Hollow Carbon Nanobelts Codoped with Nitrogen and Sulfur via a Self‐Templated Method for a High‐Performance Sodium‐Ion Capacitor

Sodium‐ion capacitors (SICs) have attracted enormous attention due to their high energy density and high power density. In this work, N and S codoped hollow carbon nanobelts (N/S‐HCNs) are synthesized by a self‐templated method. The as‐synthesized carbon nanobelts exhibit excellent performance in pseudocapacitance and electric double layer anions adsorption. After pairing the N/S‐HCNs cathode with a tin foil anode in a carbonate electrolyte, the obtained SIC achieves a high specific capacity of 400 mAh g^?1 at 1 A g^?1 (based on the mass of cathode material) and energy density of 250.35 Wh kg^?1 at 676 W kg^?1 (based on the total mass of cathode and anode materials). Besides, the presented SIC also demonstrates high cycling stability with almost 100% capacity retention after 10 000 cycles, which is among the best results of the reported SICs, suggesting the potential for high‐performance energy storage applications.     

Confined Amorphous Red Phosphorus in MOF‐Derived N‐Doped Microporous Carbon as a Superior Anode for Sodium‐Ion Battery

Red phosphorus (P) has attracted intense attention as promising anode material for high‐energy density sodium‐ion batteries (NIBs), owing to its high sodium storage theoretical capacity (2595 mAh g^?1). Nevertheless, natural insulating property and large volume variation of red P during cycling result in extremely low electrochemical activity, leading to poor electrochemical performance. Herein, the authors demonstrate a rational strategy to improve sodium storage performance of red P by confining nanosized amorphous red P into zeolitic imidazolate framework‐8 (ZIF‐8) ‐derived nitrogen‐doped microporous carbon matrix (denoted as P@N‐MPC). When used as anode for NIBs, the P@N‐MPC composite displays a high reversible specific capacity of ≈600 mAh g^?1 at 0.15 A g^?1 and improved rate capacity (≈450 mAh g^?1 at 1 A g^?1 after 1000 cycles with an extremely low capacity fading rate of 0.02% per cycle). The superior sodium storage performance of the P@N‐MPC is mainly attributed to the novel structure. The N‐doped porous carbon with sub‐1 nm micropore facilitates the rapid diffusion of organic electrolyte ions and improves the conductivity of the encapsulated red P. Furthermore, the porous carbon matrix can buffer the volume change of red P during repeat sodiation/desodiation process, keeping the structure intact after long cycle life.     

Birnessite Nanosheet Arrays with High K Content as a High‐Capacity and Ultrastable Cathode for K‐Ion Batteries

Potassium‐ion batteries (PIBs) are one of the emerging energy‐storage technologies due to the low cost of potassium and theoretically high energy density. However, the development of PIBs is hindered by the poor K⁺ transport kinetics and the structural instability of the cathode materials during K⁺ intercalation/deintercalation. In this work, birnessite nanosheet arrays with high K content (K_0.77MnO₂?0.23H₂O) are prepared by “hydrothermal potassiation” as a potential cathode for PIBs, demonstrating ultrahigh reversible specific capacity of about 134 mAh g^?1 at a current density of 100 mA g^?1, as well as great rate capability (77 mAh g^?1 at 1000 mA g^?1) and superior cycling stability (80.5% capacity retention after 1000 cycles at 1000 mA g^?1). With the introduction of adequate K⁺ ions in the interlayer, the K‐birnessite exhibits highly stabilized layered structure with highly reversible structure variation upon K⁺ intercalation/deintercalation. The practical feasibility of the K‐birnessite cathode in PIBs is further demonstrated by constructing full cells with a hard–soft composite carbon anode. This study highlights effective K⁺‐intercalation for birnessite to achieve superior K‐storage performance for PIBs, making it a general strategy for developing high‐performance cathodes in rechargeable batteries beyond lithium‐ion batteries.     

Superior Sodium Storage in 3D Interconnected Nitrogen and Oxygen Dual‐Doped Carbon Network

Carbonaceous materials have attracted immense interest as anode materials for Na‐ion batteries (NIBs) because of their good chemical, thermal stabilities, as well as high Na‐storage capacity. However, the carbonaceous materials as anodes for NIBs still suffer from the lower rate capability and poor cycle life. An N,O‐dual doped carbon (denoted as NOC) network is designed and synthesized, which is greatly favorable for sodium storage. It exhibits high specific capacity and ultralong cycling stability, delivering a capacity of 545 mAh g^?1 at 100 mA g^?1 after 100 cycles and retaining a capacity of 240 mAh g^?1 at 2 A g^?1 after 2000 cycles. The NOC composite with 3D well‐defined porosity and N,O‐dual doped induces active sites, contributing to the enhanced sodium storage. In addition, the NOC is synthesized through a facile solution process, which can be easily extended to the preparation of many other N,O‐dual doped carbonaceous materials for wide applications in catalysis, energy storage, and solar cells.     

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe₂) has emerged as a new material for energy storage applications. Though 2H‐MoTe₂ with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe₂, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li⁺ storage capacity. The as‐prepared 2H‐MoTe₂ electrodes exhibit an initial specific capacity of 432 mAh g^?1 and retain a high reversible specific capacity of 291 mAh g^?1 after 260 cycles at 1.0 A g^?1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe₂ anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg^?1 (based on the MoTe₂ mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.     

