Surface Heterostructure Induced by PrPO₄ Modification in Li_1.2[Mn_0.54Ni_0.13Co_0.13]O₂ Cathode Material for High-Performance Lithium-Ion Batteries with Mitigating Voltage Decay

Abstract

Lithium-rich layered oxides (LLOs) have been attractive cathode materials for lithium-ion batteries because of their high reversible capacity. However, they suffer from low initial Coulombic efficiency and capacity/voltage decay upon cycling. Herein, facile surface modification of LiMnNiCoO cathode material is designed to overcome these defects by the protective effect of a surface heterostructure composed of an induced spinel layer and a PrPO modification layer. As anticipated, a sample modified with 3 wt % PrPO (PrP3) shows an enhanced initial Coulombic efficiency of 90% compared to 81.8% for the pristine one, more excellent cycling stability with a capacity retention of 89.3% after 100 cycles compared to only 71.7% for the pristine one, and less average discharge voltage fading from 0.6353 to 0.2881 V. These results can be attributed to the fact that the modification nanolayers have moved amounts of oxygen and lithium from the lattice in the bulk crystal structure, leading to a chemical activation of the LiMnO component previously and forming a spinel interphase with a 3D fast Li diffusion channel and stable structure. Moreover, the elaborate surface heterostructure on a lithium-rich cathode material can effectively curb the undesired side reactions with the electrolyte and may also extend to other layered oxides to improve their cycling stability at high voltage.

Oxygen Release Degradation in Li‐Ion Battery Cathode Materials: Mechanisms and Mitigating Approaches

“…Schematic illustration of coating strategies utilized to improve the structural stability of cathodes. A) Schematic representation of phosphate coating on layered oxide cathode particles: Reproduced with permission . Copyright 2017, American Chemical Society.…”

LiVOPO4‐Modified Lithium‐Rich Layered Composite Cathodes for High‐Performance Lithium‐Ion Batteries

“…The oxidation peak at ca. 4.5 V corresponds to the electrochemical activation of the Li 2 MnO 3 component, removal of Li 2 O from Li 2 MnO 3 , and structural rearrangement [63–65] . During the discharging process, two reduction peaks could be observed at around 3.75 V and 3.25 V, which refer to the reduction of Co 4+ /Ni 4+ and Mn 4+ , respectively [54] .…”

Suppressing Nickel Dissolution in Ni‐rich Layered Oxide Cathodes Using NiF2 as Electrolyte Additive

“…[43] The growth of chargetransfer impedance is regard as the mainly increase of Li-ion cell impedance by Amine et al [44] The R ct of pristine sample increases from 54.51 to 1004 Ω, while the increase of R ct of 100-NiF 2 sample is greatly suppressed (from 52.25 to 650.7 Ω) after 100 ppm NiF 2 is added, implying the TMs of pristine cathode dissolves severely and further results in the cracks of the bulk material. [43,45] By contrast, the TMs dissolution of 100-NiF 2 cathode is restrained, maintaining a better cathode structure. The result indicates that NiF 2 can reduce both the SEI resistance and charge-transfer impedance growth in cycling, enabling the cell relatively stable cycling performance.…”