In-situ formation of hybrid Li3PO4-AlPO4-Al(PO3)3 coating layer on LiNi0.8Co0.1Mn0.1O2 cathode with enhanced electrochemical properties for lithium-ion battery

By Ze Feng, Ranjusha Rajagopalan, Dan Sun, You-gen Tang, Hai-yan Wang. 2020

166 citations recorded by the source corpus.

Abstract Irreversible phase transition and surface residual lithium, which cause the fast capacity fading of LiNi0.8Co0.1Mn0.1O2 (NCM811), are the main obstacles that hinder their commercial application. Herein, to modify the surface/interphase properties of NCM811, we elaborately propose a hybrid Li3PO4-AlPO4-Al(PO3)3 coating layer that combines the advantages of ionic conductor (Li3PO4) and thermal stable compound (AlPO4) via reacting aluminum metaphosphate (Al(PO3)3) precursor with the surface residual lithium (Li2CO3 or/and LiOH) during the coating process. When used as cathode for lithium-ion battery, the optimized NCM811 delivers a high initial discharge capacity of 201.8 mAh g−1 and 218.9 mAh g−1 at 0.1C under the temperature of 30 °C and 50 °C, with capacity retention of 85.4% and 78.89% after 50 cycles, respectively, which are much higher than that of uncoated sample (73.93% and 57.98%). Moreover, when it is coupled with graphite anode to form a lithium-ion full cell, it delivers an impressively high energy density of 467.5 Wh kg−1 (based on mass of positive and negative material), and retains 71.8% of its initial energy density after 100 cycles. The significantly enhanced electrochemical properties should be attributed to the multifunctional hybrid nano-coating layer that could efficiently reduce the surface residual lithium, suppress the irreversible phase transition, and prevent the active materials from the erosion of HF as verified by the ex-situ X-ray diffractometry, Raman spectroscopy and transmission electron microscopy. This work provides new insights into the surface/interphase design strategies to improve the structural stability of Ni-rich cathode, which will promote the development of high capacity cathode materials.

Subfields: Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/62057ffb1775773d8e3a001d031394d45fa7dcf2