The Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 layered oxide (NCM811) is attracting considerable attention as a high-capacity cathode material for rechargeable Li-ion batteries. However, due to its inherent structural/chemical/electrochemical instability, NCM811 with high Ni content suffers from significant performance degradation upon storage even in ambient atmospheres as well as during charge–discharge cycling. Herein, we demonstrate a simple but effective surface-tuning approach to mitigate storage-induced degradation of NCM811, which is based on the conversion of undesirable Li residues to a protective Li 3 PO 4 nanolayer via phosphate treatment. The accelerated storage stability test shows that phosphate-modified NCM811 exhibits remarkably improved electrochemical performance (capacity, cycle life, and rate capability) over the pristine one after being stored under harsh environmental conditions. A combined analytical study indicates that surface tuning through phosphate treatment enhances the storage stability of NCM811 by eliminating impurity-forming Li residues and producing a Li 3 PO 4 nanolayer that inhibits parasitic reactions at the electrode–electrolyte interface. Furthermore, Li 3 PO 4 provides an effective barrier to H 2 O and CO 2 infiltration into the particle agglomerates, thereby suppressing the loss of particle integrity.
Bibliographical noteFunding Information:
This work was supported by the R&D Program of National Research Council of Science & Technology (project no. CAP-14-2-KITECH ). This work was also supported by the National Research Foundation ( NRF-2018R1A5A1025594 ) of the Ministry of Science and ICT and by the Korea Institute of Energy Technology Evaluation and Planning (Project No. 20172420108680 ) of Ministry of Trade, Industry and Energy, Republic of Korea .
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry