Browsing by Author "Issa, TB"

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    Effect of B4C addition to MnO2 in a cathode material for battery applications.
    (Elsevier, 2010-01-01) Minakshi, M; Blackford, MG; Thorogood, GJ; Issa, TB
    Boron 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.
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    Study 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, KE
    The 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.