Reaching Highly Stable Specific Capacity with Integrated 0.6Li2MnO3 : 0.4LiNi0.6Co0.2Mn0.2O2 Cathode Materials

Tirupathi Rao Penki; Prasant Kumar Nayak; Elena Levi; Judith Grinblat; Yuval Elias; Shalom Luski; Boris Markovsky; Doron Aurbach

Index: 10.1002/celc.201701193

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Abstract

The work described herein was performed to find guidelines for the optimal selection of high‐specific‐capacity cathode materials for Li‐ion batteries. In this study, we compared the electrochemical behavior of three cathode materials working over wide potential domains in Li cells: Li1.2Ni0.24Co0.08Mn0.48O2 (0.6Li2MnO3 : 0.4LiNi0.6Co0.2Mn0.2O2), Li1.2Ni0.16Co0.08Mn0.56O2 (0.6Li2MnO3 : 0.4LiNi0.4Co0.2Mn0.4O2), and LiNi0.6Co0.2Mn0.2O2 (as a reference material). The first two compositions are Li‐ and Mn‐rich cathode materials that contain Li2MnO3 and LiNixCo1‐x‐yMnyO2 components, as established by structural analysis using X‐ray and electron diffraction. The main focus was the possibility to obtain a stable capacity and average voltage while working over a wide potential domain, in order to extract high specific capacity. The three materials were prepared through the self‐combustion reaction and were characterized by using SEM, ICP, HRTEM, and electrochemical techniques. Li1.2Ni0.24Co0.08Mn0.48O2 cathodes operating over the potential range 2.0–4.6 V vs. Li demonstrated stable specific capacities greater than 200 mAh g−1 and stable average voltages, thus rivaling LiNi0.6Co0.2Mn0.2O2 and Li1.2Ni0.16Co0.08Mn0.56O2 cathodes in terms of electrochemical performance. The consequences of these findings are discussed herein. Li‐ and Mn‐rich cathode materials may be advantageous compared to Ni‐rich cathode materials in terms of cost and safety.