In situ observation of the electrochemical behavior of Li-CO2/O2 batteries in an environmental transmission electron microscope

Li-CO2/O-2 batteries, a promising energy storage technology, not only provide ultrahigh discharge capacity but also capture CO2 and turn it into renewable energy. Their electrochemical reaction pathways' ambiguity, however, creates a hurdle for their practical application. This study used copper selenide (CuSe) nanosheets as the air cathode medium in an environmental transmission electron microscope to in situ study Li-CO2/O-2 (mix CO2 as well as O-2 at a volume ratio of 1:1) and Li-O-2 batteries as well as Li-CO2 batteries. Primary discharge reactions take place successively in the Li-CO2/O-2-CuSe nanobattery: (I) 4Li(+) + O-2 + 4e(-) -> 2Li(2)O; (II) Li2O + CO2 -> Li2CO3. The charge reaction proceeded via (III) 2Li(2)CO(3) -> 4Li(+) + 2CO(2) + O-2 + 4e(-). However, Li-O-2 and Li-CO2 nanobatteries showed poor cycling stability, suggesting the difficulty in the direct decomposition of the discharge product. The fluctuations of the Li-CO2/O-2 battery's electrochemistry were also shown to depend heavily on O-2. The CuSe-based Li-CO2/O-2 battery showed exceptional electrochemical performance. The Li-CO2/O-2 battery offered a discharge capacity apex of 15,492 mAh g(-1) and stable cycling 60 times at 100 mA g(-1). Our research offers crucial insight into the electrochemical behavior of Li-CO2/O-2, Li-O-2, and Li-CO2 nanobatteries, which may help the creation of high-performance Li-CO2/O-2 batteries for energy storage applications.

Automated summary

Li-CO2/O-2 batteries are a promising energy storage technology that not only provide ultrahigh discharge capacity but also capture CO2 and convert it into renewable energy. This study used copper selenide nanosheets as the air cathode medium to investigate the electrochemical behavior of Li-CO2/O-2, Li-O-2, and Li-CO2 batteries. The research offers insights into the potential development of high-performance Li-CO2/O-2 batteries for energy storage applications.