Stabilizing Cathode Materials of Lithium-Ion Batteries by Controlling Interstitial Sites on the Surface

Abstract

A surface-vacant-site-occupation (SVSO) strategy is reported to be very effective at stabilizing the high-voltage cathode. The precise control of the interstitial lattice sites on the surface is able to modulate the movement of metal ions by suppressing the diffusion and dissolution of transition metal ions while maintaining the mobility of Li + , resulting in a very stable cathode with excellent cyclability and rate capability.

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

“…To verify our site-selective doping and better understand the structural differences induced by Mg doping, STEM was employed in high-angle annular dark-field (HAADF) mode, enabling direct observation of the atomic-level crystal structure.T he STEM HAADF images of LNMO and Mg0.1-LNMO ( Figure 1g,h, respectively) are viewed along the [110] direction, allowing identification of the positions of the heavy atomic columns. [5,7] We note that the observed bright atomic columns in the images correspond to heavy atoms,w hilst lighter elements such as Li and Oare undetectable.InLNMO (Figure 1g,i), at ypical diamond-shape atomic structure is observed, confirming its spinel structure as consistent with previous STEM observations. [5,7] Line-profile analysis (Figure 1j)s hows continuous peaks with an interval of approximately 0.8 nm in the LNMO structure,c oinciding well with the diagonal distance of two TM atoms within the spinel structure.…”

“…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.…”

One-Step Integrated Surface Modification To Build a Stable Interface on High-Voltage Cathode for Lithium-Ion Batteries

“…32 To build a steady interface, Piao et al introduced an epitaxial surface layer of AlPO4 outside LNMO, followed by an Al 3+ diffusion process, in order to suppress the structural degradation during cycling by increasing the surface stability. 33 coating and subsequent infusion route, leading to a long-term cycling stability in both capacity and voltage. 35 The above findings indicate that, surface lattice pinning, as a supplement approach for traditional surface coating/bulk doping, has a great chance to be utilized to build a desirable interface for cathode materials.…”

Role of Al-doping with different sites upon the structure and electrochemical performance of spherical LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

“…Cao et al stated that a surface-doping strategy with Al in the interstitial sites (16c) of LNMO could control the migration of transition-metal ions effectively by decreasing the number of possible routes to guarantee the stability of LNMO. 56 Therefore, Al introduced at 16d sites may help to maintain the stability of LNMO in a similar way.…”