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

Abstract

Li-richl ayered oxides with high capacity are expected to be the next generation of cathode materials. However,t he irreversible and sluggish anionic redox reaction leads to the O 2 loss in the surface as well as the capacity and voltage fading.I nt he present study,asimple gas-solid treatment with ferrous oxalate has been proposed to uniformly coat at hin spinel phase layer with oxygen vacancy and simultaneously realize Fe-ion substitution in the surface.T he integration of oxygen vacancy and spinel phase suppresses irreversible O 2 release,p revents electrolyte corrosion, and promotes Li-ion diffusion. In addition, the surface doping of Fe-ion can further stabilizet he structure.A ccordingly,t he treated Feox-2 %c athode exhibits superior capacity retention of 86.4 %a nd 85.5 %a t1Ca nd 2C to that (75.3 %a nd 75.0 %) of the pristine sample after 300 cycles,r espectively. Then, the voltage fading is significantly suppressed to 0.0011 V per cycle at 2Cespecially.T he encouraging results may play asignificant role in paving the practical application of Li-rich layered oxides cathode.

Facilitating Reversible Cation Migration and Suppressing O2 Escape for High Performance Li‐Rich Oxide Cathodes

“…[22][23][24][25][26][27][28][29] Oxygen vacancies have been proved to inhibit voltage decay and lattice oxygen escape in some studies. [30,31] Nakamura et al found that the oxygen-deficient materials exhibited a greater hysteresis voltage than the bare sample due to a facilitated cation migration. [30] But the underlying mechanism still needs to be further clarified.…”

Inhibiting Mn Migration by Sb‐Pinning Transition Metal Layers in Lithium‐Rich Cathode Material for Stable High‐Capacity Properties

“…It can be seen that the surface O 1s spectrum can be roughly divided into three peaks, 529, 531, and 533 eV, attributed to O 2− lattice oxygen in MO 6 , partially oxidized per‐oxygen species O n − (0 < n < 2), and carbonate deposition species CO 3 2− on the surface, respectively. [ 34,43,48 ] Prominently, the O 1s spectrum of SLNMO can hardly separate the peak of oxidized sedimentary species on surfaces, and the O n − content has almost doubled compared with LNMO, affirming that SLNMO has stronger oxygen anion redox activity. After charging to 4.8 V, compared to LNMO, SLNMO still has less surface deposition and more per‐oxygen species O n − .…”

Scalable Nitrate Treatment for Constructing Integrated Surface Structures to Mitigate Capacity Fading and Voltage Decay of Li‐Rich Layered Oxides

“…The broadened and low intensity peaks located at a range of 20–25° are characteristic of the monoclinic Li 2 MnO 3 ‐like component ( C 2/ m ) owing to the lithium‐cation ordering in the transition‐metal layers [14] . The well spilt peaks of (006)/(102) and (108)/(110) illustrate the high order of the hexagonal structure [15] …”