Li2ZnTi3O8 Research Articles

Boosted electrochemical performance of Li2ZnTi3O8 enabled by ion-conductive Li2ZrO3 concomitant with superficial Zr-doping

The poor electronic and ionic conductivities restrict the application of Li2ZnTi3O8 (LZTO) especially at high current rates. In this work, LZTO is modified with Li2ZrO3 (LZO) by simply reacting LiNO3 and Zr(NO3)4·5H2O on the surface of the as-prepared LZTO particles to improve the electrochemical performance. The modified LZTO with a LZO/LZTO mass ratio of 0.008 and sintered at 750 °C for 5 h exhibits greatly enhanced rate capabilities (acquiring reversible capacities of 196.1, 175.9, 154.9, 135.1, 109.8, and 223.6 mAh g−1 at 100, 200, 400, 800, 1600, and 100 mA g−1, respectively), and outstanding long-term cyclability (retaining a capacity of 199.2 mAh g−1 after 600 cycles at 500 mA g−1). On the basis of detailed characterizations on structure and composition as well as DFT calculations, the dispersed LZO nanoparticles and LZO coating bridge the LZTO particles to facilitate Li+ migration among the LZTO particles, while the superficial Zr4+ doping in LZTO promotes electron transfer, resulting in the simultaneously ameliorated electronic and ionic conductivities of LZTO, as well as alleviated polarization.

Uniform Surface Modification of Li2ZnTi3O8 by Liquated Na2MoO4 To Boost Electrochemical Performance.

Poor ionic and electronic conductivities are the key issues to affect the electrochemical performance of Li2ZnTi3O8 (LZTO). In view of the water solubility, low melting point, good electrical conductivity, and wettability to LZTO, Na2MoO4 (NMO) was first selected to modify LZTO via simply mixing LZTO in NMO water solution followed by calcining the dried mixture at 750 °C for 5 h. The electrochemical performance of LZTO could be enhanced by adjusting the content of NMO, and the modified LZTO with 2 wt % NMO exhibited the most excellent rate capabilities (achieving lithiation capacities of 225.1, 207.2, 187.1, and 161.3 mAh g-1 at 200, 400, 800, and 1600 mA g-1, respectively) as well as outstanding long-term cycling stability (delivering a lithiation capacity of 229.0 mAh g-1 for 400 cycles at 500 mA g-1). Structure and composition characterizations together with electrochemical impedance spectra analysis demonstrate that the molten NMO at the sintering temperature of 750 °C is beneficial to diffuse into the LZTO lattices near the surface of LZTO particles to yield uniform modification layer, simultaneously ameliorating the electronic and ionic conductivities of LZTO, and thus is responsible for the enhanced electrochemical performance of LZTO. First-principles calculations further verify the substitution of Mo6+ for Zn2+ to realize doping in LZTO. The work provides a new route for designing uniform surface modification at low temperature, and the modification by NMO could be extended to other electrode materials to enhance the electrochemical performance.

Microstructural and microwave dielectric properties of LZT (Li2ZnTi3O8) ceramics sintered in presence of bismuth borate glass for LTCC applications

In the present research, the Li2ZnTi3O8(LZT) ceramics were synthesized throughout solid-state ceramic processing, then mixed with bismuth borate (BiBO) glass prepared based on conventional melt quenching method. Wetting behavior of BiBO glass on the LZT ceramic substrate was monitored by hot stage microscopy. Afterward, dielectric LZT ceramics containing different amounts of BiBO glass (0.25–6wt%) were sintered at various temperatures. X-ray diffraction and electron back scatter diffraction examinations revealed the presence of two crystalline phases of Li2ZnTi3O8 and Bi2Ti2O7. The maximum value of relative density (above 95%) was obtained in the case of specimens contained more than 5wt% glass. The microwave dielectric properties of the finally sintered BiBO glass containing LZT ceramics were as follows: dielectric constant (εr) = 21.44–25.09, quality factor (Q × f) = 10839–54708GHz and temperature coefficient of resonant frequency (τf) = (− 15.58) − (− 12.86)ppm/°C.

Improved electrochemical performance of Li2ZnTi3O8 using carbon materials as loose and porous agent

Li2ZnTi3O8 (LZTO) was synthesized by solid-state reaction using TiO2-anatase, Li2CO3, Zn(CH3COO)2·2H2O as raw materials. Three well-designed modified samples including LZTO-K (keqin black), LZTO-M (carbon microspheres) and LZTO-S (super-P) were prepared by extra adding carbon materials as loose and porous agent in the synthesis process without any crystal structure change. Among the all samples, LZTO-M exhibits excellent electrochemical performances in terms of high capacities (209.6, 187.2, 178.0, 161.8, 154.4 mAh g−1 at current densities of 0.1, 0.5, 1.0, 2.0, 3.0 A g−1, respectively) after 100 circulations and shows remarkable stable cycling performance, retaining capacity of 133.6 mAh g−1 compared with that (82.6 mAh g−1) of LZTO over 500 cycles at 3.0 A g−1. The utilization of carbon microspheres not only reduces particle size of LZTO-M and makes particles well-distributed, but also promotes loose structure with uniform porous and increases the surface area.

