Improving the Electrochemical Performance of Ni‐Rich LiNi_0.8Co_0.1Mn_0.1O₂ by Enlarging the Li Layer Spacing

Abstract

Ni-rich cathode materials have high capacities but exhibit serious capacity attenuation. Therefore, a strategy for modifying a LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode material by Na doping of the Li + sites is proposed to improve its electrochemical performance. In this work, Li 1À x Na x Ni 0.8 Co 0.1 Mn 0.1 O 2 (x = 0, 0.01, 0.03) materials are synthesized by a co-precipitation and solid-state sintering method, and their structures and electrochemical properties are analyzed. X-ray diffraction (XRD) results suggest that all the prepared materials have a typical hexagonal layered structure with no impurities. The spacing of the Li layers increases from 2.59251 Å to 2.59805 Å, which shows that a small amount of larger Na ions (0.102 nm) occupy the Li sites (0.076 nm). Additionally, electrochemical measurements show that the high-rate performance and cycling stability are significantly improved when some of the Li + sites in LiNi 0.8 Co 0.1 Mn 0.1 O 2 are occupied by Na + . Specifically, the capacity retention of Li 0.99 Na 0.01 Ni 0.8 Co 0.1 Mn 0.1 O 2 is 91 % after 100 cycles at a rate of 10 C. Meanwhile, the mechanism about electrochemical performance was improved by doping Na + into Li + sites of LiNi 0.8 Co 0.1 Mn 0.1 O 2 has been further discussed.

In Situ Surface Modification for Improving the Electrochemical Performance of Ni‐Rich Cathode Materials by Using ZrP2O7

“…[25] There are no other miscellaneous phase peaks because of the negligible modification amount. [26] Figure 1b shows the XRD patterns of pure ZrP 2 O 7 (p-ZPO), which perfectly matches the characteristic peaks of PDF#71-2286, indicating that the ZrP 2 O 7 at 600 8Ch as high purity, [27] suggesting that ZrP 2 O 7 can be generated under the modification processing of pristine NCM811,w hichi sc onsistent with the HRTEM lattice fringe diffraction results below.…”

“…The XRD patterns of pristine NCM811 and 1.0 wt % ZrP 2 O 7 ‐modified NCM811 (1.0 ZPO–NCM811) have no significant differences in the material phase and have a typical layered structure (α‐NaFeO 2 ) with the R m space group, corresponding to PDF#74‐0919 (Figure a) . There are no other miscellaneous phase peaks because of the negligible modification amount . Figure b shows the XRD patterns of pure ZrP 2 O 7 (p‐ZPO), which perfectly matches the characteristic peaks of PDF#71‐2286, indicating that the ZrP 2 O 7 at 600 °C has high purity, suggesting that ZrP 2 O 7 can be generated under the modification processing of pristine NCM811, which is consistent with the HRTEM lattice fringe diffraction results below.…”

Enhancing the High-Voltage Cycling Performance and Rate Capability of LiNi0.8Co0.1Mn0.1O2 Cathode Material by Codoping with Na and Br

“…The peak at 289.8 eV in the C 1s spectrum (Figure e) can be specified as Li 2 CO 3 , while the peak at 284.8 eV corresponds to hydrocarbons . In Figure S3a, the Na 1s binding energy measured in NCM-NB2 is ∼1 072 eV, which is consistent with the binding energy of sodium oxide; therefore, this result indicates that the valence state of Na in the doped material is +1 . Additionally, it can be seen from Figure S3b that the peaks at 67.3 and 69.2 eV are characteristic of Br – .…”

“…41 In Figure S3a, the Na 1s binding energy measured in NCM-NB2 is ∼1 072 eV, which is consistent with the binding energy of sodium oxide; therefore, this result indicates that the valence state of Na in the doped material is +1. 42 Additionally, it can be seen from Figure S3b that the peaks at 67.3 and 69.2 eV are characteristic of Br − . The peak energy of Br 3d 5/2 is 69.2 eV and belongs to LiBr, which indicates that Br not only forms M (Ni, Co, Mn)-Br bonds but also forms LiBr with some Br ions and residual Li on the surface.…”

Study on the Performance of Different Valence Cations Doped into LiCoO2 Cathode for Li-Ion Batteries

“…This is consistent with the discovery by Wu's research group that the layered cathode material can be modified to improve the diffusion rate of Li-ions by Na doping of the Li + sites. 27 For LMCO and LACO, the density of states of Li-ions is more dispersed, as shown in Fig 4b and c, so it is not as good as Na-ions in improving the diffusion rate of Li-ions. They also further support the difference in the height of the Li slab.…”