The main shortcomings of NCM811 could be solved at the same time via a facile Zr surface modification approach.

While zirconium-based coatings are known to improve the cycling stability of a number of lithium ion battery cathodes, the microstructural origin of this enhancement remains uncertain. Here we combine advanced transmission electron microscopy (high-resolution transmission electron microscopy, high-angle annular dark field, electron energy loss spectroscopy, and energy-dispersive X-ray spectroscopy) with electrochemical impedance analysis to provide new insight into the dramatic role of Zr surface modification on the electrochemical performance of Li- and Mn-rich (LMR) cathodes (Li­[Li0.2Ni0.13Co0.13Mn0.54]­O2). It is demonstrated that a Zr-based rock-salt structure layer with a thickness of 1–2 nm is formed on the surface of the LMR. This layer is effective in suppressing the deleterious phase transformation of LMR from initial layered composite combining Li2MO3 and LiMO2 to the disordered rock-salt phase, leading to an enhanced long-term cycling performance and rate capability. Electrochemical impedance spectroscopy analysis demonstrates that the Zr coating does not affect the cathode electrolyte interface (CEI), with the surface film impedance (R sf) being virtually identical in both cases after 100 cycles, at 45.1 versus 45.6 Ω. Conversely, the Zr coating tremendously stabilizes the cathode interfacial structure. The charge-transfer impedance (R ct) in the baseline unmodified LMR increases from 34.2 Ω at cycle 3 to 729.2 Ω at cycle 100. For the Zr-modified specimen, R ct increases dramatically less, from 19.7 to 76.9 Ω. The key finding of this study is then that Zr is actively incorporated into the structure of the cathode but does not affect CEI stability. This fundamental result should guide future surface modification strategies for a range of cathode materials.

In this work, a LiNi1/3Co1/3Mn1/3O2/CNT/Graphene (NCM/CNT/GN) hybrid material with 3D conductive network and excellent rate capability has been successfully prepared by a facile wet chemical method.

A novel Ni-rich LiNi0.68Co0.10Mn0.22O2 cathode with excellent cycling and rate performances is suitable for high energy density LIBs.