Nanoscaled Lithium Powders with Protection of Ionic Liquid for Highly Stable Rechargeable Lithium Metal Batteries

Abstract

specific capacity of 3860 mAh g −1 and a low gravimetric density of 0.53 g cm −2 with the lowest negative electrochemical potential (−3.04 V vs standard hydrogen electrode). [2] A theoretical energy density of 2600 Wh kg −1 for Li-S battery and 3500 Wh kg −1 for Li-air battery might be achieved with a Li metal anode. [3] Practically, however, the use of Li metal anode in rechargeable batteries faces huge technical challenges in safety and short cycle life caused by the potential short circuit due to the Li-dendrite growth and by the low coulombic efficiency (CE) due to the formation of unstable solid-electrolyte interface (SEI) layer, respectively. [4] Considerable effort has been devoted to the improvement of electrochemical performance of Li metal anode and development of rechargeable Li metal batteries. [5] Attempts were made typically by the modification of electrolytes, [6] or protection of Li metal anode, [7] or use of advanced separators [8] and solid-state electrolytes. [9] Nevertheless, most of these studies were based on thick dense Li foil, especially at laboratory level, which means economically not only the massive waste of Li source. The practical power operation of Li metal anode at high current density is also problematic due to the limited accessibility of the active surface of Li foil. [2][3][4][5][6][7][8][9] Although construction of 3D nanostructured Li hosts with graphene oxide, [10] hollow carbon spheres, [11] nanofiber matrix, [12] and nanoporous scaffolds [13] may be effective alternatives in homogenizing Li deposition and stabilizing SEI layer, the complicated manufacturing process of materials and electrodes, additional electrodeposition or thermal infusion process for prestoring Li into the hosts, in particular, is energy and time consuming, and consequently restricts their practical applications on the whole in battery manufacture industry.Unlike Li foils, Li metal in powder form has advantages in the specific surface area and better compatibility with the existing battery manufacturing processes. In theory, the specific surface area of Li powder of ≈20 µm in diameter is 4.5 times higher than that of Li foil, [14] which may substantially lower the local current density of the electrode, and hence decrease the polarization of Li anode. For the Li dendrite growth, multiple models have been developed, including Chazalviel model, Monroe-Newman model, Tikekar-Archer model, surface energy model, and phase field kinetics model. [5b,15-17] In Chazalviel model, [16] it was demonstrated that the growth of To suppress the dendrite formation and alleviate volume expansion upon striping/platting is a key challenge for developing practical lithium metal anodes. Lithium metal in powder form possesses great potential to address this issue due to large specific surface area. However, the fabrication of powdery metallic lithium is largely restricted because of its unique softness, stickiness, and high reactivity. Here, a safe and readily accessible cryomilling process toward lithium powders is ...

Robust Cycling of Ultrathin Li Metal Enabled by Nitrate‐Preplanted Li Powder Composite

“…In contrast to existing thin Li foil manufacturing technologies, such as the extrusion‐laminate process, [ 43,44 ] electroplating, [ 45–47 ] and vapor deposition, [ 47 ] the LMP slurry‐mixing and coating processes enable faster, economical manufacturing of large‐area Li metal electrode with controllable thicknesses. [ 21,48 ] Besides, slurry‐mixing and coating technologies have been well‐established in the battery industry. Indeed, we successfully fabricated a 145 mm wide and 20 µm‐thick large‐area LN‐LMP composite laminate (Figure S1, Supporting Information).…”

Prelithiation/Presodiation Techniques for Advanced Electrochemical Energy Storage Systems: Concepts, Applications, and Perspectives

“…Interestingly, the lab‐made Li metal composites have been successfully fabricated by cryomilling Li foil with ionic liquid [P 4444 ]TFSI, which are stable and easy handling. [ 96 ] The as‐prepared Li composites as anodes could deliver excellent electrochemical properties with a very low overpotential and an ultrahigh area capacity, which could be utilized as an effective prelithiation reagent for the compensation for the large irreversible capacity loss of Li‐free anode materials. In addition, the Li‐dendrite growth is greatly effectively suppressed or prevented.…”

Structure‐Controlled Li Metal Electrodes for Post‐Li‐Ion Batteries: Recent Progress and Perspectives

“…[ 118–123 ] However, Li metal powders produced by DET are highly reactive toward residual vapor or oxygen even in inert gases and exhibit ductility. These problems can be solved by coating the surface of Li metal powder with Li 2 CO 3 , [ 124–126 ] LiF, [ 115,127,128 ] wax, [ 129,130 ] and ionic liquids [ 131 ] to improve stability and ductility.…”

“…Reproduced under the terms of the Creative Commons CC‐BY license. [ 131 ] Copyright 2019, The Authors, published by Wiley‐VCH. c) EDS image (O 1s mapping) of Li metal powder to observe Li 2 CO 3 protection layer behavior according to pressing level.…”

“…To strengthen the protective layer influence on Li metal powder, Pu et al used a cryo‐milling technique to embed Li metal powder into a high‐melting‐point ionic liquid phase (Figure 6b) that acted as a milling assistor and a protective/dispersion agent. [ 131 ] As a result, smaller‐particle‐size Li metal powders were formed and dispersed within the protective phase to significantly suppress dendrite growth and volume expansion. However, as the ionic liquid: Li metal powder ratio was high, only one third of Li metal powder (13 mg out of 40 mg in total) was electrochemically active, with the rest being electrically isolated by excess ionic liquid.…”