Li₄Ti₅O₁₂/Co₃O₄Composite for Improved Performance in Lithium-Ion Batteries

Abstract

To take advantage of the best properties of both LTO and Co 3 O 4 , Li 4 Ti 5 O 12 /Co 3 O 4 composites were synthesized by the solution combustion and solution precipitation methods. The diffraction patterns of Li 4 Ti 5 O 12 (LTO), Co 3 O 4 , and LTO/Co 3 O 4 composites were well-indexed as a cubic spinel structure with the Fd-3m space group. As shown in the FE-SEM images, the Co 3 O 4 particles are attached on the surface of LTO, especially in the pore, and this structure is expected to prevent volume expansion and particle aggregation of Co 3 O 4 particles. As expected, the LTO/Co 3 O 4 composite had higher capacity than that of LTO, with a decreased slope and an extended plateau region over the voltage range of 0.01-3.0 V. LTO/Co 3 O 4 -20 delivered a reversible discharge capacity of 300 mAh g −1 at a constant current density of 160 mA g −1 . Also, it exhibited only a slight capacity drop with increasing current density. Galvanostatic intermittent titration technique and X-ray absorption near-edge structure spectroscopy were also conducted to Spinel Li 4 Ti 5 O 12 (LTO) has an excellent reversibility of Li-ion intercalation/de-intercalation and exhibits zero-strain volume change during cycling with excellent safety performance. Moreover, LTO has a high voltage plateau at 1.55 V vs. Li/Li + , which can avoid the formation of metallic lithium. Therefore, LTO has been investigated to use as the anode material of lithium ion batteries for energy storage, electric vehicles, and hybrid electric vehicles.1-3 However, unfortunately LTO has a low electronic conductivity with a low theoretical capacity of 175 mAh g −1 . These drawbacks restrict its applications in high-power storage devices. In this work, we attempted to overcome the low theoretical capacity of LTO and the poor cycling performance of Co 3 O 4 by synthesizing the LTO/Co 3 O 4 composites. Firstly, pristine LTO was synthesized by a two-step solution-combustion method and then LTO/Co 3 O 4 composites were synthesized by a solution precipitation method. ExperimentalMaterials synthesis.-LTO was synthesized using a solutioncombustion reaction.14 Titanium (IV) isopropoxide [Ti{OCH(CH 3 ) 2 } 4 ] was slowly dropped into distilled water under 10• C. After white precipitates (TiO(OH) 2 ) were observed, nitric acid was added and the mixture was constantly stirred until the appearance turned to transparent. Then, lithium nitrate was dissolved in distilled water and glycine was added as a fuel. After stirring at 80• C for 5 h to form a viscous gel, the precursor was dropped into an alumina crucible preheated to 500• C. This crucible was placed in a muffle furnace and heated at 750• C for 12 h. LTO/Co 3 O 4 composites were synthesized by using precipitation reaction of Co 2+ ion. The as-prepared LTO was uniformly dispersed in distilled water under stirring for 30 min, after that a certain quantity of Co(NO 3 ) 6 · H 2 O was dropped into the solution with mass ratios of 20 and 40, respectively. Then, NH 3 · H 2 O was slowly added into the above suspension and then s...

Tuning fermi level and band gap in Li4Ti5O12 by doping and vacancy for ultrafast Li+ insertion/extraction

“…As shown in Figure 3, the weak pre-edge peak near 4972 eV correlates with the transition of 1s→3d unoccupied state, which is due to the electric dipoleforbidden and quadruple-allowed transitions caused by the hybridization of 3d and 4p orbitals. 52 As the deformation of the octahedron decreases during the discharge process, the intensity of pre-edge peaks decreased. Moreover, the main Ti K-edge shifted to low energy during the discharge process, indicating Ti 4+ was reduced to Ti 3+ accompanied with the insertion of Li + .…”

Conversion-type Anode Materials for Alkali-Ion Batteries: State of the Art and Possible Research Directions

“…(e) Larger irreversible capacity loss and attendant initial low Columbic efficiency in Fe 2 O 3 conversion material . (f) Drastic decrease in capacity of conversion materials compared to alloying materials (reprinted with permission from refs − , and ).…”

The design and fabrication of Co 3 O 4 /Co 3 V 2 O 8 /Ni nanocomposites as high-performance anodes for Li-ion batteries

“…On the other hand, both the Co 3 O 4 and Co 3 V 2 O 8 were active materials to reversibly undergo redox reactions with lithium ion, thus contributing to high lithium ion storage capacity. The capacity retention of Co 3 O 4 /Co 3 V 2 O 8 /Ni nanocomposites was also higher than previously reported Co 3 O 4based, Co 3 V 2 O 8 -based and other anodes as summarized in Table S1[19,27,[32][33][34]38,39,[47][48][49][50][51][52][53] .Apart from the high capacity and good cycling stability, the Co3 O 4 /Co 3 V 2 O 8 /Ni nanocomposites also exhibited significantly enhanced rate capabilities as shown in Fig. 5 (d).…”

“…This phenomenon for the initial drop followed by gradual rise of the capacity was probably due to the reversible formation of a polymeric gel-like film derived from the decomposition of electrolyte [45] , commonly occurring in various metal oxide anode materials [12,46] . Furthermore, the [19,27,[32][33][34]38,39,[47][48][49][50][51][52][53] .…”