Reaching Highly Stable Specific Capacity with Integrated 0.6Li₂MnO₃: 0.4LiNi_0.6Co_0.2Mn_0.2O₂ Cathode Materials

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: Li_1.2Ni_0.24Co_0.08Mn_0.48O₂ (0.6Li₂MnO₃ : 0.4LiNi_0.6Co_0.2Mn_0.2O₂), Li_1.2Ni_0.16Co_0.08Mn_0.56O₂ (0.6Li₂MnO₃ : 0.4LiNi_0.4Co_0.2Mn_0.4O₂), and LiNi_0.6Co_0.2Mn_0.2O₂ (as a reference material). The first two compositions are Li- and Mn-rich cathode materials that contain Li₂MnO₃ and LiNi_xCo_1-x-yMn_yO₂ 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. Li_1.2Ni_0.24Co_0.08Mn_0.48O₂ 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 LiNi_0.6Co_0.2Mn_0.2O₂ and Li_1.2Ni_0.16Co_0.08Mn_0.56O₂ 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.