Surface oxygen vacancy engineering and physical protection by in-situ carbon coating process of lithium rich layered oxide

Abstract

Lithium-rich layered oxide (LLO) with a large specific capacity (>250 mAhg −1 ) and the wider voltage window (2.0–4.8 V) delivers an energy density of about 1000 Wh/kg. However, oxygen release from the surface of LLO and decomposition of electrolyte solvents leads to increased electrode-electrolyte interface resistance. To achieve the maximum energy density of LLO, it becomes mandatory to protect the surface structure and simultaneously activate the cationic and anionic redox reaction. Here, we demonstrate a novel in-situ carbon encapsulation on Li 1.15 Ni 0.23 Co 0.08 Mn 0.54 O 2 by the industrially viable co-precipitation process followed by solid-state reaction. Effect of carbon encapsulation on structure formation, chemical composition, and elemental oxidation states of Li 1.15 Ni 0.23 Co 0.08 Mn 0.54 O 2 are analyzed by the techniques such as X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. The enhanced electrochemical performance is confirmed by increased coulombic efficiency, reduced interfacial resistance, and suppressed voltage fading. Moreover, carbon-coated LLO retains an excellent capacity of 94% after 300 cycles at 2C rate cycling, while the pristine LLO retained only 77.8% of capacity. Further, electrochemical cycling of carbon encapsulated LLO with pre-lithiated graphite delivers an energy density of 500 Wh/kg after 100 cycles at 0.5C rate (150 mAg −1 ). • In-situ Carbon coating on Li1.15Ni0.23Co0.08Mn0.54O2. • Surface oxygen vacancy engineering. • Electrochemical cycling of Li1.15Ni0.23Co0.08Mn0.54O2with pre-lithiated graphite. • Surface protection from carbon coating.