The Influences of Surface Coating Layers on the Properties of Layered/Spinel Heterostructured Li-Rich Cathode Material

Abstract

Layered/spinel heterostructured Li-rich material is prepared by controlling the conditions of a solvothermal method to obtain precursor and the subsequent high-temperature solid phase reaction, and then, 3 wt % LiF, 3 wt % Li2TiO3, and 3 wt % Li3PO4 are coated on the surface of the layered/spinel heterostructured Li-rich oxide by a wet chemical method. The influences of different lithium salt coating layers on the layered/spinel heterostructured material are investigated by transmission electron microscopy, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy. It can be seen that after coating a Li salt layer, the initial charge–discharge efficiency, cycle, and rate performance are obviously improved. Especially, the sample coated with Li3PO4 shows an optimum result in improving the rate capability of layered/spinel heterostructured Li-rich material and effectively inhibiting the side reaction between the layered/spinel heterostructured Li-rich material and organic electrolyte as well as maintaining the structural stability of the material. Therefore, the layered/spinel heterostructured Li-rich material coated with Li3PO4 has the highest rate capability of 148.2 mAh g–1 at 10 C, the best cycle ability with capacity retention of 85.3% cycling 200 times at 0.5 C, and improved initial Coulombic efficiency of 88.3%.

Phase Compatible NiFe2O4 Coating Tunes Oxygen Redox in Li-Rich Layered Oxide

“…Various functional coatings have been applied to limit unwanted oxygen activities and restrict structure degradation. These coatings include metal oxides (Al 2 O 3 , TiO 2 , ZrO 2 ), − metal fluorides (LiF, FeF 3 , AlF 3 ), − phosphate (Li 3 PO 4 , AlPO 4 ), , etc . The above-reported strategies have shown positive effects on suppressing O 2 release and stabilizing the crystal structure.…”

Stable Li2TiO3 Shell–Li1.17Mn0.50Ni0.16Co0.17O2 Core Architecture Based on an In-Site Synchronous Lithiation Method as a High Rate Performance and Long Cycling Life Lithium-Ion Battery Cathode

“…The comparison suggests that the LTO shell benefits more oxygen anions to involve in the initial charge 47 and that more lattice oxide ion vacancies can be retained at high voltages. That is, more vacancies are available for Li + ions to be inserted in the following discharge, 24 therefore exhibiting an increased discharge capacity for xLTO-LNCM. More importantly, the initial Coulombic efficiency of LNCM is significantly improved after LTO modification.…”

“…However, due to their poor intrinsic ionic conductivity, these traditional coatings will increase the interfacial charge-transfer resistance and hence can deteriorate the rate capability. Thus, coating materials with both chemical stability and high ionic conductivity (∼10 –7 S·cm –1 ) are essential in mitigating this issue, − and selecting suitable coating materials is desperately needed.…”

Investigation of the structure and performance of Li[Li0.13Ni0.305Mn0.565]O2Li-rich cathode materials derived from eco-friendly and simple coating techniques

“…[6][7][8] In the meantime, non-negligible voltage degradation during cycling and poor rate performance [9][10][11] severely hinder the performance and potential application of these materials on a large scale. Generally, surface coating, 12,13 interface modication [14][15][16][17] and ion-doping [18][19][20][21][22][23][24][25][26] are widely used and have been proven to be effective strategies to enhance the electrochemical performance of Li-rich cathode materials. [27][28][29][30][31][32] Among these methods, surface coating with a ceramic layer, such as Al 2 O 3 , TiO 2 or SiO 2 , is a facile and valid technique for improving the cycling stability of Li-rich cathode materials.…”