TiO2(B) Nanoribbons As Negative Electrode Material for Lithium Ion Batteries with High Rate Performance

Nanosized TiO2(B) has been investigated as a possible candidate to replace Li4Ti5O12 or graphite as the negative electrode for a Li-ion battery. Nanoribbon precursors, classically synthesized in autogenous conditions at temperatures higher than 170 °C in alkaline medium, have been obtained, under reflux (T ∼ 120 °C, P = 1 bar). After ionic exchange, these nanoribbons exhibit a surface area of 140 m2 g−1, larger than those obtained under autogenous conditions or by solid state chemistry. These nanoparticles transform after annealing to isomorphic titanium dioxide. They mainly crystallize as the TiO2(B) variety with only 5% of anatase. This quantification of the anatase/TiO2(B) ratio was deduced from Raman spectroscopy measurement. TEM analysis highlights the excellent crystallinity of the nanosized TiO2(B), crystallizing as 6 nm thin nanoribbons. These characteristics are essential in lithium batteries for a fast lithium ion solid state diffusion into the active material. In lithium batteries, the TiO2(B) nanoribbons exhibit a good capacity and an excellent rate capability (reversible capacity of 200 mA h g−1 at C/3 rate (111 mA g−1), 100 mA h g−1 at 15C rate (5030 mA g−1) for a 50% carbon black loaded electrode). The electrode formulation study highlights the importance of the electronic and ionic connection around the active particles. The cycleability of the nano-TiO2(B) is another interesting point with a capacity loss of 5% only, over 500 cycles at 3C.