Optimizing Li Plating Behavior via Controlling Areal Capacity of a Cathode for Cycling Stability on 600 W h kg-1 Lithium-Metal Batteries.

To meet the requirements of long-range electric vehicles and aviation, the high-mass-loading electrode with high areal capacity is a promising solution to realize ultrahigh-energy lithium-metal batteries (LMBs). However, enabling the operation of high mass loading with a long cycling life is still a challenge without in-depth investigation. Herein, we figured out that the polarization appearing in the cycled lithium-metal anodes (LMAs) is responsible for the poor cycling of LMBs with high mass loading. Moreover, the origin of fast degradation of LMAs is affected by mass loading through the Li plating process, which is decided by the Li plating morphology. Hence, manipulating the mass loading can directly promote lithium reversibility and further mitigate cell polarization in LMBs, endowing high-mass-loading LMBs with excellent cycling stability. Consequently, we achieved an ultrahigh energy density (605 W h kg-1) of a 10.1 A h pouch cell with an excellent retention of 91.7% capacity and 86% energy after 50 cycles. The feasible strategy points out a promising approach for designing high-energy-density LMBs in the future.

Effect of High-Voltage Additives on Formation of Solid Electrolyte Interphases in Lithium-Ion Batteries.

Solid electrolyte interphase (SEI) formed at the interface in lithium-ion batteries plays an important role in isolating electrons and permeating ions during charging/discharging processes. Therefore, the formation of a good interface is crucial for better battery performance. In this study, additives based on adiponitrile (ADN) and trimethyl borate (TMB) were employed to broaden the electrochemical window and form a good SEI layer. Electrochemical Atomic force microscopy (EC-AFM) was used for in situ studies of film-formation mechanisms in high-voltage electrolytes on high-temperature pyrolytic graphite (HOPG), as well as Li- and Mn-rich (LMR) materials. X-ray photoelectron spectroscopy (XPS) combined with electrochemical methods revealed a synergistic reaction between the two additives to form a more stable interfacial film during charging/discharging processes to yield assembled batteries with improved cycle performance, its capacity increased from below 100 mAh/g to 200 mAh/g after 50 cycles. In sum, these findings would have great significance for the development of high voltage lithium-ion batteries with enhanced performance.

Mg2SiO4/Si-Coated Disproportionated SiO Composite Anodes with High Initial Coulombic Efficiency for Lithium Ion Batteries.

Silicon monoxide (SiO) is considered as one of the most promising anode material candidates for next-generation high-energy-density lithium ion batteries (LIBs) due to its high specific capacity and relatively lower volume expansion than that of Si. However, a large number of irreversible products are formed during the first charging and discharging process, resulting in a low initial Coulombic efficiency (ICE) of SiO. Herein, we report an economical and convenient method to increase the ICE of SiO without sacrificing its specific capacity by a solid reaction between magnesium silicide (Mg2Si) and micron-sized SiO. The reaction product (named MSO) exhibits a unique core-shell structure with uniformly distributed Mg2SiO4 and Si as the shell and disproportionated SiO as the core. MSO exhibits a superior ICE and a high reversible capacity of 81.7% and 1306.1 mAh g-1, respectively, which can be further increased to 88.7% and 1446.4 mAh g-1 after carbon coating, and improved cyclic stability compared to bare SiO. This work provides a simple yet effective strategy to address the low ICE issue of SiO anode materials to promote the practical application of SiO.