Synthesis of Nb-Doped Li₂ZnTi₃O₈ Anode with Long Cycle Life and Applications in the LiMn₂O₄/Li₂ZnTi₃O₈ Full Cell

Abstract

An easy solid-state method is used to prepare Li2ZnTi3O8 (LZTO) doped by the Nb element (LZTN1O). Nb-doping not only improves the specific surface area, total pore volume, and ionic conductivity but also reduces the particle size and transfer resistance of LZTN1O. In addition, the structure has been stabilized, and good electrical contact has been obtained for the LZTN1O electrode via Nb-doping. Compared with LZTO, the electrochemical performance of LZTN1O at 0–55 °C is greatly improved. After 600 cycles, 99.1% of the capacity for the second cycle is obtained at 25 °C at 1 A g–1. For the current densities up to 2–4 A g–1, no capacity loss based on the specific capacity of the second cycle occurs at the 200th cycle at 25 °C. At 3 A g–1, 180.8 mA h g–1 is delivered at the 120th cycle. At 1 A g–1 for 55 °C, no capacity is lost (corresponding to the second cycle) after 100 cycles. At 0.8 A g–1 for 0 °C, 178.8 mA h g–1 can be obtained for the 60th cycle, and even no capacity is lost (corresponding to the second cycle) for the 500th cycle at 0.5 A g–1. Moreover, when LZTN1O was applied in the LiMn2O4/LZTN1O full cell, the initial discharge specific capacity based on the mass of LiMn2O4 is 90.2 mA h g–1 at 0.5 C in 2.1–3.8 V.

Li2ZnTi3O8anode: design from material to electrode and devices

“…21a). 46 When x values were up to 0.03–0.5, Ti 2 O 3 was detected from the samples. Compared with LZTNO-05 with the secondary phase of TiO 2 prepared by the Naila Firdous et al , the rate capability was significantly enhanced for Li 2 ZnTi 2.99 Nb 0.01 O 8 (LZTN1O), with 180.8 mA h g −1 at 3 A g −1 for the 120 th cycle.…”

“…Our group synthesized Nb-doped, La-doped, and oxygen-deficient LZTO (LZTO-FA). 26,46,47 The ever-increasing trend of the specific capacities before 150–200 cycles for the three samples may originate from the continuous decomposition of the electrolyte and the appearance of the new active materials for Li 2 Ti 3 O 7 and ZnO (Fig. 4).…”

“…Ti-site replacement is the most popular for LZTO. Various elements have been doped into the 12d site to replace some Ti 4+ ions, such as Ag + , 48 Al 3+ , 49 Fe 3+ , 43 Ti 3+ , 117 Sm 3+ , 90 Cr 3+ , 118,119 Ce 4+ , 120 Nb 5+ , 46,121 Ta 5+ , 91 and Mo 6+ . 28…”

“…In addition, it was reported that coating could suppress the continuous reduction decomposition of the electrolyte. 46 The time of side reactions between LZTO and the electrolyte slightly shortened via doping. 47 However, the effects are not obvious for inhibiting the continuous decomposition of the electrolyte via coating or doping.…”

“…Ti-site replacement is the most popular for LZTO. Various elements have been doped into the 12d site to replace some Ti 4+ ions, such as Ag + , 48 Al 3+ , 49 Fe 3+ , 43 Ti 3+ , 117 Sm 3+ , 90 Cr 3+ , 118,119 Ce 4+ , 120 Nb 5+ , 46,121 Ta 5+ , 91 and Mo 6+ . 28 Tang's group has done some work on the substitution of ions with low valences into the 12d site for some Ti 4+ ions with high valences.…”