Tuning Electrochemical Properties of Li-Rich Layered Oxide Cathodes by Adjusting Co/Ni Ratios and Mechanism Investigation Using in situ X-ray Diffraction and Online Continuous Flow Differential Electrochemical Mass Spectrometry

Abstract

Owing to high specific capacity of ∼250 mA h g, lithium-rich layered oxide cathode materials (LiNi CoMnO) have been considered as one of the most promising candidates for the next-generation cathode materials of lithium ion batteries. However, the commercialization of this kind of cathode materials seriously restricted by voltage decay upon cycling though Li-rich materials with high cobalt content have been widely studied and show good capacity. This research successfully suppresses voltage decay upon cycling while maintaining high specific capacity with low Co/Ni ratio in Li-rich cathode materials. Online continuous flow differential electrochemical mass spectrometry (OEMS) and in situ X-ray diffraction (XRD) techniques have been applied to investigate the structure transformation of Li-rich layered oxide materials during charge-discharge process. The results of OEMS revealed that low Co/Ni ratio lithium-rich layered oxide cathode materials released no lattice oxygen at the first charge process, which will lead to the suppression of the voltage decay upon cycling. The in situ XRD results displayed the structure transition of lithium-rich layered oxide cathode materials during the charge-discharge process. The LiNiMnO cathode material exhibited a high initial medium discharge voltage of 3.710 and a 3.586 V medium discharge voltage with the lower voltage decay of 0.124 V after 100 cycles.

Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

“…The initial charge–discharge curves of the pristine and coated materials were tested at a current density of 0.05 C (1 C = 250 mAh g −1 ) and a voltage of 2–4.8 V, as shown in Figure a and Figure S6 (Supporting Information). During charging, the voltage plateau below 4.5 V corresponds to Li + extraction from the layered structure of the sample and the oxidation of the extremely few Mn 3+ ions in the spinel structure, as observed for all samples . The prominent plateau at ≈4.5 V indicates the irreversible removal of Li and O atoms from Li 2 MnO 3 , and the activation of this layered component.…”

Boosting Superior Lithium Storage Performance of Alloy‐Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid‐Electrolyte Interphase

“…[51] Calculation Methods: The Pwscf code of the QUANTUM-ESPRESSO package under the generalized gradient approximation, the Perdew-Burke-Ernzerhof functional, [52,53] and the ultrasoft pseudopotentials were used for all the DFT calculations which considered spinpolarization, in which the kinetic energy cutoff and charge-density cutoff were 30 and 300 Ry, respectively. Pre-dehydrated helium (99.999%) was employed as the carrier gas.…”

Investigation of Li1.17Ni0.20Mn0.53Co0.10O2 as an Interesting Li‐ and Mn‐Rich Layered Oxide Cathode Material through Electrochemistry, Microscopy, and In Situ Electrochemical Dilatometry

“…The changes in electrodes thickness during cycling can be monitored in situ by electrochemical dilatometry (ECD) . HENCM cathodes were investigated already in situ by XRD and Raman spectroscopy, but there is no report yet on tracking the expansion/contraction (“breathing”) of these cathodes due to the deintercalation/intercalation of Li + ions upon cycling. We note that the usefulness of in situ dilatometry has been already demonstrated for graphite anodes and NCM cathodes, but not for HENCM cathodes.…”