Microstructure-Controlled Li-Rich Mn-Based Cathodes by a Gas–Solid Interface Reaction for Tackling the Continuous Activation of Li₂MnO₃

Abstract

Li-rich Mn-based cathodes have attracted much attention due to their high capacity stemming from anion redox above 4.5 V. However, the continuous activation of Li 2 MnO 3 in Lirich Mn-based materials, which correlates with O 2 release and TM migration, is usually unfavorable to structural stability. Herein, based on a gas−solid interface reaction, we tackle this continuous activation phenomenon by restricting the capacity release of Li 2 MnO 3 via NH 4 HCO 3 treatment in the Li 1.2 Ni 0.36 Mn 0.44 O 2 cathode. After modification, oxygen vacancies associated with the spinel phase are introduced on the surface. The 4 mol % NH 4 HCO 3 -modified material's capacity starts at 182 mAh g −1 at 1 C instead of increasing from 173 to 186 mAh g −1 for 25 cycles in the pristine material. Meanwhile, it also exhibits an excellent capacity retention of 93.24% after 200 cycles (at 1 C), with a small voltage decay rate of 1.19 mV cycle −1 .

Surface Spinel-Coated and Polyanion-Doped Co-Free Li-Rich Layered Oxide Cathode for High-Performance Lithium-Ion Batteries

“…Meanwhile, the Li + diffusion coefficients of Co-free LLOs is 2.74 × 10 –17 cm 2 s –1 ; in contrast, the value of NP-3 is calculated to be 2.31 × 10 –16 cm 2 s –1 . Moreover, all materials show higher Li + diffusion coefficients than Co-free LLOs, which firmly demonstrate that our spinel coating indeed enlarges the Li + intercalation/deintercalation channel and, with PO 4 3– doping, can effectively decrease interface resistance and improve electrochemical performance. ,, …”

“…Moreover, all materials show higher Li + diffusion coefficients than Co-free LLOs, which firmly demonstrate that our spinel coating indeed enlarges the Li + intercalation/ deintercalation channel and, with PO 4 3− doping, can effectively decrease interface resistance and improve electrochemical performance. 47,58,59 In order to explore the structure changes, in situ XRD was performed on Co-free LLOs and NP-3 cathode materials at 0.5C; the results obtained are shown in Figure 7. 60 In the first charge cycle, the (003) peak slowly moves to a low angle from 2.0 V to 4.4 V; Li + was extracted from the lithium layer and the c-axis interlayer spacing is increased during this process.…”

Enabling both ultrahigh initial coulombic efficiency and superior stability of Na2Ti3O7anodes by optimizing binders

“…First of all, it can be seen that in the 5 th circle, the redox peak positions and intensities of the three are almost similar, exhibiting This journal is © The Royal Society of Chemistry 2022 a polarization voltage gap (D) of 0.195 V between oxidation and reduction. 51 When it came to the 10 th circle, the redox peaks of NTO@PVDF became a little weaker and shied slightly; although the oxidation peaks of NTO@CR and NTO@CMC were the same, the reduction peak of NTO@CMC shied to the position of NTO@PVDF. Thus, the three electrodes displayed different polarization values of 0.193 V, 0.171 V, and 0.150 V, corresponding to NTO@PVDF, NTO@CMC, and NTO@CR, respectively.…”

Deciphering the degradation discrepancy in Ni‐rich cathodes with a diverse proportion of [003] crystallographic textures

“…The rock salt phase (Fm-3m) will hinder Li + transportation. 36,[43][44][45][46][47] These Li + ions that fail to return to the original sites may be deposited on the anode, forming an SEI film, which will induce deterioration in battery performance. 48 Concurrently, the tensile forces generated by the rock salt phase and the layered phase in the structure are different during battery cycling, which will lead to structural tear and then cause intragranular cracks, resulting in rapid structural deterioration.…”