The use of a single-crystal nickel-rich layered NCM cathode for excellent cycle performance of lithium-ion batteries

Abstract

With the continuous development and progress of new energy electric vehicles, high-capacity nickel-rich layered oxides are widely used in lithium-ion battery cathode materials, and their cycle performance and safety performance have also attracted more and more attention.

Design of a hydrolysis‐supported coating layer on the surface of Ni‐rich cathodes in secondary batteries

“…An anodic peak at around 3.8 V is resulted from the oxidation of Ni 2+ to Ni 3+ /Ni 4+ , accompanied by a hexagonal to monoclinic (H1–M) phase transformation, and two peaks at approximately 4.03 and 4.22 V are attributed to (M–H2) and (H2–H3) phase conversions, respectively. The corresponding three reduction peaks during the lithiation process appear at about 4.14, 3.97, and 3.7 V, respectively 64 . The voltage difference (DV) between the anodic peak and the cathodic peak is generated by the construction of an SEI layer or an undesirable reaction on the electrode surface, and in general, its value can be reflected in the reversibility of the electrodes during a reaction.…”

“…The corresponding three reduction peaks during the lithiation process appear at about 4.14, 3.97, and 3.7 V, respectively. 64 The voltage difference (DV) between the anodic peak and the cathodic peak is generated by the construction of an SEI layer or an undesirable reaction on the electrode surface, and in general, its value can be reflected in the reversibility of the electrodes during a reaction. Lesser values of DV normally mean higher electrochemical reversibility and reduced polarization of the cathode.…”

Assessing Long‐Term Cycling Stability of Single‐Crystal Versus Polycrystalline Nickel‐Rich NCM in Pouch Cells with 6 mAh cm−2 Electrodes

“…[ 11 ] Pouch cells with Ni‐rich single‐crystal LiNi 0.83 Co 0.11 Mn 0.06 O 2 electrodes with an areal capacity of 8.7 mAh cm −2 on both side fabricated from uncoated particles with a diameter of 2–4 µm showed a capacity retention of 84% after 600 cycles to a cut‐off voltage of 4.2 V as compared to 57% for polycrystalline LiNi 0.83 Co 0.11 Mn 0.06 O 2 electrodes. [ 12 ] More recently, a pouch cell with LiNi 0.83 Co 0.12 Mn 0.05 O 2 electrodes with 5.1 mAh cm −2 on both side reached 89% capacity retention after 500 cycles to an upper cut‐off voltage of 4.2 V. [ 13 ] However, the above work does not show a systematic investigation of degradation/improvement mechanism of single‐crystalline NCM and also does not quantify the negative contribution of cracks and the following issues, such as transition metal dissolutions and gas generations.…”

Mechanical Pulverization of Co-Free Nickel-Rich Cathodes for Improved High-Voltage Cycling of Lithium-Ion Batteries

“…To mitigate the above issues, several strategies have been attempted: doping, − surface modification, surface modification via intentional electrolyte additive decomposition, − process refinement, , TM concentration gradient, core–shell structures, grain boundary tailoring, and single-crystalline morphology. , Individually, these modifications fail to generate nickel-rich cathode materials with optimum cycle life retention and air stability for commercial use. Particle cracking may still occur with high-voltage cycling, slowly degrading performance, and air instability allows residual lithium compounds to form during material synthesis and electrode production.…”