Li2ZnTi3O8 based High κ LTCC tapes for improved thermal management in hybrid circuit applications

A low temperature co-fired ceramic based on Li2ZnTi3O8 (LZT), that possess auspicious thermal and dielectric properties is reported. In order to achieve the low sintering temperature suitable for LTCC applications (875°C), 1wt% of 20:Li2O-20: MgO-20: ZnO-20:B2O3-20: SiO2 (LMZBS) glass was added to LZT ceramics. The post-milled powder had an average particle size of 450nm with an effective surface area of 0.812m2g−1. A well dispersed tape casting slurry was prepared using xylene/ethanol mixture as solvent and fish oil as dispersant. The crystal structure and microstructure of the tapes were analyzed through XRD and scanning electron microscopy (SEM). The microwave dielectric properties of the green as well as sintered tapes were measured at different frequencies (5, 10 and 15GHz). The Li2ZnTi3O8+1wt% LMZBS has shown excellent thermal conductivity of 5.8W/mK, thermal expansivity (11.97ppm/°C) closer to silver electrode, low temperature coefficient of dielectric constant (−29ppm/°C) and ultralow dielectric losses (tanδ~10−4).

Investigation of N-doped carbon-coated lithium zinc titanate using chitin as a carbon source for lithium-ion batteries

Nitrogen-doped carbon-coated Li2ZnTi3O8 (NC-LZTO) anode material was fabricated with chitin as a carbon source by precoating process via a facile solid-state reaction method. The effects of nitrogen-doped carbon layer on the crystal structure, surface morphology, and electrochemical performances were studied. The NC-LZTO samples show the significant improvement in rate capability compared with carbon-coated Li2ZnTi3O8 (C-LZTO) sample derived from glucose and naked Li2ZnTi3O8 (LZTO) sample. At the current rates of 0.5, 1, 2, 5, and 10 C, the discharge-specific capacities of the NC-LZTO sample are 275.6, 262.8, 244.8, 217, and 190.6 mAh g−1, respectively. After 200 cycles at 2 C, its capacity retention is 98.7%. The increased electrochemical performance of NC-LZTO can be ascribed to the larger specific surface, smaller particle size, and better electronic conductivity.

Microwave dielectric properties of Li2ZnTi3O8 ceramics prepared by reaction-sintering process

Li2ZnTi3O8 (LZT) microwave dielectric ceramics prepared by reaction-sintering process were investigated. Li2CO3, ZnO and TiO2 powders were mixed, pressed and sintered directly into ceramic pellets without any calcination stage involved. Pure LZT phase was obtained after sintering at temperatures above 1,100 °C for 2 h. LZT ceramic with the maximum bulk density of 3.81 g/cm3 (96.2 % of the theoretical value) and excellent microwave dielectric properties of ɛ r = 25.8, Q × f = 78,216 GHz and τ f = −10.5 ppm/°C was obtained after sintering at 1,100 °C for 2 h. The results show that the reaction-sintering process is a simple and effective method to produce LZT ceramics.

Low-Temperature Sintering and Microwave Dielectric Properties of Li2ATi3O8 (A=Mg, Zn) Ceramics

New temperature-stable low-loss ceramic–glass composites based on Li2ATi3O8 (A=Mg, Zn) ceramics have been prepared by the conventional solid-state ceramic route. The effect of lithium magnesium zinc borosilicate (LMZBS) glass addition on the sinterability, phase purity, microstructure, and microwave dielectric properties of Li2MgTi3O8 (LMT) and Li2ZnTi3O8 (LZT) dielectric ceramics has been investigated for low-temperature co-fired ceramic applications. The LMT+3 wt% of LMZBS glass sintered at 925°C/4 h has ɛr=24.5, Qu×f=44,000 GHz, and τf=(+)0.2 ppm/°C. Addition of LZT ceramics with 3 wt% of LMZBS glass sintered at 900°C/4 h has ɛr=23.2, Qu×f=31,300 GHz, and τf=(−)15.6 ppm/°C. The LMT and LZT ceramic–glass composites do not react with the commonly used silver electrode material.