Hierarchically-structured electrodes for Li-air batteries

锂空气电池的分层结构电极

• 批准号: 2748670
• 金额: --
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2748670
• 关键词: Hierarchically; structured; electrodes; Li; air

Li-air batteries are secondary batteries with the highest theoretical energy density of any battery system. In order to achieve this in practice, many technical problems must first be resolved. One key issue limiting the discharge capacity at higher rates is that of oxygen diffusion through the cathode material. At higher discharge rates, oxygen from the air side of the cathode does not have time to diffuse throughout the whole electrode before being consumed, resulting in a build up of discharge product at the air side. This results in eventual pore blockage and the underutilisation of the cathode volume. Another issue affecting the energy efficiency of these batteries is the high overpotentials caused by the slow kinetics of the oxygen reduction and evolution reactions on discharge and charge. One of the main goals of this project is to develop an understanding of the relationship between oxygen diffusivity and discharge capacity of Li-air batteries at high discharge rates. In this project, the oxygen diffusivity through the cathode will initially be controlled via laser processing of carbon nanotube (CNT) mats. Building from this, more advanced material synthesis methods can be employed, such as nano-lithography to define a patterned catalyst followed by CNT forest growth. The material properties and electrochemical performance of this cathode material will be characterised, and correlated with the effective oxygen diffusivity through the electrode. Using this system as an experimental basis, operando XRD and gas pressure monitoring will be used to study the effects of varying oxygen diffusivity and cycling rate on cell kinetics in detail. Following this, cathodes functionalised with catalytic nanoparticles will be synthesised and have their electrochemical performance characterised. The operando techniques developed earlier in the project will be used to study the effects of heterogeneous catalysis on discharge product formation in Li-air batteries. These studies will help improve the cell capacity and efficiency of Li-air batteries, particularly athigh discharge rates, relevant for commercial applications.

锂空气电池是具有任何电池系统中最高理论能量密度的二次电池。为了在实践中实现这一点，必须首先解决许多技术问题。限制较高速率下放电容量的一个关键问题是氧扩散通过阴极材料。在较高的放电速率下，来自阴极的空气侧的氧在被消耗之前没有时间扩散遍及整个电极，导致放电产物在空气侧积聚。这导致最终的孔隙堵塞和阴极体积的利用不足。影响这些电池的能量效率的另一个问题是由放电和充电时氧还原和析出反应的缓慢动力学引起的高过电位。该项目的主要目标之一是了解锂空气电池在高放电速率下的氧扩散率和放电容量之间的关系。在这个项目中，通过阴极的氧气扩散率最初将通过碳纳米管（CNT）垫的激光加工来控制。以此为基础，可以采用更先进的材料合成方法，例如纳米光刻法来定义图案化的催化剂，然后是CNT森林生长。该阴极材料的材料性质和电化学性能将被表征，并与通过电极的有效氧扩散率相关。使用该系统作为实验基础，operando XRD和气体压力监测将被用来研究不同的氧扩散率和循环速率对电池动力学的影响。在此之后，将合成用催化纳米颗粒官能化的阴极，并表征其电化学性能。该项目早期开发的操作技术将用于研究多相催化对锂空气电池放电产物形成的影响。这些研究将有助于提高锂空气电池的电池容量和效率，特别是高放电率，与商业应用相关。