Nanoionics

离子在固体中的传输是固体科学中最基本的过程之一。这一现象对许多设备的功能至关重要，包括燃料电池、电池以及传感器、显示器和新兴的纳米离子电子器件。前两个例子是在努力减少二氧化碳排放从而解决全球变暖问题方面正在开发的关键能量转换和存储技术。固体中离子传输的研究被称为固态离子学，包括支持离子导电性(例如CaF2中的F-导电性)和离子/电子混合导电性或插层化合物(例如锂电池中的正极LiCoO2)的固体。自从法拉第第一次发现固体中的离子传输以来，研究一直集中在散装固体(由微米大小的颗粒组成)上。然而，现在有许多例子表明，纳米离子材料(由纳米尺寸的颗粒组成的离子材料)可以表现出与其块状材料相比截然不同的行为，包括极大地增强甚至是独特的性能。Li在体相β-MnO2中不可能嵌入，但在介孔β-MnO2中很容易嵌入。与Al_2O_3复合后，LiI的电导率提高了3个数量级，在RT时达到2.6×10~(-4)S/厘米。从科学上讲，纳米离子材料代表着固态离子学的一个重要的新前沿，但人们对此知之甚少。纳米离子材料之所以重要，是因为它们有可能带来许多设备所必需的性能阶梯变化，包括储能设备。例如，纳米LiFePO4材料被用作新一代可充电锂电池的阴极，以提供混合动力汽车等应用所需的高功率。该提案的目的不是探索纳米离子材料在设备中的实际应用。事实上，我们认为，由于缺乏基本的理解，探索纳米离子材料在应用中的应用范围受到了阻碍。挑战在于理解纳米电子学的科学。纳米离子材料的粘附性增强的起源是什么？控制和影响纳米材料中载流子浓度和迁移率的因素有哪些？表面附近的电中性击穿、近表面区域的应变、表面附近的结构扭曲和界面失配引起的扭曲的作用是什么？形状(如纳米管)和尺寸如何影响固态离子特性？这样的理解将代表着固态离子的一个重要和热门领域的重大科学进步。发展对纳米离子的科学理解是学术界和工业界探索和利用纳米离子材料非常特殊的性质的基本先决条件，例如在可充电锂电池中。迄今为止，关于纳米离子的工作一直是由个人、使用单独的技术和在单独的系统上进行的。为了取得进展，有必要组建一个团队，从而汇集计算机模拟、纳米材料合成、结构确定和物理测量方面的基本专业知识，并将这种技能组合应用于跨越主要类别的固态离子材料的一系列模型系统。这就是我们计划要做的事情，也是我们寻求项目资助的原因。英国在固态离子领域拥有传统的优势，拥有许多优秀的团队。该计划的拨款将有助于维持英国在国际上的显赫地位，并有助于制定该领域的国际议程。新一代学生将接受该领域的培训，能够无缝地跨越传统的实验/计算鸿沟，掌握广泛的方法和技能

Ion transport through solids is one of the most fundamental processes in solid state science. The phenomenon is crucialto the function of many devices including fuel cells and batteries as well as sensors, displays and the emerging topic ofnanoionic electronic devices. The first two examples are key energy conversion and storage technologies underdevelopment in the effort to mitigate CO2 emissions and hence address Global Warming.The study of ion transport in solids is known as solid state ionics and embraces solids that support ionic conductivity ( e.g.F- conduction in CaF2) and mixed ionic/electronic conductivity or intercalation compounds ( e.g. the positive electrode inlithium batteries, LiCoO2). Since Faraday first discovered ion transport in solids, investigation has focused on bulk solids(composed of micron-sized particles). However, there are now numerous examples demonstrating that nanoionicmaterials (ionic materials composed of nanometre-sized particles) can exhibit profoundly different behaviour comparedwith their bulk counterparts, including greatly enhanced or even unique properties. Intercalation of Li is impossible intobulk beta-MnO2 but facile in mesoporous beta-MnO2. The conductivity of LiI is raised by 3 orders of magnitude to 2.6x10-4 S/cm at RT when combined with Al2O3 in a nanocomposite. Scientifically, nanoionic materials represent an importantnew frontier in solid state ionics but one that is poorly understood. Nanoionic materials are important because they havethe potential to deliver the step change in performance essential for many devices, including energy storage devices. Forexample, nano-LiFePO4 materials are used as the cathode in a new generation of rechargeable lithium batteries in orderto deliver the high power necessary for applications such as hybrid electric vehicles.It is not the purpose of the proposal to explore the practical applications of nanoionic materials in devices. Indeed wecontend that exploring the extent to which nanoionic materials could be used in applications is hindered by a lack offundamental understanding. The challenge is to understand the science of nanoionics. What is the origin of the muchenhanced properties of nanoionic materials? What are the factors that control and influence the concentration andmobility of charge carriers in nanoscale materials? What is the role of electroneutrality breakdown near the surface, strainin the near surface region, structural distortions near the surface and distortions due to mismatch at interfaces? How doesshape (e.g. nanotubes) as well as size influence solid state ionic properties? Such understanding would represent asignificant scientific advance in an important and topical area in solid state ionics. Developing the scientific understandingof nanoionics is an essential pre requisite for the academic/industrial communities to explore and exploit the very specialproperties of nanoionic materials e.g. in rechargeable lithium batteries.Work to date on nanoionics has been carried out by individuals, using individual techniques and on individual systems. Tomake progress it is necessary to assemble a team thus bringing together the essential expertise in computer simulation,synthesis of nanomaterials, structure determination and physical measurements, and to apply this combination of skills toa range of model systems spanning the major classes of solid state ionic materials. This is what we propose to do andwhy we seek a programme grant.The UK has a traditional strength in solid state ionics with a number of excellent groups. The programme grant wouldcontribute to maintaining the UK's international prominence and help set the international agenda in the field.A new generation of students would be trained in the field, capable of working seamlessly across the traditionalexperimental/computational divide and on a wide range of methods and skills