Ultrahigh-Areal-Capacity Battery Anodes Enabled by Free-Standing Vanadium Nitride@N-Doped Carbon/Graphene Architecture.

Nanostructured anode materials have attracted significant attention for lithium-ion batteries (LIBs) due to their high specific capacity. However, their practical application is hindered by the rather low areal capacity in the ultrathin electrode (∼1 mg cm-2). Herein, we propose a new strategy of an all-conductive electrode to fabricate a flexible and free-standing vanadium nitride@N-doped carbon/graphene (VN@C/G) thick electrode. Due to the free-standing structure and absence of any nonconductive components in the electrode, the obtained thick electrode displays excellent cycling performances. With the high mass loading of 5 mg cm-2, VN based electrodes achieve a reversible capacity of 2.6 mAh cm-2 after 200 cycles. Moreover, the all-conductive electrode allows an ultrahigh areal capacity of 7 mAh cm-2 with a high mass loading of 18.3 mg cm-2, which is comparable to state-of-the-art graphite anodes (4 mAh cm-2). Theoretical calculations prove the metallic conductivity of VN, which allows fast charge transport in the thick electrode. This strategy of fabricating all-conductive electrodes shows great potentials to achieve high areal capacity in practical lithium-ion batteries.