Facile Synthesis of The Li-Rich Layered Oxide Li_1.23Ni_0.09Co_0.12Mn_0.56O₂ with Superior Lithium Storage Performance and New Insights into Structural Transformation of the Layered Oxide Material during Charge–Discharge Cycle: In Situ XRD Characterization

Abstract

In this work, the Li-rich oxide Li1.23Ni0.09Co0.12Mn0.56O2 was synthesized through a facile route called aqueous solution-evaporation route that is simple and without waste water. The as-prepared Li1.23Ni0.09Co0.12Mn0.56O2 oxide was confirmed to be a layered LiMO2-Li2MnO3 solid solution through ex situ X-ray diffraction (ex situ XRD) and transmission electron microscopy (TEM). Electrochemical results showed that the Li-rich oxide Li1.23Ni0.09Co0.12Mn0.56O2 material can deliver a discharge capacity of 250.8 mAhg(-1) in the 1st cycle at 0.1 C and capacity retention of 86.0% in 81 cycles. In situ X-ray diffraction technique (in situ XRD) and ex situ TEM were applied to study structural changes of the Li-rich oxide Li1.23Ni0.09Co0.12Mn0.56O2 material during charge-discharge cycles. The study allowed observing experimentally, for the first time, the existence of β-MnO2 phase that is appeared near 4.54 V in the first charge process, and a phase transformation of the β-MnO2 to layered Li0.9MnO2 is occurred in the initial discharge process by evidence of in situ XRD pattrens and selected area electron diffraction (SAED) patterns at different states of the initial charge and discharge process. The results illustrated also that the variation of the in situ X-ray reflections during charge-discharge cycling are clearly related to the changes of lattice parameters of the as-prepared Li-rich oxide during the charge-discharge cycles.

Stress Evolution in Lithium-Ion Composite Electrodes during Electrochemical Cycling and Resulting Internal Pressures on the Cell Casing

“…The complex behavior described above is partially related to lattice parameter changes in Li 1.2 Ni 0.15 Mn 0.55 Co 0.1 O 2 during the initial delithiation of a similar oxide as described by previous investigators. 16,21 Their in operando X-ray diffraction measurements reveal an increase in c-and decrease in a-lattice parameters leading to a gradual non-monotonic decrease in unit cell volume during the first charge to 4.8 V. The observed crystal structure changes do not correlate exactly with the measured stress, which indicates that the supposedly 'inactive' electrode components such as the carbons and the binder also contribute to stress evolution. For instance, intercalation of PF 6 − anions at voltages >4.45 V vs. Li/Li + leads to lattice expansion and structure disordering of graphite contained in the positive electrode.…”

Surface modification of Li(Li0.17Ni0.2Co0.05Mn0.58)O2 with LiAlSiO4 fast ion conductor as cathode material for Li-ion batteries

“…It is a daunting challenge for people to conquer the above mentioned problems of the Li-rich layered oxides to keep pace with the rapidly increasing requirement for satisfying batteries. Recently, people have made great efforts including cation and anion doping [10,12,13], surface modification [9,11,[14][15][16][17][18][19][20][21], innovation of synthesis method [22,23], and fabrication of nano-sized particles [6,24,25], to achieve the goal of commercialization of the Li-rich layered cathode materials. In particular, the surface modification by coating some materials such as metal oxides [15][16][17], phosphates [18][19][20], fluorides [9,11,21] has been regarded as one of the most effective measures to overcome drawbacks of Li-rich layered oxides.…”

Surface Structural Transition Induced by Gradient Polyanion‐Doping in Li‐Rich Layered Oxides: Implications for Enhanced Electrochemical Performance

“…[15][16][17][18] The origin of voltage/capacity decay upon cycling stems from cation migration between TM layers and Li layers and subsequent phase transformation. [19,20] The cationic doping with other metallic cations (such as Mg, [21] Al, [22] Ti, [23] Sn, [24] Ru, [25] Y, [26] Zn, [27] etc.) and polyanion doping based on nonmetal elements, such as BO 4 5− , [28] SiO 4 4− , [29] PO 4 3-, [30] etc., have been employed to improve the cyclic durability by weakening the TM-O covalency in the oxygen closepacked structure.…”