Abstract
A simple and rapid electrochemical method for the quantitative analysis of $Mn^{2+}$ ion is demonstrated with a view to examine the $Mn^{2+}$ dissolution behavior of $LiMn_2O_4$. The method described herein is based on the oxidation reaction of $Mn^{2+}$ to $Mn^{4+}(MnO_2)$ in aqueous buffer solution. Under the optimum condition (pH 8.9 0.04 M $NH_3-NH_4Cl$ buffer solution and glassy carbon working electrode), the linear range of $5{\mu}M-100{\mu}M$ (0.275-5.5 ppm) [$Mn^{2+}$] is obtained for the Linear sweep voltammetry(LSV) and $0.2{\mu}M-10{\mu}M$ (0.011-0.55 ppm) [$Mn^{2+}$] for the differential pulse voltammetry (DPV), respectively. It is also noted that the oxidation reaction of $Mn^{2+}$ ion is reduced with increasing amount of the electrolyte ($LiPF_6$, EC, EMC) added to the measuring solution, which is found to be mainly due to $LiPF_6$ and EC rather than EMC.
[ $LiMn_2O_4$ ] $Mn^{2+}$이온 용출현상 연구를 위한 간단하고 신속한 전기화학적 $Mn^{2+}$이온 분석법을 정립하였다. 이 분석법은 완충용액에서 $Mn^{2+}$이온이 $Mn^{4+}(MnO_2)$로 산화되는 원리를 이용한다. 최적조건 (pH 8.9 0.04 M $NH_3-NH_4Cl$ 완충용액 및 glassy carbon 작업전극)에서, Linear sweep voltammetry(LSV) 측정에 대해 $5{\mu}M-100{\mu}M$ (0.275-5.5 ppm) $Mn^{2+}$이온 범위에서, differential pulse voltammetry (DPV) 측정에 대해 $0.2{\mu}M-10{\mu}M$ (0.011-0.55 ppm) 범위에서 선형적 응답 특성을 확인하였다. 또한, 측정용액에 리튬 이차전지용 전해액 ($LiPF_6$, EC, EMC)이 첨가할 경우, 첨가량에 비례하여 $Mn^{2+}$ 이온의 산화 전류 감소하였는데, 이러한 감소의 주요 원인은 EMC보다는 $LiPF_6$와 EC성분임을 확인하였다.