Cheap, safe and high-energy batteries are required for applications such as the electrification of transport, the large-scale storage of energy from renewable resources and consumer portable devices. Lithium-oxygen and lithium-sulphur batteries are very promising candidates because they have the potential to store more than 5 times higher energy than today's lithium-ion batteries of the same weight and volume. Currently, the performance of lithium-oxygen and lithium-sulphur batteries is limited by several fundamental challenges. This project will develop an experimental-based physical-chemical understanding of the underlying processes and will develop tailored solutions to overcome these problems. Our approach will be to fundamentally change the reaction mechanism in order to boost battery performance. Homogeneous catalysts capable of transferring several electrons will be explored with the aim of eliminating problematic reaction intermediates. This is expected to not only enhance reaction kinetics but also to suppress degradation reactions. Novel electrolytes will be developed which are designed to provide ultrafast charge transport of the homogeneous catalysts. Novel lithium protection approaches will also be explored, which are designed to suppress unwanted reactions on the lithium electrode as well as enhancing the safety of these batteries. In conclusion, this project aims to achieve a step change in rechargeable lithium batteries based on a full mechanistic understanding and tailored innovative approaches.