Tungsten Boride Stabilized Single‐Crystal LiNi_0.83Co_0.07Mn_0.1O₂ Cathode for High Energy Density Lithium‐Ion Batteries: Performance and Mechanisms

Abstract

Transition metal doped LiNiO2 layered compounds have attracted significant interest as cathode materials for lithium‐ion batteries (LIBs) in recent years due to their high energy density. However, a critical issue of LiNiO2‐based cathodes is caused particularly at highly delithiated state by irreversible phase transition, initiation/propagation of cracks, and extensive reactions with electrolyte. Herein, a tungsten boride (WB)‐doped single‐crystalline LiNi0.83Co0.07Mn0.1O2 (SNCM) cathode is reported that affectively addresses these drawbacks. In situ/ex situ microscopic and spectroscopic evidence that B3+ enters the bulk of the SNCM, enlarging the interlayer spacing, thus facilitating Li+ diffusion, while W3+ forms an amorphous surface layer consisting of LixWyOz (LWO) and LixByOz (LBO), which aids the construction of a robust cathode‐electrolyte interphase (CEI) film, are shown. It is also shown that WB doping is effective in controlling the degree of the c‐axis contraction and release of oxygen‐containing gases at high voltages. The best doping concentration of WB is 0.6 wt.%, at which the capacity retention rate of the SNCM reaches 93.2% after 200 cycles at 2.7–4.3 V, while the morphology and structure of the material remain largely unchanged. The presented modification strategy offers a new way for the design of new stable SNCM cathodes for high‐energy‐density LIBs.

Enhanced Li-ion intercalation kinetics and lattice oxygen stability in single-crystalline Ni-rich Co-poor layered cathodes

“…This confirms that the Li/Ni mixing is greatly reduced after Ba and Al co-doped. 31,32 Besides, the Ba 3d and Al 2p spectra of XPS reveal that Ba and Al are present in +2 and +3 forms, respectively (Fig. S8†).…”

Al- and Nb-Comodified Ni-Rich NCM Cathode for High-Performance Lithium-Ion Batteries

“…When the voltage increased to 4.1 V, the (003) peak shifted to a lower 2θ accompanied by the delithiation process and phase transition from H1 to M and H2, illustrating the lattice expansion along with the c -axis. As the voltage increased to 4.3 V, the (003) peak quickly shifted to a higher 2θ because of the phase transition from H2 to H3, indicating the lattice contraction in the c -axis direction. , During the lithiation process, the phase underwent a reverse transition. The shift angles of the H2–H3 phase transition are 0.32 and 0.2° for NCM83 and NCM83-NA, respectively, which means the doped Ni-rich cathode has a smaller volume change and a better structural stability.…”

“…Figure j exhibits the spectra of O 1s of NCM83 and NCM83-NA. The peaks at 531.58 and 528.98 eV correspond to the reactive oxygen and lattice oxygen bonds on the surface, respectively . The peak intensity of TM–O in NCM83-NA is significantly stronger than that in NCM83, indicating that Al/Nb can suppress the formation of oxygen vacancies. − In addition, the doping of Al and Nb ions decreases the amount of surface residual lithium compounds.…”

Mg/Al Double-Pillared LiNiO2 as a Co-Free Ternary Cathode Material Ensuring Stable Cycling at 4.6 V

“…Cathode materials play a crucial role in the key components of LIBs. LiNiO 2 -based cathode materials, including LiNi x Co y Mn z O 2 and LiNi x Co y Al z O 2 ( x + y + z = 1), have garnered significant attention due to their high voltage platform and specific capacity. − The demand for low-cost and high-energy cathode materials has been increasing, driving the development of cobalt-free (Co-free) and nickel-rich (Ni-rich) LiNiO 2 -based alternatives. − However, increasing the nickel content presents a certain challenges. For example, the cathode is more susceptible to irreversible phase transition during the delithiation process.…”