Phosphorus and Boron Co‐Doped Carbon Coating of LiNi_0.5Mn_1.5O₄ Cathodes for Advanced Lithium‐ion Batteries

Abstract

A facile approach for the preparation of phosphorus and boron co‐doped carbon coated LiNi0.5Mn1.5O4, which is then applied as cathode materials for lithium ion batteries has been investigated. The effect of carbon coating amounts on the battery performance has been studied systematically. The 5 wt.% carbon coated sample exhibits the most outstanding performance, including an excellent capacity retention of 96.7 % after 200 cycles, superior rate capability (111 mAh g−1 capacity at 5 C), and significantly improved cycle life under 1 C. It is believed that the phosphorus and boron co‐doped carbon coating layer could suppress side‐reactions between the electrolyte and LiNi0.5Mn1.5O4, and alleviate the dissolution of manganese ions into the electrolyte effectively. Moreover, electrochemical impedance spectroscopy results reveal that the phosphorus and boron co‐doped carbon coating on LiNi0.5Mn1.5O4 could reduce the charge transfer resistance significantly. The composite cathode therefore provides good conductivity as well as fast Li‐ion diffusion, then resulting in better rate capability and cycle life, even under a high temperature of 55 °C.

N-doped engineering of a high-voltage LiNi0.5Mn1.5O4 cathode with superior cycling capability for wide temperature lithium–ion batteries

“…There are three typical reversible peaks, two of which in the high voltage of 4.6–4.8 V correspond to Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ redox couples. 60 The LNMON sample shows the lower polarization than other samples, which is probably related to the small size of the particles and better crystallization. Besides, a couple of weak peaks at around 4.0 V can be noted, which should associate with the redox couple of Mn 3+ /Mn 4+ .…”

Boron‐Based High‐Performance Lithium Batteries: Recent Progress, Challenges, and Perspectives

“…[77] Therefore, to improve the electrochemical performance of LBs, by applying a stable nitrogen-and-boron-codoped carbon material coating on the surface of the active material, the interaction between the active material and the electrolyte can be effectively inhibited, thus protecting the electrode and stabilizing the structure of the electrode material. Gu et al [78] first used phosphorus-andboron-codoped carbon as a specific coating on LiNi 0.5 Mn 1.5 O 4 (LNMO) (as shown in Figure 5c). The coating of phosphorus-andboron-codoped carbon material on the LNMO can adequately protect the LNMO from side reactions with the electrolyte, while providing a conductive and dense coating for battery cycling that results in higher capacity retention, rate capability, and Coulombic efficiency.…”

“…c) Schematic diagram of phosphorus-and-boron-codoped carbon coating over LNMO. Reproduced with permission [78]. Copyright 2019, Wiley-VCH.…”

Simple and Eco‐Friendly Fabrication of Electrode Materials and Their Performance in High‐Voltage Lithium‐Ion Batteries

“…Figure 5a and bs hows the Mn 2p and Ni 2p photoemission spectra.T he two peaks of Mn spectrum( 2p 3/2 and 2p 1/2 ;F igure 5a)a re rather symmetric and their binding energies, 642.6 and 654.1 eV,a re consistent with Mn 4 + . [48] Nevertheless, the Mn signal is often fitted to two components (Mn 3 + and Mn 4 + ) [49][50][51][52] but the relative contributiono fb oth valences is very irregular, with contents of Mn 3 + between about 50 % [50][51][52] to scarcely 10 %( the latter value being more consistentw ith the composition of the spinel). [49] These discrepancies result from the small differencei nt he binding energies of these two valences.…”