Nano/micro structure ammonium cerium nitrate tetrahydrate/carbon nanotube as high performance lithium storage material

Abstract

Using carbon nanotube (CNT) as conductive additive, (NH4)2Ce(NO3)5·4H2O/CNT is prepared from (NH4)2Ce(NO3)6 by a facile solution method and used as high capacity anode material for the first time. Morphology and structure investigation shows that (NH4)2Ce(NO3)5·4H2O/CNT exhibits high purity phase with particle size of 0.1–1.0 μm. In the composite, CNT provides a three-dimensional conductive network for electron transportation and can maintain the whole structure upon electrochemical cycles. For comparison, (NH4)2Ce(NO3)5·4H2O and (NH4)2Ce(NO3)5·4H2O/carbon black ((NH4)2Ce(NO3)5·4H2O/CB) are also prepared by the same method. Impurity phase of (NH4)3Ce2(NO3)9 can be detected in both (NH4)2Ce(NO3)5·4H2O and (NH4)2Ce(NO3)5·4H2O/CB. Electrochemical testing results reveals that (NH4)2Ce(NO3)5·4H2O/CNT shows lower initial discharge capacity (1683.6 mAh g−1) than (NH4)2Ce(NO3)5·4H2O (1972.8 mAh g−1) in the first cycle. However, (NH4)2Ce(NO3)5·4H2O/CNT shows the highest reversible capacity among all the three samples. After 30 cycles, it can deliver a reversible capacity of 818.5 mAh g−1, which is much higher than that of (NH4)2Ce(NO3)5·4H2O (50.6 mAh g−1) and (NH4)2Ce(NO3)5·4H2O/CB (208.8 mAh g−1). It suggests that the enhanced electrochemical properties are attributed to the introduction of CNT, which improves the electronic conductivity and structural stability during repeated cycles.