Multifunctional ZrF4 nanocoating for improving lithium storage performances in layered Li[Li0.2Ni0.17Co0.07Mn0.56]O2

• ZrF4 nanolayer is coated on the surface of Li[Li0.2Ni0.17Co0.07Mn0.56]O2 via simple chemical deposition.
• ZrF4 nanocoating enhances the cycling and thermal stabilities of Li[Li0.2Ni0.17Co0.07Mn0.56]O2.
• The optimum coating content of ZrF4 was found to be 1 wt.%.
• ZrF4 can help to stabilize the structure by decreasing the oxygen loss and suppressing the fast growth of interface resistance.

Layered Li[Li0.2Ni0.17Co0.07Mn0.56]O2 is successfully synthesized by a sol–gel method and is further coated with ZrF4 (0.5, 1, 2 and 3 wt.%) through a simple wet chemical strategy. Physical characterizations indicate that the ZrF4 nanocoating layers have little impact on cathode structure. Comparison of electrochemical performances demonstrates that 1 wt.% ZrF4 modified electrode exhibits the highest reversible capacity (193 mAh g− 1) and best cycling performance (capacity retention of 89%) after 100 cycles at 0.1 C. Electrochemical impedance spectroscopy (EIS) analysis reveals that charge transfer resistance grows much slower after coating. Fourier transform infrared (FTIR) results further confirm that the surface ZrF4 effectively suppresses the fast growth of solid electrolyte interface (SEI) film. The improved electrochemical properties are thus attributed to the multifunctional ZrF4 nanocoating layer, which not only suppresses the side reaction(s) and oxygen loss, but also accelerates the lithium ion transportation due to the reduced resistance. Additionally, differential scanning calorimetry (DSC) tests show that the ZrF4 layer also helps in enhancing the thermal stability. This work provides a new insight into surface modification in achieving high energy cathodes for the next-generation lithium-ion batteries.