Li2MnO3 rich-LiMn0.33Co0.33Ni0.33O2 integrated nano-composites as high energy density lithium-ion battery cathode materials

Alternative to LiCoO2 cathode without sacrificing its structure and capacity, layered-layered composites with Li2MnO3-LiMO2 formula have been pursued in this article. In this study, we have optimized the Li2MnO3 content in the composite based on its electrochemical performances (in terms of specific capacity, mAh g(-1)). All the samples are synthesized either by self-combustion reaction (SCR) or solid-state method. Phase composition, morphology, particle size and distribution are characterized by using X-ray diffraction (XRD), field emission gun scanning electron microscope (FEG-SEM) and high resolution transmission electron microscope (HR-TEM), respectively. The X-ray diffraction study confirms that the material has layered LiNi0.3Co0.3Mn0.3O2 structure with a space group of R (3) over barm along with the formation of Li2MnO3 phase with super lattice ordering (C2/m). Charge/discharge capacity of the composite cathode materials increases with cycle number due to more and more activation of the Li2MnO3 and get stabilized after 20th cycle with good coulombic efficiency. A composite of 0.7Li(2)MnO(3)-03LiMn(0.33)Co(0.33)Ni(0.33)O(2) composition delivered a maximum stable specific discharge capacity of similar to 190 mAh g(-1) over 50 cycles at C/10 rate at 20 degrees C once it reaches the activation stage. A detail electrochemical study has been performed to understand the complicated electrochemistry during charge-discharge reaction at 20 degrees C. (C) 2013 Elsevier Ltd. All rights reserved

Electrochemical Properties of Spinel Cobalt Ferrite Nanoparticles with Sodium Alginate as Interactive Binder

We introduce a process of making high-capacity and rate-capable metal-ferrite-based conversion anodes for lithium-ion batteries. Cobalt ferrite (CoFe2O4) exhibits a discharge capacity that is two-times higher compared to the state-of-the-art graphite anode, but at the same time it shows high volume change (ca. 95%) during conversion reaction with lithium in an electrochemical environment. This large volume expansion is responsible for the particle-particle and conductive-carbon particles-active materials detachment, which leads to cyclic instability during subsequent cycles. As observed in our earlier work, any kind of weak or strong chemical interaction between active materials and binder is necessary to achieve excellent electrochemical performance in case of conversion or alloying reactions. To compare the electrochemical activity of CoFe2O4 nanoparticles against lithium, we use conventional polyvinylidene fluoride and sodium alginate binder to fabricate electrodes. Fourier-transform infrared measurements reveal weak hydrogen-bond formation between surface -OH groups of CoFe2O4 and -COOH groups of the alginate binder. Indentation tests further confirm the increased hardness of the alginate/CoFe2O4-based electrode films. CoFe2O4-alginate-carbon anode exhibits a high specific capacity of 890 mAhg (1) at 0.1 C rate (91.4 mAg(-1)) after 50 charge-discharge cycles. Even at high rate cycling with current densities such as 18280 mAg(-1) (20 C), the same electrode material exhibits a specific capacity of 470 mAhg(-1), which is much higher than that of conventional graphite anode at the same electrochemical conditions