Enhancing the Structure and Interface Stability of LiNi_0.83Co_0.12Mn_0.05O₂ Cathode Material for Li-Ion Batteries via Facile CeP₂O₇ Coating

Abstract

High-energy Ni-rich layered cathode materials (LiNi x Co y Mn 1−x−y O 2 , x ≥ 0.8) for lithium-ion batteries (LIBs) suffer greatly from cation disorder and poor thermal, structure, and interface stability, causing an unsatisfactory cycle and safety performance. Herein, cerium pyrophosphate (CeP 2 O 7 , abbreviated as CPPO) was coated on the secondary particle surface of LiNi 0.83 Co 0.12 Mn 0.05 O 2 via a facile PEG assisted aqueous deposition method. Compared with the bare material, lower cation disorder occurs in the modified sample due to lower Ni 2+ content. A wellordered CPPO crystalline coating layer could be observed on the particle surface. Suppressed structural deterioration due to more stable interface properties leads to better rate capability. Also, better thermal stability has been achieved after the surface treatment. The modified sample maintains 92.38% of the initial capacity after 100 cycles at a 2C rate and upper cutoff voltage of 4.3 V. After cycling for 200 cycles at a 1C rate and higher cutoff voltage of 4.4 V, 80.54% of the initial capacity is maintained. In addition, the discharge capacity under a higher rate is greatly improved under the upper cutoff voltage of 4.3/4.5 V.

High-Performance High-Nickel Multi-Element Cathode Materials for Lithium-Ion Batteries

“…After modification, the capacity loss after 200 cycles was 17.8%, which was greatly improved compared to the capacity loss of 28.2% without modification. Coating with metal phosphates is also a more common modification method for cathode materials, including Co 3 (PO 4 ) 2 [176], Ni 3 (PO 4 ) 2 [177], Mn 3 (PO 4 ) 2 [178], FePO 4 [179], AlPO 4 [180], Y(PO 3 ) 3 [181], CeP 2 O 7 [182], LaPO 4 [183], etc. Liu et al [179] designed and prepared Y(PO 3 ) 3 -coated LiNi 0.8 Co 0.15 Al 0.05 O 2 to reduce the surface residual alkali and improve the gas generation problem of cathode materials.…”

“…Even at a high temperature of 55 • C, the electrode modified with 2 mol% Y(PO 3 ) 3 still maintained a high reversible capacity, with a capacity retention rate of 89.4% after 100 cycles. Cao et al [182] synthesized CeP 2 O 7 -coated high-nickel cathode LiNi 0.83 Co 0.12 Mn 0.05 O 2 through a PEGassisted water deposition method. The coating material has good interface stability and can inhibit structural degradation, improving the thermal stability and rate performance of the cathode material.…”