Chemical deposition synthesis of desirable high-rate capability Al2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 as a Lithium ion battery cathode material

Abstract

Al2O3-coated layered oxide Li1.2Mn0.54Ni0.13Co0.13O2 (AO-LMNCO) is synthesized by a facile sol-gel reaction to prepare a preliminary formation of Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO), and then coating process with Al2O3 nano layer is followed via a chemical deposition route. Galvanostatic charge-discharge tests show that 1.5 wt% Al2O3 coated sample presents the optimum electrochemical performance. It delivers a discharge capacity 285 mAh g-1 in the potential window of 2.0-4.8 V at 0.2 C, which is superior to that 274 mAh g-1 for the pristine one. The initial columbic efficiency is significantly enhanced from 80.60% to 87.40% after the coating process. Moreover, the optimal sample presents a superior high-rate capacity of 120 mAh g-1 at 10 C, and the value is much greater than the pristine one. Physical characterization results show that the as-prepared Li-rich oxide has a typical layered structure, and the Al2O3 nano layer (~4 nm thick) is coated on the surface of the cathode grains. We could ascribe the remarkably enhancement of cycling stability and high-rate capability to the Al2O3 protective coat, which could obstruct the electrolyte from the close contact with the active material. Thus the corrosion of the electrode structure effectively decreases and the dissolution of Mn from the pristine material greatly suppresses.

Construction of a Stable LiNi0.8Co0.1Mn0.1O2 (NCM811) Cathode Interface by a Multifunctional Organosilicon Electrolyte Additive

“…Figure shows the EIS results of NCM811/Li cells after different cycles, and the obtained data were fitted by the equivalent circuit (Figure e). It is generally believed that the EIS curve mainly includes the following parts: a semicircle in high frequency reflects diffusion of Li ions through the surface film on the cathode ( R CEI ); another semicircle in intermediate frequency reflects the charge transfer resistance of Li ions on the electrode/electrolyte interface ( R ct ); and a diagonal in low-frequency reflects the diffusion of Li ions inside the active material particles (Warburg resistance, W ). − As shown in Figure a, the R CEI value of the cell with baseline electrolyte was 6.0 Ω cm 2 after the formation process and increased to 13.2 Ω cm 2 after 200 cycles. However, the R CEI value of the cell with 0.5% BSA additive was decreased from 13.4 Ω cm 2 to 1.8 Ω cm 2 , and the larger R CEI after the formation process may be due to the participation of BSA in film formation.…”

Insight into the Improved Performances of Ni-Rich/Graphite Cells by 1,3,5-Trimethyl-1,3,5-tris(3,3,3-trifluoropropyl) Cyclotrisiloxane as an Electrolyte Additive

“…This improvement is related to the chemical stability and ionic conductivity of the cathode interphase derived from the preferential oxidation of D 3 F, which can be confirmed by electrochemical impedance spectroscopy. As presented in Figure c, the Li/NCM811 coin cells with or without D 3 F after three initial cycles show their Nyquist plots with a semicircle at high frequencies, reflecting Li-ion transportation through the interphase film on the cathode ( R f ), another semicircle at intermediate frequencies, reflecting the charge transfer resistance on the electrode/electrolyte interface ( R ct ), and a slope line at low frequencies, attributed to the diffusion of Li ions in the bulk electrode ( W o ). − Figure c shows the fitting result of the experimental data. As presented in Figure S5a, the cell with D 3 F after three initial cycles has a smaller R f than that without D 3 F, suggesting that the cathode interphase constructed from the preferential oxidation of D 3 F is more conductive ionically than that originated from electrolyte oxidation decomposition.…”

Large-scale synthesis of lithium- and manganese-rich materials with uniform thin-film Al2O3 coating for stable cathode cycling

“…Directly coating on the interface is an effective way to suppress the interfacial reactions [23][24][25][26][27][28][29][30][31]. A number of approaches, such as spray pyrolysis [32], sol-gel method [33], and vapor deposition method [34], have been employed to inhibit the electrolyte decomposition. However, it is still challenging to achieve a controlled uniform coating at nanoscale.…”