The development of high‐energy density batteries is critical to the decarbonization of the transportation and power generation sectors. For any given lithium‐containing cathode system, the anode‐free full cell configuration, which eliminates excess lithium and pairs the fully lithiated cathode with a bare current collector, can deliver the maximum possible energy density. The absence of free lithium metal during cell assembly confers significant practical advantages as well. It is also the ideal framework for developing a thorough understanding of lithium deposition in conjunction with various cathode systems. However, the poor efficiencies of lithium plating and stripping lead to rapid lithium inventory loss and poor cycle life. In the last few years, multiple studies have demonstrated the application of advanced electrolytes, modified current collectors, and optimized formation and cycling parameters to stabilize lithium deposition and improve cycle life (80% capacity retention) to 100 cycles and beyond. This review provides an overview of the various strategies toward sustaining lithium inventory in anode‐free full cells and summarizes the work undertaken in this nascent field. It is expected that further improvement upon these strategies and a combinatorial approach can enable cycle lives far in excess of what has been achieved so far.

Most simple magnesium salts tend to passivate the Mg metal surface too quickly to function as electrolytes for Mg batteries. In the present work, an electroactive salt [Mg(THF)6 ][AlCl4 ]2 was synthesized and structurally characterized. The Mg electrolyte based on this simple mononuclear salt showed a high Mg cycling efficiency, good anodic stability (2.5 V vs. Mg), and high ionic conductivity (8.5 mS cm(-1) ). Magnesium/sulfur cells employing the as-prepared electrolyte exhibited good cycling performance over 20 cycles in the range of 0.3-2.6 V, thus indicating an electrochemically reversible conversion of S to MgS without severe passivation of the Mg metal electrode surface.

For realizing practically viable lithium-sulfur (Li-S) batteries, it is imperative to stabilize Li deposition and improve cyclability while reducing excess Li and electrolyte. We have discovered that introducing tellurium (Te) into the Li-S system as a cathode additive significantly improves the reversibility of Li plating and stripping by forming a tellurized and sulfide-rich solid-electrolyte interphase (SEI) layer on the Li surface. A remarkable improvement in cyclability is demonstrated in anode-free full cells with limited Li inventory and large-area Li-S pouch cells under lean electrolyte conditions. Tellurium reacts with polysulfides to generate soluble polytellurosulfides that migrate to the anode side and form stabilizing lithium thiotellurate and lithium telluride in situ as SEI components. A significant reduction in electrolyte decomposition on the Li surface is also engendered. This work demonstrates Te inclusion as a viable strategy for stabilizing Li deposition and establishes a robust evaluation framework for preserving electrochemical performance under limited Li and limited electrolyte conditions.

The development of lithium-sulfur batteries necessitates a thorough understanding of the lithium-deposition process. We present here a novel full-cell configuration comprising a Li2S cathode and a bare copper foil on the anode side. The absence of excess lithium allows for the

Anode-free full cells enable a quantitative estimate of lithium inventory loss rates, which is correlated with the growth of an electrolyte decomposition layer, even as metallic lithium stays intact with cycling.