Ionic liquid-assisted synthesis of hierarchical Ti2Nb10O29 porous microspheres coated by ultrathin N-doped carbon layers for high-performance lithium-ion battery

Nanoparticle-assembled Ti2Nb10O29 porous microspheres coated by N-doped carbon layers ([email protected]–C-M) have been synthesized using ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([Emim]DCA) as carbon and nitrogen sources. Owing to the wide liquid range, low vapor pressure, and low surface tension of [Emim]DCA, the as-obtained N-doped carbon layers possess ultrathin thickness (~3 nm) and the primary TNO nanoparticles have ultrasmall sizes (20–30 nm). The synergistic effects from the particular structure lead to high electronic conductivity, fast ion/electron transport kinetics, and increscent pseudocapacitive contribution. Accordingly, the [email protected]–C-M anode has large discharge capacity (309.6, 262.2, 240.6, 216.5 and 204.5 mA h g−1 at 1, 5, 10, 20, and 30 C, respectively), good rate capacity (304.9 and 208.1 mA h g−1 at 1 and 30 C, respectively), and superior cycle stability (219.5 mA h g−1 after 500 cycles at 10 C). Also, the LiNi0.5Mn0.3Co0.2O2//[email protected]–C-M full cell also exhibits superior electrochemical properties with promising application prospect.