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Enhancing anchoring and catalytic conversion of polysulfides by nitrogen deficient cobalt nitride for advanced lithium-sulfur batteries

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Journal of Energy Chemistry 2022年第10期31卷 407-415,I0010页

作者： Min Luo Yu Bai Rui sun Meixiu Qu Mengyuan Wang Zhanfeng Yang Zhenhua Wang Wang sun kening sun Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

While lithium-sulfur(Li-S)battery has attracted remarkable attention owing to the high theoretical capacity,its practical application is still hindered by the shuttle and sluggish conversion kinetics of intermediate lithium polysulfides(Li PSs).Defect engineering,which can regulate the electronic structure and in turn influence the surface adsorption and catalytic capability,has been regarded as a feasible strategy to deal with the above challenges.However,few studies on nitrogen vacancies and their mechanisms are reported.Herein,cobalt nitride with nitrogen vacancies grown on multi-walled carbon nanotube(CNTCo N-VN)is designed and applied as the separator modification material to investigate the enhancing mechanism of nitrogen vacancies on Li-S batteries.The experimental evidence and theoretical calculation indicate that the introduction of nitrogen vacancies into cobalt nitride can enhance the chemical affinity to Li PSs and effectively hamper the shuttle effect.Meanwhile the reduced band gap of the d-band center of Co and p-band center of N for CNT-Co N-VNand the promoted diffusion of Li^(+) can expedite the solid-liquid and liquid-liquid conversions of sulfur species.Due to these superiorities,the cell with CNT-Co NVNmodified separator delivers a favorable initial capacity of 901 m Ah g^(-1)and a capacity of 660 m Ah g^(-1)can be achieved after 250 cycles at 2 C.This work explores the application of metal nitride with nitrogen vacancies and sheds light on the development of functional separators for high-efficient Li-S batteries.

关键词： Cobalt nitride Nitrogen vacancy Redox kinetics Separators Li-S batteries

Nanoscale transition metal catalysts anchored on perovskite oxide enabling enhanced kinetics of lithium polysulfide redox in lithium-sulfur batteries

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能源化学:英文版 2023年第6期81卷 432-442,I0010页

作者： Wenshuo Hou Ruilong Li Zhenhua Wang Li Fang Zhe Bai Tan Wang Yu Bai kening sun Beijing Key Laboratory of Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.

关键词： Nanoscale transition metal Lithium polysulfide Catalytic activity Redox reaction Lithium-sulfur battery

Sn and Y co-doped BaCo_(0.6)Fe_(0.4)O_(3)-δcathodes with enhanced oxygen reduction activity and CO_(2) tolerance for solid oxide fuel cells

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Chinese Chemical Letters 2022年第5期33卷 2658-2662页

作者： Nan Han Rongzheng Ren Minjian Ma Chunming Xu Jinshuo Qiao Wang sun kening sun Zhenhua Wang Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Applying mixed oxygen ionic and electronic conducting(MIEC)oxides as the cathode offers a promis-ing solution to enhance the performance of solid oxide fuel cells(SOFCs).However,the phase instability in CO_(2)-containing air and sluggish oxygen reduction activity of MIEC cathodes remain a long-term chal-lenge for optimizing the electrochemical performance of SOFCs.Herein,a heterovalent co-doping strategy is proposed to enhance the oxygen reduction activity and CO_(2)tolerance of SOFCs cathodes,which can be demonstrated by developing a novel BaCo_(0.6)Fe_(0.4)O_(3)-δ(BCF)-based MIEC oxide,BaCo_(0.6)Fe_(0.2)Sn_(0.1) Y_(0.1)O_(3-δ)(BCFSY).In addition to improving the stability of BCF-based perovskites,this strategy achieves an opti-mized balance of ionic mobility and oxygen vacancies due to the synergies between the effects of the co-dopants.Compared with single-doped materials,BCFSY exhibits improved CO_(2)tolerance and consider-ably higher ORR activity,which is reflected in a significantly lower polarization resistance of 0.15Ωcm^(2) at 600℃.The results of this work provide an efficient tactic for designing electrode materials for SOFCs.

