Zr⁴⁺ Doping in Li₄Ti₅O₁₂ Anode for Lithium‐Ion Batteries: Open Li⁺ Diffusion Paths through Structural Imperfection

Abstract

One-dimensional nanomaterials have short Li(+) diffusion paths and promising structural stability, which results in a long cycle life during Li(+) insertion and extraction processes in lithium rechargeable batteries. In this study, we fabricated one-dimensional spinel Li4Ti5O12 (LTO) nanofibers using an electrospinning technique and studied the Zr(4+) doping effect on the lattice, electronic structure, and resultant electrochemical properties of Li-ion batteries (LIBs). Accommodating a small fraction of Zr(4+) ions in the Ti(4+) sites of the LTO structure gave rise to enhanced LIB performance, which was due to structural distortion through an increase in the average lattice constant and thereby enlarged Li(+) diffusion paths rather than changes to the electronic structure. Insulating ZrO2 nanoparticles present between the LTO grains due to the low Zr(4+) solubility had a negative effect on the Li(+) extraction capacity, however. These results could provide key design elements for LTO anodes based on atomic level insights that can pave the way to an optimal protocol to achieve particular functionalities.

Cu/Li4Ti5O12 scaffolds as superior anodes for lithium-ion batteries

“…For example, the Cu/LTO electrode can maintain a high capacity when the current density is increased to 5 C or 20 C. Notably, at a very high current rate of 80 C, corresponding to a charge time of~45 s, the reversible capacity of Cu/LTO can still reach 127 mAh g − 1 . These results are far superior to those of other anode materials, [14][15][16][17][18][19][20][21][22] which clearly demonstrates that Cu/LTO is a promising high-energy and high-power electrode material for LIBs. In addition, Cu/LTO exhibits high-rate cycling performance, maintaining ultrastable capacity at 1 C for over 2000 cycles (Figure 3d).…”

“…13 High rate capability and high capacity of Cu/LTO scaffold for lithium storage The Cu/LTO was fabricated into coin cells to investigate its potential application in Li ion batteries. [14][15][16][17][18][19][20][21][22][23] As illustrated in Figure 3a, the as-made Cu/LTO not only can deliver ultrahigh capacity close to the theoretical value, but also possesses super cyclic capacity retention. For instance, after 1200 charge/discharge cycles, Cu/LTO can deliver an ultrahigh reversible capacity of 172 mAh g − 1 , which is comparable to the theoretical value (175 mAh g − 1 ).…”

“…The performance of the as-made Cu/LTO at such high rates is significantly better than that of other Li 4 Ti 5 O 12 -based high-rate electrodes in recently reported works. 5,[14][15][16][17][18][19][20][21][22] As shown in the compared results presented in Figure 3e, these reported electrodes include rutile TiO 2 -coated LTO, 5 nanocrystalline LTO, 14 Zr-doped LTO, 15 carbon-coated LTO, 16 Cr-doped LTO, 17 …”

“…1.5 V vs Li + /Li) and zero-strain insertion property, but its low electrical conductivity (~10 − 13 S cm − 1 ) and lithium diffusion coefficient (~10 − 13 cm 2 s − 1 ) hinder ultrafast lithium storage. 4,14,15 As illustrated in Figure 1a, in the commonly constructed LTO electrode architecture, there exist four primary resistances during the charging-discharging process: (1) Li + transport in the electrolyte; (2) Li + transfer from the electrolyte to the LTO electrode; (3) Li + diffusion in the electrode; and (4)electron conductance in the electrode and current collector. To realize the supercapacitor-like rate performance, a nanoporous Cu scaffold (NPCu) is used here as a template, and LTO NPs are then encapsulated into the nanopores of NPCu, as depicted in Figure 1c.…”

Li5Cr9Ti4O24: A new anode material for lithium-ion batteries

“…3. Consequently, the Li + ion diffusion coefficient D can be calculated based on the Randles-Sevcik equation [21][22][23][24][25][26][27][28][29]:…”