Overall structural modification of a layered Ni-rich cathode for enhanced cycling stability and rate capability at high voltage

Abstract

Overall structural modification, integrating coating and doping, was developed to enhance the structural stability and Li+ transport kinetics in a layered Ni-rich cathode, which significantly improves the electrochemical performance at high voltage.

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

“…A significant achievement from this approach is that the increase in voltage hysteresis is largely decreased during cycling at high temperatures. Similarly, Yang and co‐workers develop an overall structural modification strategy for the NCM811, which integrates a Li‐conductive Li 2 GeO 3 coating phase at the surface region (Figure d) with the gradient Ge‐doping at the surface/interface zones (Figure e) via the interfacial fusion at high temperatures . The findings show that the Li 2 GeO 3 coating can inhibit the adverse interfacial side reactions at the electrode/electrolyte interface, while the Ge‐doping can significantly suppress cation mixing and ameliorate electrochemical performance deterioration of the NCM811 during high cutoff voltage cycling .…”

“…Similarly, Yang and co‐workers develop an overall structural modification strategy for the NCM811, which integrates a Li‐conductive Li 2 GeO 3 coating phase at the surface region (Figure d) with the gradient Ge‐doping at the surface/interface zones (Figure e) via the interfacial fusion at high temperatures . The findings show that the Li 2 GeO 3 coating can inhibit the adverse interfacial side reactions at the electrode/electrolyte interface, while the Ge‐doping can significantly suppress cation mixing and ameliorate electrochemical performance deterioration of the NCM811 during high cutoff voltage cycling . With the guidance of theoretical calculations of migration energy difference, Li and co‐workers rationally design and prepare a Ti‐doped and La 4 NiLiO 8 ‐coated NCM811 cathode, which can be evidenced from the HRTEM and corresponding fast Fourier transformation (FFT) images (Figure f,g) .…”

“…d) Surface TEM image and e) corresponding line scan of Ge elements in Li 2 GeO 3 ‐coated NCM811. Reproduced with permission . Copyright 2019, Royal Society of Chemistry.…”

Degradation and Aging Routes of Ni-Rich Cathode Based Li-Ion Batteries

“…Among the principal cations in Ni-rich cathode materials, i.e., Ni 2+ , Co 2+ , and Mn 2+ , Ni 2+ ions have the strongest propensity to mix with Li + ions (Figure 4), which results in the reduction of both capacity and Li mobility (thus conductivity) and at the same time transforming the layered over spinel crystal to NiO-like rock salt phase, both during preparation and application [43][44][45][46]. The mixing tendency is assumed to be favored from the similarity in the ionic radius of Ni 2+ (0.69 Å) and Li + (0.76 Å) [47,48].…”

O3‐Type Layered Ni‐Rich Oxide: A High‐Capacity and Superior‐Rate Cathode for Sodium‐Ion Batteries

“…Li‐intercalated layered Ni‐rich oxide, such as well‐known LiNi 0.8 Co 0.1 Mn 0.1 O 2 , has an open layered framework for Li + ions extraction/insertion reaction to deliver a high reversible capacity up to 200 mAh g −1 , which is benefited from the multielectron reaction of high‐content active nickel ions. Likewise, an analogous oxide is expected to be promising intercalated host for accommodating more Na + ions to achieve higher reversible capacity.…”