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Rechargeable sodium–oxygen batteries (NaOBs) are receiving extensive research interests because of their advantages such as ultrahigh energy density and cost efficiency. However, the severe failure of Na metal anodes has impeded the commercial development of NaOBs. Herein, combining in situ synchrotron X‐ray computed tomography (SXCT) and other complementary characterizations, a novel electro‐chemo‐mechanical failure mechanism of sodium metal anode in NaOBs is elucidated. It is visually showcased that the Na metal anodes involve a three‐stage decay evolution of a porous Na reactive interphase layer (NRIL): from the initially dot‐shaped voids evolved into the spindle‐shaped voids and the eventually‐developed ruptured cracks. The initiation of this three‐stage evolution begins with chemical‐resting and is exacerbated by further electrochemical cycling. From corrosion science and fracture mechanics, theoretical simulations suggest that the evolution of porous NRIL is driven by the concentrated stress at crack tips. The findings illustrate the importance of preventing electro‐chemo‐mechanical degradation of Na anodes in practically rechargeable NaOBs. [ABSTRACT FROM AUTHOR]

Hydrogel electrolytes hold great promise in developing flexible and safe batteries, but the presence of free solvent water makes battery chemistries constrained by H2 evolution and electrode dissolution. Although maximizing salt concentration is recognized as an effective strategy to reduce water activity, the protic polymer matrices in classical hydrogels are occupied with hydrogen‐bonding and barely involved in the salt dissolution, which sets limitations on realizing stable salt‐concentrated environments before polymer‐salt phase separation occurs. Inspired by the role of protein methylation in regulating intracellular phase separation, here we transform the "inert" protic polymer skeletons into aprotic ones through methylation modification to weaken the hydrogen‐bonding, which releases free hydrogen bond acceptors as Lewis base sites to participate in cation solvation and thus assist salt dissolution. An unconventionally salt‐concentrated hydrogel electrolyte reaching a salt fraction up to 44 mol % while retaining a high Na+/H2O molar ratio of 1.0 is achieved without phase separation. Almost all water molecules are confined in the solvation shell of Na+ with depressed activity and mobility, which addresses water‐induced parasitic reactions that limit the practical rechargeability of aqueous sodium‐ion batteries. The assembled Na3V2(PO4)3//NaTi2(PO4)3 cell maintains 82.8 % capacity after 580 cycles, which is the longest cycle life reported to date. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) metal secondary batteries have attracted much attention for their high safety and high energy density characteristics. However, the significant issues of the cathode/electrolyte interphase (CEI) in Mg batteries are still being ignored. In this work, a significant CEI layer on the typical Mo6S8 cathode surface has been unprecedentedly constructed through the oxidation of the chloride‐free magnesium tetrakis(hexafluoroisopropyloxy)borate (Mg[B(hfip)4]2) salt under a proper charge cut‐off voltage condition. The CEI has been identified to contain BxOy effective species originating from the oxidation of [B(hfip)4]− anion. It is confirmed that the BxOy species is beneficial to the desolvation of solvated Mg2+, speeding up the interfacial Mg2+ transfer kinetics, thereby improving the Mg2+‐storage capability of Mo6S8 host. The firstly reported CEI in Mg batteries will give deeper insights into the interface issues in multivalent electrochemical systems. [ABSTRACT FROM AUTHOR]

Aqueous zinc batteries (AZBs) show promising applications in large-scale energy storage and wearable devices mainly because of their low cost and intrinsic safety. However, zinc metal anodes suffer from dendrite issues and side reactions, seriously hindering their practical applications. Two-dimensional (2D) materials with atomic thickness and large aspect ratio possess excellent physicochemical properties, providing opportunities to rationally design and construct practically reversible zinc metal anodes. Here, we systematically summarize the recent progress of 2D materials (e.g., graphene and MXene) that can be used to enable dendrite-free zinc metal anodes for AZBs. Firstly, the construction methods and strategies of 2D materials/Zn hybrid anodes are briefly reviewed, and are classified into protecting layers on Zn foils and host materials for Zn. Secondly, various 2D material/Zn hybrid anodes are elaborately introduced, and the key roles played by 2D materials in stabilizing the Zn/Zn2+ redox process are specially emphasized. Finally, the challenges and perspectives of advanced 2D materials for advanced Zn anodes in next-generation AZBs are briefly discussed. [ABSTRACT FROM AUTHOR]

Rechargeable magnesium batteries (RMBs) have great potential in the field of high‐temperature specialized batteries owing to the superior thermostability and lower propensity for dendrite formation of Mg metal anodes. And the development of Mg2+‐conducting electrolytes that can operate stably under elevated temperature conditions (>100 °C) is the key to high‐temperature RMBs. Here, a robust self‐standing single‐ion polymer electrolyte (SSPE) enabling high‐safety RMBs working at elevated temperature is presented. This SSPE exhibits an expanded electrochemical stability window of 4.8 V (vs Mg2+/Mg), a remarkable Mg2+‐ion transference number of 0.79, and a highly reversible Mg plating/stripping performance. This rationally designed SSPE enables home‐made Mo6S8//Mg batteries with superior high‐temperature (up to 150 °C) performance and significantly improved safety characteristics under abuse conditions. This design concept for a robust SSPE provides a promising path to high‐safety specialized RMBs operating at the elevated temperature, which also offers a new path for the development of functionalized electrolytes. [ABSTRACT FROM AUTHOR]

