The effect of B4C addition to MnO2 in a cathode material for battery applications

✍ Scribed by Manickam Minakshi; Mark G. Blackford; Gordon J. Thorogood; Touma B. Issa

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 889 KB
• Volume: 55
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/j.electacta.2009.09.062

✦ Synopsis

Boron carbide (B 4 C) added manganese dioxide (MnO 2 ) used as a cathode material for a Zn-MnO 2 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 MnO 2 (additive free). The performance is reversed when using potassium hydroxide (KOH) as the electrolyte. Herein, the MnO 2 was mixed with 0, 5, 7 and 10 wt.% of boron carbide during the electrode preparation. The discharge performance of the Zn|LiOH|MnO 2 battery was improved by the addition of 5-7 wt.% boron carbide in MnO 2 cathode as compared with the pure MnO 2 . However, increasing the additive to 10 wt.% causes a decrease in the discharge capacity. The performance of the Zn|KOH|MnO 2 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 MnO 2 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|MnO 2 battery. This observed improvement may be a consequence of B 4 C 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.