Iron oxide based anode material for lithium ion battery
Date of Issue2018
Interdisciplinary Graduate School
Energetics Research Institute
Iron oxide is ntensively studied as a potential anode material of lithium ion battery. Although it has a high theoretical capacity, the potential application is still limited due to its volumetric instability, relative high working voltage and low 1st cycle efficiency. In this thesis, strategies to alleviate these issues in iron oxide are addressed, such as morphology design, elemental modification and lithium addition. 1D rod-like morphology of iron oxide is firstly investigated as one of the optimized structure to overcome volumetric instability. It is seen that tuning the size of the nanorod led to optimal electrochemical performance, which is due to better structural retaining ability of the particles. It was seen that intermediate sized nanorod showed ~1000mAh g-1 capacity at the end of 50 cycles which is more than powder iron oxide. Elemental modification of iron oxide has also proven to be an effective strategy to lower the reaction voltage of hematite. Among several of tested material, Mg and Ti modified sample has shown the greatest potential also on enhancing the capacity at higher current density region. A capacity of 556 mAh g-1 at a delithiation current rate of 3C is achieved for Mg modified nanorod, which is five times higher than for pure hematite. Further synthesis of iron oxide microsphere, nanosphere and chunky-like particles showed has shown an unexpected high reversible capacity of ~800mAh g-1, which is not fully understood up to date. However, it can be inferred from these studies that in addition to particle morphology, there are other intrinsic factors that dominate the electrochemical behavior of iron oxide. The last section presents a lithium addition strategy that successfully forms a pre-lithiated form of iron oxide that has proven to increase the 1st cycle efficiency of iron oxide material from ~68% to ~80%.