Enhanced Rate Capability of Oxide Coated Lithium Titanate within Extended Voltage Ranges

Abstract

Lithium titanate (Li 4 Ti 5 O 12 or LTO) is a promising negative electrode material of high-power lithium-ion batteries, due to its superior rate capability and excellent capacity retention. However, the specific capacity of LTO is less than one half of that of graphite electrode. In this work, we applied ultrathin oxide coating on LTO by the atomic layer deposition technique, aiming for increasing the energy density by extending the cell voltage window and specific capacity of LTO. We demonstrated that a few nanometer thick Al 2 O 3 coating can suppress the mechanical distortion of LTO cycled at low potential, which enable the higher specific capacity and excellent capacity retention. Furthermore, the surface coating can facilitate the charge transfer, leading to significantly improved rate capabilities, comparing with the uncoated LTO.

Nanoscale Porous Lithium Titanate Anode for Superior High Temperature Performance

“…However, during the first cycle discharge, the amount of lithium ions deintercalated from LTO was lower due to SEI formation which resulted in low Coulombic efficiency and high irreversibility for the first cycle. Similar results have been reported by other researchers. , Another important factor to consider is the electrode loading. The LTO-anode based cells were built with very high electrode loading of 3.14 mg cm –2 .…”

“…This is because of the high active surface area of the LTO nanoparticles that participate in the surface side reactions to form the SEI. Similar behavior in the initial cycle was reported in the prior works. ,,,− In the next two cycles, the charge–discharge curves of the LTO were nearly repeatable, implying good reversibility. Cycling performance and Coulombic efficiency of the LTO for 500 cycles are shown in Figure b.…”

“…For instance, the 115.53 mA h g –1 capacity at the end of the 100th cycle at 5C and 50 °C reported is high compared to the previously reported ∼110 mA h g –1 at 5 C and 55 °C with carbon coated LTO nanowires ,, In addition, it should be noted that all this was achieved without performing any additional post surface treatments on the synthesized LTO anode material.…”

“…The Coulombic efficiency of LTO in the first cycle can be very low depending on the particle size, loading, and other factors. Especially the nanosized active material can lead to a very low first cycle Coulombic efficiency. , The synthesized LTO was a spray-dried, porous, and nanosized material with high surface area. Thus, there were more active sites on the anode surface during the first cycle charging, and the charge capacity was much higher (136.05 mA h g –1 ).…”

“…In addition, the grain size of the LTO particles can be tuned and controlled by the calcination temperature . The synthesis was performed in a total time of around 12–14 h and no further treatments like surface coating ,,− , were performed, and the prepared LTO material based cells were found to exhibit stable electrochemical performance. Scheme summarizes the stable performance achieved from the synthesized nanoscale porous LTO.…”