Oxygen vacancy modulated Ti2Nb10O29-x embedded onto porous bacterial cellulose carbon for highly efficient lithium ion storage

Highlights: • Construct oxygen vacancy modulated titanium niobium oxide (TNO_x) on bacterial cellulose carbon (BCC). • Oxygen vacancy can effectively enhance the internal ion/electron transfer in TNO_x. • The TNOx/BCC electrode shows superior lithium storage performance. -- Abstract: Rational design & modulation of ion/electron transfer paths are critical for achieving high-performance anode materials for lithium ion batteries. In this work, we first time realize smart assembly of oxygen vacancy modulated titanium niobium oxide (Ti₂Nb₁₀O_29-x, TNO_x) onto highly conductive bacterial cellulose carbon (BCC) forming BCC/TNO_x electrode through a facile solvothermal-annealing method. BCC consists of interlinked (N, S & P) co-doped carbon fibres uniformly decorated with TNO_x nanoparticles. Impressively, the introduction of oxygen vacancy can effectively enhance the internal ion/electron transfer in TNO_x and enhancement effect is elaborated by synchrotron radiation technology (XANES and XAFS) and DFT calculation. Meanwhile, with the aid of conductive BCC skeleton, the external ion/electron transfer path on TNO_x is also greatly improved leading to better reaction kinetics. The synergistic dual internal plus external modulation on transfer path show positive advantages including smaller band gap with better electrical conductivity, and larger lattice parameters with faster ion/electron transfer. Accordingly, the BCC/TNO_x electrode is endowed with outstanding lithium ion storage performance with high-rate capability (281 mA h g⁻¹ at 5 C, and 160.5 mA h g⁻¹ at 40 C). Our finding provides valuable insights into design of other advanced electrodes via dual transfer path modulation strategy.