Spinel LiMn 1.5 Ni 0.5 O 4 (LMNO) is one of the promising cathode materials for the next generation Li-ion batteries due to its voltage platform. However, the dissolution of the transition metal at high voltage is the biggest obstacle that LMNO suffers from. In this study, we successfully suppressed transition metal dissolution in LMNO by the morphology control from regular octahedron to spherical. Niobium was integrated as a dopant, which restricted the growth of (1 1 1) crystal face, and increased the indices of crystal faces by homogenizing the surface energy. By changing to a smaller surface area with spherical morphology, the contact area with the electrolyte was reduced, thus suppressing the dissolution of the Mn ion. Consequently, the niobium-doped LMNO exhibited superior rate performance, capacity retention with 74.1% at 1C after 500 cycles in half-cell, and thermal stability compared to pristine LMNO.
Li-rich cathodes have potential for use in next-generation Li-ion batteries (LIBs) owing to their high specific capacity and low cost. However, their intrinsic cycling decay and voltage fading limit practical applications. In addition, these cathodes contain Co, which is nonrenewable, scarce, and expensive. This situation severely limits the rapid and sustainable development of low-cost LIBs. This paper introduces a novel dilute electrolyte to overcome these limitations based on the Co-free Li-rich Li1.2Mn0.54Ni0.26O2 (LMNO) cathode. An even and robust cathode-electrolyte interface (CEI) formed on the surface of LMNO further protects it from side reactions in the dilute electrolyte. This Co-free Li-rich cathode exhibits the best electrochemical performance reported to date among Li-rich cathodes in terms of outstanding cycling stability (capacity retention of 99.8% at 0.5 C) and dramatically suppressed voltage fading (only 0.3% after 100 cycles). This study demonstrates the potential of Co-free Li-rich cathodes for applications in next-generation LIBs.
To solve the major problem of interfacial side reactions between LiMn 1.5 Ni 0.5 O 4 (LMNO) and liquid electrolyte at high voltages, zirconium phosphate (ZrP) wrapped cathode material LMNO@ZrP, with different aspect of ZrP in 2 wt% and 4 wt%, have been prepared by a hydrothermal method. In particular, we focus on the distribution of ZrP on the LMNO surface to find out the optimal coating material and amount. The effects of ZrP coating layer have been investigated by comparison of the properties of the ZrP coated LMNO (LMNO@ZrP) and pristine LMNO electrodes by several electrochemical characterizations. The electrochemical impedance spectroscopy results show that LMNO@ZrP-3M-2 electrode exhibits an improved electrochemical property of suppressing the impedance increase. In the cell life test, LMNO@ZrP-3M-2 electrode shows a high capacity retention of 94.6% after 200 cycles at 55 °C.
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