Irreplaceable carbon boosts Li-O2 batteries: From mechanism research to practical application

Highlights: • Li−O₂ battery has the highest theoretical energy density in existing battery systems. • Carbon plays an irreplaceable role in the development of Li−O₂ battery. • We reviewed ongoing progresses of carbon in Li−O₂ battery. • We discussed electrochemical performance and mechanism of carbon in Li−O₂ batteries. • We prospected structural design and synthesis strategies of carbon for Li−O₂ battery. Li-O₂ battery represents one of the promising candidates for beyond Li-ion batteries with ultra-high energy density, possessing great potential for efficient energy storage applications to resolve future energy and environmental issues. Since the initial concept of Li-O₂ battery was proposed in 1996, carbon have played a vital role in the development of Li-O₂ battery, for both mechanism research and potential applications. In this review, we look into the ongoing progresses that are being made with carbon materials and carbon chemistry in Li-O₂ batteries, including material manufacturing, structural properties, electrochemical behavior and mechanism analysis. Meanwhile, we successively examine the electrochemical performance of main families of carbon materials and carbon-based derivatives. It is noteworthy that the design and synthesis strategies for carbon materials and their electrochemical performance in Li-O₂ battery are comprehensively reviewed and discussed, together with the challenges being faced and prospects for them. We anticipate that this review could provide a good systematic understanding on carbon in the development of Li−O₂ battery.