The Effects of AlF[sub 3] Coating on the Performance of Li[Li[sub 0.2]Mn[sub 0.54]Ni[sub 0.13]Co[sub 0.13]]O[sub 2] Positive Electrode Material for Lithium-Ion Battery

Abstract

AlF 3 -coated Li͓Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ͔O 2 materials have been synthesized as positive electrode materials for lithium-ion batteries. The pristine and AlF 3 -coated Li͓Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ͔O 2 materials were characterized by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and charge-discharge techniques. The electrochemical studies indicated that the AlF 3 -coated Li͓Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ͔O 2 showed initial irreversible capacity loss of only 47 mA h/g compared to 75.5 mA h/g for pristine material. Meanwhile, the coated material also exhibited better rate capability and cyclic performance, which has higher capacity retention of 87.9% after 80 cycles at 0.5 C rate at room temperature in comparison with only 67.8% for the pristine one. The functional mechanism of AlF 3 coating on the performance of Li͓Li 0.2 Ni 0.13 Mn 0.54 Co 0.13 ͔O 2 was also investigated by electrochemical impedance spectroscopy ͑EIS͒ and in situ differential electrochemical mass spectrometry ͑DEMS͒. EIS analysis indicated that AlF 3 -coated Li͓Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ͔O 2 had stable charge transfer resistance ͑R ct ͒. In situ DEMS results revealed that the activity of extracted oxygen species from layered positive electrode material was greatly reduced and the decomposition of the electrolyte was significantly suppressed for AlF 3 -coated Li͓Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ͔O 2 . Therefore, more oxygen molecules rather than carbon dioxide were observed in the coated material system. It is demonstrated again that the AlF 3 coating layer played an important role in the stabilization of the electrode/electrolyte interface for the coated material.

Li3V2(PO4)3-coated Li1.17Ni0.2Co0.05Mn0.58O2 as the cathode materials with high rate capability for Lithium ion batteries

“…The poor intrinsic electronic conductivity and low lithium ion diffusion rate are the main barriers for the high-rate capability due to the occupancy of the excess lithium ions in the transition metal layer, blocking the electron flow and lithium ion diffusion in Li-rich layered oxides [5,6]. Surface modification by coating inert or active materials are demonstrated to be effective for improving the high-rate capability of Li-rich layered oxides, coating materials includes fluorides [7][8][9][10][11], metal oxides [12][13][14], phosphates [15][16][17] and so on. For these coating materials, the reasons for improvement of their electrochemical performance are mainly attributed to the aspects as following: 1.…”

“…For these coating materials, the reasons for improvement of their electrochemical performance are mainly attributed to the aspects as following: 1. Suppress the decomposition of the electrolyte [7][8]10]; 2. Reduce the activity of extracted oxygen species in the layered positive electrode material [7,12,14,16]; 3.…”

“…Suppress the decomposition of the electrolyte [7][8]10]; 2. Reduce the activity of extracted oxygen species in the layered positive electrode material [7,12,14,16]; 3. Stabilize the interface between cathode and electrolyte [9,15]; Generally, the coating materials are almost inactive for electrochemical lithium insertion/extraction.…”

Simple solid-state method for synthesis of Li[Li0.20Mn0.534Ni0.133Co0.133]O2 cathode material with improved electrochemical performance in lithium-ion batteries

“…This material can deliver an initial discharge capacity as high as 250 mAhg −1 when discharged from 4.8 to 2.0 V at room temperature [16], or 286 mAhg −1 when discharged from 4.6 to 2.5 Vat 50°C [9]. [17].…”

“…Different modification treatments, such as substitution with Ru, [20] Cr or Mg, [21] precondition with NH 3 or HNO 3 [22], and surface modification with nanostructured Al 2 O 3 , AlPO 4 , RuO 2 [23], or AlF 3 [16] were introduced. Such surface coating treatment on LLOs was proved to reduce the surface reactivity and improve the cycle stability.…”