Fig. 4. In situ XRD analysis of the lithium-storage mechanism of the as-prepared Ni(HCO3)2/rGO electrodes: (a) cycles 1 to 4.5 and the corresponding image plots of the diffraction patterns in a 2θ range of 36.5–45.5° within the voltage window of 0.01–3 V at a current density of 300 mA g–1, and (b) waterfall diagram showing the evolution of the XRD patterns at different discharge/charge states (the peaks 1–3 are assigned to Ni(HCO3)2); (c) cycles 1 to 4 and the corresponding image plots of the diffraction patterns in a 2θ range of 47.9–57.1° within the voltage window of 0.01–3 V at a current density of 250 mA g–1.
