MnO/Nitrogen-doped graphene composite cathode for high performance lithium oxygen batteries

本文采用水热法制备了MnO/氮掺杂石墨烯复合材料. 作为非水锂空气电池的正极催化剂, 该复合材料表现出了优异的电化学性能以及循环稳定性.; 在充放电电流密度为0.05 mA cm~(-2)时, 其能量效率高达84.6%, 远高于目前文献所报道的非贵金属催化剂的能量效率,; 也超过了基于贵金属的催化剂. 其氧还原反应(ORR)和氧析出反应(OER)的过电势分别仅为0.11和0.41 V.; 扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果表明, 所制备的MnO纳米颗粒能够均匀地分散在氮掺杂石墨烯的表面.; 密度泛函理论(DFT)计算揭示, MnO(100)面是主要的催化活性面, 其理论ORR和OER的过电势分别仅为0.21与0.24 V,; 充放电电势差为0.45 V, 与实验结果0.52 V相当.MnO/nitrogen-doped graphene (MnO/NG) composite cathode was fabricated by; a facile one-pot method as cathode catalyst for non-aqueous lithium; oxygen batteries. It exhibited superior electrochemical performance with; higher round-trip efficiency and better cyclic stability. It showed a; high round-trip efficiency of 84.6% at the current density of 0.05 mA; cm~(-2) with the discharge and charge overpotentials of 0.11 and 0.41 V,; respectively. Through scanning electron microscopy, transmission; electron microscopy and X-ray photoelectron spectroscopy, it was; confirmed that MnO nanoparticles were homogeneously dispersed on NG; surface. The density functional theory calculations demonstrated that; the superior electrochemical performance of MnO/NG might be attribute to; the exposure of stoichiometric MnO (100) surface, with the ORR and OER; overpotential only to be 0.21 and 0.24 V, respectively. The; discharging-charging voltage gap is 0.45 V, in good agreement with the; experimental value of 0.52 V.国家重点基础研究发展计划; 国家自然科学基金; 国家基础科学人才培养基

Controlling Reversible Expansion of Li2O2 Formation and Decomposition by Modifying Electrolyte in Li-O2 Batteries

锂空电池分别使用空气中的氧气和金属锂作为正负极活性材料，具有极高的能量密度。但是，这一体系尚不能实现商业化的应用，其中一些关键问题未能解决。由于其正极活性材料是气体，使得电化学反应涉及气-液-固三相界面，电极过程十分复杂。与其它二次电池相比，空气电极需要考虑结构因素和催化因素。不仅要改善氧气电化学反应的动力学迟缓问题，还要考虑放电产物的驻留空间问题。董全峰教授课题组在前期开展了基于空气电极固相表面电催化研究，并结合电极结构方面的问题，构筑了有利于氧气发生反应的仿生开放式结构电极。 该研究工作主要由化学化工学院2015级iChEM直博生林晓东（第一作者）在董全峰教授、郑明森副教授和龚磊副教授的共同指导下完成，理论计算由袁汝明助理教授（共同第一作者）完成，曹勇、丁晓兵、蔡森荣、韩博闻等学生参与了部分工作。周志有教授和洪宇浩博士生在电化学微分质谱方面给予大力的帮助与支持。【Abstract】The aprotic lithium-oxygen (Li-O2) battery has attracted worldwide attention because of its ultrahigh theoretical energy density. However, its practical application is critically hindered by cathode passivation, large polarization, and severe parasitic reactions. Here, we demonstrate an originally designed Ru(Ⅱ) polypyridyl complex (RuPC) though which the reversible expansion of Li2O2 formation and decomposition can be achieved in Li-O2 batteries. Experimental and theoretical results revealed that the RuPC can not only expand the formation of Li2O2 in electrolyte but also suppress the reactivity of LiO2 intermediate during discharge, thus alleviating the cathode passivation and parasitic reactions significantly. In addition, an initial delithiation pathway can be achieved when charging in turn; thus, the Li2O2 products can be decomposed reversibly with a low overpotential. Consequently, the RuPC-catalyzed Li-O2 batteries exhibited a high discharge capacity, a low charge overpotential, and an ultralong cycle life. This work provides an alternative way of designing the soluble organic catalysts for metal-O2 batteries.This work was supported by the National 973 Program (2015CB251102), the Key Project of National Natural Science Foundation of China (21673196, 21621091, 21703186, 21773192),and the Fundamental Research Funds for the Central Universities (20720150042,20720150043). The authors thank Prof. Eric Meggers at Philipps-Univeristaet Marburg for his discussion about the synthesis of RuPC complex; Prof. Gang Fu at Xiamen University for his instructive discussions in DFT calculations; Lajia Yu and Dandan Tao at Xiamen University for their assistance in EPR experiments and UV-Vis spectroscopy experiments, respectively; and Yu Gu and Tao Wang at Xiamen University for their discussions in XPS results and CV data,respectively. 该工作得到科技部重大基础研究计划（项目批准号：2015CB251102）、国家自然科学基金（项目批准号：21673196、21621091、21703186、21773192）和中央高校基本科研业务费专项资金（项目批准号：20720150042、20720150043）的资助。 此外，感谢傅钢教授在理论计算方面的讨论和建议，Eric Meggers教授在配合物合成上的讨论，泉州师范学院吴启辉教授和化学化工学院谷宇博士生在X射线光电子能谱方面的帮助，于腊佳老师在电子顺磁共振实验上的帮助，陶丹丹博士生在紫外可见光谱测试上的帮助以及王韬博士生在循环伏安方面的讨论

