Search

Lithium (Li) metal has been strongly regarded as the ultimate anode option for next‐generation high‐energy‐density batteries. Nevertheless, the insufficient Coulombic efficiency induced by the extensive active Li loss largely hinders the practical operation of Li metal batteries under wide temperature range. Herein, the temperature‐mediated dynamic growth of inactive Li from −20 to 60°C via titration gas chromatograph measurements is quantitatively decoupled. Combined X‐ray photoelectronic spectroscopy, cryo‐transmission electronic microscopy, and scanning electronic microscopy methods depicted that both solid electrolyte interphase (SEI) characteristics and Li deposition compactness can be profoundly manipulated by working temperature. The elevation of temperature is found to fundamentally aggravate the parasitic reactions and deteriorate the spatial uniformity of SEI, yet promote the lateral growth of Li by kinetic reason. The opposite effects of temperature on SEI properties and Li deposition compactness can properly explain the intricate temperature‐dependent growth rates of SEI‐Li+ and dead Li0 capacity loss observed under titration gas chromatograph measurements. Design implications towards more stable Li metal anodes with higher reversibility can thus be yielded. [ABSTRACT FROM AUTHOR]

The enthusiasm of reviving lithium metal anodes has motivated the battery community to pursue higher Li utilization. To this end, an exhaustively complete stripping pattern (C‐stripping) is conventionally adopted to obtain a higher apparent Coulombic efficiency (CE) in individual cycles while ignoring the effects of Li stripping state on subsequent Li plating behavior. In this contribution, a partial stripping (P‐stripping) protocol, in which a tiny amount of active Li is intentionally reserved, is validated as beneficial for an improved realistic Li reversibility. Compared to the C‐stripping protocol, the partially reserved active Li in P‐stripping mode serves critically as nucleation sites for following Li plating, which not only reduces the nucleation overpotential for flattened Li deposition morphology, but also favorably facilitates the re‐utilization of the original solid electrolyte interphase (SEI). This explains the lower growth rates of both "dead Li" and SEI‐Li+ under the P‐stripping protocol. Benefitting from the intrinsically more reversible Li cycling, the anode‐free Cu||LiNi0.5Co0.2Mn0.3O2 cells using the P‐stripping protocol acquire higher available capacities in long‐term cycles. This work uncovers the crucial significance of the former state of Li stripping on regulating the following Li plating manner and SEI re‐utilization, providing fresh design implications toward more sustainable cycling of Li anodes. [ABSTRACT FROM AUTHOR]

Extreme fast charging (XFC) of high‐energy Li‐ion batteries is a key enabler of electrified transportation. While previous studies mainly focused on improving Li ion mass transport in electrodes and electrolytes, the limitations of charge transfer across electrode–electrolyte interfaces remain underexplored. Herein we unravel how charge transfer kinetics dictates the fast rechargeability of Li‐ion cells. Li ion transfer across the cathode–electrolyte interface is found to be rate‐limiting during XFC, but the charge transfer energy barrier at both the cathode and anode have to be reduced simultaneously to prevent Li plating, which is achieved through electrolyte engineering. By unlocking charge transfer limitations, 184 Wh kg−1 pouch cells demonstrate stable XFC (10‐min charge to 80 %) which is otherwise unachievable, and the lifetime of 245 Wh kg−1 21700 cells is quintupled during fast charging (25‐min charge to 80 %). [ABSTRACT FROM AUTHOR]

Lithium (Li) metal has been considered a promising anode for next-generation high-energy-density batteries. However, the low reversibility and intricate Li loss hinder the widespread implementation of Li metal batteries. Herein, we quantitatively differentiate the dynamic evolution of inactive Li, and decipher the fundamental interplay among dynamic Li loss, electrolyte chemistry, and the structure of the solid electrolyte interphase (SEI). The actual dominant form in inactive Li loss is practically determined by the relative growth rates of dead Li 0 and SEI Li + because of the persistent evolution of the Li metal interface during cycling. Distinct inactive Li evolution scenarios are disclosed by ingeniously tuning the inorganic anion-derived SEI chemistry with a low amount of film-forming additive. An optimal polymeric film enabler of 1,3-dioxolane is demonstrated to derive a highly uniform multilayer SEI and decreased SEI Li + /dead Li 0 growth rates, thus achieving enhanced Li cycling reversibility., (© 2021 Wiley-VCH GmbH.)

Lithium (Li) metal anodes hold great promise for next-generation high-energy-density batteries, while the insufficient fundamental understanding of the complex solid electrolyte interphase (SEI) is the major obstacle for the full demonstration of their potential in working batteries. The characteristics of SEI highly depend on the inner solvation structure of lithium ions (Li + ). Herein, we clarify the critical significance of cosolvent properties on both Li + solvation structure and the SEI formation on working Li metal anodes. Non-solvating and low-dielectricity (NL) cosolvents intrinsically enhance the interaction between anion and Li + by affording a low dielectric environment. The abundant positively charged anion-cation aggregates generated as the introduction of NL cosolvents are preferentially brought to the negatively charged Li anode surface, inducing an anion-derived inorganic-rich SEI. A solvent diagram is further built to illustrate that a solvent with both proper relative binding energy toward Li + and dielectric constant is suitable as NL cosolvent., (© 2021 Wiley-VCH GmbH.)