Titanium dioxide nanotrees for high-capacity lithium-ion microbatteries

Abstract

Li-ion microbatteries find wide applications in microdevices. It is of importance to develop electrode materials with high areal capacity, excellent rate capability and superior safety for microbatteries. TiO 2 nanowire arrays satisfy the requirements of high areal capacity, short transport lengths and superior safety for microbatteries, but their areal/volumetric capacity is hindered by the insufficient surface area. TiO 2 nanotrees can effectively eliminate these disadvantages of TiO 2 nanowires; however, the electrochemical performances of TiO 2 nanotrees for Li-ion microbatteries remain unexplored. It is highly desired yet challenging to construct two-dimensional TiO 2 nanobranches with ultrathin thickness and large length on nanoarrays, to maximize the surface area and structural hierarchy of electrodes. Herein, we developed a novel synthetic strategy to fabricate TiO 2 nanotrees by depositing anatase/TiO 2 (B) mixed phase ultrathin nanobelts onto single-crystalline anatase nanowire arrays. The nanobelt branches were several nanometers in thickness and 200-260 nm in length. The growth process and the electrochemical mechanism were investigated. The unique nanoarchitecture and optimal phase structure endow the electrode with high areal capacity and rate capability, which is the best performance for TiO 2 nanowire arrays ever documented. The 2nd discharge capacity of the TiO 2 nanotrees at 0.1 mA cm -2 is ca. 267 μAh cm -2 , corresponding to a volumetric capacity of 330 mAh cm -3 . The TiO 2 nanotrees have an areal capacity of 205, 141, 97 and 69 μAh cm -2 at the current density of 0.5, 2.0, 5.0 and 10.0 mA cm -2 , respectively. The capacity can maintain stable for 400 charge-discharge cycles at 1.0 mA cm -2. The present strategy may give hints to elegant electrode designs for energy applications.This journal is

SiO2/TiO2 Composite Film for High Capacity and Excellent Cycling Stability in Lithium‐Ion Battery Anodes

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