Benchmarking and Critical Design Considerations of Zero‐Excess Li‐Metal Batteries

Abstract

Zero-excess Li metal batteries (ZELMBs), in which a Li-anode is formed in situ during charging, have received much attention in recent years. ZELMBs bear great potential to increase energy density and facilitate battery production, thereby reducing cost as well as material and energy consumption. Practical application of ZELMBs has so far been limited by challenges related to the non-uniform deposition behavior of Li, leading to inadequate performance and safety concerns. To address these issues, promising approaches have been developed in recent years, including modifications of the current collector, electrolyte, and cycling protocols. While these approaches improve the long-term stability of ZELMB, they also reduce the energy density by introducing inactive materials into the cell. Herein, critical design criteria for the various optimization approaches in ZELMB research are established. Nominal volumetric and gravimetric energy densities are determined based on the degree of modification. Thresholds are determined for each of the strategies at which the energy density gain of ZELMB vanishes compared to other cell configurations. These findings are compared to literature results to provide guidance for the further development of ZELMB.

Optimizing Current Collector Interfaces for Efficient “Anode‐Free” Lithium Metal Batteries

“…For this reason, AFLMBs are more correctly described by the name "zero excess Li-metal batteries". [18,19] Unfortunately, the real-world application of AFLMBs is mainly hindered by safety and efficiency issues. Upon cycling, Li metal unhomogenuously deposits to form Li dendrites that are known to be the cause of internal short circuits and safety concerns (e.g.…”

“…For this reason, AFLMBs are more correctly described by the name “zero excess Li‐metal batteries”. [ 18,19 ]…”

Elucidating the lithium deposition behavior in open-porous copper micro-foam negative electrodes for zero-excess lithium metal batteries

“…47 Further research has also been directed towards the use of non-planar current collectors such as patterned materials and porous media as substrates for Li deposition. 46,48–52 These concepts focus on using 3D materials that provide internal spaces for Li deposition instead of the conventionally used 2D foil substrates, potentially preventing volume and pressure fluctuation as well as Li dendrite growth. 48,50,53…”

Effect of cell pressure on the electrochemical performance of all‐solid‐state lithium batteries with zero‐excess Li metal anode

“…24 ASSBs with zero-excess Li metal anodes (also called anode-free Li metal batteries) have been proposed; various cell designs have been developed to overcome the limitations of lithium metal anodes; the limitations include the low Coulombic efficiency, dendrite growth, and high production cost. [25][26][27] Recently, Lee et al reported that an all-solid-state lithium metal battery with a sulfide-based solid electrolyte and an Ag-C composite anode exhibited a high energy density (> 900 Wh⋅L −1 ) and Coulombic efficiency (> 99.8%). 28 The Ag-C nanocomposite layer was crucial in ensuring a dense, uniform, and dendrite-free plating of Li metal.…”

“…ASSBs with zero‐excess Li metal anodes (also called anode‐free Li metal batteries) have been proposed; various cell designs have been developed to overcome the limitations of lithium metal anodes; the limitations include the low Coulombic efficiency, dendrite growth, and high production cost 25–27 . Recently, Lee et al.…”