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Exploring electrode materials with a high volumetric energy density and high rate capability remains of a great challenge for nanosized-Li4Ti5O12(LTO)batteries.Here,hierarchical porous Ti3+-C-N-Br co-doped LTO(LTOCPB-cc)is synthesized using carboxyl-grafted nanocarbon(CC)and cetylpyridinium bromide(CPB)as combined structure-directing agents.Ti4+-O-CPB/Li+-CC is designed as a new molecular chelate,in which CPB and CC promote the uniform mixing of Li+and Ti4+and control the morphology of TiO2 and the final product.The defects(oxygen vacancies and ion dopants)formed during the annealing process increase the electron/hole concentration and reduce the band gap,both of which enhance the n-type electron modification of LTO.As-prepared LTOCPB-cc has a large specific surface area and high tap density,as well as a high electronic conductivity(2.84 × 10-4 S cm-1)and ionic conductivity(3.82 × 10-12cm2s-1),which are responsible for its excellent rate capability(157.7 mA h g-1 at 20 C)and stable long-term cycling performance(0.008％fade per cycle after 1000 cycles at 20 C).