Browsing by Author "Minakshi, M"
Now showing 1 - 13 of 13
Results Per Page
Sort Options
- ItemAnodic behavior of zinc in Zn-MnO2 battery using ERDA technique(Elsevier, 2010-07) Minakshi, M; Ionescu, MThe commercial, alkaline zinc-manganese dioxide (Zn-MnO2) primary battery has been transformed into a secondary battery using lithium hydroxide electrolyte. Galvanostatic discharge–charge experiments showed that the capacity decline of the Zn-MnO2 battery is not caused by the MnO2 cathode, but by the zinc anode. The electrochemical data indicated that a rechargeable battery made of porous zinc anode can have a larger discharge capacity of 220 mAh/g than a planar zinc anode of 130 mAh/g. The cycling performance of these two anodes is demonstrated. Structural and depth profile analyses of the discharged anodes are examined by X-ray diffraction (XRD) and elastic recoil detection analysis (ERDA) techniques. © 2010, Elsevier Ltd.
- ItemEffect of B4C addition to MnO2 in a cathode material for battery applications.(Elsevier, 2010-01-01) Minakshi, M; Blackford, MG; Thorogood, GJ; Issa, TBBoron carbide (B4C) added manganese dioxide (MnO2) used as a cathode material for a Zn–MnO2 battery using aqueous lithium hydroxide (LiOH) as the electrolyte is known to have higher discharge capacity but with a lower average discharge voltage than pure MnO2 (additive free). The performance is reversed when using potassium hydroxide (KOH) as the electrolyte. Herein, the MnO2 was mixed with 0, 5, 7 and 10 wt.% of boron carbide during the electrode preparation. The discharge performance of the Zn|LiOH|MnO2 battery was improved by the addition of 5–7 wt.% boron carbide in MnO2 cathode as compared with the pure MnO2. However, increasing the additive to 10 wt.% causes a decrease in the discharge capacity. The performance of the Zn|KOH|MnO2 battery was retarded by the boron carbide additive. Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy analysis (EDS) results show evidence of crystalline MnO2 particles during discharging in LiOH electrolyte, whereas, manganese oxide particles with different oxygen and manganese counts leading to mixture of phases is observed for KOH electrolyte which is in agreement with X-ray diffraction (XRD) data. The enhanced discharge capacity indicates that boron atoms promote lithium intercalation during the electrochemical process and improved the performance of the Zn|LiOH|MnO2 battery. This observed improvement may be a consequence of B4C suppressing the formation of undesirable Mn(III) phases, which in turn leads to enhanced lithium intercalation. Too much boron carbide hinders the charge carrier which inhibits the discharge capacity. © 2009, Elsevier Ltd.
- ItemEffect of non-ionic surfactants and its role in K intercalation in electrolytic manganese dioxide(Springer, 2014-06-17) Biswal, A; Tripathy, BC; Subbaiah, T; Meyrick, D; Ionescu, M; Minakshi, MThe effect of non-ionic surface active agents (surfactants) Triton X-100 (TX-100) and Tween-20 (Tw-20) and their role in potassium intercalation in electrolytic manganese dioxide (EMD) produced from manganese cake has been investigated. Electrosynthesis of MnO2 in the absence or presence of surfactant was carried out from acidic MnSO4 solution obtained from manganese cake under optimized conditions. A range of characterization techniques, including field emission scanning electron microscopy, transmission electron microscopy (TEM), Rutherford back scattering (RBS), and BET surface area/porosity studies, was carried out to determine the structural and chemical characteristics of the EMD. Galvanostatic (discharge) and potentiostatic (cyclic voltammetric) studies were employed to evaluate the suitability of EMD in combination with KOH electrolyte for alkaline battery applications. The presence of surfactant played an important role in modifying the physicochemical properties of the EMD by increasing the surface area of the material and hence, enhancing its electrochemical performance. The TEM and RBS analyses of the discharged EMD (γ-MnO2) material showed clear evidence of potassium intercalation or at least the formation of a film on the MnO2 surface. The extent of intercalation was greater for EMD deposited in the presence of TX-100. Discharged MnO2 showed products of Mn2+ intermediates such as MnOOH and Mn3O4. © 2014 ASM International (ASM) and The Minerals, Metals & Materials Society (TMS)
- ItemEffect of TiS2 additive on LiMnPO4 cathode in aqueous solutions(American Chemical Society, 2010-11-18) Minakshi, M; Pandey, A; Blackford, MG; Ionescu, MIncorporation of TiS2 additive by physical admixture into the LiMnPO4 cathode leads to modification of the electrochemical performance of the cathode, such as an improved delithiation and lithiation mechanism. Cyclic voltammetry suggests that the TiS2 additive suppresses proton deinsertion/insertion mechanism and does not contribute directly to the reduction/oxidation reactions of the LiMnPO4 working electrode. © 2010, American Chemical Society