关键词： Solid oxide fuel cells Cathode Heterovalent co-doping Oxygen ion conduction Oxygen vacancy formation

A homogeneous and mechanically stable artificial diffusion layer using rigid-flexible hybrid polymer for high-performance lithium metal batteries

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Journal of Energy Chemistry 2023年第1期76卷 631-638,I0015页

作者： Zhenkang Lin Yuyan Ma Wei Wang Yu He Menghao Wang Jun Tang Cheng Fan kening sun Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Artificial solid electrolyte interphase(SEI) is promising to inhibit uncontrollable lithium dendrites and enable long cycling stability for lithium metal batteries. However, the essential mechanical stability is limited since organic layers generally have low modulus whereas intrinsic brittleness for inorganic ones remains a great concern. Polymer-based SEIs with rigid and flexible chains in adequate mechanical properties are supposed to address this issue. Herein, a homogeneous and mechanically stable diffusion layer is achieved by blending rigid chains of polyphenylene sulfone(PPSU) with flexible chains of poly(vinylidene fluoride)(PVDF) in a hybrid membrane, enabling uniform diffusion and stabilizing the lithium metal anode. The Li||Cu cell with the protected electrode exhibits a long lifetime more than 450 cycles(0.5 m A cm^(-2), 1.0 m A h cm^(-2))(fourfold longer than the control group) with higher average Coulombic efficiency of 98.7%. Enhanced performances are also observed at Li||Li and full cell configurations. The improved performances are attributed to the controlled morphology and stable interphase, according to scanning electron microscopy(SEM) and electrochemical impedance. This research advances the idea of uniform lithium plating and provides a new insight on how to create a homogeneous and mechanically stable diffusion layer using rigid-flexible polymers.

关键词： Lithium metal battery Lithium dendrite Uniform diffusion Rigid-flexible artificial layer Electrochemical impedance

High-entropy perovskite oxide BaCo_(0.2)Fe_(0.2)Zr_(0.2)Sn_(0.2)Pr_(0.2)O_(3-δ) with triple conduction for the air electrode of reversible protonic ceramic cells

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Chinese Chemical Letters 2023年第7期34卷 298-302页

作者： Jiaxiang sun Rongzheng Ren Hualiang Yue Wencan Cui Gaige Wang Chunming Xu Jinshuo Qiao Wang sun kening sun Zhenhua Wang Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of Technology.Beijing100081China

Reversible protonic ceramic cells(RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stability of air electrodes exposed to concentrated vapor under operating conditions. Herein, we report a high-entropy air electrode with the composition BaCo_(0.2)Fe_(0.2)Zr_(0.2)Sn_(0.2)Pr_(0.2)O_(3-δ)(BCFZSP), which shows integrated electronic, protonic and oxygenic conduction in a single perovskite phase and excellent structural stability in concentrated steam. Such triple conduction can spread the electrochemically active sites of the air electrode to the overall electrode surface, thus optimizing the kinetics of the oxygen reduction and evolution reactions(0.448 Ω cm^(2) of polarization resistance at 550℃). As-prepared RPCCs with a BCFZSP air electrode at 600℃ achieved a peak power density of 0.68 W/cm^(2) in fuel-cell mode and a current density of 0.92 A/cm^(2) under a 1.3 V applied voltage in electrolysis mode. More importantly, the RPCCs demonstrate an encouragingly high stability during 120 h of reversible switching between the fuelcell and electrolysis modes. Given their excellent performance, high-entropy perovskites can be promising electrode materials for RPCCs.

关键词： High-entropy perovskite oxide Triple-conducting oxide Air electrode Reversible protonic ceramic cells Hydrogen production

Upgrading Siberian(Russia) crude oil by hydrodesulfurization: Kinetic parameter estimation in a trickle-bed reactor

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Chinese Journal of Chemical Engineering 2021年第1期34卷 212-220页

作者： kening sun Xixi Ma Ruijun Hou Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Hydrodesulfurization(HDS) of sour crude oil is an effective way to address the corrosion problems in refineries and is an economic way to process sour crude oil in an existing refinery built for sweet oil.Siberian crude oil transported through the Russia-China pipeline could be greatly sweetened and could be refined directly in local refinery designed for Daqing crude oil after the effective HDS treatment.In this study,the HDS of Siberian crude oil was carried out in a continuous flow isothermal trickle-bed reactor over Ni-Mo/γ-Al_2 O_(3).The effects of temperature,pressure and LHSV were investigated in the ranges of 320-360℃,3-5 MPa and 0.5-2 h^(-1),keeping constant hydrogen to oil ratio at 600 L·L^(-1).The HDS conversion could be up to 92.89% at the temperature of 360℃, pressure of 5 MPa,and LHSV of 0.5 h^(-1), which is sufficient for local refineries(>84%).A three phase heterogeneous model was established to analyze the performance of the trickle-bed reactor based on the two-film theory using Langmuir-Hinshelwood mechanism.The order of sulfur component is estimated as 1.28,and the order of hydrogen is 0.39.By simulating the reactor using the established model,the concentration of H_(2), H_(2) S and sulfur along the catalyst bed is discussed.The model is significantly useful for industrial application with respect to reactor analysis,optimization and reactor design,and can provide further insight of the HDS of Siberian crude oil.

