during cycling.In addition,differential scanning calorimetry measurements measurement combined with in situ X-ray diffraction confirms the thermo-stabilization effect of the Pr dopant.

关键词： Single-crystal cathode material Pr doping Rate capability Safety Lithium-ion battery

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Critical rate capability barrier by the(001)microtexture of a singlecrystal cathode for long lifetime lithium-ion batteries

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Journal of Materiomics 2022年第3期8卷 649-655页

作者： Xiaopei Zhu Lina Cheng Han Yu Feifei Xu Wei Wei Li-Zhen Fan Key Laboratory of new Energy materials and Technologies Institute of Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China tianjin guoan mengguli new materials science&technology limit corporation Tianjin301811China CITIC guoan mengguli Power Sources technology limit corporation Beijing102200China

In practical pouch cell,LiNi0.5Mn0.3Co0.2O2/artificial graphite lithium ion battery using single-crystal LiNi0.5Mn0.3Co0.2O2(S-NMC532)as cathode can have excellent cycle performance.However,singlecrystal LiNi0.5Mn0.3Co0.2O2 inevitably suffers poor rate capability compared to the polycrystalline materials.Here,we systematically studied the relationship between microstructural characteristics and the practical rate performance,as well as explored the impedance change during the cycling process in the pouch cell.This work shows that the(001)plane microtexture of the electrode surface structure is a critical barrier for rate capability.Electron backscatter diffraction(EBSD),electrochemical impedance spectroscopy(EIS)and distribution of relaxation times(DRT)are conducted on the cathodes.These analyses allow to conclude on the influence of the(001)plane microtexture on the electrode surface,which illustrates a diffusion resistance of lithium ions,and then,leading a high interfacial resistance.Thus,this work confirms the main cause of the inferior rate capability of S-NMC532 and offers guidance for developing a battery with high rate and ultralong cycling life.

关键词： Lithium-ion batteries Single-crystal Failure mechanism Crystal orientation Microtexture

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A Mode-switching Strategy of Droop Control for VSC-MTDC Systems Considering Maximum DC Voltage Regulation Capability

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 903-912页

作者： Yizhen Wang Fengliang Qiu Zhongguan Wang Yirun Ji Zhengguang Chen Chengshan Wang Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China Electric Power Research Institute of State Grid JiBei Electric Power Co.Ltd. Beijing 100045China State Grid corporation of China Beijing 100031China IEEE

To achieve the goal of carbon neutrality,renewable energy integration through a voltage source converter based multi-terminal direct current(VSC-MTDC)system has been identified as a promising solution.To tackle the significant DC voltage over-limit problem in a VSC-MTDC system during disturbances,this paper proposes a mode-switching strategy of droop control considering maximum DC voltage regulation capability.The close relationship between node injection powers and node DC voltages in the MTDC system is elaborated,and the most effective regulation approach of local injection power for limiting DC voltage deviation is presented.The operating point trajectories of different droop control explains that the DC voltage deviation can be minimized by fully utilizing the capacity of converters.Therefore,the mode-switching strategy with the maximum DC voltage regulation capability is realized by the switching between the voltage droop control and the constant maximum power control.In addition,a mode recovery process and a smooth switching method are developed to make converters regain the capability of maintaining DC voltage and reduce power fluctuation during mode switching,respectively.Furthermore,three cases are investigated to verify the effectiveness of the proposed mode-switching strategy.Compared with simulation results of the conventional droop control and the DC voltage deviation-dependent droop control,better performance of transient and steady-state DC voltage deviation is achieved through the proposed strategy.

关键词： Droop control maximum DC voltage regulation capability mode-switching VSC-MTDC

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Adaptive Reference Power Based Voltage Droop Control for VSC-MTDC Systems

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Journal of Modern Power Systems and Clean Energy 2023年第1期11卷 381-388页

作者： Yizhen Wang Fengliang Qiu Guowei Liu Ming Lei Chao Yang Chengshan Wang Key Laboratory of Smart Grid of Ministry of Education Key Laboratory of Smart Energy&Information Technology of Tianjin MunicipalityTianjin 300072China Shenzhen Power Supply Bureau Co. Ltd.Shenzhen 518001China Sichuan Energy Internet Research Institution Tsinghua UniversityChengdu 610213China IEEE

Featuring low communication requirements and high reliability,the voltage droop control method is widely adopted in the voltage source converter based multi-terminal direct current(VSC-MTDC)system for autonomous DC voltage regulation and power-sharing.However,the traditional voltage droop control method with fixed droop gain is criticized for over-limit DC voltage deviation in case of large power disturbances,which can threaten stable operation of the entire VSCMTDC system.To tackle this problem,this paper proposes an adaptive reference power based voltage droop control method,which changes the reference power to compensate the power deviation for droop-controlled voltage source converters(VSCs).Besides retaining the merits of the traditional voltage droop control method,both DC voltage deviation reduction and power distribution improvement can be achieved by utilizing local information and a specific control factor in the proposed method.Basic principles and key features of the proposed method are described.Detailed analyses on the effects of the control factor on DC voltage deviation and imbalanced power-sharing are discussed,and the selection principle of the control factor is proposed.Finally,the effectiveness of the proposed method is validated by the simulations on a five-terminal VSC based high-voltage direct current(VSC-HVDC)system.

