Nanoarchitecture Multi‐Structural Cathode Materials for High Capacity Lithium Batteries

Abstract

Lithium‐rich composite cathodes have been extensively investigated for lithium‐ion batteries. Nanoarchitecture hydroxide precursor for these cathodes with two levels of particle agglomeration (1–2 μm and 10 μm) is produced using a co‐precipitation method. Transmission electron microscopy and X‐ray diffraction confirm that the precursor is a composite comprising transition metal hydroxides and Mn3O4. Cathode materials synthesized based on the precursor are “layered (R$ \bar 3 $m)‐layered (C2/m)‐spinel (Fd$ \bar 3 $m)” composite phase. The electrochemical performance of lithium cells utilizing this material as the cathode is determined to be excellent. Both the layered‐layered‐spinel composite structure and the nanoarchitecture morphology contribute to the electrochemical performance advantage of this material over other cathode materials.

Synthesis of high capacity cathodes for lithium-ion batteries by morphology-tailored hydroxide co-precipitation

“…6 correspond to a Mn 3 O 4 phase (space group I4 1 /amd), which is the result of Mn 2þ oxidation. Select area electron diffraction confirmed the precursor was TM(OH) 2 rather than TMOOH, which was discussed in detail in our previous study [32]. The composite structure of the precursors indicates that even though N 2 cover gas was applied during the synthesis process, a certain amount of Mn 2þ oxidized to Mn 3þ during synthesis, washing, or drying.…”

“…The peak intensity at glomerates are narrowly distributed. A process involving two levels of particle agglomeration (1e2 mm and 10 mm) was proposed in our previous report [32]. We concluded that even though the growth rates varied for experiments with different M S /M A ratios, the particle growth follows the same two-level agglomeration mechanism.…”

An Ion‐Exchange Promoted Phase Transition in a Li‐Excess Layered Cathode Material for High‐Performance Lithium Ion Batteries

“…In contrast, it is found that these two pairs of well-separated peaks are combined into broad (222) S and (440) S peaks at 500 °C in portions III and IV, respectively, revealing a complete layered-to-spinel phase transformation. [ 14 ] Increasing the annealing temperature above 600 °C causes undesired decomposition of the newly formed spinel structure, resulting in a MnCo 2 O 4 impurity and recovery of layered Li 2 MnO 3 , which is consistent with the continuous mass reduction in the TG curves during the heating segment. Formation of MnCo 2 O 4 is apparently detected at 600 °C in portion II at 2 θ = 30° -31°, and the restored layered Li 2 MnO 3 is confi rmed by the obvious intensity increase of its XRD peaks in portions I, III, and IV.…”

“…[ Protonation is the prerequisite for the second ion-exchange process, which also results in a distinct morphological change in the LHMNCO derivative and induces formation of a detectable spinel phase within a predominant layered structure. The scanning electron microscopy (SEM) image in Figure 2 b shows distinct layered cake-shaped LHMNCO blocks, which are drastically different from solid polyhedrons of the original LMNCO (Figure 2 a) 14 ] As such, the merger of well-separated (113) M /(006) R and (131) M /(012) R doublets indicates a certain degree of distortion in the layered structure, while the peak splits of (108) R -(110) R pair are preserved, showing that the layered structure is mainly retained in the protonated intermediate. [ 14 ] Since the vibrational models involving the Mn−O bonds in the layered structure are different from those in the spinel phase, Raman spectroscopy is also used to confi rm the formation of spinel structures.…”

Anticorrosive flexible pyrolytic polyimide graphite film as a cathode current collector in lithium bis(trifluoromethane sulfonyl) imide electrolyte

“…Improved battery performance is closely related to the development of materials for various battery components. Except for numerous achievements on high-density positive materials [4][5][6][7][8], the enhancement in energy density is also closed related to the application of novel electrolytes with high potential windows and stability. Lithium hexafluorophosphate (LiPF 6 ) is commonly used as electrolyte salt in commercial LIBs.…”