Multiscale Crystal Field Effect for High-Performance Ultrahigh-Ni Layered Cathode

Abstract

Further popularization of ultrahigh-Ni layered cathodes for high-energy lithium-ion batteries (LIBs) is hampered by their grievous structural and interfacial degeneration upon cycling. Herein, by leveraging the strong electronegativity and low solubility properties of Sb element, a multifunctional modification that couples atomic/microstructural reconstruction with interfacial shielding is well designed to improve the LiNi 0.94 Co 0.04 Al 0.02 O 2 (NCA) cathode by combining Sb 5+ doping and Li 7 SbO 6 coating. Notably, a robust O framework is established by regulating local O coordination owing to the incorporation of a strong Sb−O covalence bond, leading to the inhibited lattice O evolution at high voltage, as revealed by synchrotron X-ray absorption spectroscopy. Moreover, the radially aligned primary particles with (003) crystallographic texture and refined/elongated sizes are achieved by the pinning of Sb on grain boundaries and are confirmed by scanning transmission electron microscopy, resulting in the fast Li + diffusion and mitigated particle cracking. Additionally, in situ construction of the Li 7 SbO 6 ionic conductive layer on grain boundaries can effectively boost interfacial stability and Li + kinetics. As a result, the optimal Sb-modified NCA delivers a high capacity retention of 94.6% after 200 cycles at 1 C and a good rate capacity of 183.9 mAh g −1 at 10 C, which is expected to be applied to next-generation advanced LIBs.

Enhancing the Structural Stability of LiCoO2 at Elevated Voltage via High-Valence Sb Doping

“…It is evident that the –ICOHP of Sb–LCO is higher than that of PLCO, signifying the reinforced Co–O bonds in Sb–LCO. This affirms that doping enhances structural stability, aligning with experimental findings. In addition, the Sb–O COHP (Figure S14) confirms the successful formation of sturdy Sb–O bonds through the doping process.…”

Lattice and Local Electronic Structure Modulation Enables Ultra-Long-Life Li-Rich Cathode Materials

“…The Mn pre-edge peak of the SLLO sample is higher than that of PLLO (Figure 3e), indicating individual MnO 6 octahedra experience slight compression along the b-axis direction. 39 Besides, the normalized Sb K-edge hard XAS in fluorescence yield mode of the SLLO sample (Figure 3f) demonstrates a main peak position and shape akin to the Sb 2 O 5 reference sample, confirming that the valence state of the Sb element is +5. The XPS peak shapes of SLLO are very similar to that of PLLO (Figure S4), indicating that the valence states of these elements did not show an obvious change.…”

A synergetic promotion of surface stability for high-voltage LiCoO2 by multi-element surface doping: a first-principles study

“…Developing cathode materials with larger specific capacities and higher operating voltage has been a hot research topic. 1–3 LiCoO 2 , as the first commercialized cathode material for lithium-ion batteries, still presents competitive advantages over other cathode materials in the portable electronics market due to its high theoretical capacity, high volumetric energy density, and excellent cycle performance. 4–8 Although the theoretical capacity of LiCoO 2 can be as high as 274 mAh g −1 , 9 the commercially available LiCoO 2 cathode is typically limited to a decent charge cut-off voltage of 4.5 V ( vs. Li/Li + ) with capacity as low as 180 mAh g −1 .…”