Improving the electrochemical performance of layered lithium-rich transition-metal oxides by controlling the structural defects

Abstract

We report the electrochemical properties of layered lithium-rich Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode materials with various degrees of stacking faults, which are prepared via a facile molten-salt method using a variety of fluxes including KCl, Li 2 CO 3 , and LiNO 3 . The frequency of the stacking faults is highly dependent on the temperature and molten salt type used during the synthesis. A well-crystallized Li 1.18 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanomaterial with a larger amount of stacking faults synthesized at 800 C for 10 h in an inactive KCl flux delivers a high reversible capacity of $310 mA h g À1 at room temperature, while the samples prepared in the chemically active fluxes with a smaller amount of stacking faults show poor electrochemical performance. Broader contextAdvanced lithium-ion batteries (LIBs) that deliver more energy at rapid charge and discharge rates are essential for on-board storage technology in hybrid electric vehicles (HEVs) or electric vehicles (EVs). High energy density lithium-rich transition metal oxide cathodes represent an important milestone in materials design for advanced lithium-ion batteries due to their high reversible capacities of $250 mA h g À1 at low cost. Although much progress has been achieved on the lithium-rich transition-metal oxides, the relationship between the microstructure e.g. stacking faults and electrochemical properties of lithiumrich transition-metal oxides remains unclear. In this study, we report the electrochemical performance of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 electrodes with various degrees of stacking faults and reveal that structural defects in the crystal structure of the Li 2 MnO 3 component play a key role in the electrochemistry of xLi 2 MnO 3 $(1 À x)LiMO 2 electrodes using powder X-ray diffraction (XRD), selected area electron diffraction (SAED), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results reported herein provide new insights into the design and synthesis of advanced electrode materials with various degrees of structural defects for use in high-performance energy storage and conversion devices.

Synthesis of LiNi0.5Mn1.5O4 Hollow Microspheres and Their Lithium‐Storage Properties

“…[34,35] As indicated previously, the electrode with a hollow structure can accommodate the volume change during repeated Li + insertion/extraction, which is crucial for cycling performance. [9,[36][37][38][39] tion method with excellent rate capability and cyclability. [9] Nevertheless, they only reported that LNMO has good electrochemical properties at room temperature, but the performances at elevated temperature have not been discussed.…”

High-performance lithium-rich layered oxide materials: Effects of chelating agents on microstructure and electrochemical properties

“…In this regard, a class of layered transition metal oxides, namely, the lithium-rich layered oxides (shorted as LLMO) of the general formula xLi 2 MnO 3 ·(1-x)LiMO 2 (M = Mn, Ni, Co) have attracted much attention, which are reported to deliver 230−285 mAh g -1 reversible capacity, reaching nearly the theoretical one e -/metal capacity of the transition metal dioxide [6][7][8][9][10][11][12]. The electrochemical performance of the LLMO materials is strongly dependent on the synthesis technique [13,14].…”

Uniform Na+ Doping‐Induced Defects in Li‐ and Mn‐Rich Cathodes for High‐Performance Lithium‐Ion Batteries

“…2019, 6, 1802114 is confirmed by the X-ray photoelectron spectroscopy (XPS) analysis in Figure S7, Supporting Information. [6,44,48] As illustrated in Figure 3f, the prolonged cycles (120 cycles) of LMR oxide cathodes have been promoted dramatically by the uniform Na + -doping and defective structures; the electrode of Na/SDS-LMR maintain 93.1% of capacity (221.5 mAh g −1 ) at 0.5C rate after 200 cycles while only 64.8% (139 mAh g −1 ) is retained for the pristine-LMR. Compared with the pristine-LMR, the activation effect is alleviated in Na-LMR and even disappears completely in Na/SDS-LMR, which originates from the good contact of solid-liquid interface and the large specific surface area.…”