Suppressed voltage decay and improved electrochemical performance by coating LiAl5O8 on the surface of Li1.2Mn0.54Ni0.13Co0.13O2

Abstract LiAl 5 O 8 -coated Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode materials were synthesized by using the co-precipitation method along with a facile sol-gel coating process. Homogeneous and 3–5 nm thin LiAl 5 O 8 film was formed on the LMNC surface. After the coating modification, discharge specific capacity, the initial Coulombic efficiency, and rate performance were improved to some extent. It was particularly important to note that the voltage decay of the battery after the charge and discharge cycle was well suppressed. Specifically, the 3 wt% LiAl 5 O 8 -coated electrode can deliver the initial discharge capacity of 243.5 mAh g −1 with a low irreversible capacity loss of 51.1 mAh g −1 and the initial Coulombic efficiency reached the maximum of 82.63% at 0.1 C rate. Although the 1 wt% LiAl 5 O 8 -coated electrode was cycled through 100 cycles at a rate of 0.5 C, the capacity retention rate was still up to 95.8%, while that of the LiAl 5 O 8 -free one was only 82.8%. The stable and thin LiAl 5 O 8 coating layer protected the electrode structure from HF corrosion and other side reactions and reduced the oxygen loss (in the form of Li 2 O) by suppressing the initial activation of Li 2 MnO 3 .