TiNb₂O₇ nanoparticles assembled into hierarchical microspheres as high-rate capability and long-cycle-life anode materials for lithium ion batteries

Abstract

As a competitor for Li4Ti5O12 with a higher capacity and extreme safety, monoclinic TiNb2O7 has been considered as a promising anode material for next-generation high power lithium ion batteries. However, TiNb2O7 suffers from low electronic conductivity and ionic conductivity, which restricts the electrochemical kinetics. Herein, a facile and advanced architecture design of hierarchical TiNb2O7 microspheres is successfully developed for large-scale preparation without any surfactant assistance. To the best of our knowledge, this is the first report on the one step solvothermal synthesis of TiNb2O7 microspheres with micro- and nano-scale composite structures. When evaluated as an anode material for lithium ion batteries, the electrode exhibits excellent high rate capacities and ultra-long cyclability, such as 258 mA h g(-1) at 1 C, 175 mA h g(-1) at 5 C, and 138 mA h g(-1) at 10 C, extending to more than 500 cycles.

Porous TiNb2O7 Nanospheres as ultra Long-life and High-power Anodes for Lithium-ion Batteries

“…4c). Compared to previous report, it is the first report on such a long cycling life about TNO materials [15][16][17][18][19][20][21][22][23][24][25][26].However, the capacity of m-TNO gradually drops to around 80 mA h/g after 1000 cycles with capacity retention of only 52% as shown in Fig. 4b.The result suggests that fabricating nanostructured materials may be a powerful means to improve the electrochemical performance of TNO.…”

“…Mesoporous TiNb2O7 fabricated through a block copolymer (BCP)-assisted self-assembly, showed a capacity retention of 48% during 2000 cycles at 10 C and rate performance of 116 mA h/g at 50 C [21]. Porous TiNb2O7 microspheres with diameter of 2~3 µm were obtained without any surfactant assistance, which exhibited an initial discharge capacity of 357.1 mA h/g at 0.1 C and maintained at ~115 mA h/g at 10 C after 500 cycles [22]. In addition, Lou's group synthesized porous TiNb2O7 microspheres with nitridation treatment, which exhibited a specific capacity of 190 mA h/g after 1000 cycles and a capacity retention of 61% at 100 C [23].…”

“…Recently, porous TiNb2O7 materials have attracted much attention for enhancing the electrochemical property [15,[21][22][23]. For example, faveolate-like porous TiNb2O7 materials, synthesized via sol-gel method, was first reported by Guo's group and showed good capacity retention of 84% after 1000 cycles at 5C [15].…”

“…Their advantage is to avoid the formation of passivating solid-electrolyte interphase (SEI) layer [4]. Among these candidates [5][6][7][8][9][10][11][12][13][14][15], TiNb2O7 with a voltage platform at about 1.65 V has attracted considerable interests owing to the high theoretical capacity of 387.6 mA h/g [15][16][17][18][19][20][21][22][23][24][25][26]. However, the low ionic and electronic conductivity of TiNb2O7 materials have limited the electrochemical performance [15,16].…”

Advanced composites of complex Ti-based oxides as anode materials for lithium-ion batteries

“…A simple method is to decrease particle sizes. As the Li + -ion and electron transport lengths in the primary particles are shortened, and the contact areas between the electroactive material and electrolyte are enlarged, improved rate capabilities can be achieved [16][17][18]. Crystal-structure modification performed by means of doping is another common approach.…”