• P Periasamy

      Articles written in Bulletin of Materials Science

    • Solid-state synthesis and characterization of LiCoO2 and LiNiyCo1−y solid solutions

      P Periasamy B Ramesh Babu R Thirunakaran N Kalaiselvi T Prem Kumar N G Renganathan M Raghavan N Muniyandi

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      Solid solutions of compositions LiNiyCo1−yO2 (y = 0.0, 0.1 and 0.2) were prepared by solid-state fusion synthesis from carbonate precursors. Material characterization was carried out using XRD. Formation mechanisms of the products are discussed in the light of TG/DTA results. Nickel-containing compositions gave higher discharge capacities and smaller hystereses in their charge-discharge profiles which make them more attractive than pristine LiCoO2 as cathode materials in high-energy lithium cells. The lower loss in capacity per cycle for cells with unsubstituted LiCoO2, as determined from cycling studies up to 25 cycles, makes it more suitable than the substituted ones for long cycle-life cells with low capacity fade.

    • Electrochemical behaviour of LiM𝑦Mn2–𝑦O4(M = Cu, Cr; 0 𝑦 0 4)

      R Thirunakaran B Ramesh Babu N Kalaiselvi P Periasamy T Prem Kumar N G Renganathan M Raghavan N Muniyandi

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      Spinel lithium manganese oxide, LiMn2O4, is beset with problems of capacity fade upon repeated cycling. The loss in capacity upon cycling is attributable to Jahn–Teller distortion and manganese dissolution in the electrolyte in the charged state. One way to circumvent this capacity fade is to introduce other 3𝑑 transition metal ions in the LiMn2O4 lattice. In this paper, we report on the effect of partial substitution of manganese in the LiMn2O4 phase with copper (II) and chromium (III) ions. It has been shown that the higher octahedral stabilization energy of trivalent chromium imparts greater structural stability to chromium-doped LiMn2O4 spinels. Both copper and chromium reduce the capacity of the spinel in the 4 V region. In terms of its good reversible capacity and ability to sustain cycling with minimal capacity fade, LiCr0.1Mn1.9O4 may be considered as a potential cathode material for lithium rechargeable cells.

    • Structural, electrical and electrochemical behaviours of LiNi0.4M0.1Mn1.5O4 (𝑀 = Al, Bi) as cathode material for Li-ion batteries

      G P Nayaka J Manjanna K C Anjaneya P Manikandan P Periasamy V S Tripathi

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      In order to improve the cycling performance of LiMn2O4 based cathode materials, we have synthesized a new composition, LiNi0.4M0.1Mn1.5O4 (𝑀 = Al, Bi), by the sol–gel method. The formation of solid solutions is confirmed by structural characterization using TG/DTA, XRD, FT–IR, EPR, SEM and EPR. A.c.-impedance (Nyquist plot) showed a high frequency semicircle and a sloping line in the low-frequency region. The semicircle is ascribed to the Li-ion migration through the interface from the surface layer of the particles to the electrolyte. Cyclic voltammogram (between 3.5 and 4.9 V) for these materials using CR2032 coin-type cell shows two pairs of redox peaks corresponding to two-step reversible intercalation process, wherein Li-ions occupy two different tetragonal 8a sites in spinel Li𝑥Mn2O4 (𝑥 < 1) lattice. The galvanostatic charge/discharge curves for 𝑀 = Al (77 mAh g-1) showed reasonably good capacity retention than that of 𝑀 = Bi (11 mAh g-1) at the end of 17th cycle.

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