Stress-Regulation Design of Lithium Alloy Electrode toward Stable Battery Cycling

Metallic tin(Sn)foil is a promising candidate anode for lithium-ion batteries(LIBs)due to its metallurgical processability and high capacity.However,it suffers low initial Coulombic efficiency and inferior cycling stability due to its uneven alloying/dealloying reactions,large volume change and stress,and fast electrode structural degradation.Herein,we report an undulating LiSn electrode fabricated by a scalable two-step procedure involving mechanical lithography and chemical prelithiation of Sn foil.With the combination of experimental measurements and chemo-mechanical simulations,it was revealed the obtained undulating LiSn/Sn electrode could ensure better mechanical stability due to the pre-swelling state from Sn to Li x Sn and undulating structure of lithography in comparison with plane Sn,homogenize the electrochemical alloying/dealloying reactions due to the activated surface materials,and compensate Li loss during cycling due to the introduction of excess Li from Li_(x)Sn,thus enabling enhanced electrochemical performance.Symmetric cells consisting of undulating LiSn/Sn electrode with an active thickness of∼5 um displayed stable cycling over 1000 h at 1 mA cm^(-2) and 1 mAh cm^(-2) with a low average overpotential of<15 mV.When paired with commercial LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cathode with high mass loading of 15.8 mg cm^(-2),the full cell demonstrated a high capacity of 2.4 mAh cm^(-2) and outstanding cycling stability with 84.9% capacity retention at 0.5 C after 100 cycles.This work presents an advanced LiSn electrode with stress-regulation design toward high-performance LIBs,and sheds light on the rational electrode design and processing of other high-capacity lithium alloy anodes.

科研渗透式有机化学综合实验设计——一种防伪墨水的制备

有机化学实验作为有机化学理论课程的互补内容,是一门重要的专业基础课程。因该课程具有培养学生理论联系实际、实事求是、严格认真的科学态度的重要作用,使其在高校教学计划中占据着非常重要的地位,其主要内容已成为从事化学相关专业科研工作的入门技能。因此,开展一个联系科学前沿的有机化学综合创新实验势在必行。本实验设计将具有光致异构化特性的螺吡喃分子的合成、分离提纯、结构表征和应用功能融为一体,并以该综合实验为载体,将科研内容与操作技能渗透其中,初步培养学生的科研兴趣与能力。本实验不但涵盖了有机化学的重要理论知识、基本实验操作,更注重培养学生使用现代仪器对产物进行结构分析的专业科研能力,通过产物在防伪墨水中的应用,加强学生主动挖掘有机分子在生活中应用的意识。更重要的是本实验设计在教学安排上极具灵活性,可用于整体性教学或模块化教学,该特点使其更适宜作为科研渗透式有机化学综合创新实验进行本科教学。

跨国经营企业员工的外派动机形成机理:基于扎根理论的研究

以任务为导向的企业外派是促进企业国际化、实施企业“走出去”战略的重要举措。如何有效识别员工个体的动机水平,以提升企业外派有效性是我国企业外派管理实践中亟待解决的问题。本研究以自我决定理论作为切入点,重点关注中国跨国经营企业员工的外派动机形成机理和理论构建,通过扎根理论方法,对27名外派员工进行访谈。本文深入挖掘中国跨国经营企业员工的外派动机因素,并构建了外派动机形成机理的理论框架。研究发现,外派动机依据自我决定程度的高低可分为自我发展性动机和职责驱动性动机两类,二者并非相互对立的动机,而是处于一个连续体中。研究对员工的外派动机形成的前因也进行了探索,发现外派自主性需求、社交需求和胜任需求对个体外派动机的形成具有关键影响。此外,受到跨文化环境的影响,来自外部的支持性环境和限制性环境在外派动机形成过程中发挥了重要的边界作用。本研究拓展了动机理论在外派领域的应用,为企业有效识别、激励和管理外派员工提供了理论指导。