Synthesis and characterization of Zr-doped LiNi_0.4Co_0.2Mn_0.4O₂ cathode materials for lithium ion batteries

Abstract

Li(Ni0.4Co0.2Mn0.4)0.99Zr0.01O2 has better cyclic performance than that of LiNi0.4Co0.2Mn0.4O2 with more stable layered structure due to larger radii of Zr4+.

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

“…Inductively coupled plasma atomice mission spectroscopy( ICP-AES) was used to determine the chemical compositiono ft he undoped and Zr-doped materials to be Li Figure 1d.All the diffraction patterns could be indexed to the hexagonal a-NaFeO 2 -type structure (space group of R3 m)w ithout as econdary phase. [31,33,[37][38][39][40] It also indicates increased interlayer spacing in the layered structure, which is beneficial for Li-ion transportation. [31,33,[37][38][39][40] It also indicates increased interlayer spacing in the layered structure, which is beneficial for Li-ion transportation.…”

“…[42] The shift of the diffraction peaks to lower angles is attributed to the larger ionic radius of Zr 4 + (0.72 )c ompared with Ni 2 + (0.69 ), Co 3 + (0.545 ), andM n 4 + (0.53 ). [34,35,40] The potential gap between the anodic and cathodic peaks was smaller in Zr-doped LNCM, implying that the reversibility of the electrochemical reactions was improved by Zr doping. In both CV curves, ap air of sharp redox peaks were observedi nt he range of 3.6-3.9 V corresponding to the Ni 2 + /Ni 4 + redox couple.…”

“…[43] The electrochemical reactiono fu ndoped andZ r-doped (1 mol %) LNCM electrodes was evaluated by using cyclic voltammetry (CV) in ap otentialr ange of 3.0-4.3 V( vs. Li/Li + )a ta scan rate of 0.04 mV s À1 (Figure 2a). [40] The initial chargea nd discharge profiles of undoped and Zr-doped LNCM electrodes at ar ate of 0.1 C( 18 mA g À1 )i nt he voltage range of 3.0-4.3 V( vs. Li/Li + )i ss hown in Figure 2b.B oth curvesh ave stable and smooth voltage plateausa nd no distinct difference was observed. [34,35,40] The potential gap between the anodic and cathodic peaks was smaller in Zr-doped LNCM, implying that the reversibility of the electrochemical reactions was improved by Zr doping.…”

“…[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,[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. [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.…”

“…[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.…”