In the present work, we performed electrochemical measurements to investigate Li (de)intercalation behavior and Raman spectroscopic studies to understand structural changes during charge−discharge processes and verify the structural stability after electrochemical cycling of the AlPO 4 -coated Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 composite cathode. Physicochemical characterization techniques confirmed the well-crystalline layered composite nature of the prepared material. Electrochemical measurements indicated high discharge capacities of ∼230 and 160 mAh/g at C/20 and 1C, respectively, with good cycling performance. In-situ Raman spectroscopic studies revealed extraction of lithium and oxide ions from the lattice followed by rearrangement of cations during the first cycle charging process and extraction of oxide ions followed by insertion of lithium ions back in the structure without any major change during the discharging process. Ex-situ Raman and microscopic measurements on the cathode before and after electrochemical cycling indicated the structural stability of the material. Studies performed on the AlPO 4 -coated composite cathode demonstrate the possibility of using it as nextgeneration cathode material for advanced lithium-ion batteries.
First-principles calculations are used to analyze the phase stability, formation energy, and Li intercalation potential for a series of layered cathode materials. The calculations show LiNi 0.66 Co 0.17 Mn 0.17 O 2 as a promising cathode for lithium-ion batteries. The layer-structured LiNi 0.66 Co 0.17 Mn 0.17 O 2 is prepared via wet chemical route, followed by annealing at 1123 K and characterized using powder X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The characterization techniques reveal single-phase LiNi 0.66 Co 0.17 Mn 0.17 O 2 with highly ordered structure. Galvanostatic chargeedischarge curves recorded at 1C show the discharge capacity of ca. 167 mAh g À1 and good cyclic performance for 25 cycles.
a b s t r a c tLi 2 MnO 3 is known to be electrochemically inactive due to Mn in tetravalent oxidation state. Several compositions such as Li 2 MnO 3 , Li 1.5 Al 0.17 MnO 3 , Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 were synthesized by a sol-gel Pechini method. All the samples were characterized with XRD, Raman, XPS, SEM, Tap density and BET analyzer. XRD patterns indicated the presence of monoclinic phase for pristine Li 2 MnO 3 and mixed monoclinic/spinel phases (Li 2 − x Mn 1 − y Al x + y O 3 + z ) for Al-substituted Li 2 MnO 3 compounds. The Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. XPS analysis for Mn 2p orbital reveals a significant decrease in binding energy for Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 compounds. Cyclic voltammetry, charge/discharge cycles and electrochemical impedance spectroscopy were also performed. A discharge capacity of 24 mAh g −1 for Li 2 MnO 3 , 68 mAh g −1 for Li 1.5 Al 0.17 MnO 3 , 58 mAh g −1 for Li 1.0 Al 0.33 MnO 3 and 74 mAh g −1 for Li 0.5 Al 0.5 MnO 3 were obtained. Aluminum substitutions increased the formation of spinel phase which is responsible for cycling.Published by Elsevier B.V.
Layer-structured LiNi0.66Co0.17Mn0.17O2 is prepared via sol-gel route followed by annealing at 1173 K for 12 h. Structural and morphological features of the prepared material are examined with powder X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Energy dispersive X-ray spectroscopy. Characterization techniques depict the single-phase LiNi0.66Co0.17Mn0.17O2 with particle size in the range of 700 to 900 nm. Graphene is added to LiNi0.66Co0.17Mn0.17O2 particles as conductive additive during electrode fabrication and its influence on the electrochemical performance of LiNi0.66Co0.17Mn0.17O2 is investigated. The results indicate the better electrochemical performance of LiNi0.66Co0.17Mn0.17O2 mixed with graphene in terms of high discharge capacity (246 mAh/g at 5 mA/g) and good cycling performance compared to LiNi0.66Co0.17Mn0.17O2. The improved electrochemical performance is attributed to the decrease in the charge-transfer resistance.
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