A Universal Strategy toward the Precise Regulation of Initial Coulombic Efficiency of Li‐Rich Mn‐Based Cathode Materials

Abstract

Li‐rich Mn‐based cathode materials (LRMs) are potential cathode materials for high energy density lithium‐ion batteries. However, low initial Coulombic efficiency (ICE) severely hinders the commercialization of LRM. Herein, a facile oleic acid‐assisted interface engineering is put forward to precisely control the ICE, enhance reversible capacity and rate performance of LRM effectively. As a result, the ICE of LRM can be precisely adjusted from 84.1% to 100.7%, and a very high specific capacity of 330 mAh g−1 at 0.1 C, as well as outstanding rate capability with a fascinating specific capacity of 250 mAh g−1 at 5 C, are harvested. Theoretical calculations reveal that the introduced cation/anion double defects can reduce the diffusion barrier of Li+ ions, and in situ surface reconstruction layer can induce a self‐built‐in electric field to stabilize the surface lattice oxygen. Moreover, this facile interface engineering is universal and can enhance the ICEs of other kinds of LRM effectively. This work provides a valuable new idea for improving the comprehensive electrochemical performance of LRM through multistrategy collaborative interface engineering technology.

Advanced Nanoparticle Coatings for Stabilizing Layered Ni‐Rich Oxide Cathodes in Solid‐State Batteries

“…According to the authors, the as‐formed heterostructure is capable of stabilizing the surface, thereby suppressing O 2 release and preventing related phase transformations and side reactions from occurring. [ 58 ] Because the coating method employed in this work comprised the use of oleic acid as a stabilizing agent for the ZrO 2 NPs, surface reconstruction may play a role here as well. In fact, EELS mapping of the C‐NCM85 indicated Mn enrichment at the particle surface (Figure S29, Supporting Information), but this needs further study.…”

Inhibiting Mn Migration by Sb‐Pinning Transition Metal Layers in Lithium‐Rich Cathode Material for Stable High‐Capacity Properties

“…[ 23,46,47 ] And the lower fingerprint vibration at around 350–400 cm −1 can be indexed to C2/m Li 2 MnO 3 . [ 34,35 ] Both LNMO and SLNMO have obvious TMO bending and stretching vibration peaks as well as the weak peak at 423 cm −1 , reflecting that anions and cations are in a state of chemical coupling in short‐range order local structure, in line with XRD diffraction analysis. [ 23,46,47 ] Gaussian function peak fitting in Figure S13, Supporting Information, exhibits that the peak area represented Li 2 MnO 3 in SLNMO occupies 11.5% of the total peak area, indicating the more efficient anionic redox for providing the higher capacity.…”

“…The honeycomb hexagons (white circles) formed by clusters of bright spots with varying degrees indicate the existence of TM and heavier Sb elements because of their different atomic mass. [ 34,35 ] At the same time, the crystal structure model with atomic arrangement features also can be observed in Figure 1d. [ 36 ] As shown in Figure 1e, through modulation of Sb, the distance between Mn and O becomes larger, realizing the decrease of energy level of Mn 3d and O 2p orbitals, beneficial to restrain the over redox of anions and cations.…”

In Situ Surface Self‐Reconstruction Strategies in Li‐Rich Mn‐Based Layered Cathodes for Energy‐Dense Li‐Ion Batteries

“…Due to the enhanced electronic conductivities provide by the CNT and fast ionic conductivities endowed by spinel structure, such a designed sample exhibited a high energy density (1077 Wh kg −1 at 0.1 C) and excellent rate capability (195 mAh g −1 at 10 C) (Figure 5b). In addition to carbon nanotubes, many surface treatment agents also have been used, such as PH 3 , [ 41 ] NH 3 , [ 42 ] H 2 C 2 O 4 , [ 14d ] oleic acid, [ 43 ] Mn(AC) 2 , [ 44 ] KClO 3 , [ 45 ] Na 2 S 2 O 3 , [ 46 ] Na 2 S 2 O 8 , [ 47 ] PVdF, [ 14b ] ammonium salt [ 14e,34,48 ] and other carbon source. [ 13g,14c,f,h,40,49 ] Most of the surface treatments were able to result in other surface modifications besides spinel layer.…”