关键词： HDS Trickle-bed reactor Heterogeneous model Kinetics Siberian crude oil

微氧化MXene/MoS_(2)复合膜分离净化效能及稳定性增强机制研究

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北京理工大学学报 2024年第2期44卷 210-218页

作者：刘婷蔡微翼李瑶孙克宁北京理工大学化学与化工学院化学电源与绿色催化北京市重点实验室北京100081

二维纳米材料由于优异的理化性质和易于调控的特点,在新型膜材料的开发与应用中受到了广泛关注.基于二维材料层层堆叠可以制备二维膜,而如何对二维膜进行结构性能上的改进是目前该领域聚焦的前沿问题.MXene膜是一种新型二维膜,在分离净... 详细信息

二维纳米材料由于优异的理化性质和易于调控的特点,在新型膜材料的开发与应用中受到了广泛关注.基于二维材料层层堆叠可以制备二维膜,而如何对二维膜进行结构性能上的改进是目前该领域聚焦的前沿问题.MXene膜是一种新型二维膜,在分离净化领域具有较大应用潜力.然而,目前MXene膜的分离净化效能主要受到膜的结构稳定性和改性方法的限制.本研究采用了通过异质纳米材料MoS_(2)插层,随后进行温和且快速预氧化,可获得稳定的纳米层状结构,从而得到一种MXene(Ti_(3)C_(2)Tx)/MoS_(2)高性能复合膜.MXene/MoS_(2)复合膜的水通量显著提高,对目标污染物染料的去除率高达99.9%.与未氧化的MXene膜相比,复合膜对NaCl和MgCl_(2)的渗透抑制效率分别提高了48.4%和82.0%.此外,复合膜在结构/外观和通量方面表现出长期的稳定性.因此,利用预氧化/插层法制备的复合膜对MXene膜结构调控和性能优化提供了新策略和新思路.

关键词：二维膜 MXene MoS_(2) 分离净化稳定性

Progress and challenges of carbon-fueled solid oxide fuel cells anode

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Journal of Energy Chemistry 2021年第5期30卷 209-222页

作者： Minjian Ma Xiaoxia Yang Jinshuo Qiao Wang sun Zhenhua Wang kening sun Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Carbon-fueled solid oxide fuel cells(CF-SOFCs)can electrochemically convert the chemical energy in carbon into electricity,which demonstrate both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells.However,using solid carbon as the fuel of SOFCs also faces some challenges,the fluid mobility and reactive activity of carbon-based fuels are much lower than those of gaseous fuels.Therefore,the anode reaction kinetics plays a crucial role in determining the electrochemical performance of CF-SOFCs.Herein,the progress of various anodes in CF-SOFCs is reviewed from the perspective of material compositions,electrochemical performance and microstructures.Challenges faced in developing high performance anodes for CF-SOFCs are also discussed.

关键词： Carbon Anodes Solid oxide fuel cells Energy conversion Reaction processes

GPCR activation:protonation and membrane potential

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Protein & Cell 2013年第10期4卷 747-760页

作者： Xuejun C.Zhang kening sun Laixing Zhang Xuemei Li Can Cao National Laboratory of Macromolecules National Center for Protein Science-BeijingInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China

GPCR proteins represent the largest family of signaling membrane proteins in eukaryotic cells.Their importance to basic cell biology,human diseases,and pharma-ceutical interventions is well established.Many crystal structures of GPCR proteins have been reported in both active and inactive conformations.These data indicate that agonist binding alone is not suffi cient to trigger the conformational change of GPCRs necessary for binding of downstream G-proteins,yet other essential factors re-main elusive.Based on analysis of available GPCR crystal structures,we identifi ed a potential conformational switch around the conserved Asp2.50,which consistently shows distinct conformations between inactive and active states.Combining the structural information with the current literature,we propose an energy-coupling mechanism,in which the interaction between a charge change of the GPCR protein and the membrane potential of the living cell plays a key role for GPCR activation.

关键词： GPCR membrane potential protonation ac-tivation