실리콘 합금 전극을 이용한 리튬이온 전지의 수명특성

Abstract

리튬 이온 전지는 휴대용 전자기기, 전기자동차(EV) 및 에너지 저장 시스템에서 중요한 요소이다. 리튬 이온 전지에서 에너지 밀도를 높이기 위하여 전극 물질의 용량을 높이는 것은 필수적이다. 여러 자료에서 실리콘 기반의 음극 물질은 매우 높은 이론 용량에 대해서 높은 주목을 받고 있다. 그러나 실리콘 기반 음극 물질은 충방전 사이클 동안 심한 부피 팽창으로 인하여 전기 전도도가 떨어지게 되어 급격한 성능저하로 이어진다. 이러한 문제를 해결하기 위해 많은 연구가 진행되어 왔는데, 이러한 연구에는 실리콘의 나노 구조화, 부피팽창의 버퍼링, 충방전 전위 조절, 바인더 변화 그리고 실리콘 합금 등이 있다. 본 연구에서 리튬이온 전지 음극의 높은 에너지 밀도를 위하여 실리콘 기반 합금을 이용 하였다. 실리콘 기반의 합금 음극과 니켈-코발트-망간 3성분계 양극으로 용량비를 다르게 하여 리튬이온 전지를 제작하여 수명특성을 평가하였다. 실리콘 합금 전극 전지의 성능과 계면현상은 전기화학적 임피던스 분광학, FE-SEM 그리고 X-선 광전자 분광법으로 확인하였다. 본 연구에서 실리콘 합금 전극의 계면 특성은 차세대 음극재료의 개발에 중요한 초석을 제공할 것으로 기대 되었다.|Lithium-ion batteries are essential power sources for hand-held electronic devices, electric vehicles (EV) and energy storage systems. In order to improve the energy densities of lithium-ion batteries, it is necessary to increase the specific capacity of electrode materials. To date, the silicon-based anode materials have received considerable attention for their extremely high theoretical capacity. However silicon-based anode materials suffer from significant volume change during cycling, which leads to the loss of electrical contacts resulting in drastic performance degradation. To solve this issue, many approaches have been employed including design of nanostructures, buffering, controlled potential, using improved binder and silicon-alloy. In this study, we report a Si-based alloy developed for commercial application as an anode material for high energy density lithium-ion batteries. The lithium-ion cells composed of Si alloy anode and LiNi0.6Co0.2Mn0.2O2 cathode with different N/P ratio were assembled and their cycling performances were evaluated. The battery performance and interfacial phenomena at the Si-alloy electrode in the cell were investigated by electrochemical impedance spectroscopy, FE-SEM and XPS analyses. Our interfacial characterization of Si-alloy electrode is expected to provide important mechanistic insight for the development of advanced anode materials for lithium-ion batteries.; Lithium-ion batteries are essential power sources for hand-held electronic devices, electric vehicles (EV) and energy storage systems. In order to improve the energy densities of lithium-ion batteries, it is necessary to increase the specific capacity of electrode materials. To date, the silicon-based anode materials have received considerable attention for their extremely high theoretical capacity. However silicon-based anode materials suffer from significant volume change during cycling, which leads to the loss of electrical contacts resulting in drastic performance degradation. To solve this issue, many approaches have been employed including design of nanostructures, buffering, controlled potential, using improved binder and silicon-alloy. In this study, we report a Si-based alloy developed for commercial application as an anode material for high energy density lithium-ion batteries. The lithium-ion cells composed of Si alloy anode and LiNi0.6Co0.2Mn0.2O2 cathode with different N/P ratio were assembled and their cycling performances were evaluated. The battery performance and interfacial phenomena at the Si-alloy electrode in the cell were investigated by electrochemical impedance spectroscopy, FE-SEM and XPS analyses. Our interfacial characterization of Si-alloy electrode is expected to provide important mechanistic insight for the development of advanced anode materials for lithium-ion batteries.