Nitrogen-doped Nb2CTx MXene as anode materials for lithium ion batteries

MXene, a recently discovered family of 2D materials, is well known for its application in energy storage areas due to its excellent properties. However, the low capacity of pristine MXene limits its application in energy storage devices such as lithium ion batteries. To solve this problem, we synthesized a new type of N-doped two-dimensional Nb2CTx MXene. The nitrogen content of N-doped MXene was 4.5 at% after thermal reaction with urea. The introduction of nitrogen into MXene nanosheets increases c-lattice parameter of Nb2CTx MXene from 22.32 Å to 34.78 Å. And the incorporation of nitrogen into MXene nanosheets leads to superior electrochemical performance. For example, the N-doped Nb2CTx shows an increased reversible capacity of 360 mAh /g at 0.2C, which is much higher than that of the un-doped Nb2CTx MXene (190 mAh/g at 0.2C). And the N-doped Nb2CTx MXene also shows excellent cycling stability (288 mAh/g at 0.5C after 1500 cycles). Our results suggest N-doped Nb2CTx MXene is promising for energy storage applications.