The superior electrochemical performance of a Li-rich layered cathode material with Li-rich spinel Li₄Mn₅O₁₂ and MgF₂ double surface modifications

Abstract

Li-rich spinel Li4Mn5O12 and MgF2 are constructed on the surface of a Li-rich layered material, and the material exhibits superior electrochemical performance.

A Simple Gas–Solid Treatment for Surface Modification of Li‐Rich Oxides Cathodes

“…The Raman spectra (Figure 3 a) further verify the existence of spinel phase in Li‐rich materials before the treatment. According to the existed reports, [5b, 14] the vibrations of the R ‐3 m layered structure locates at 480 cm −1 and 596 cm −1 , named E g and A 1g . Some weak peaks, at about 365 cm −1 and 420 cm −1 are related with Li 2 MnO 3 , and the peak at 625 cm −1 can be assigned to the LiMn 2 O 4 of Cubic (spinel) Fd ‐3 m structure.…”

“…O 2 nÀ where n 2 (1,2,3)) with irreversible O 2 loss,w hich leads large initial reversible capacity loss,obvious voltage decay,poor-rate capability,and inferior cycling performance. [2] So far,s everal strategies including surface modification of doping, [3] coating, [4] spinel formation, [5] and the defects structure [6] have been developed to overcome those issues.R ecently,g as-solid treatment with the advantages of uniform handling of surface and easy operation has been applied to stabilize the LLR structure via generating the oxygen vacancy.Huang et al [7] introduced CO 2 to generate oxygen vacancy and resulted in enhanced cycling and rate performance.Peng et al [8] in situ constructed aspinel membrane by exposing the pristine material to pure CO atmosphere,which effectively prevents the side reactions with electrolyte.F urthermore,t he spinel membrane also acted to inhibit the irreversible transformation and promote the Li + diffusion. Nevertheless,i t ss till ag reat challenge to develop advanced LLR with precisely controlled gas-solid treatment.…”

A Simple Gas–Solid Treatment for Surface Modification of Li‐Rich Oxides Cathodes

“…O 2 nÀ where n 2 (1,2,3)) with irreversible O 2 loss,w hich leads large initial reversible capacity loss,obvious voltage decay,poor-rate capability,and inferior cycling performance. [2] So far,s everal strategies including surface modification of doping, [3] coating, [4] spinel formation, [5] and the defects structure [6] have been developed to overcome those issues.R ecently,g as-solid treatment with the advantages of uniform handling of surface and easy operation has been applied to stabilize the LLR structure via generating the oxygen vacancy.Huang et al [7] introduced CO 2 to generate oxygen vacancy and resulted in enhanced cycling and rate performance.Peng et al [8] in situ constructed aspinel membrane by exposing the pristine material to pure CO atmosphere,which effectively prevents the side reactions with electrolyte.F urthermore,t he spinel membrane also acted to inhibit the irreversible transformation and promote the Li + diffusion. Nevertheless,i t ss till ag reat challenge to develop advanced LLR with precisely controlled gas-solid treatment.…”

Upgrading the Performance and Stability of Lithium, Manganese‐Rich Layered Oxide Cathodes with Combined‐Formic Acid and Spinel Coating Treatment

“…The coating can be synthesized via a facile method similar to that reported by Guo et al [23] Apart from suppressing lattice O loss and Mn dissolution, this spinel coating can also improve the overall rate capability due to the three-dimensional Li interstitial network in the crystal structure. [22,24] Here, a combination approach of low-cost formic acid washing and Li 4 Mn 5 O 12 coating is employed on LMR cathode particles to enhance the rate and cycle life. Compared to the pristine LMR material (PR), the rate performance of the dualtreated cathode (FA-C-300C) is significantly improved at high charge/discharge rates, where FA-C-300C offers 48 % higher reversible capacity at C. From the galvanostatic charge/ discharge cycling, the capacity and voltage decay are also alleviated for the treated sample, with a capacity retention of 89 % (vs. 71 % of PR) and specific energy density retention of 77 % (vs. 62 % of PR) for the best treated sample after 150 cycles, respectively.…”

“…The coating can be synthesized via a facile method similar to that reported by Guo et al [23] . Apart from suppressing lattice O loss and Mn dissolution, this spinel coating can also improve the overall rate capability due to the three‐dimensional Li interstitial network in the crystal structure [22,24] …”