“…The diffraction peaks were observed at 18.13• , 29.05 • , 31.2 • , 32.5 • , 36.24 • , 38.19 • , 44.53 • , 50.91 • , 58.67 • , 60.01 • , and 64.8 • , corresponding to the (101), (112), (200), (103), (211), (004), (220), (204), (321), (224), and (400) crystal planes of the Mn 3 O 4 , respectively (according to the JCPDS card No. 24-0734)[30].However, after chitosan was added to prepare the Mn 3 O 4 @C material and underwent carbonization, the diffraction peaks of the Mn 3 O 4 @C hybrid material became boarder and shifted a little to a lower 2θ, indicating that the Mn 3 O 4 @C electrode material had smaller particle sizes. There were no distinct diffraction peaks corresponding to the carbon crystals, indicating that carbon also existed in an almost amorphous form in the Mn 3 O 4 @C hybrid material.…”