Browsing by Subject "Lithium ion batteries"

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    Improved lithium-ion battery anode performance via multiple element approach
    (Elsevier, 2018) Ghobadi, T. G. U.; Kunduraci, M.; Yilmaz, Eda
    In this work, single (Co3O4), binary (Co3O4/ZnO) and ternary (Co3O4/ZnO/NiO) nanomaterials were successfully synthesized by Pechini method followed by a calcination step. Electrochemical lithium storage capabilities of the anode materials were studied. The results showed that the best capacity retention and lowest voltage hysteresis was achieved with ternary material. The ternary material showed a first cycle charge capacity of 649 mAh/g at 70 mA/g and maintained 83% of this capacity after 39 cycles. The results demonstrated the positive impact of multiple element strategy on the cycle life of anode materials.
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    ItemOpen Access
    Lyotropic liquid crystalline mesophases made of salt-acid-surfactant systems for the synthesis of novel mesoporous lithium metal phosphates
    (Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim, 2019) Uzunok, Işıl; Kim, J.; Çolak, Tuluhan O.; Kim, D.; Kim, H.; Kim, M.; Yamauchi, Y.; Dağ, Ömer
    Mesoporous lithium metal phosphates are an important class of materials for the development of lithium ion batteries. However, there is a limited success in producing mesoporous lithium metal phosphates in the literature. Here, a lyotropic liquid crystalline (LLC) templating method was employed to synthesize the first examples of LiMPO4 (LMP) of Mn(II), Co(II), and Ni(II). A homogeneous aqueous solution of lithium and transition metal nitrate salts, phosphoric acid (PA), and surfactant (P123) can be spin coated or drop‐cast coated over glass slides to form the LLC mesophases which can be calcined into mesoporous amorphous LMPs (MA‐LMPs). The metal salts of Mn(II), Co(II) and Ni(II) produce MA‐LMPs that crystallize into olivine structures by heat treatment of the LLC mesophase. The Fe(II) compound undergoes air oxidation. Therefore, both Fe(II) and Fe(III) precursors produce a crystalline Li3Fe2(PO4)3 phase at over 400 °C. The MA‐LMPs show no reactivity towards lithium, however the crystalline iron compound exhibits electrochemical reactivity with lithium and a good electrochemical energy storage ability using a lithium‐ion battery test.
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    Phenothiazine-based polymer cathode materials with ultrahigh power densities for lithium ion batteries
    (American Chemical Society, 2018) Peterson, B. M.; Ren, D.; Shen, L.; Wu, Y. -C. M.; Ülgüt, Burak; Coates, G. W.; Abruna, H. D.; Fors, B. P.
    Lithium ion batteries (LIBs) currently deliver the highest energy density of any known secondary electrochemical energy storage system. However, new cathode materials, which can deliver both high energy and power densities, are needed to improve LIBs. Herein, we report on the synthesis of a new organic-based redox-active material centered about phenothiazine and phenylenediamine units. Improved Coulombic efficiencies and greater capacity retention during cycling are observed through the copolymerization of a phenothiazine-based monomer that yields cross-linked materials. With this as the positive electrode in Li-coin cells, high specific capacities (150 mAh/g) are delivered at very positive operating voltages (2.8−4.3 V vs Li+ /Li), yielding high energy densities. The material has low charge transfer resistance as verified by electrochemical impedance spectroscopy, which contributes in delivering previously unseen power densities in coin cells for organic-based cathodes. Excellent retention of capacity (82%) is observed at ultrafast discharge rates (120 C).