Short communication
Low-temperature preparation of mesoporous TiO2 honeycomb-like structure on TiO2 nanotube arrays as binder-free anodes for lithium-ion batteries

https://doi.org/10.1016/j.jelechem.2020.114088Get rights and content

Highlights

  • Mesoporous TiO2 honeycomb-like structure was generated on TiO2 nanotube arrays.

  • This special structure facilitated Li-ions transmission and electrolyte penetration.

  • As a binder-free anode, TiO2 NTAs/HS avoided using binders and additives.

  • TiO2 NTAs/HS exhibited high specific capacities and good cycling stability.

Abstract

TiO2 is a typical intercalated-type anode material for lithium-ion batteries (LIBs). TiO2 nanotube arrays (NTAs) were prepared by anodic oxidation method on Ti foils. Then treated with TiF4 solution at 60 °C for 4 h, anatase TiO2 honeycomb-like structure (HS) was uniformly distributed on the top of TiO2 NTAs. The thickness and diameter of the generated TiO2 HS are about 59 nm and 121–153 nm, respectively. Furthermore, the TiO2 HS has uniform mesopores (~ 3 nm), which can supply abundant Li-ion diffusion and transport channels. The as-prepared TiO2 NTAs/HS served as binder-free anodes of LIBs and exhibited high invertible specific capacities (290 mAh g−1, 0.1 A g−1 and 96 mAh g−1, 2 A g−1). The TiO2 NTAs/HS electrode also showed a good cycling stability with the specific capacity of 40 mAh g−1 after 1000 cycles at a current density of 1 A g−1. Hence, this low-temperature in situ preparation of mesoporous TiO2 HS is an effective way to improve the performance of TiO2 as anode for LIBs.

Introduction

Lithium-ion battery (LIB) is one of rechargeable batteries with promising applications in electronic products, such as smartwatch, toys, laptops and so on. Recently, more and more electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by LIBs emerge rapidly in the LIB markets. However, the power density and cycling stability of LIBs still remained to be improved [[1], [2], [3]]. Meanwhile, the most commercial LIBs with graphite anode exhibit the low specific capacity and poor lithiation rate capability [4]. Hence, to design and fabricate high-performance anodes for LIBs are still highly demanded.

Titanium-based compounds such as lithium titanate (Li4Ti5O12) and titanium dioxide (TiO2) are promising anode materials for LIBs. During the discharge/charge process, volume changes of Li4Ti5O12 (0.2%) and TiO2 (<4%) are both smaller than graphite (10%) [5,6]. But the theoretical specific capacity of Li4Ti5O12 is only 175 mAh g−1, that limits its further application. Compared to Li4Ti5O12, TiO2 has high theoretical specific capacity (336 mAh g−1), low cost and easy for preparation [7,8]. However, the poor electric conductivity and sluggish Li-ion diffusion hinder the practical application of TiO2 in LIBs, too.

For far, many methods have been used to improve the electrochemical performance of TiO2 anode. Amongst, designing nanostructured TiO2 is considered as a common approach to improve its Li-ion transport kinetics [9]. TiO2 with many different morphologies were prepared and their electric conductivities and Li-ion diffusion properties were studied. It has been demonstrated that, in particularly, one-dimensional (1D) TiO2 such as nanotubes, nanorods, nanowires could well avoid agglomeration of nanoparticles and exhibit excellent electrochemical performance as anodes [[10], [11], [12]]. Furthermore, the 1D TiO2 nanowire arrays (NWAs) or nanotube arrays (NTAs) on Ti foils can not only supply favorable electron and ion transport channels, but also avoid using the binder agent during the anode preparation. In a previous study, our group developed a simple hydrothermal method to prepare hierarchical TiO2-x on Ti foils, that showed manifest pseudocapacitive property [13]. Besides, the template method is also commonly used to prepare mesoporous TiO2 [14,15]. For instance, Zhao et al. [16] prepared single-layered TiO2 mesopores coated SiO2 (SiO2@SL-m TiO2) using Pluronic triblock copolymer F127 as a template, showed excellent electrochemical performance for sodium-ion storage. However, the template method usually needs to remove the template by etching or high-temperature treatment. Imai et al. prepared mesoporous anatase TiO2 through a template-free method on various substrates using TiF4 solution as precursor at 40–70 °C [[17], [18], [19]]. Cheng and Jiao et al. [20] synthesized mesoporous succulents-like TiO2/graphene aerogel in TiF4 solution at 60 °C. As an anode material for LIBs, this composite showed high reversible capacities of 663.2 and 215.5 mA h−1 at current densities of 0.1 and 5 A g−1, respectively.

In this work, mesoporous TiO2 honeycomb-like structure (HS) was generated in situ on the top of TiO2 nanotube arrays (NTAs) in TiF4 solution at 60 °C. It can be seen after treating with TiF4 for 4 h, the thickness and diameter of the as-generated TiO2 HS are about 59 nm and 121–153 nm, respectively. Meanwhile, the homogeneous mesopores (~3 nm) were formed also on the nanosheets of TiO2 HS. As binder-free anode of LIBs, TiO2 NTAs/HS exhibited a high discharge specific capacity (422 mAh g−1, 0.1 A g−1) even at a high current density of 2 A g−1 (96 mAh g−1) and good cycling stability. The outstanding electrochemical performance of TiO2 NTAs/HS should be contributed from the synergistic effects of NTAs morphology and the mesoporous structure of TiO2, supplying enriched electron transmission and Li-ion diffusion channels. Hence, TiO2 NTAs/HS should be a promising anode material for LIBs.

