Self-assembled Li4Ti5O12/TiO2/Li3PO4 for integrated Li-ion microbatteries

This work aims to maximize the number of active sites for energy storage per geometric area, by approaching the investigation to 3D design for microelectrode arrays. Self-organized Li4Ti5O12/TiO2/Li3PO4 composite nanoforest layer (LTL) is obtained from a layer of self organized TiO2/Li3PO4 nanotubes. The electrochemical response of this thin film electrode prepared at 700 degrees C exhibited lithium insertion and de-insertion at 1.55 and 1.57 V respectively, which is the typical potential found for lithium titanates. The effects of lithium phosphate on lithium titanate are explored for the first time. By cycling between 2.7 and 0.75 V the LTL/LiFePO4 full cell delivered 145 mA h g(-1) at an average potential of 1.85 V leading to an energy density of 260 W h kg(-1) at C/2. Raman spectroscopy revealed that the gamma-Li3PO4/lithium titanate structure is preserved after prolonged cycling. This means that Li3PO4 plays an important role for enhancing the electronic conductivity and lithium ion diffusion. (C) 2015 Elsevier B.V. All rights reserved.