As the pressures of climate change becomes larger there is great interest in making highly efficient methods for generating and storing electrical energy. There is enormous interest in making batteries that exploit various lithium-based materials. These devices contain a solid anode and a solid cathode immersed in either a polymer, or solvent based electrolyte. Efficient batteries require that the thickness of both the cathode and anode materials are small in order both to reduce electrical resistance and to allow lithium to rapidly insert and de-insert itself from the solid electrode materials (by a process called intercalating). Furthermore they require that the surface area of the interface between the electrolyte and the anode (and cathode) should be made as large as possible in order to give sufficient lithium intercalation to allow practical levels of charging and discharging. As a result of these requirements batteries are currently designed with a nanostructured anode (and cathode) made either in a organised manner or by pressing grains together. Understanding how such nanostructures should be optimised in order to maximise energy efficiency is a major challenge. This is further complicated by the fact that the solid materials expand significantly (up to three times) when lithium is intercalated during charge and discharge of the battery creating both mechanical deformations and changes in the electrochemical behaviour of the surfaces. In order for such designs to be understood, and to be optimised, requires mathematical models to be developed and analysed that account for the critical properties of the nanostructure, the intercalation processes and the electrical properties of the materials. To replace existing high-efficiency high-cost silicon based solar cells there is significant interest in developing inexpensive polymer-based, and dye-sensitised, solar cells.Design of solar cells may seem unconnected from batteries but there is considerable similarity in the physical processes, mathematical models and geometry of the nanostructure of both these devices which provide the opportunity for a concerted theoretical program of research with significant technology transfer. Both types of solar cell that we consider here consist of two materials with different electrochemical properties separated by an interface (in the case of a dye-sensitised solar cell this interface is coated with a photo-absorbing dye monolayer). Efficient solar absorbtion requires that the interface between the two main materials is as large as possible while maintaining good electrical conduction. Nanostrucutred materials are being explored in order to meet these requirements. In order to optimise solar cell design models are required that account for solar absorbtion, the complex geometry of the nanostructure and charge transportation in the materials and across the interface.The purpose of this proposal is to develop novel mathematical techniques and models motivated by and closely aligned to practical developments in the complex nanostructure of these electrochemical systems. By analysing such models the most important mechanisms and features of the devices in determining their efficiency will be explored and identified.

Electrical energy storage can contribute to meeting the UK's binding greenhouse emission targets by enabling low carbon transport through electric vehicles (EVs) in the expanding electric automotive industry. However, challenges persist in terms of performance, safety, durability and costs of the energy storage devices such as lithium ion batteries (LIBs). Although there has been research in developing new chemistry and advanced materials that has significantly improved electrical energy storage performance, the structure of the electrodes and LIBs and their manufacturing methods have not been changed since the 1980s. The current manufacturing methods do not allow control over the structures at the electrode and device levels, which leads to restricted ion transport during cycling. The approach of this research is to develop a complete materials-manufacture-characterisation chain for LIBs, solid-state LIBs (SSLIBs) and next generation of batteries. Novel structures at the electrode and device levels will be designed to promote fast directional ion transport, increase energy and power densities, improve safety and cycling performance and reduce costs. New, scalable manufacturing techniques will be developed to realise making the designed structures and reduce interfacial resistance in SSLIBs. Finally, state-of-the-art physical and chemical characterisation techniques including a suite of X-ray photoelectron spectroscopy (XPS), X-ray computed tomography (XCT) and electrochemical testing will be used to understand the underlining charge storage mechanism, interfacial phenomena and how electrochemical performance is influenced by structural changes of the energy storage devices. The results will subsequently be used to guide iterations of the structure design. The fabricated batteries will be packaged into pouch cells and rigorously tested by EV protocols through close collaborations with industry to ensure flexible adaptability to the current industry match to create near-term high impact in industry. The commercialisation strategy is to license developed intellectual property (IP) to material and battery manufacturers.

