Materials chemistry and electrochemistry of the lithium-air battery

能量储存是我们这个时代最大的科学挑战之一。锂离子电池的发展引发了便携式电子行业的革命，随后该技术的改进在电动汽车中得到了应用。然而，由于电池组件的质量，锂离子电池的比能量本质上是有限的。很少有技术能够超过锂离子电池的性能，但在这些技术中，锂空气电池承诺了最高的理论比能量，并可能产生与内燃机竞争的续航里程。锂-空气电池通常由锂金属负极、有机电解液和多孔炭阴极组成。放电时，空气中的氧气在阴极被还原，并与来自阳极的锂离子结合，形成双电子电荷转移的过氧化锂。放电产物过氧化锂给锂空气电池带来了几个问题。它在阴极表面的形成导致了循环时的极化问题，因为它的电子传导性很差。除此之外，多孔电极中过氧化锂的积聚可能会阻止气体扩散路径，导致容量降低和电池过早死亡。该项目旨在提高锂空气电池的寿命和效率。这将通过建立在我们对含锂有机电解液中氧氧化还原电化学形成过氧化锂的基本理解的基础上实现，并在充电时逆转。将对促进氧还原和放出的新型化学介体进行研究。为了提高锂空气电池的循环寿命，需要提高电池反应动力学的介质剂。锂-空气电池不同于锂离子系统，因为它包含固态、液态和气态。因此，电池内液体和气相的质量传输限制是一个需要研究的独特问题。新的电池架构将专门为锂-空气系统设计，以优化质量传输并实现电池容量的实际收益。本项目将使用一系列电化学(循环和电化学阻抗谱)、光谱(拉曼、FTIR、XPS和原位质谱学)和微观技术(如扫描电子显微镜和原子力显微镜)来研究氧氧化还原电化学。这种技术非常适合于研究反应中间体和产物的存在和性质。这项工作旨在开发锂-空气电池领域的新科学和知识产权，因此符合EPSRC的储能主题。布鲁斯集团在锂-空气研究和固态材料领域处于世界领先地位，并处于有利地位，可以为这项技术的发展贡献更多的基础知识。

Energy storage represents one of the greatest scientific challenges of our time. The development of the lithium-ion battery led to the revolution of the portable electronics industry and the subsequent improvement of this technology has found application in electric vehicles. However, due to the mass of the cell components, the specific energy of the lithium-ion battery is intrinsically limited. Few technologies are able to exceed the performance of lithium-ion batteries, but of these the lithium-air battery promises the highest theoretical specific energy and may produce a driving range to compete with that of the internal combustion engine. The lithium-air battery normally consists of a lithium metal anode, an organic electrolyte and a porous carbon cathode. On discharge, oxygen from the atmosphere is reduced at the cathode and combines with lithium cations from the anode forming lithium peroxide in a two electron charge transfer. The discharge product, lithium peroxide, poses several problems for the lithium-air battery. It's formation on the cathode surface leads to polarisation issues on cycling due to its poor electronic conductivity. As well as this, the build-up of lithium peroxide in the porous electrode can block gas diffusion pathways leading to reduced capacity and early cell death. The project aims to improve the longevity and efficiency of the lithium-air battery. This will be achieved by building on our fundamental understanding of oxygen redox electrochemistry in lithium containing organic electrolytes to form lithium peroxide, and its reversal on charging. An investigation into novel chemical mediators to facilitate the oxygen reduction and evolution will be carried out. Mediators that enhance battery reaction kinetics are needed to improve the cycling life of the lithium-air battery. The lithium-air battery differs from lithium-ion systems as it contains solid, liquid and gaseous phases. Hence mass transport limitations in both liquid and gaseous phases within the battery presents a unique problem that needs to be investigated. New battery architectures will be designed specifically for the lithium-air system to optimise mass transport and realise practical gains in battery capacity. This project will use a range of electrochemical (cycling and electrochemical impedance spectroscopy), spectroscopic (Raman, FTIR, XPS and in situ mass spectrometry) and microscopic techniques such as SEM and AFM to study the oxygen redox electrochemistry. Such techniques are well-suited to the study of the presence and nature of reaction intermediates and products. This work aims to develop new science and intellectual property in the field of lithium-air batteries and as such is in line with EPSRC's theme of Energy Storage. The Bruce group is world-leading in the field of lithium-air research and solid state materials, and is well placed to contribute further fundamental knowledge for development of this technology.