Characterization of Nano-Sized Epitaxial Li4Ti5O12(110) Film Electrode for Lithium Batteries

Abstract

Electrochemical properties and structure changes of nano-sized Li 4 Ti 5 O 12 during lithium (de)intercalation were investigated using a two-dimensional thin film electrode. Li 4 Ti 5 O 12 thin films were deposited on a Nb:SrTiO 3 (110) substrate by a pulsed laser deposition technique. X-ray diffraction and reflectometry measurements confirmed the epitaxial growth of 27.6-nm-thick Li 4 Ti 5 O 12 (110) films. Galvanostatic charge-discharge curves showed a large discharge capacity of 217 mAh g −1 at the initial discharge cycle, although the reversible capacity decreased in subsequent cycles. In situ X-ray diffraction measurements clarified the drastic structural changes of the Li 4 Ti 5 O 12 film upon soaking in the electrolyte and during the first intercalation and deintercalation processes. The surface region of Li 4 Ti 5 O 12 had a different structure from the bulk during electrochemical cycling and could cause the nanosized Li 4 Ti 5 O 12 electrodes to have high capacities and poor stabilities.

Physical Vapor Deposition in Solid‐State Battery Development: From Materials to Devices

“…[ 137 ] For PLD processes, 700 °C was determined as the ideal deposition temperature to obtain well‐crystallized thin films. [ 138 ] Phase pure LTO was formed at oxygen pressures of 1.3 × 10 −2 Pa [ 139 ] and 3 Pa, [ 140 ] whereas the formation of LiTi 2 O 4 took place at 1.3 × 10 −4 Pa, [ 139 ] and secondary phases were formed at 6 Pa and above. [ 140 ] A full all‐solid‐state battery with a LTO thin‐film cathode deposited by PLD on a LLZ pellet at 500 °C and a Li‐foil anode was cycled at low C‐rates (highest C‐rate = 0.15C), and showed discharge capacities close to the theoretical value of LTO at 0.015C.…”

Pulsed Laser Deposited Films for Microbatteries

“…These films (~28 nm thick) were tested by cyclic voltammetry at a scan rate of 1 mV·s −1 and exhibited redox peaks at 1.53 and 1.60 V, corresponding to the insertion and extraction of Li + ions. As-deposited films at a substrate temperature of 700 • C in a 6.6 Pa oxygen partial pressure exhibited a high initial capacity (~200 mAh·g −1 ) but poor stability [311]. Kumatani…”

Pulsed Laser Deposition‐based Thin Film Microbatteries

“…[194] PLD grown Li has also been explored but these focus on what forms on the film during cycling. [195] The spinel Li 4 Ti 5 O 12 , which typically undergoes intercalation reactions, was investigated as a PLD grown electrode with factors such as orientation or surface planes, [196] role of electrolyte soaking and surface layers, [197] kinetic parameters, [198] annealing times, [199] role of colour change on insertion [200] and thickness [201] examined. PLD films grown for 20 minutes were found to deliver 141 mAh/g after 20 cycles at 1 C. [196] Related titanates have also utilised the Ti 3 + /Ti 4 + couple, e. g., SrLi 2 Ti 6 O 14 .…”

“…The spinel Li 4 Ti 5 O 12 , which typically undergoes intercalation reactions, was investigated as a PLD grown electrode with factors such as orientation or surface planes, role of electrolyte soaking and surface layers, kinetic parameters, annealing times, role of colour change on insertion and thickness examined. PLD films grown for 20 minutes were found to deliver 141 mAh/g after 20 cycles at 1 C .…”