Effect of Chromium and Niobium Doping on the Morphology and Electrochemical Performance of High-Voltage Spinel LiNi_0.5Mn_1.5O₄ Cathode Material

Abstract

Undoped, Cr-doped, and Nb-doped LiMn(1.5)Ni(0.5)O4 (LNMO) is synthesized via a PVP (polyvinylpyrrolidone)-combustion method by calcinating at 1000 °C for 6 h. SEM images show that the morphology of LNMO particles is affected by Cr and Nb doping. Cr doping results in sharper edges and corners and smaller particle size, and Nb doping leads to smoother edges and corners and more rounded and larger particles. The crystal and electron structure is investigated by XRD- and synchrotron-based soft X-ray absorption spectroscopy (sXAS). Cr doping and light Nb doping (LiNb(0.02)Ni(0.49)Mn(1.49)O4) improve the rate performance of LNMO. To explore the reason for rate-performance improvement, we conducted potential intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) tests. The Li(+) chemical diffusion coefficient at different state of charge (SOC) is calculated and suggests that both Cr and light Nb doping speeds up Li(+) diffusion in LNMO particles. The impedance spectra show that both R(SEI) and R(ct) are reduced by Cr and light Nb doping. The cycling performance is improved by Cr or Nb doping, and Cr doping increases both Coulombic efficiency and energy efficiency of LNMO at 1 C cycling. The LiCr(0.1)Ni(0.45)Mn(1.45)O4 remains at 94.1% capacity after 500 cycles at 1 C, and during the cycling, the Coulombic efficiency and energy efficiency remain at over 99.7% and 97.5%, respectively.

High‐Voltage LiNi0.45Cr0.1Mn1.45O4 Cathode with Superlong Cycle Performance for Wide Temperature Lithium‐Ion Batteries

“…The substitution of Mn and Ni by cations, such as Al 3+ , Co 3+ , can also stabilize the structure of LNMO and eliminate the formation of Li y Ni 1− y O impurity phase . Mao et al synthesized Cr doped LNMO via a PVP (polyvinylpyrrolidone) combustion method by calcinating at 1000 °C for 6 h. Yang et al prepared Cr doped LNMO by adopting a soft combustion reaction with benzoyl peroxide as the oxidizer, followed by calcination at 800 °C for 20 h. Li et al prepared Cr 0.05 Ni 0.225 Mn 0.725 (OH) 2 precursors by a coprecipitation method, the precursors were mixed with Li 2 CO 3 followed by heating at 950 °C for 6 h and then at 730 °C for another 3 h. They focused on the elimination of Li y Ni 1− y O impurity phase and improvement of structure stability using Cr doping. Herein, we report the unique characteristic of Cr 3+ to substitute the Ni and Mn ion to improve the electrochemical performance of LNMO, especially the cycling performance at low temperature.…”

Structure and electrochemical performance modulation of a LiNi0.8Co0.1Mn0.1O2 cathode material by anion and cation co-doping for lithium ion batteries

“…There could be seen the good agreement between the experimental and calculated results (R e < 5%, R p < 4%), which proves that the structural model is reasonable. 31 Besides, the lattice parameter a and c of the NCM sample is 2.8715 and 14.2008Å. Aer Co doping, a and c increase to 2.8719 and 14.2019Å, respectively.…”

Research Progress in Improving the Cycling Stability of High-Voltage LiNi0.5Mn1.5O4 Cathode in Lithium-Ion Battery

“…Jing et al [70] synthesized undoped, Cr-doped, and Nb-doped LNMO via a polyvinylpyrrolidone combustion method by calcinating at 1000 °C for 6 h. Scanning electron microscopy (SEM) images showed that Cr doping resulted in sharper edges and corners and smaller particle size (Fig. 4a), while Nb doping led to smoother edges and corners and more rounded and larger particles (Fig.…”

“…4SEM images of a Cr doping and b Nb doping, c rate cycle performance and d cycle performance of all samples. Nb-0.02: LiNb 0.02 Ni 0.49 Mn 1.49 O 4 , Nb-0.04: LiNb 0.04 Ni 0.48 Mn 1.48 O 4 , Cr-0.1: LiCr 0.1 Ni 0.45 Mn 1.45 O 4 , Cr-0.2: LiCr 0.2 Ni 0.4 Mn 1.4 O 4 [70] …”

“…Nb-0.02: LiNb 0.02 Ni 0.49 Mn 1.49 O 4 , Nb-0.04: LiNb 0.04 Ni 0.48 Mn 1.48 O 4 , Cr-0.1: LiCr 0.1 Ni 0.45 Mn 1.45 O 4 , Cr-0.2: LiCr 0.2 Ni 0.4 Mn 1.4 O 4 [70]…”