Enhanced rate performance and high current cycle stability of LiNi_0.8Co_0.1Mn_0.1O₂ by sodium doping

Abstract

Sodium ions have been successfully doped into LiNi0.8Co0.1Mn0.1O2 (NCM811) by solid phase method. The influences of Na doping on the electrochemical properties of the electrode at high current intensities were studied. The experimental results show that 3% Na modified LiNi0.8Co0.1Mn0.1O2 has superior rate performance and cycling behavior due to the cation mixing is suppressed and the structural stability is enhanced by Na doping. The capacity retention of Li0.97Na0.03Ni0.8Co0.1Mn0.1O2 is 64.33% after 100th cycles at 10 C (1 C = 200 mA · g–1) in the potential range from 2.8 V to 4.3 V, which is greatly higher than the pristine NCM (only 35.01%). Li0.97Na0.03Ni0.8Co0.1Mn0.1O2 also shows excellent rate performance of 140.5 mAh · g–1 at 10 C, and the discharge capacity of 3% Na-NCM is higher than that of the pristine NCM when the current intensity is returned from 10 C to 0.5 C. The analysis of the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements confirm that the Na doping plays an important role in inhibiting the electrochemical polarization of LiNi0.8Co0.1Mn0.1O2 and improving the diffusion of lithium ions.

Nano-TiO2 coated single-crystal LiNi0.65Co0.15Mn0.2O2 for lithium-ion batteries with a stable structure and excellent cycling performance at a high cut-off voltage

“…Therefore, the electrochemical polarization caused by the increase of current density reduces the discharge potential and capacity of the material. 35,36 The primary particle size in this study is 3-5 mm, which is much larger than the primary particle size of about 1 mm in other literature reports. 20,26,[37][38][39] However, by comparing with these literature reports, it can be seen that our single crystal material still shows a higher capacity at 5C current density.…”

A Synergistic Effect of Na+ and Al3+ Dual Doping on Electrochemical Performance and Structural Stability of LiNi0.88Co0.08Mn0.04O2 Cathodes for Li-Ion Batteries

“…No impurity peaks were observed in the XRD patterns of bare NCM, NNCM, NCMA, and NNCMA, indicating that Na + and/or Al 3+ were embedded well into the crystal of the host layers. 35,36 According to previously reported results, we assumed that Al 3+ was doped at the Ni sites, indicating that Al 3+ preferably replaced Ni over Co and Mn. 37 In addition, three layers appeared in the supercells used for DFT calculations: the Nionly, Ni/Co, and Ni/Co/Mn layers (Figure 1a).…”

“… The (006)/(102) and (018)/(110) diffraction peaks observed at approximately 38° and 65°, respectively, indicated that the cathode materials presented well-regulated layered structures. No impurity peaks were observed in the XRD patterns of bare NCM, NNCM, NCMA, and NNCMA, indicating that Na + and/or Al 3+ were embedded well into the crystal of the host layers. , …”

“…39,41,42 The Na1p and Al2p peaks of the NNCMA were located at 1071 and 66 eV, which indicates that Na and Al were doped in bare NCM. 14,36,43 SEM was conducted to analyze the surface structure and morphology changes of all samples induced by the effect of Na + and/or Al 3+ doping. Figure 2e−h present the SEM images of bare NCM, NNCM, NCMA, and NNCMA.…”

Diffusion coefficient analysis of aluminum electrolysis spent cathode as anode material for lithium-ion battery

“…It can be seen that the EIS impedance of the two samples is composed of SEI film impedance (Rsf) corresponding to semicircle in high frequency region, charge transfer impedance (Rct) corresponding to semicircle in medium frequency region and Warburg impedance corresponding to oblique line in low frequency region 23 . The resistance values of each part are fitted by ZSimpWin software.…”