Large Polarization of Li₄Ti₅O₁₂ Lithiated to 0 V at Large Charge/Discharge Rates

Abstract

The ability to enhance the specific capacity of Li4Ti5O12 (LTO) is of practical significance and offers the opportunity to increase the energy density of a full LTO-based battery. Widening the discharge cutoff voltage to 0 V is an effective way to increase the capacity of LTO at low current density. However, whether the specific capacity of LTO at large current rates can be enhanced remains largely unknown. Herein, intriguingly, we found that, when cycled down to 0 V (i.e., from 1.0-2.5 to 0-25 V), LTO exhibited greatly enhanced specific capacity at low rates (<5 C), while it showed a rapid capacity fading and a greatly increased charge/discharge potential gap at high rates (>10 C). The decreased lithium-ion diffusion caused by extra lithium-ion intercalation together with increased internal impedance significantly enhances the polarization and reduces the electrochemical reaction kinetics, which, in turn, hinders the lithiation reaction from LTO to Li7Ti5O12 and further to Li9Ti5O12.

Challenges of Spinel Li4Ti5O12 for Lithium‐Ion Battery Industrial Applications

“…[52] Lu et al [141] observed an abnormal interface layer on lithiated Li 4 Ti 5 O 12 samples using spherical aberration-corrected scanning transmission electron microscopy (STEM). Han et al [142] found that, when cycled down to 0 V at low rates (<5 C), Li 4 Ti 5 O 12 exhibited a greatly enhanced specific capacity; meanwhile at high rates (>10 C), the capacity rapidly faded, and the composite demonstrated a greatly increased charge/discharge potential gap. The stable reversible cycling capacity reached ≈330 mA h g −1 .…”

Recent Developments in Using Computational Materials Design for High-Performance Li4Ti5O12 Anode Material for Lithium-Ion Batteries

“…Extra discharge capacity and higher nominal voltage can be achieved with LTO as anode material when using the overlithiated phase. However, previous studies show that optimum utilization of this extra capacity still needs more mechanistic studies and large irreversible capacities have previously been attributed to the large polarization caused by substantial activation energy [55], the stability of the overlithiated phase [23,43] and SEI formation.…”

Nanostructured Anode Materials for Non‐aqueous Lithium Ion Hybrid Capacitors

“…Insertion‐type electrodes, include Li 4 Ti 5 O 12 , TiO 2 (anatase, bronze), TiNb 2 O 7 , Nb 2 O 5 , Li 3 VO 4 , H 2 Ti 6 O 13 , LiMnBO 3 , etc., have been explored for LIHC applications . The volume change accompanying this Li intercalation process is comparatively small (nearly 0% for Li 4 Ti 5 O 12 and <4% for anatase TiO 2 ), which ensures the structural integrity of the host lattice and renders high coulombic efficiency and long cycling life …”

“…Lithium titanate (Li 4 Ti 5 O 12 , LTO) is the firstly studied anode material for LIHC due to the following advantages: 1) the spinel structure of LTO provides a three‐dimensional network of channels for lithium ion diffusion, giving excellent rate capability for Li insertion and extraction, in particular at high charging/discharging rate; 2) the crytal structure undergoes almost no volume changes during Li insertion/extraction process, which ensures a long cyclic life and high coulombic efficiency; and 3) safe charging and discharging at a constant potential of 1.55 V versus Li/Li + , which is above the deposition potential of lithium ions and the reduction potential of most electrolytes or solvents . These properties render LTO a promising anode candidate for LIHC.…”