Electrical engineering

Engineering

Composite material

Voltage

Nanotechnology

Organic chemistry

Chemistry

Materials science

Citric acid

Coating

Sol-gel

Chemical engineering

Thermal stability

High voltage

Journal of Power Sources

A surface coating of Li 3 PO 4 null was applied to a Ni-rich LiNi 0.6 Co 0.2 Mn 0.2 O 2 null (NCM) material to improve its thermal stability and electrochemical properties via a citric acid assisted sol-gel method. The addition of citric acid effectively suppressed the instant formation of Li 3 PO 4 null in solution, resulting in successful coating of the NCM surface. The improved thermal stability of NCM after Li 3 PO 4 null surface coating was demonstrated by differential scanning calorimetry (DSC) analysis and in situ time-resolved X-ray diffraction (TR-XRD). In particular, the TR-XRD results showed that the improved thermal stability after Li 3 PO 4 null surface coating originates from suppression of the phase transition of charged NCM at high temperatures. Furthermore, the charge–discharge tests demonstrated that Li 3 PO 4 -coated LiNi 0.6 Co 0.2 Mn 0.2 O 2 null (LP-NCM) has excellent electrochemical properties. LP-NCM exhibited a specific capacity of 192.7 mAh g −1 , a capacity retention of 44.1% at 10 C, and a capacity retention of 79.7% after 100 cycles at a high cut-off voltage of 4.7 V; these values represent remarkably improved electrochemical properties compared with those of bare NCM. These improved thermal and electrochemical properties were mainly attributed to the improvement of the structural stability of the material and the suppression of the interface reaction between the cathode and the electrolyte owing to the Li 3 PO 4 null coating.

Li3PO4 surface coating on Ni-rich LiNi0.6Co0.2Mn0.2O2 by a citric acid assisted sol-gel method: Improved thermal stability and high-voltage performance