Highly Reversible Anion Redox of Manganese‐Based Cathode Material Realized by Electrochemical Ion Exchange for Lithium‐Ion Batteries

Abstract

Anion energy storage provides the possibility to achieve higher specific capacity in lithium‐ion battery cathode materials, but the problems of capacity attenuation, voltage degradation, and inconsistent redox behavior are still inevitable. In this paper, a novel O2‐type manganese‐based layered cathode material Lix[Li0.2Mn0.8]O2 with a ribbon superlattice structure is prepared by electrochemical ion exchange, which realizes the highly reversible redox of anions and excellent cycle performance. Through low‐voltage pre‐cycling treatment, the specific capacity of the material can reach 230 mAh g−1 without obvious voltage attenuation. During the electrochemical ion exchange, the precursor with P2 structure transforms into Lix[Li0.2Mn0.8]O2 with O2 structure through the slippage and shrink of adjacent slabs, and the special superlattice structure in Mn slab is still retained. Simultaneously, a certain degree of lattice mismatch and reversible distortion of the MnO6 octahedron occur. In addition, the anion redox catalyzes the formation of the solid electrolyte interface, stabilizing the electrode/electrolyte interface and inhibiting the dissolution of Mn. The mechanism of electrochemical ion exchange is systematically studied by comprehensive structural and electrochemical characterization, opening an attractive path for the realization of highly reversible anion redox.

Enhancing the Low/Middle‐Frequency Electromagnetic Wave Absorption of Metal Sulfides through F− Regulation Engineering

“…Reports have shown that some structural defects and lattice mismatches inevitably will be introduced during the ion exchange process because of the large radius gap between F − and S 2− . [ 51 ] As observed in Figure 2e, the high‐magnification images of the nanoneedles further revealed the presence of numerous defects (such as point defects and unclear lattice fringes) in F‐12 (Figure 2f,h). Also, as marked by the dotted red line in Figure 2g and Figure S8, Supporting Information, some obvious lattice distortions were found, which may have been caused by a drastic dislocation of atoms due to F − introduction.…”

Mitigating the Surface Reconstruction of Ni-Rich Cathode via P2-Type Mn-Rich Oxide Coating for Durable Lithium Ion Batteries

“…SS NMR measurements were taken on a 400 MHz Bruker AVANCE III spectrometer by employing a 1.3 mm doubleresonance HX probe at a spinning rate of 50 kHz. For 23 Na NMR spectrum, a recycle delay of 20 ms and a 90°pulse length of 1.2 μs were used for Hahn-echo pulse. The 90°pulse length for 7 Li was 1.4 μs, and the recycle delay was 30 ms. For the ex situ XRD and NMR measurements, coin cells were disassembled in an Ar-filled glovebox and the electrodes were washed with dimethyl carbonate solvent.…”

Multi-dimensional correlation of layered Li-rich Mn-based cathode materials

“…The conspicuous O2-type LRMO materials are prepared by molten salt ion exchange based on the precursor of P2-type Na-ion battery cathode materials [126] . Specifically, the P2-type precursor is mixed with an excessive amount of composite lithium salt (LiNO 3 :LiCl = 88:12 w/w) with a lower eutectic point and then heated to melt the composite lithium salt and cause the Li/Na ion exchange to occur.…”