Advances in sodium-ion batteries at low-temperature: Challenges and strategies

With the continuing boost in the demand for energy storage,there is an increasing requirement for batteries to be capable of operation in extreme environmental conditions.Sodium-ion batteries(SIBs) have emerged as a highly promising energy storage solution due to their promising performance over a wide range of temperatures and the abundance of sodium resources in the earth's crust.Compared to lithiumion batteries(LIBs),although sodium ions possess a larger ionic radius,they are more easily desolvated than lithium ions.Fu rthermore,SIBs have a smaller Stokes radius than lithium ions,resulting in improved sodium-ion mobility in the electrolyte.Nevertheless,SIBs demonstrate a significant decrease in performance at low temperatures(LT),which constrains their operation in harsh weather conditions.Despite the increasing interest in SIBs,there is a notable scarcity of research focusing specifically on their mechanism under LT conditions.This review explores recent research that considers the thermal tolerance of SIBs from an inner chemistry process perspective,spanning a wide temperature spectrum(-70 to100℃),particularly at LT conditions.In addition,the enhancement of electrochemical performance in LT SIBs is based on improvements in reaction kinetics and cycling stability achieved through the utilization of effective electrode materials and electrolyte components.Furthermore,the safety concerns associated with SIBs are addressed and effective strategies are proposed for mitigating these issues.Finally,prospects conducted to extend the environmental frontiers of commercial SIBs are discussed mainly from three viewpoints including innovations in materials,development and research of relevant theoretical mechanisms,and intelligent safety management system establishment for larger-scale energy storage SIBs.

A modified single edge V-notched beam method for evaluating surface fracture toughness of thermal barrier coatings

The surface fracture toughness is an important mechanical parameter for studying the failure behavior of air plasma sprayed(APS)thermal barrier coatings(TBCs).As APS TBCs are typical multilayer porous ceramic materials,the direct applications of the traditional single edge notched beam(SENB)method that ignores those typical structural characters may cause errors.To measure the surface fracture toughness more accurately,the effects of multilayer and porous characters on the fracture toughness of APS TBCs should be considered.In this paper,a modified single edge V-notched beam(MSEVNB)method with typical structural characters is developed.According to the finite element analysis(FEA),the geometry factor of the multilayer structure is recalculated.Owing to the narrower V-notches,a more accurate critical fracture stress is obtained.Based on the Griffith energy balance,the reduction of the crack surface caused by micro-defects is corrected.The MSEVNB method can measure the surface fracture toughness more accurately than the SENB method.

复合治理:地方脱贫进路的一个理论解释——基于153个脱贫摘帽县的扎根研究

准确诠释精准脱贫战略实践以来的地方治理经验是一项亟待推进的研究议题。论文以153个脱贫摘帽县作为分析样本,基于扎根方法提炼“复合治理”分析性概念诠释地方脱贫经验。“复合”属性表明地方减贫过程受到多重机制共同作用而形塑出复杂叠加的治理样态,具体表现为:(1)中央政府建构“刚性时间约束”要件,为地方政府“复合治理”提供外在驱动力;(2)贫困县党委、政府调用“党政统合”形式凸显任务首位、塑造体制联动效应,它是“复合治理”的组织轴心;(3)“复合治理”实践运作依托于横向维度“利益整合”与纵向维度“政治关联”,前者表征政府与市场主体建构治理共识以形成长效治理机制,后者表征地方政府将外生性政治权威嵌入村庄场域提升治理合力。“复合治理”为精准脱贫实践提供了一个理论视角,后续研究应强化对2020年后相对贫困治理实践的实证解读。

地方减贫“分类瞄准”治理绩效实证研究--基于“激励响应-机制执行”视角

在脱贫攻坚等重要治理领域,地方政府的激励响应行为与分类施策机制如何影响绩效生产,是有待厘清的问题。论文基于“激励响应-机制执行”视角,选取A县减贫“分类瞄准”案例作初步探索。研究发现,“分类瞄准”将贫困户划定为“一般户”与“重点户”,实施差异化帮扶,旨在回应精准脱贫“帮能援手”与“保障兜弱”的目标导向。但是,双重目标的实现样态并不均衡,减贫成效凸显“兜弱”导向。剖析绩效形塑机理,论文认为地方政府受“减贫人口规模最大化”激励信号的驱动,从快从速的执行风格成为其达成绩效的理性选择。然而,产业发展的同质化竞争与市场波动弱化了“帮能”功效,政府部门瞄向“重点户”的专项转移支付则强化了“兜弱”效应。由此,在农村减贫“帮能援手”功效未充分溢出的情境下,地方政府面临发展型项目效果巩固与“兜弱”型资源支出规模增加的压力。基于实证结论,论文进一步提出了助推乡村振兴实践的政策建议:一是在治理框架内统合“发展”与“兜弱”价值,注重政策设计的平衡性;二是优化激励信号设计,使之适配治理需求;三是加强府际互动与治理信息共享,推动纵向政府间关系转向“协作-赋能”。