Chlorine (Cl)‐based batteries such as Li/Cl2 batteries are recognized as promising candidates for energy storage with low cost and high performance. However, the current use of Li metal anodes in Cl‐based batteries has raised serious concerns regarding safety, cost, and production complexity. More importantly, the well‐documented parasitic reactions between Li metal and Cl‐based electrolytes require a large excess of Li metal, which inevitably sacrifices the electrochemical performance of the full cell. Therefore, it is crucial but challenging to establish new anode chemistry, particularly with electrochemical reversibility, for Cl‐based batteries. Here we show, for the first time, reversible Si redox in Cl‐based batteries through efficient electrolyte dilution and anode/electrolyte interface passivation using 1,2‐dichloroethane and cyclized polyacrylonitrile as key mediators. Our Si anode chemistry enables significantly increased cycling stability and shelf lives compared with conventional Li metal anodes. It also avoids the use of a large excess of anode materials, thus enabling the first rechargeable Cl2 full battery with remarkable energy and power densities of 809 Wh kg−1 and 4,277 W kg−1, respectively. The Si anode chemistry affords fast kinetics with remarkable rate capability and low‐temperature electrochemical performance, indicating its great potential in practical applications.

Anode-free lithium (Li) metal batteries are desirable candidates in pursuit of high-energy-density batteries. However, their poor cycling performances originated from the unsatisfactory reversibility of Li plating/stripping remains a grand challenge. Here we show a facile and scalable approach to produce highperforming anode-free Li metal batteries using a bioinspired and ultrathin (250 nm) interphase layer comprised of triethylamine germanate. The derived tertiary amine and Li x Ge alloy showed enhanced adsorption energy that significantly promoted Li-ion adsorption, nucleation and deposition, contributing to a reversible expansion/shrinkage process upon Li plating/stripping. Impressive Li plating/stripping Coulombic efficiencies (CEs) of � 99.3 % were achieved for 250 cycles in Li/Cu cells. In addition, the anode-free LiFePO 4 full batteries demonstrated maximal energy and power densities of 527 Wh kg À 1 and 1554 W kg À 1 , respectively, and remarkable cycling stability (over 250 cycles with an average CE of 99.4 %) at a practical areal capacity of � 3 mAh cm À 2 , the highest among state-of-the-art anodefree LiFePO 4 batteries. Our ultrathin and respirable interphase layer presents a promising way to fully unlock large-scale production of anode-free batteries.

Potassium‐ion battery represents a promising alternative of conventional lithium‐ion batteries in sustainable and grid‐scale energy storage. Among various anode materials, elemental phosphorus (P) has been actively pursued owing to the ideal natural abundance, theoretical capacity, and electrode potential. However, the sluggish redox kinetics of elemental P has hindered fast and deep potassiation process toward the formation of final potassiation product (K3P), which leads to inferior reversible capacity and rate performance. Here, it is shown that rational design on black/red P heterostructure can significantly improve K‐ion adsorption, injection and immigration, thus for the first time unlocking K3P as the reversible potassiation product for elemental P anodes. Density functional theory calculations reveal the fast adsorption and diffusion kinetics of K‐ion at the heterostructure interface, which delivers a highly reversible specific capacity of 923 mAh g−1 at 0.05 A g−1, excellent rate capability (335 mAh g−1 at 1 A g−1), and cycling performance (83.3% capacity retention at 0.8 A g−1 after 300 cycles). These results can unlock other sluggish and irreversible battery chemistries toward sustainable and high‐performing energy storage.

An abundant hollow nanostructure is crucial for fast Li+ and K+ diffusion paths and sufficient electrolyte penetration, which creates a highly conductive network for ionic and electronic transport. In this study, we successfully developed a molecular-bridge-linked, organic–inorganic hybrid interface that enables the preparation of in situ nitrogen-doped hollow carbon nanospheres. Moreover, the prepared HCNSs, with high nitrogen content of up to 10.4%, feature homogeneous and regular morphologies. The resulting HCNSs exhibit excellent lithium and potassium storage properties when used as electrode materials. Specifically, the HCNS-800 electrode demonstrates a stable reversible discharge capacity of 642 mA h g−1 at 1000 mA g−1 after 500 cycles for LIBs. Similarly, the electrode maintains a discharge capacity of 205 mA h g−1 at 100 mA g−1 after 500 cycles for KIBs. Moreover, when coupled with a high-mass-loading LiFePO4 cathode to design full cells, the HCNS-800‖LiFePO4 cells provide a specific discharge capacity of 139 mA h g−1 at 0.1 C. These results indicate that the HCNS electrode has promising potential for use in high-energy and environmentally sustainable lithium-based and potassium-based batteries.