In situ formation of LiF decoration on a Li-rich material for long-cycle life and superb low-temperature performance

Abstract

The electrochemical properties of Li1.2Ni0.13Co0.13Mn0.54O2 (LLO) are improved by LiPF6 coating and subsequent heating.

A review on the stability and surface modification of layered transition-metal oxide cathodes

“…Besides, the generated insulating rock-salt phases cause sluggish kinetics on the surface. To address these structural issues, various oxides [140][141][142] and fluorides [35,38,[143][144][145] have been contributed as coating materials for LMR cathode materials. Ding et al [35] reported NaF as a coating material that can establish a gradient Na 1-x Li x F layer on the surface of Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 cathode.…”

“…As summarized in Tables [1][2][3][4], which are categorized by the types of materials, surface control can be multi-functional and act as inhibitors of phase transition, oxygen release and gas generation, protective barriers for electrolyte decomposition and TM dissolution, mechanical buffers, moisture and air shields, HF scavengers, and electronic/ionic conductivity facilitator, greatly enhancing the energy density, rate capability, cycle life, and safety [33]. Defining the chemical/physical/structural changes of the outer and inner surfaces as surface modification, three types can be categorized: (1) surface coating, the dominant strategies, including electrochemically inactive compounds coating (e.g., metal oxides, fluorides, and phosphates) [34][35][36][37][38], Li impurities-reactive coating (Co 3 O 4 ) [39] and Li-reactive coating (MoO 3 ) [40], Li ion conductive coating (LiTi 2 O 4 , Li 2 ZrO 3 and Li 4 -Mn 5 O 12 ) [41][42][43], conducting polymer coating (e.g., polypyrrole (PPy), polyaniline (PANI) and poly (3,4-ethylenedioxythiophene) (PEDOT)) [44][45][46], and other materials coatings, such as MXene (e.g. Ti 3 C 2 T x ) [47] and conductive graphene matrix [48]; (2) gradient structure design, including core-shell structures [49][50][51][52], hierarchical architectures (i.e., multi-shell) [53][54][55], and concentration gradient (CG) structures [56][57][58]; and (3) other surface treatments, such as rinsing with water to form an oxygendepleted surface layer [59,60], utilizing atomic surface reduction to alter the electronic structure of the surface …”

Li1.2Mn0.54Ni0.13Co0.13O2 nanosheets with porous structure as a high-performance cathode material for lithium-ion batteries

“…Generally, the intercept in the high-frequency range represents the solution resistance (R s ); the quasi-semicircle corresponds to the charge transfer resistance (R ct ); the constant phase element is relate to the double layer capacitance (CPE); and the sloping line is ascribed to Warburg impedance (Z w ). 41,42 Based on the observation in Fig. 6a, the nanosheets have a smaller semicircle and a more vertical straight line than the agglomerated nanoparticles, indicating a lower charge transfer resistance and a faster Li + diffusion behavior.…”

LiF‐Induced Stable Solid Electrolyte Interphase for a Wide Temperature SnO2‐Based Anode Extensible to −50 °C

“…These should be attributed to the good structure stability of the SLG composite and especially the fast charge (electron, ion) transport kinetics (in Figure S7, Supporting Information) among SnO 2 , LiF, and graphite. [23,33,34] Figure 3d shows the differential charge capacity (dQ/dV) curves of the SLG electrode operated under 30, 45, and 60 °C. The peaks within potential range of 0.01-1.0 V correspond to the de-alloying reactions, and those within 1.0-3.0 V represent to the de-conversion reactions.…”

“…[21] And for the stability of the electrode/electrolyte interface, it has been reported that a multilayer SEI, which contains an LiF-rich inner phase and an amorphous outer layer induced by electrolyte additives, can ensure high-rate charging Li metal anode at −15 °C by effectively sealing the Li surface to suppress galvanic Li corrosion and self-discharge. [22,23] However, it is not clear whether a similar strategy is feasible to the SnO 2 -based anode or other anodes, and whether it is feasible at even lower temperatures. And thus, further microstructure and/or composition adjustments should be conducted on the SnO 2 to ensure ultrafine Sn grains and stable electrode/electrolyte interfaces for fast, stable, and reversible alloying and conversion reactions at both high and low temperatures.…”