Preparation and Electrochemical Performances of Cofe_2O_4/GNS Nanocomposites as Anode Material for Lithium Ion Battery

采用溶剂热法一步合成纳米尺寸COfE2O4/gnS复合材料(直径约为15 nM),其颗粒尺寸均一,且均匀分散于石墨烯表面.电化学测试结果表明,该复合物电极具有良好的循环和倍率性能,500 MA·g-1电流密度下100周期循环比容量稳定在709 MAH·g-1,容量保持率高达95.8%;2 A·g-1电流密度,其比容量仍高达482 MAH·g-1.The Cofe2O4/GNS was synthesized by a simple one-pot solvothermal method.The results obtained by X-ray diffraction(XRD) and transmission electron microscopy(TEM) showed that the Cofe2O4 particles with sizes of 15 nm dispersed on the surface of graphene uniformly.Electrochemical tests indicated that the Cofe2O4/GNS nanocomposite exhibited excellent cyclic stability with almost 95.8% capacity retention after 100 cycles at the current density of 500 mA·g-1and delivered a high reversible capacity of 482 mAh·g-1at the current density of 2 A·g-1.国家自然科学基金项目(No.200933005;No.21021002); 国家973计划项目(No.2009CB220102); 厦门市纯电动汽车重大专项(I期)(No.3502Z20121002); 国家基础科学人才培养基金项目(No.J1210014)资

Preparation and Electrochemical Performances of CoFe2O4/GNS Nanocomposites as Anode Material for Lithium Ion Battery

采用溶剂热法一步合成纳米尺寸CoFe2O4/GNS复合材料（直径约为15 nm），其颗粒尺寸均一，且均匀分散于石墨烯表面. 电化学测试结果表明，该复合物电极具有良好的循环和倍率性能，500 mA·g-1电流密度下100周期循环比容量稳定在709 mAh·g-1, 容量保持率高达95.8%；2 A·g-1电流密度，其比容量仍高达482 mAh·g-1.The CoFe2O4/GNS was synthesized by a simple one-pot solvothermal method. The results obtained by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the CoFe2O4 particles with sizes of 15 nm dispersed on the surface of graphene uniformly. Electrochemical tests indicated that the CoFe2O4/GNS nanocomposite exhibited excellent cyclic stability with almost 95.8% capacity retention after 100 cycles at the current density of 500 mA·g-1 and delivered a high reversible capacity of 482 mAh·g-1 at the current density of 2 A·g-1.国家自然科学基金项目（No. 200933005，No. 21021002）、国家973计划项目（No. 2009CB220102）、厦门市纯电动汽车重大专项（Ⅰ期）（No. 3502Z20121002）和国家基础科学人才培养基金项目（No. J1210014）资助作者联系地址：厦门大学 固体表面物理化学国家重点实验室，化学化工学院化学系，福建 厦门 361005Author's Address: State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen 361005, Fujian, China通讯作者E-mail：[email protected]

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies