Extended Data Fig. 2: Characterization of the discharge product in Ca-O2 batteries.
From: A rechargeable calcium–oxygen battery that operates at room temperature
a, XRD patterns of the cathode after the 1st discharge and the pristine cathode (CNT) suggesting that the main discharge product of Ca-O2 batteries at room temperature is CaO2. References: CaO2 (mp-634859) and CaO (mp-2605) from the Materials Project database. b, TEM image and the corresponding selected area electron diffraction (SAED) pattern (inset) of the discharge product. Scale bar, 100 nm. c, Tof-SIMS depth profile of various secondary ion species obtained by sputtering the fully discharged cathode, indicating the formation of CaO2 in the discharge process. d, Tof-SIMS two-dimensional view images of CaO2− from the discharged cathode showing the uniform distribution of CaO2. e, Tof-SIMS depth profile of various secondary ion species obtained by sputtering the recharged cathode, indicating the decomposition of CaO2 in the charge process. f, Tof-SIMS two-dimensional view images of CaO2− from the recharged cathode showing the decomposition of CaO2.
