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.

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.

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.

Lithium/thionyl chloride (Li/SOCl2) primary batteries are appealing power solutions because of their remarkable electrochemical performances. However, their mass applications are hindered by the challenges in sustainability, cost and safety concerns owing to the employed Li chemistry. Here, magnesium (Mg) chemistry is shown as a promising alternative through synergistic optimization of electrolyte solvation and electrode reaction kinetics. The first Mg/SOCl2 primary battery yields surprisingly high specific capacities up to ≈14 000 mAh g−1 at a decent discharge voltage of ≈1.67 V, which outperforms the state‐of‐the‐art Mg‐based primary batteries. In addition, it retains almost 100% of the original capacity after 20‐day reservation. The impressive battery performances are originated from the stabilized MgCl2 formation on high‐surface‐area carbon cathode and suppressed Mg anode corrosion via the Mg‐induced solvation effect. Mg/SOCl2 primary batteries are promising candidates for low‐cost and recyclable power supplies, and they thus open new avenues for the development of sustainable battery chemistries.