Promoting grain growth in Ni-rich single-crystal cathodes for high-performance lithium-ion batteries through Ce doping

Journal of Solid State Electrochemistry - Preparing a high-performance Ni-rich single-crystal cathode for Li-ion batteries is challenging. This is because calcination must be performed at a high...     

Mesoporous TiO2 nano networks: Anode for high power lithium battery applications

Anatase phase mesoporous TiO₂ with I41/amd space group was synthesized via the urea assisted hydrothermal method. The existence of mono phasic TiO₂ sub-microspheres of uniform particle size (ca. 400 nm) encompassing an average crystallite size of 14 nm was demonstrated using the XRD, FE-SEM and TEM analysis. Surface area of ca. 116.49 m²/g along with a pore size of 7 nm was calculated using the BET and adsorption isotherm measurements which authenticated the mesoporous nature of the synthesized material. Suitable calcination temperature for the better electrochemical property was established via the optimization process. Accordingly, the mesoporous TiO₂ calcined at 400 °C displayed improved cycleability with excellent rate capability ever reported, even at 20 C-rate of discharge. The reason for the superior rate capability is corroborated to the highly mesoporous nature of the TiO₂ sub-microspheres that has imparted desirable surface area apposite for enhanced ionic and electronic diffusion.     

Co-synthesis of nano-sized LSM–YSZ composites with enhanced electrochemical property

Nano-sized LSM–YSZ composite was co-synthesized by a glycine–nitrate process (GNP). Transmission electron microscopy revealed that the as-prepared LSM–YSZ particles consist of nano-sized powders with a dominant YSZ phase. Backscatter electron image shows that LSM and YSZ phases were regularly dispersed within the composite. Alternating current impedance measurement revealed that the co-synthesized LSM–YSZ electrode shows lower polarization resistance and activation energy than the physically mixed LSM–YSZ electrode. This electrochemical improvement would be attributed to the increase in three-phase boundary and good dispersion of LSM and YSZ phases within the composite. This paper is dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday.     

Improvement of high voltage cycling performance and thermal stability of lithium–ion cells by use of a thiophene additive

This study demonstrates that the addition of thiophene improves the cycle life of lithium–ion cells at high voltage. Electrochemical impedance spectroscopy results suggest that addition of thiophene significantly suppresses the increase of the charge transfer resistance that occurs during cycling up to high voltage. Differential scanning calorimetric studies showed that the thermal stability of fully charged LiCoO₂ cathode was also enhanced in the presence of thiophene.     

Synthesis and physical properties of N-substituted polyimides based on imidazole

AB-type monomers based on imidazole for the preparation of polyimides were synthesized by carrying out a substitution at the 1-position of 2-amino-4,5-dicyanoimidazole, followed by hydrolysis. Thus, pendant groups such as hexyl and 2,4-dinitrophenyl as an aliphatic long chain and an electron-withdrawing group, respectively, were introduced at the 1-position of the imidazole monomer. A solid-state polymerization was employed to prepare the poly(imidazoleimide)s in the form of a film from poly(imidazoleamic acid chloride)s by heating up to 180–200°C. The carbonyl stretching peaks of the imide ring appear at 1808 (sym) cm^?1 and 1756 (antisym) cm^?1. The effects of monomer structure on reactivity and the degree of imidization were investigated by comparing the viscosity of the resultant polymers and intensity of carbonyl peak at 1808 cm^?1. The difference in the hydrolysis rate between polyimides having short or long aliphatic pendant groups at the 1-position was observed using FT-IR. The inherent viscosity of the N-hexyl polyimide was 1.26 dL/g in N-methyl pyrrolidinone (NMP) and 0.22 dL/g in the case of N-2,4-dinitrophenyl poly(amic acid) in methanesulfonic acid at 30°C. The structural, physical, and material properties of the polyimides were characterized by infrared, nuclear magnetic resonance, luminescence, viscosimetric methods, differential scanning calorimetry, thermogravimetric analysis, optical microscopy, and wide angle x-ray scattering. Solution properties were also investigated by monitoring the viscosity as a function of time at 30°C. Luminescence spectroscopy of the poly(1-methyl imidazole imide) and poly(1-methyl imidazoleamic acid) films shows an emission band centered at 535 and 505 nm, respectively. Thermal properties are described comparing the weight loss and decomposition temperature as a function of the polymer structure and the degree of imidization. © 1993 John Wiley & Sons, Inc.     