- ItemElectrochemical characteristics of B4C or BN added MnO2 cathode material for alkaline batteries(Elsevier, 2010-10-01) Minakshi, M; Blackford, MGBoron compounds generally produce a battery with high energy density. Since boron is an excellent conductor of electricity a battery with a high power density can also be achieved. With this objective, the electrochemical characteristics of boron carbide (B4C) added manganese dioxide (MnO2) for use as a cathode in alkaline battery were investigated during the discharge–charge process. Results of electrochemical measurements, X-ray diffraction and transmission electron microscopy show that boron aids the formation of lithium intercalated MnO2 (LixMnO2) during discharge with some degree of reversibility, however, capacity fade and a steep voltage profile is observed. The addition of boron nitride (BN) improved the discharge performance and characteristics of the cell are also compared and discussed. © 2010, Elsevier Ltd.
- ItemElectrochemical characterization of an aqueous lithium rechargeable battery: the effect of CeO2 additions to the MnO2 cathode(Elsevier, 2009-06-24) Minakshi, M; Nallathamby, K; Mitchell, DRGThe effect of CeO2 additions on an aqueous rechargeable lithium battery has been investigated. The CeO2 additions (0, 2, and 5 wt.%) were made to the manganese dioxide (MnO2) cathode of a cell comprising zinc as an anode and an aqueous saturated lithium hydroxide solution as the electrolyte. The CeO2 enhances the performance of the cell in terms of capacity and resistance to capacity fade with cycling. This effect is only evident after the first charge cycle. The mechanism by which this occurs may be due to suppression of the oxygen evolution reaction during charging. This results in full reversion of the products of discharge (principally LixMnO2) to MnO2 during charging, and suppresses the formation of non-rechargeable oxyhydroxides. CeO2 additions of 2 wt.% were found to be most effective, since additions at the 5 wt.% level caused a decrease in capacity during long-term cycling. This could be due to a synchronizing effect. The effect of additions of a rare earth oxide (CeO2) and an alkaline earth oxide (CaO) on the electrochemical behavior of the cell is also compared and discussed. © 2009, Elsevier Ltd.
- ItemLithium extraction-insertion from/into LiCoPO4 in aqueous batteries(American Chemical Society, 2011-02-16) Minakshi, M; Singh, P; Sharma, N; Blackford, MG; Ionescu, MA novel 1 V battery composed of Sn−LiCoPO4 using aqueous lithium hydroxide electrolyte is described. Reversible extraction and insertion of lithium from and into the olivine-type LiCoPO4 is reported. The electrochemical behavior of the Sn−LiCoPO4 battery was analyzed using charge/discharge cycling and cyclic voltammetry. Sn−LiCoPO4 battery exhibited charge/discharge voltages of 1.3 V/0.8 V versus Sn with a reversible capacity of 80 mAh/g. The structural and morphological changes of LiCoPO4 particles before and after electrochemical measurements were investigated by X-ray diffraction (XRD) and transmission electron microscopy. XRD data showed that extraction of lithium proceeds via at least a two-phase mechanism with LiCoPO4 and CoPO4 phases. Upon lithium reinsertion crystalline LiCoPO4 was formed. The cell voltage indicated these batteries were not completely charged, forming single-phase CoPO4 material. Energy-dispersive X-ray analysis coupled with transmission electron microscopy confirmed the chemical quality of the charged and discharged LiCoPO4 in terms of crystallinity and elemental distribution. © 2011, American Chemical Society
- ItemMicrostructural and spectroscopic investigations into the effect of CeO2 additions on the performance of a MnO2 aqueous rechargeable battery(Elsevier, 2009-04-30) Minakshi, M; Mitchell, DRG; Carter, ML; Appadoo, D; Nallathamby, KThe influence of CeO2 additions on the electrochemical behaviour of the MnO2 cathode in a Zn–MnO2 battery using lithium hydroxide (LiOH) as an electrolyte is investigated using microscopy and spectroscopic techniques. The results showed that such additions greatly improve the discharge capacity of the battery (from 155 to 190 mAh g−1) but only from the second discharge cycle onwards. Capacity fade with subsequent cycling is also greatly reduced. With an aim to understand the role of CeO2 on the discharge–charge characteristics of MnO2 and its mechanism, we have used a range of microscopy, spectroscopy and diffraction-based techniques to study the process. The CeO2 is not modified by multiple discharged and charged cycles. The CeO2 may enhance the discharge–charge performance of the battery by raising the oxygen evolution potential during charging but does not take part directly in the redox reaction. © 2009, Elsevier Ltd.
