Fig shows the charge discharge curves of

Fig. 7 shows the charge-discharge curves of different cycles at a current density of 20 mA g−1 and the corresponding differential capacity (dQ/dV) plots of the two samples. As shown in Fig. 7(a,c), the eminent coulomb efficiency of sample Hs is 81.8% with a charge capacity of 357 mA h g−1 and a discharge capacity of 292 mA h g−1. However, the coulomb efficiency of sample Cs is only 59.3%, much lower than that BIM 23056 of sample Hs. The higher coulomb efficiency indicates the favorable surface and appropriate primary particle size of sample Hs. The first charge curves of the two samples are both composed of two plateaus marked as the region I and II, belong to the de-intercalation of Li+ from LiMO2 (M=Mn, Ni, Co) and the irreversible extraction of Li2O from Li2MnO3, respectively [51] and [52]. The capacities of sample Hs associated with the region I and II are 142 and 168 mAh g−1. Different from sample Hs, the capacity of the region I for sample Cs is only 75 mAh g−1, clearly lower than compact bone for sample Hs. Moreover, relative higher capacity at about 206 mAh g−1 observed for the region II of sample Cs demonstrates its relative high content of Li2MnO3, which is consistent with the ICP results.