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 ...

A first attempt to understand the relationship between the particle size and the electrochemical properties of SiO was conducted.

In this study, an amorphous Li2CO3‐coated nanocrystalline α‐Fe2O3 hierarchical structure is synthesized for the first time using a facile one‐step mechanochemical process at room temperature, taking advantage of the concurrence of repeated fracture‐cold welding of material's particles and a gas‐solid redox reaction. The conformal coating and hierarchical structure significantly increase the cycling durability and rate capability. Typically, a 1–3 nm thick amorphous Li2CO3 layer is conformally coated on Fe2O3 nanocrystallines (≈10 nm in size) that form hierarchically aggregated particles 400–800 nm in size by ball milling α‐Fe2O3 with LiH in CO2. The prepared Li2CO3‐coated nanocrystalline α‐Fe2O3 exhibits highly stable long‐term cyclability as it delivers a reversible capacity of 975 mAh g−1 with 99% of retention after 400 cycles at 100 mA g−1. At a high rate of 3000 mA g−1, its reversible capacity still remains at 537 mAh g−1, superior to the uncoated counterpart (311 mAh g−1). Moreover, amorphous Li2O and Li2CO3 coatings are also similarly produced on Fe2O3 and NiO nanocrystallines, respectively, representing the general applicability of this mechanochemical approach.

No abstract