The UK electricity system faces challenges of unprecedented proportions. It is expected that 35 to 40% of the UK electricity demand will be met by renewable generation by 2020, an order of magnitude increase from the present levels. In the context of the targets proposed by the UK Climate Change Committee it is expected that the electricity sector would be almost entirely decarbonised by 2030 with significantly increased levels of electricity production and demand driven by the incorporation of heat and transport sectors into the electricity system. The key concerns are associated with system integration costs driven by radical changes on both the supply and the demand side of the UK low-carbon system. Our analysis to date suggests that a low-carbon electricity future would lead to a massive reduction in the utilisation of conventional electricity generation, transmission and distribution assets. The large-scale deployment of energy storage could mitigate this reduction in utilisation, producing significant savings. In this context, the proposed research aims at (i) developing novel approaches for evaluating the economic and environmental benefits of a range of energy storage technologies that could enhance efficiency of system operation and increase asset utilization; and (ii) innovation around 4 storage technologies; Na-ion, redox flow batteries (RFB), supercapacitors, and thermal energy storage (TES). These have been selected because of their relevance to grid-scale storage applications, their potential for transformative research, our strong and world-leading research track record on these topics and UK opportunities for exploitation of the innovations arising. At the heart of our proposal is a whole systems approach, recognising the need for electrical network experts to work with experts in control, converters and storage, to develop optimum solutions and options for a range of future energy scenarios. This is essential if we are to properly take into account constraints imposed by the network on the storage technologies, and in return limitations imposed by the storage technologies on the network. Our work places emphasis on future energy scenarios relevant to the UK, but the tools, methods and technologies we develop will have wide application. Our work will provide strategic insights and direction to a wide range of stakeholders regarding the development and integration of energy storage technologies in future low carbon electricity grids, and is inspired by both (i) limitations in current grid regulation, market operation, grid investment and control practices that prevent the role of energy storage being understood and its economic and environmental value quantified, and (ii) existing barriers to the development and deployment of cost effective energy storage solutions for grid application. Key outputs from this programme will be; a roadmap for the development of grid scale storage suited to application in the UK; an analysis of policy options that would appropriately support the deployment of storage in the UK; a blueprint for the control of storage in UK distribution networks; patents and high impact papers relating to breakthrough innovations in energy storage technologies; new tools and techniques to analyse the integration of storage into low carbon electrical networks; and a cohort of researchers and PhD students with the correct skills and experience needed to support the future research, development and deployment in this area.

Solid-state Li-ion batteries (SSLBs) represent the ultimate in battery safety, eliminating the flammable organic electrolyte. The SSLB would find potential uses in industries where battery safety is paramount, such as the automotive industry (in cars, e-bikes and buses) and also in smaller applications where the elimination of the liquid electrolyte results in more ready compatibility with other devices, e.g., a battery on a chip or sensor. These batteries can compete with traditional lithium ion batteries in terms of volumetric energy density but they suffer from low power density. Very recently several viable inorganic solid Li-ion conducting electrolytes been identified with conductivities approaching those of liquids, which motivates this research proposal. Strategies for lowering interfacial resistances, particularly between the electrolyte and electrodes, and for building inherently scaleable devices that can be cycled multiple times, without mechanical failure, are now urgently required to produce practical devices. This multi-institutional project brings together experienced, world-leading researchers from the University of Cambridge, the University of Oxford, and Imperial College with distinct but complementary expertise to attack a number of challenging critical issues in this field. Two classes of these solid electrolytes, oxide garnets and sulphide glass ceramics, have been found to have very high room-temperature ionic conductivities. A number of characteristics have been identified that may provide either relative benefits or disadvantages: higher-modulus materials may cycle more stably in batteries; tougher materials may be more easily brought into industrial practice; polycrystalline character may limit apparent bulk-transport rates, lowering power efficiency; interfaces may be chemically unstable, affecting long-term state of health; etc. We propose to implement fundamental studies that shed light on the relative benefits and disadvantages of the oxide and sulphide ion-conductor paradigms, using the Li6.55Ga0.15*0.3La3Zr2O12 (* = vacancy) (LLZO) garnet and the P2S5-Li2S (PSLS) glass ceramic as model materials. The project centres around three experimental work packages that focus on 1) quantifying bulk properties and making them reproducible; specifically, issues of moisture and carbon-dioxide sensitivity of the electrolytes will be addressed to produce films with reduced resistances at the interfaces between particles. LLZO and PSLS films will be contrasted, and transport through them will be investigated via a number of in operando (in situ) metrologies, e.g., 6Li tracer and NMR studies in close concert with theoretical studies of ionic transport. 2) illustrating chemistry of the solid-electrolyte/Li two-dimensional interface and probing its morphological stability over time; we seek to identify the critical parameters needed to mitigate Li-metal dendrite formation and growth, and which allow smooth Li-plating on the electrolyte surface. 3) producing tailored, cohesive three-dimensional interfaces with complex morphologies that do not crack on extensive cycling. The development of materials with much larger electrode/electrolyte contact areas will increase Li+ exchange between phases within the electrode, increasing rate performance. A multiscale modelling effort cuts across the 3 work packages, aiming to produce fundamental physical insight, synthesize experimental outputs, and guide experimental design. The goals for the theory portion are unique in the sense that the models will aim for true 'multiscale' character, integrating atomistic and continuum perspectives. Overall, the project aims to provide new new strategies to improve the performance of SSLBs but will also result in new electrolyte designs that are suitable for to protect Li metal in other so-called "beyond Li-ion" batteries such as Li-air and Li-S and smaller batteries for internet communications technologies.

