Heterostructured lithium-rich layered oxides core@ spinel- MgAl2O4 shell as high-performance cathode for lithium-ion batteries

Lithium-rich layered oxides (LLO) with ultra-high specific capacity are one of the most promising cathodes for the next-generation lithium-ion batteries. However, the irreversible release of lattice oxygen will cause LLO surface reconstruction and electrolyte decomposition, resulting in low initial coulombic efficiency (ICE), high interface resistance as well as severe voltage and capacity degradation. Herein, a facile and effective strategy is proposed to stabilize the cathode materials by coating the LLO with spinel MgAl2O4. It is found that the robust MgAl2O4 (MAO) decoration layer can not only alleviate the lattice mismatch to sustain the structure integrity, but also inhibit the side reactions with electrolyte during long-term cycles. Furthermore, density functional theory calculations show that the surface oxygen release energy barrier is increased with the surface decoration of MAO. Accordingly, the coated LLO-based hetero-structured cathode exhibits a higher ICE (80.14%) and lower interface resistance than that of LLO electrode. Moreover, a reversible capacity of 176.6 mAh g−1 (with a capacity retention as high as 78.1%) and small voltage drop of 0.27 V are achieved even after 200 cycles at 1 C. This work sheds new light on the facile preparation and modification of lithium-rich layered oxides-related cathode for high-energy density lithium-ion batteries.