Nanoscale Manipulation of Spinel Lithium Nickel Manganese Oxide Surface by Multisite Ti Occupation as High‐Performance Cathode

Abstract

A novel two-step surface modification method that includes atomic layer deposition (ALD) of TiO followed by post-annealing treatment on spinel LiNi Mn O (LNMO) cathode material is developed to optimize the performance. The performance improvement can be attributed to the formation of a TiMn O (TMO)-like spinel phase resulting from the reaction of TiO with the surface LNMO. The Ti incorporation into the tetrahedral sites helps to combat the impedance growth that stems from continuous irreversible structural transition. The TMO-like spinel phase also alleviates the electrolyte decomposition during electrochemical cycling. 25 ALD cycles of TiO growth are found to be the optimized parameter toward capacity, Coulombic efficiency, stability, and rate capability enhancement. A detailed understanding of this surface modification mechanism has been demonstrated. This work provides a new insight into the atomic-scale surface structural modification using ALD and post-treatment, which is of great importance for the future design of cathode materials.

Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

“…Moreover, the cycle stability test conducted at the current density of 1 C at 55 °C is shown in Figure f. The specific capacity of each sample type sharply increases during the initial cycles, which may be caused by the more thorough activation and more vigorous kinetics of Li + at this comparatively high test temperature relative to room temperature . Interestingly, the discharge capacity of all materials is substantially improved at 55 °C in comparison with that of room temperature.…”

A Long Cycle‐Life High‐Voltage Spinel Lithium‐Ion Battery Electrode Achieved by Site‐Selective Doping

“…Lin et al explored the atomic structure evolution of functioning LNMO by aberration-corrected scanning transmission electron microscopy (STEM). [5] Interestingly,Mn 3 O 4like spinel and rock-salt structures were found to form on the surface and subsurface of LNMO particles,o wing to the migration of transition metals (TM) into tetrahedral (8a sites of Fd3 m)a nd octahedral sites (16c sites of Fd3 m), respectively.T hese irreversible phase transformations initiated through TM migration lead to the TM dissolution and increased charge transfer impedance,s everely deteriorating battery performance.Xiao et al used atomic layer deposition (ALD) coupled with post-treatment to incorporate Ti 4+ into surface Fd3 m 8a sites, [6] with this relieving impedance accumulation and alleviating side reactions at the electrodeelectrolyte interphase.P iao et al doped Al 3+ into empty Fd3 m 16c octahedral sites at LNMO surface by ALD and heat treatment, [7] suppressing TM dissolution and reducing side reactions with the electrolyte.T herefore,doping at both tetrahedral and octahedral sites is evidently the key to the structural stabilization of LNMO during long-term cycling. Moreover,afacile and low-cost atomic-doping-engineering strategy to effectively improve LNMO performance is also urgently needed.…”

Effectively enhanced structural stability and electrochemical properties of LiNi0.5Mn1.5O4cathode materialsviapoly-(3,4-ethylenedioxythiophene)-in situcoated for high voltage Li-ion batteries

“…[15][16][17][18] Furthermore, dissolution of Mn 3+ in LNMO is another serious issue, which would cause destroyed material structure and reduced cycle life of LNMO. [19][20][21] Meanwhile, decomposition of electrolyte causes an electrolyte/ electrode interface (SEI) on the surface of LNMO during cycling, it would prevent the insertion/extraction of Li + and result in poor cycle life. [22][23][24][25] In this regard, many strategies have been proposed to tailor the structures and morphologies of the LiNi 0.5 Mn 1.5 O 4 materials through ion-doping, nanoarchitecture, or surface modication.…”