关键词： DC voltage deviation power-sharing reference power voltage droop control voltage source converter(VSC) multi-terminal direct current(MTDC)

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板边离缝对桥上CRTSⅢ型板式无砟轨道动力特性的影响

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Journal of Central South University 2022年第8期29卷 2665-2674页

作者：闫斌程瑞琦潘文彬谢浩然付贺鑫 School of Civil Engineering Central South UniversityChangsha 410075China China Railway Design corporation Tianjin 300308China

CRTSⅢ型板式无砟轨道结构中的自密实混凝土层损伤会致使轨道板部分脱空,进而影响列车行驶的舒适性、安全性以及轨道板和桥梁结构的耐久性。为研究板边离缝对桥上CRTSⅢ型板式无砟轨道系统动力响应的影响,基于多体动力学理论,利用ANSYS+... 详细信息

CRTSⅢ型板式无砟轨道结构中的自密实混凝土层损伤会致使轨道板部分脱空,进而影响列车行驶的舒适性、安全性以及轨道板和桥梁结构的耐久性。为研究板边离缝对桥上CRTSⅢ型板式无砟轨道系统动力响应的影响,基于多体动力学理论,利用ANSYS+SIMPACK联合仿真,建立了考虑墩台纵向支座刚度、轨道结构及层间接触特性的列车-轨道-桥梁一体化动力仿真模型,分析了不同离缝宽度、长度以及离缝位置工况下系统的动力特性,并归纳了板边离缝的长度和宽度的限值。研究表明:在自密实混凝土没有沿轨道板横向完全脱空时,板边离缝对列车-轨道-桥梁系统动力特性的影响不大。当自密实混凝土沿轨道板横向完全脱空时,在离缝长度超过1 m后,系统动力响应变化幅度增大。当离缝长度达到1.6 m时,轮重减载率达到0.769,超过限值,威胁列车行驶的安全性;当轨道板竖向加速度增幅达到250.1%的,将影响轨道系统的使用寿命。

关键词：高速铁路铁路桥梁无砟轨道板边离缝动力特性有限元

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3D Identification and Stability Analysis of Key Surface Blocks of Rock Slope

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Transactions of tianjin University 2016年第4期22卷 317-323页

作者：李明超周四宝王刚 State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Chengdu Engineering corporation limited Power China

Complicated geological structures make it difficult to analyze the stability of rock slopes, such as faults, weak intercalated layers or joint fissures. Based on 3D geological modeling and surface block identifying methods, an integrated methodology framework was proposed and realized to analyze the stability of surface blocks in rock slopes. The surface blocks cut by geological structures, fissures or free faces could be identified subjected to the four principles of closure, completeness, uniqueness and validity. The factor of safety(FOS)of single key block was calculated by the limit equilibrium method. If there were two or more connected blocks, they were defined as a block-group. The FOS of a block-group was computed by the Sarma method. The proposed approach was applied to an actual rock slope of a hydropower project, and some possible instable blocks were demonstrated and analyzed visually. The obtained results on the key blocks or block-groups provide essential information for determining potential instable region of rock slopes and designing effective support scheme in advance.

关键词： rock slope 3D model surface block block-group stability factor of safety(FOS)

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Set-Membership Filtering for Uncertain Systems with Censored Measurements under Weighted Try-Once-Discard Protocol

Set-Membership Filtering for Uncertain Systems with Censored...

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第37届中国控制会议

作者： Xuerong Li Hongli Dong Fei Han Qinjiang Sun Jiahui Li Institute of Complex Systems and Advanced Control Northeast Petroleum University Heilongjiang Provincial Key Laboratory of Networking and Intelligent Control Northeast Petroleum University tianjin Branch China National Offshore Oil Corporation Company Limited

In this paper, the set-membership filtering problem is investigated for a class of time-varying uncertain systems with censored measurements under Weighted Try-Once-Discard（WTOD） protocol. The system uncertainties are formulated by the norm-bounded conditions. The well-known Tobit Type I model is employed to formulate the censored measurements, which is caused by occlusion region, limit-of-detection or sensor faults. An indicator variable is introduced to obtain a unified form in order to address the censored nonlinearity. The WTOD protocol is designed to prevent data conflicts, under which only one node is allowed to transmit data at each instant. Via the mathematical induction, the existence condition of the set-membership filter is derived in terms of a set of recursive linear matrix inequalities, which can guarantee that the filtering error dynamics satisfies the given ellipsoid constraint. Then, the parameters of the filter can be obtained by using the convex optimization method, and the corresponding ellipsoid parameters are optimized. Finally, a simulation example is given to illustrate the effectiveness of the proposed methods.

关键词： Set-membership Filtering Weighted Try-Once-Discard Protocol Uncertain Systems Censored Measurements

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