Synthesis and electrochemical study of Zr-doped Li[Li0.2Mn0.54Ni0.13Co0.13]O2 as cathode material for Li-ion battery

On the Ageing of High Energy Lithium-Ion Batteries—Comprehensive Electrochemical Diffusivity Studies of Harvested Nickel Manganese Cobalt Electrodes

“…Cation mixing is a structural disorder where a partial occupation of $N{i}^{2+}$ on the crystallographic 3b sites of a $L{i}^{+}$ and conversely a partial occupation of $L{i}^{+}$ in 3a sites of $N{i}^{2+}$ in transition metal layers may occur considering the close ionic radii of $L{i}^{+}$ (0.76 Å) and $N{i}^{2+}$ (0.69 Å). In practice, this phenomenon is known for deteriorating the electrochemical performance of the layered oxides materials by decreasing their discharge capacity and hindering the diffusion pathway of $L{i}^{+}$ [34,35]. A higher concentration of cation mixing would lead to materials that are less ordered with a greater $L{i}^{+}$ diffusion barrier [36].…”

The Role of Zr Doping in Stabilizing Li[Ni0.6Co0.2Mn0.2]O2 as a Cathode Material for Lithium‐Ion Batteries

“…For the Zr-doped LNCM electrode, the reversible capacity of the fifth cycle at each current density was 184.5, 176.3, 168.2,1 60.7, and1 52.9 mAh g À1 at 0.1, 0.2, 0.5, 1.0, and 2.0 C, respectively.U pon returning the C-rate to 0.1 C, the reversible capacityr ecovered to 174.6 mAh g À1 ,c orresponded to 95 %o f the initial capacity.T he superior rate capability can be attribut- The fast electrochemical kinetics of the Zr-doped LNCM electrode were further supported by the Nyquistp lots obtained using EIS, in which the semicircle of high to intermediate frequencies represents the charge-transfer resistance (R ct ), whereas the straight line at low frequencies corresponds to Li-ion diffusion within the bulk electrode ( Figure 3). [31][32][33] The Zr-doped LNCM electrode displayed similar semicircles (similar R ct values) and as teeper diffusion-based line both before and after 100 cycles at ar ate of 0.1C compared with the undoped LNCM electrode, indicating similar electron transfer and faster Li-ion diffusioni nt he Zr-doped LNCM electrode. [45] The Li-ion diffusion coefficient was calculated using the slope of the line in the low frequency region, [31-33, 40, 41] whichw as determined to be 2.65 10 À10 and 5.01 10 À10 cm 2 s À1 for the undoped and Zr-doped LNCM electrodes, respectively.T herefore, Zr doping apparently improved the Li-ion diffusion in the bulk and enhanced the rate capability.…”

“…[10][11][12][13] The Li + /Ni 2 + cation mixingi sb elieved to be ak ey factor for the structural instability and phase transformation during the electrochemical cycling and it also leads to the high activationenergy barrierfor Li diffusion. [26][27][28][29][30][31][32][33][34][35][36] Among these, bulk doping has proved to be an effective method to enhancet he cycle and rate performance by stabilizing the structure and increasing the Li + diffusion rate. [26][27][28][29][30][31][32][33][34][35][36] Among these, bulk doping has proved to be an effective method to enhancet he cycle and rate performance by stabilizing the structure and increasing the Li + diffusion rate.…”

“…[14][15][16][17][18] Various strategies have been proposed to improvet he electrochemical performance of layered Ni-rich cathode materials including composite material design, [8,19,20] surface coating, [21][22][23][24][25] and bulk doping. [31][32][33] Several doping elements have been investigated, [26][27][28][29][30] of which Zr is considered to be ap romising dopant because of itsl arger ionic radius compared to other transition metals (Ni 2 + ,C o 3 + ,a nd Mn 4 + )a long with as trongerZ r ÀO bond formation compared with Ni, Co, andM n. Zr-doped layered cathode materials have shown enhanced cycle life and rate capability.T he improved electrochemical performance of Zr-doped layered cathode materials has been attributedt or educed cation mixing, fast Li + -transportation kinetics, and lower impedance, which has been mainly confirmed by Rietveld refinementa nd electrochemical impedance spectroscopy (EIS). [31][32][33] Several doping elements have been investigated, [26][27][28][29][30] of which Zr is considered to be ap romising dopant because of itsl arger ionic radius compared to other transition metals (Ni 2 + ,C o 3 + ,a nd Mn 4 + )a long with as trongerZ r ÀO bond formation compared with Ni, Co, andM n. Zr-doped layered cathode materials have shown enhanced cycle life and rate capability.T he improved electrochemical performance of Zr-doped layered cathode materials has been attributedt or educed cation mixing, fast Li + -transportation kinetics, and lower impedance, which has been mainly confirmed by Rietveld refinementa nd electrochemical impedance spectroscopy (EIS).…”

“…[26][27][28][29][30][31][32][33][34][35][36] Among these, bulk doping has proved to be an effective method to enhancet he cycle and rate performance by stabilizing the structure and increasing the Li + diffusion rate. [31][32][33] Several doping elements have been investigated, [26][27][28][29][30] of which Zr is considered to be ap romising dopant because of itsl arger ionic radius compared to other transition metals (Ni 2 + ,C o 3 + ,a nd Mn 4 + )a long with as trongerZ r ÀO bond formation compared with Ni, Co, andM n. Zr-doped layered cathode materials have shown enhanced cycle life and rate capability.T he improved electrochemical performance of Zr-doped layered cathode materials has been attributedt or educed cation mixing, fast Li + -transportation kinetics, and lower impedance, which has been mainly confirmed by Rietveld refinementa nd electrochemical impedance spectroscopy (EIS). [31,[33][34][35][36][37][38][39][40][41] However,t he microscopici nvestigation of cation mixing and structural stabilitya tt he atomics cale has not yet been demonstrated.…”