The Department for Transport of UK government announced to ban petrol and diesel vehicles by 2030 to facilitate Net Zero strategy. Being a major part of transportation electrification, the electric vehicle (EV) market is growing quickly; there are 190,727 new registrations of pure-EVs in 2021, 76.3% increase compared to 2020. Despite such success, the driving range and fast charge capability of EVs are recognised as predominant factors limiting further market penetration. Unfortunately, the physics of these requirements results in a trade-off of the lithium-ion battery design strategy. For instance, cells with high energy density provide maximum range but cannot deliver fast charging, because thicker electrodes suffer more acutely from the concentration polarisation across the electrode due to the slow ionic transport. Likewise, cells with high power density are capable of fast charging, but suffer from low mileage. More impetus in fundamental studies on physical processes of battery and the interplay between microstructure and performance are needed to eliminate range anxiety and charge-time trauma of EVs. Graphite/silicon composite electrode is regarded as one of the most promising candidates for next-generation automotive LiBs due to its high energy density. However, it suffers from the major drawbacks such as (1) volume expansion, cracking and pulverization of Si particles; (2) fast decay of capacity due to side reactions, consuming electrolyte rapidly. There is great potential to mitigate the degradation mechanisms by improved compositional and structural design based on better understanding of the ambiguous synergistic effect between the two types of particles. Moreover, lithium plating on the graphitic negative electrode is regarded as the foremost safety concern restricting the fast charge capability, leading to the consumption of lithium, electrolyte decomposition, formation of lithium dendrite and even thermal runaway. Therefore, it is critical to suppress lithium plating employing electrode design, manufacturing and rational protocols to address the longstanding challenge of battery fast charging. In this project, we aim to develop scalable and widely applicable innovations to facilitate the advancement of battery technologies for transport electrification. Correlative in operando experiment coupling the chemical, structure, crystallographic and electrochemical information from 2D to 4D will be conducted to elucidate the failure mechanisms of the graphite/Si composite electrode at the micrometer scale, particularly the synergistic dynamics of charge transfer, lithiation and deformation. Structural evolution is characterised as a function of SOC, C-rates and Si content, and linked to the capacity decay. Advanced 3D microstructure-resolved electro-chemo-mechanical model will be developed to analyse the performance limiting mechanisms, the impact of microstructural evolution on the reaction heterogeneities and predict the cycle life; in operando experiment and 3D microstructure-resolved phase field modelling will be employed to reveal the interplay between 3D microstructure of the electrode with the phase separation phenomenon, spatial dynamics of lithiation and plating. In addition, the physical processes of the relaxation behaviour, such as lithium exchange and redistribution will be elucidated by the 3D model, which will provide valuable guidelines for the refinement of fast charge protocols in terms of the timing and period of the rest steps. Finally, building on the insights of the study above, graphite/Si composite electrodes with novel structures will be fabricated, aiming to achieve at least 280 Wh kg-1 at the cell level with 20 mins charging for 50% of the capacity, corresponding to 15% increase in energy density and over 30% decrease of charging time compared to the commercial cells; an advanced physics-based fast charge protocol will be delivered to mitigate the plating risk and capacity fade.