- ItemSodium for securing future renewable energy supply(Australian Institute of Physics, 2016-02-04) Minakshi, M; Appadoo, DThe storage and recovery of electrical energy is widely recognized as one of the most important areas for energy research. Although renewable energy such as i.e. wind and solar generated electricity is becoming increasingly available in many countries including Australia, these sources provide only intermittent energy. Thus, energy storage systems are required for load levelling, allowing energy to be stored and used on demand. Energy storage in rechargeable batteries and supercapacitors is the most promising prospect for ensuring consistent energy supply therefore allowing greater penetration of renewable energy into the electricity grid. Energy storage capability also has obvious benefits in terms of greenhouse emissions. Issues such as the environment, the rapid increase in fossil fuel prices, and the increased deployment of renewable energy sources, provide a greater need for the development of electrochemical energy storage, especially for large-scale applications. Thus, materials research and computational modelling play a key role in making further progress in the field of energy storage. Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Phosphate materials such as NaNiPO4, NaMnPO4, NaCoPO4 and NaNi1/3Mn1/3Co1/3PO4 will be discussed at the conference. Sodium transition metal phosphate has served as an active electrode material for an energy storage device. The development of sodium transition metal phosphate with special emphasis on structural changes and novel synthetic approach can underpin technological advancements in small renewable energy harvesting and power generation technologies. The characteristics of the fabricated device such as improved storage capability, cycling stability, safety and economic life - cycle cost made this an attractive alternative to conventional charge storage devices using more expensive materials.
- ItemStructural characteristics of olivine Li(Mg0.5Ni0.5)PO4 via TEM analysis(Springer Nature, 2012-01-13) Minakshi, M; Singh, P; Ralph, D; Appadoo, D; Blackford, MG; Ionescu, MThe structural characteristics of olivine-type lithium orthophosphate Li(Mg0.5Ni0.5)PO4 synthesized via solid-state reaction have been studied using X-ray diffraction, ion beam technique, scanning electron microscopy, infrared spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. The parent LiNiPO4 compound can be synthesized in olivine structure without any evidence of secondary phases as impurities. The structural quality of the parent LiNiPO4 in the absence of secondary component phases resulted in the formation of hexagonal closed packed structure. The olivine analogue compound containing mixed M (M = Mg, Ni) cations, Li(Mg0.5Ni0.5)PO4 contained Li3PO4 as a second phase upon synthesis, however a carbothermal reduction method produced a single-phase compound. The redox behaviour of carbon-coated Li(Mg0.5Ni0.5)PO4 cathode in aqueous lithium hydroxide as the electrolyte showed reversible lithium intercalation. © 2020 Springer Nature Switzerland AG.