Surface-stabilized amorphous germanium nanoparticles for lithium-storage material

Amorphous Ge nanoparticles with the particle size of approximately 10 nm were prepared by capping butyl groups and were characterized using XAS, TEM, FT-IR reflectance, and electrochemical cycling. The XAS results for the first-cycle Ge nanoparticles exhibited either a little particle aggregation after reformation of the Ge-Ge metallic bond or reformation of Ge-Ge metallic bond followed by a little particle aggregation. More interestingly, butyl groups, being electrochemically stable, remained after cycling, and the quantum mechanical calculation of the thermodynamic energy of the reaction using the GAMESS (General Atomic and Molecular Electronic Structure System) program suggested the formation of a very stable surface Ge-C bond that cannot be easily subjected to the subsequent chemical reactions. Initial charge capacity is 1470 mAh/g with an irreversible capacity ratio of 12%; no capacity fading was observed out to 30 cycles. Even at 5 C rate discharging, capacity retention was 98%, compared to that at 0.2 C rate discharging. In addition, the capacity was fully recovered at 0.2 C rate cycling.     

An advanced lithium ion battery based on high performance electrode materials

In this paper we report the study of a high capacity Sn-C nanostructured anode and of a high rate, high voltage Li[Ni(0.45)Co(0.1)Mn(1.45)]O(4) spinel cathode. We have combined these anode and cathode materials in an advanced lithium ion battery that, by exploiting this new chemistry, offers excellent performances in terms of cycling life, i.e., ca. 100 high rate cycles, of rate capability, operating at 5C and still keeping more than 85% of the initial capacity, and of energy density, expected to be of the order of 170 Wh kg(-1). These unique features make the battery a very promising energy storage for powering low or zero emission HEV or EV vehicles.     

State-of-the-art anodes of potassium-ion batteries: synthesis,chemistry, and applications

The growing demand for green energy has fueled the exploration of sustainable and eco-friendly energy storage systems. To date, the primary focus has been solely on the enhancement of lithium-ion battery (LIB) technologies. Recently, the increasing demand and uneven distribution of lithium resources have prompted extensive attention toward the development of other advanced battery systems. As a promising alternative to LIBs, potassium-ion batteries (KIBs) have attracted considerable interest over the past years owing to their resource abundance, low cost, and high working voltage. Capitalizing on the significant research and technological advancements of LIBs, KIBs have undergone rapid development, especially the anode component, and diverse synthesis techniques, potassiation chemistry, and energy storage applications have been systematically investigated and proposed. In this review, the necessity of exploring superior anode materials is highlighted, and representative KIB anodes as well as various structural construction approaches are summarized. Furthermore, critical issues, challenges, and perspectives of KIB anodes are meticulously organized and presented. With a strengthened understanding of the associated potassiation chemistry, the composition and microstructural modification of KIB anodes could be significantly improved.

State-of-the-art tendency, present critical issues and future opportunities of anode active materials in potassium ion batteries are systematically summarized.     

Synthesis and electrochemical characteristics of oxysulfide spinel material for lithium secondary batteries

Oxysulfide spinel LiMn₂O_3.98S_0.02 powders with monodispersed, and highly homogeneous particles were synthesized by a sol-gel method using an aqueous solution of metal acetates and sulfide containing glycolic acid as a chelating agent. The oxysulfide spinel, LiMn₂O_3.98S_0.02 electrode initially delivers 80 mAh g⁻¹, steadily increases during cycling, and reaches 99 mAh g⁻¹ at the 20th cycle. The substitution of a small amount S for O in LiMn₂O₄ spinel helps to maintain structural integrity during cycling, which then overcomes the Jahn–Teller distortion in the spinel Mn phase in the 3 V region.