Enhanced Structural Stability of Boron-Doped Layered@Spinel@Carbon Heterostructured Lithium-Rich Manganese-Based Cathode Materials

Abstract

Layered Li-rich 3d-transition-metal cathode materials, xLi 2 MnO 3 •(1−x)LiMO 2 , have increasingly triggered immense interest for their use in Li-ion batteries due to their advantages in terms of energy density. Nevertheless, poor cycle and rate performances cause limitations in practical commercial applications. We modified the material with boron bulk doping and carbon surface modification to form a B-doped layered@spinel@carbon heterostructure. Herein, B-doping can increase the lattice spacing favorable for Li + insertion/extraction and inhibit oxygen loss successfully. The spinel layer and carbon on the surface can protect the material from corrosion due to electrolyte decomposition, which can accelerate Li + and electron conduction and lessen the phase transition. The co-modified material reveals outstanding cycle and rate capability. Especially, it not only shows superior thermal stability at the high temperature of 45 °C, with a capacity retention rate of 83.3%, but also shows a higher discharge capacity of 108.9 mAh g −1 at the low temperature of −20 °C. Furthermore, the mechanism of the Li-rich cathode material with improved performance was also detected systematically. The proposed facile synthesis and co-modification of the boron-doped layered@spinel@carbon heterostructure can shed light on the design direction for cathode materials of lithium-ion batteries to solve the problem of electrochemical performance degradation caused by structural instability.

Enhanced Cathode Performance: Mixed Al2O3 and LiAlO2 Coating of Li1.2Ni0.13Co0.13Mn0.54O2

“…As a proven effective strategy to mitigate the capacity decline of Li-rich manganese-based materials, surface modification can suppress some issues, such as surface corrosion and electrolyte degradation. − As such, numerous compounds have been introduced as surface coatings, such as metal oxides (Al 2 O 3 , ZrO 2 , and ZnO), − metal fluorides (AlF 3 ), metal phosphates (Mn 3 (PO 4 ) 2 , FePO 4 , AlPO 4 , etc. ), ,, and Li-ion conductors (LiPO 4 , Li 2 MnO 3 , and LiFePO 4 ). − Reduced side reactions and improved Li + diffusion efficiency have been achieved via the improvement of interfacial stability between the cathode material and the electrolyte due to these surface modification strategies. , Among the above-mentioned compounds, Al 2 O 3 , as a special oxide, has been reported by many researchers.…”

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

“…Further, The peaks at 855 and 857 eV of Ni 2p 3/2 orbitals are indexed to Ni 2+ and Ni 3+ , respectively, as presented in Figure S17b, Supporting Information. [ 50 ] The surface of SLNMO has a higher Ni 2+ content through quantifying analysis. This can attribute to the introduction of Sb with +5 valence into crystal lattices, as the indexing result of Sb 4d orbitals in Figure S17c, Supporting Information [ 51 ] because foreign cations with higher valence can make original cations tend to a lower valence to maintain charge balance of system.…”

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

“…[16] Forall the three samples,the two peaks can be observed in Ni 2p 3/2 with the binding energy of 854.9 eV and 856.5 eV (Figure 3e), which means the existence of Ni 2+ and Ni 3+ ,r espectively. [17] As illustrated in Figure S3, the peak of Fe 2p 3/2 appears around 708.3 eV,7 09.3 eV, 710.4 eV (Fe 2+ )a nd 710.2 eV, 7 11.3 eV,7 12.4 eV,7 13.6 eV (Fe 3+ ), [18] in which the major content is Fe 3+ .T oc onfirm the Mn valence,M n3ss pectra is deconvoluted (Figure 3d). In some details,the DE 3s of the three samples are alike,4.56 eV for the PLLR sample,4 .43 eV for the intermediate sample, and 4.48 eV for the Fe-2 %sample.Furthermore,the splitting energy of Mn 3s(DE 3s )l evel and Mn valence (u Mn )h as the following linear relationship:…”