- ItemStudy of lithium insertion into MnO2 containing TiS2 additive a battery material in aqueous LiOH solution(Elsevier, 2007-08-01) Minakshi, M; Singh, P; Mitchell, DRG; Issa, TB; Prince, KEThe electrochemical behavior and surface characterization of manganese dioxide (MnO2) containing titanium disulphide (TiS2) as a cathode in aqueous lithium hydroxide (LiOH) electrolyte battery have been investigated. The electrode reaction of MnO2 in this electrolyte is shown to be lithium insertion rather than the usual protonation. MnO2 shows acceptable rechargeability as the battery cathode. The influence of TiS2 (1, 3 and 5 wt%) additive on the performance of MnO2 as a cathode has been determined. The products formed on reduction of the cathode material have been characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), fourier transform infrared spectroscopy (IR) and transmission electron microscopy (TEM). It is found that the presence of TiS2 to <= 3 wt% improves the discharge capacity of MnO2. However, increasing the additive content above this amount causes a decrease in its discharge capacity. © 2007, Elsevier Ltd.
- ItemSynthesis and characterization of Li(Co0.5Ni0.5)PO4 cathode for li-ion aqueous battery applications(The Electrochemical Society, 2011-03-17) Minakshi, M; Sharma, N; Ralph, D; Appadoo, D; Nallathamby, KOlivine-type lithium orthophosphate Li(Co0.5Ni0.5)PO4 was synthesized in a solid state reaction at 800 degrees C in air. Infra-red spectroscopy, x-ray and neutron powder diffraction were used to characterize the as-prepared compound and its electro-oxidized analogue. Rietveld analysis was used to illustrate that the synthesized compound is isostructural with LiNiPO4 and LiCoPO4 with lattice parameters larger than the former and smaller than the latter. The Rietveld-refined Ni:Co ratio was found to be 0.498(4):0.502(4) and no evidence for long-range Ni: Co ordering or mixed Li/Ni/Co cation sites was found. The electro-oxidised electrode showed a mixture of two phases i.e. parent Li(Co0.5Ni0.5)PO4 and lithium extracted Li1-x(Co0.5Ni0.5)PO4 suggesting a delithiation process in aqueous electrolytes. Reversible Li transfer between a Li(Co0.5Ni0.5)PO4 electrode and an aqueous LiOH electrolyte was demonstrated. (C) 2011 The Electrochemical Society. [doi:10.1149/1.3561764]
- ItemTEM characterization of MnO2 cathode in an aqueous lithium secondary battery(Australian Institute of Physics, 2006-12-05) Minakshi, M; Mitchell, DRG; Singh, P; Thurgate, SThe discharge characteristics of manganese dioxide cathode in the presence of small amounts (1, 3 and 5 wt. %) of TiS2 additive has been investigated in an alkaline cell using aqueous lithium hydroxide as the electrolyte [1]. The incorporation of small amounts of TiS2 additives into MnO2 was found to improve the battery discharge capacity from 150 to 270 mAh/g. However, increasing the additive from 3 to 5 wt. % causes a decrease in the discharge capacity. Hence, the objective is to gain insight into the role of TiS2 in MnO2 and its lithiation mechanism. For this purpose, we have used transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The valence state determination of the discharged MnO2 was performed using EELS. The Mn L2,3 edge contains two white lines (strong peaks) at about 640 eV (L3) and 650 eV (L2). The relative intensities of these Mn L2,3 peaks varies as a function of valence state in the Mn oxides i.e. MnO, Mn2O3 and MnO2 [2]. As-received MnO2 has a valence state of 4, as expected. However, Li intercalated materials showed evidence for reduction, the extent of which depended on the amount of TiS2 additive. The valance state of Li intercalated MnO2 with 3 wt. % TiS2 additive was 3.1 while that for the equivalent material with 5wt. % TiS2 additive was 3.5. Reduction of Mn occurs as a result of Li intercalation, the extent being more marked for the 3 wt. % TiS2 loading. This result is in accordance with the discharge behavior, since the capacity of the 3 wt. % material (270 mAh/g) was significantly larger than that for the equivalent 5 wt. % material (75 mAh/g)). TEM imaging showed a presence of nano particulate Mn oxides, of about 50 nm diameter, in the 5 wt. % TiS2 material. This could inhibit the lithium intercalation resulting in a valence state of 3.5 and thereby low discharge capacity whereas this nano particulate material is not present in 1 and 5 wt. % TiS2 loaded material.