Aqueous cells with zinc‐metal anodes featuring safety and low cost, are beneficial for diversifying energy‐storage technologies, while their energy density and cyclability have been long limited by side‐reactions and dendrite issues, especially at the practical device level. Though sustained efforts are underway to renovate electrodes and electrolytes, the roles of other indispensable components, such as separators, in the cell operation have been not fully unexplored thus far. Here, it is demonstrated that both the reversibility and utilization of aqueous zinc anodes can be improved by using a single‐ion Zn2+‐conducting nanocellulose membrane as the separator. Even without any treatments to the electrodes and thereof interfaces, this functional membrane marked by synergetic optimization on key required properties regarding mechanical strength, preferred Zn2+ conduction and hydrophilicity, mitigates H2 evolution, corrosion, and dendrite growth on zinc anodes, thus enabling >80% depth‐of‐discharge stable cycling under practically feasible lean electrolyte (electrolyte‐to‐capacity ratio = 1.0 g Ah−1) and high areal capacity (8.0 mAh cm−2) conditions. These findings translate to an excellent capacity retention of exceeding 95% after 150 cycles for full cells with practically high‐loading cathodes (17 mg cm−2). This work provides a simple yet practical avenue to high‐energy, long‐cycling aqueous zinc‐metal batteries. [ABSTRACT FROM AUTHOR]

Rechargeable Zn batteries (ZBs) have received increasing attention due to their cheap, safe and green characteristics, but their further development is generally bottlenecked by lack of compatible electrolytes. Here we report an eco-friendly and low-cost amide-based molten salt (AMS) containing acetamide, lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) and trifluoromethylsulfonate (Zn(Tfo) 2 ) for ZBs. This AMS electrolyte enables a ∼100% Zn plating/stripping efficiency with long-term stability and suppresses Zn dendrite growth. Based on the Li + extraction/insertion on the cathodes and reversible Zn chemistry on the anode in this AMS electrolyte, both Zn/LiMn 2 O 4 and Zn/LiFePO 4 batteries show excellent electrochemical performance including large specific capacity (118 and 140 mAh g −1 , respectively) and remarkable cycle life (>150 cycles). More importantly, by virtue of the electrochemical stability of the AMS, the voltage limit can be significantly increased above 2.15 V for the Zn/LiMn 2 O 4 battery, making full use of the cathode capacity. This finding opens new opportunities for the development of low-cost and high performance ZBs. [ABSTRACT FROM AUTHOR]

Flexible batteries are essential for wearable electronic devices. To meet practical applications, they need to be mechanically robust and stable. However, strong or multiple bending may sever the interfacial contact between electrode and electrolyte, causing capacity fading or even battery failure. Herein we present a new cooling-recovery concept for flexible batteries, which involves a temperature-sensitive sol-gel transition behavior of the thermoreversible polymer hydrogel electrolyte. Once a battery has suffered from strong mechanical stresses, a simple cooling process can refresh the electrode-electrolyte interface. The energy-storage capability can be recovered with a healing efficiency higher than 98 %. It is believed that this study not only offers new valuable insights, but also opens up new perspectives to develop functional wearable devices. [ABSTRACT FROM AUTHOR]

Invited for this month′s cover is the group of Weitao Zheng at the Jilin University. The image shows the working mechanism of dual‐ion batteries (DIBs). The Review itself is available at 10.1002/cssc.202201375. [ABSTRACT FROM AUTHOR]

A LiMn 0.8 Fe 0.2 PO 4 cathode and a Zn anode, for the first time, are combined in a full cell possessing a high operating voltage exceeding 1.8 V. By virtue of a water-in-salt electrolyte containing lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) and ZnSO 4 , two reversible reactions of Li + extraction/insertion (cathode) and Zn dissolution/deposition (anode) can be realized in the aqueous system. Such novel battery delivers an energy density of 183 Wh/kg based on the total mass of the active electrode materials. The high reversibility of the system enables sustaining more than 150 cycles (0.3 C) without obvious capacity fading. Moreover, it is demonstrated that the electrochemical characteristics of the LiMn 0.8 Fe 0.2 PO 4 is critically dependent on the pH value of the electrolyte. [ABSTRACT FROM AUTHOR]

Cheap, high-rate and long-life batteries are urgently needed for grid-scale storage of renewable energy. Rechargeable zinc (Zn) batteries are potential candidates due to the high volumetric energy density and low cost of Zn anode. However, conventional Zn batteries employing metal oxide cathodes usually suffer from poor rate capabilities caused by the high migration barrier of Zn2+ in the metal oxide host structure. Here, we circumvent this dilemma by integrating Zn electrochemistry with bis(trifluoromethanesulfonyl) imide (TFSI−) anion (de)intercalation into graphite cathode based on a Zn(TFSI) 2 /acetonitrile electrolyte. Owing to the fast intercalation of TFSI− along with the efficient Zn/Zn2+ redox kinetics, our Zn/graphite batteries enable an ultrafast charging rate up to 200C (to be fully charged in 18 s) and deliver a high power density of 16.3 kW kg−1, which is comparable to those of supercapacitors. Besides, the rational utilization of the acetonitrile-based electrolyte further endows the resultant battery with dendrite-free Zn deposition, high voltage output (>2.2 V) as well as wide-temperature adaptability from −40 to 80 °C, which is quite promising for grid-scale energy storage. Our work opens a new avenue for building high-rate low-cost batteries through coupling anion intercalation chemistry with multivalent metal anodes. • A Zn/graphite battery involving TFSI− intercalation into graphite is constructed. • An ultrafast charging rate up to 200C can be realized. • The battery has wide-temperature adaptability from −40 to 80 °C. [ABSTRACT FROM AUTHOR]