Hierarchical TiO2/C nanocomposite monoliths with a robust scaffolding architecture, mesopore-macropore network and TiO2-C heterostructure for high-performance lithium ion batteries

Engineering hierarchical structures of electrode materials is a powerful strategy for optimizing the electrochemical performance of an anode material for lithium-ion batteries (LIBs). Herein, we report the fabrication of hierarchical TiO2/C nanocomposite monoliths by mediated mineralization and carbonization using bacterial cellulose (BC) as a scaffolding template as well as a carbon source. TiO2/C has a robust scaffolding architecture, a mesopore-macropore network and TiO2-C heterostructure. TiO2/C-500, obtained by calcination at 500 °C in nitrogen, contains anatase TiO 2-C heterostructure with a specific surface area of 66.5 m2g-1. When evaluated as an anode material at 0.5 C, TiO2/C-500 exhibits high and reversible lithium storage capacity of 188 mA h g-1, excellent initial capacity of 283 mA h g-1, long cycle life with 94 % coulombic efficiency preserved after 200 cycles, and very low charge transfer resistance. The superior electrochemical performance of TiO2/C-500 is attributed to the synergistic effect of high electrical conductivity, anatase TiO 2-C heterostructure, mesopore-macropore network and robust scaffolding architecture. The current material strategy affords a general approach for the design of complex inorganic nanocomposites with structural stability, and tailorable and interconnected hierarchical porosity that may lead to next generation of electrochemical supercapacitors with high energy efficiency and superior power density.Sincere gratitude goes to funding agencies for financially support: Y. Xu to NNSF China (2117 1067, 21373100), Jilin Provincial Talent Fund (802110000412) and Tang Aoqing Professor Fund of Jilin University (450091105161). T. Hasan to the Royal Academy of Engineering Research Fellowship. B.L. Su to the Thousand Talents Program of China (“Expert of the State” position), Clare Hall Life Membership at the Clare Hall College and the financial support of the Department of Chemistry, University of Cambridge, L.H. Chen and Y. Li to the Department of Education of Hubei Province for “Chutian Scholar” program, NNSF China (21301133), Hubei Natural Science Foundation (2014CFB1 60, 2015CFB428) and the financial support of SRF for ROCS (SEM [2015]311).This is the author accepted manuscript. The final version is available from the Royal Society of Chemistry via https://doi.org/10.1039/C5NR09149