Section snippets

Experimental

As illustrated in Fig. 1, TiO2 NTAs were fabricated on Ti foils by a two-step anodic oxidation. Briefly, before the anodic oxidation process, the Ti foils (thickness ~ 0.25 mm, purity > 99%, Hebei Runhe Metal Products Co. Ltd., China) were cut into pieces of 2 × 3 cm2 and treated with a polishing solution including 1 g NH4F and 30 mL HNO3 in 30 mL H2O for 5 min, then washed with deionized water and ethanol for three times, respectively. Two pieces of Ti foils were used separately as anode and

Results and discussion

As shown in Fig. 2a-b, the TiO2 NTAs are oriented perpendicularly on the surface of Ti foil. The length and diameter of TiO2 nanotubes are about 17 μm and 65–136 nm, respectively. After dipping in the TiF4 solution for certain time, a thin TiO2 HS can be observed on the top of TiO2 NTAs (Fig. 2c-h). With the time in TiF4 solution was increased from 2 h to 6 h, the thickness of TiO2 HS is increased from 36 nm to 95 nm, and the diameter also enlarged. When treated 4 h, the structure of TiO2 HS is

Conclusions

In summary, the TiO2 HS was directly prepared on TiO2 NTAs with TiF4 solution as precursor at a low-temperature. When reacted in TiF4 solution for 4 h, the TiO2 HS was relatively neat with mesopores (~ 3 nm), which was beneficial to facilitate Li-ion and electron transportations. As a binder-free anode, the TiO2-4 achieves a superior discharge specific capacity (422 mAh g−1, 0.1 A g−1), excellent rate capability (96 mAh g−1, 2 A g−1) and long cycle stability (1000 cycles, 40 mAh g−1, 1 A g−1).

CRediT authorship contribution statement

Jinghao Huo: Conceptualization, Methodology, Writing - review & editing, Funding acquisition. Yujia Xue: Software, Investigation, Data curation, Writing - original draft. Yi Liu: Formal analysis, Visualization, Funding acquisition.Shouwu Guo: Validation, Resources, Supervision, Project administration.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The Natural Science Foundation of Shaanxi University of Science and Technology (2016BJ-49) and the Natural Science Foundation of China (61704047) supported this work.

Cited by (19)

  • TiO<inf>2</inf> quantum dots decorated Si nanocage for enhanced lithium ion batteries

    2023, Journal of Electroanalytical Chemistry
    Citation Excerpt :

    However, its sluggish ion insertion/extraction kinetics and low electronic conductivity hinders the wide application in LIBs [26]. TiO2 anodes of various structures have been synthesized and used to improve the electrochemical performance [27-31]. Wang et al. [32] synthesized uniform multihulled TiO2 hollow microspheres with up to 237 mAh g-1 with minimal irreversible capacity after 100 cycles at 1 C, and a capacity of 119 mAh g-1 at 10 C even after 1200 cycles.

  • Robust hollow Bowl-like α-Fe<inf>2</inf>O<inf>3</inf> nanostructures with enhanced electrochemical lithium storage performance

    2022, Journal of Colloid and Interface Science
    Citation Excerpt :

    Therefore, designing LIBs anode materials with high energy capacity and good cycling durability has become an urgent task [5–7]. Compared to graphite anode materials, transition metal oxides such as Fe2O3 [8], Co3O4 [9], NiO [10], SnO2 [11], ZnO [12] and TiO2 [13], etc. have much higher theoretical specific capacities and show great potentials to serve as substitutions for graphite materials as LIBs anode in the future. Specifically, Fe2O3 can exhibit a high theoretical capacity of 1007.0 mAh g−1, and combining with the advantages of natural abundance, chemical stability and environment friendliness, is regarded as one of the most promising candidates for commercial anode [14,15].

  • Anatase titanium dioxide as rechargeable ion battery electrode - A chronological review

    2022, Energy Storage Materials
    Citation Excerpt :

    This electrode kept a reversible capacity of about 120 mAh g−1 after 300 cycles at 1 C (1 C = 190 mA g−1) and also reached a capacity of 92 mAh g−1 at 10 C. Similar to the previous stage, template-induced (both hard and soft templates)[485–492] and self-assembly methods[493–496] were still the main approach to achieve anatase 3D porous structures. shang et al. reported a bicontinuous shifted double diamond (SDD) structured mesoporous anatase TiO2 scaffold with highly ordered structure as a promising anode material for LIBs [491].

  • TiO<inf>2</inf> NTAs decorated with thin CuBi<inf>2</inf>O<inf>4</inf> nanosheets for efficient photocatalytic dye degradation and hydrogen generation

    2022, Ceramics International
    Citation Excerpt :

    TiO2 photocatalysts are attractive functional materials because of the strong solar absorption and efficient solar energy transformation into electrical, chemical and hydrogen energy [4,5], and therefore several thousands of papers are published every year to report the preparation and modification of TiO2 [6–9]. However, the low recycling efficiency of TiO2 powder is attributed to the complex operation and inevitable loss of photocatalysts [10,11]. Compared with TiO2 powders, TiO2 nanoparticles scattered on Ti substrates have attracted extensive attention, which could be directly used as photoelectrodes for pollutant degradation and solar cells [12–14].

  • Application of different carbon-based transition metal oxide composite materials in lithium-ion batteries

    2021, Journal of Electroanalytical Chemistry
    Citation Excerpt :

    Potential alternative anode materials [234,235]. In addition, in the sense of theoretical capacity, titanium dioxide exhibits a capacity of 336 mAh g−1 [236-238]. However, the low conductivity of TiO2 will result in poor rate capability, and the capacity will be greatly reduced during cycling, which limits its application in high-power LIB [239,240].

View all citing articles on Scopus
View full text