Construction of Bimetallic Selenides Encapsulated in Nitrogen/Sulfur Co‐Doped Hollow Carbon Nanospheres for High‐Performance Sodium/Potassium‐Ion Half/Full Batteries

Metallic selenides have been widely investigated as promising electrode materials for metal‐ion batteries based on their relatively high theoretical capacity. However, rapid capacity decay and structural collapse resulting from the larger‐sized Na⁺/K⁺ greatly hamper their application. Herein, a bimetallic selenide (MoSe₂/CoSe₂) encapsulated in nitrogen, sulfur‐codoped hollow carbon nanospheres interconnected reduced graphene oxide nanosheets (rGO@MCSe) are successfully designed as advanced anode materials for Na/K‐ion batteries. As expected, the significant pseudocapacitive charge storage behavior substantially contributes to superior rate capability. Specifically, it achieves a high reversible specific capacity of 311 mAh g^?1 at 10 A g^?1 in NIBs and 310 mAh g^?1 at 5 A g^?1 in KIBs. A combination of ex situ X‐ray diffraction, Raman spectroscopy, and transmission electron microscopy tests reveals the phase transition of rGO@MCSe in NIBs/KIBs. Unexpectedly, they show quite different Na⁺/K⁺ insertion/extraction reaction mechanisms for both cells, maybe due to more sluggish K⁺ diffusion kinetics than that of Na⁺. More significantly, it shows excellent energy storage properties in Na/K‐ion full cells when coupled with Na₃V₂(PO₄)₂O₂F and PTCDA@450 °C cathodes. This work offers an advanced electrode construction guidance for the development of high‐performance energy storage devices.     

Etching‐Assisted Crumpled Graphene Wrapped Spiky Iron Oxide Particles for High‐Performance Li‐Ion Hybrid Supercapacitor

From graphene oxide wrapped iron oxide particles with etching/reduction process, high‐performance anode and cathode materials of lithium‐ion hybrid supercapacitors are obtained in the same process with different etching conditions, which consist of partially etched crumpled graphene (CG) wrapped spiky iron oxide particles (CG@SF) for a battery‐type anode, and fully etched CG for a capacitive‐type cathode. The CG is formed along the shape of spikily etched particles, resulting in high specific surface area and electrical conductivity, thus the CG‐based cathode exhibits remarkable capacitive performance of 210 F g^?1 and excellent rate capabilities. The CG@SF can also be ideal anode materials owing to spiky and porous morphology of the particles and tightly attached crumpled graphene onto the spiky particles, which provides structural stability and low contact resistance during repetitive lithiation/delithiation processes. The CG@SF anode shows a particularly high capacitive performance of 1420 mAh g^?1 after 270 cycles, continuously increases capacity beyond the 270th cycle, and also maintains a high capacity of 170 mAh g^?1 at extremely high speeds of 100 C. The full‐cell exhibits a higher energy density up to 121 Wh kg^?1 and maintains high energy density of 60.1 Wh kg^?1 at 18.0 kW kg^?1. This system could thus be a practical energy storage system to fill the gap between batteries and supercapacitors.     

Designed Formation of Hybrid Nanobox Composed of Carbon Sheathed CoSe2 Anchored on Nitrogen‐Doped Carbon Skeleton as Ultrastable Anode for Sodium‐Ion Batteries

Research on sodium‐ion batteries (SIBs) has recently been revitalized due to the unique features of much lower costs and comparable energy/power density to lithium‐ion batteries (LIBs), which holds great potential for grid‐level energy storage systems. Transition metal dichalcogenides (TMDCs) are considered as promising anode candidates for SIBs with high theoretical capacity, while their intrinsic low electrical conductivity and large volume expansion upon Na⁺ intercalation raise the challenging issues of poor cycle stability and inferior rate performance. Herein, the designed formation of hybrid nanoboxes composed of carbon‐protected CoSe₂ nanoparticles anchored on nitrogen‐doped carbon hollow skeletons (denoted as CoSe₂@C∩NC) via a template‐assisted refluxing process followed by conventional selenization treatment is reported, which exhibits tremendously enhanced electrochemical performance when applied as the anode for SIBs. Specifically, it can deliver a high reversible specific capacity of 324 mAh g^?1 at current density of 0.1 A g^?1 after 200 cycles and exhibit outstanding high rate cycling stability at the rate of 5 A g^?1 over 2000 cycles. This work provides a rational strategy for the design of advanced hybrid nanostructures as anode candidates for SIBs, which could push forward the development of high energy and low cost energy storage devices.     

Tin Sulfide‐Based Nanohybrid for High‐Performance Anode of Sodium‐Ion Batteries

Nanohybrid anode materials for Na‐ion batteries (NIBs) based on conversion and/or alloying reactions can provide significantly improved energy and power characteristics, while suffering from low Coulombic efficiency and unfavorable voltage properties. An NIB paper‐type nanohybrid anode (PNA) based on tin sulfide nanoparticles and acid‐treated multiwalled carbon nanotubes is reported. In 1 m NaPF₆ dissolved in diethylene glycol dimethyl ether as an electrolyte, the above PNA shows a high reversible capacity of ≈1200 mAh g^?1 and a large voltage plateau corresponding to a capacity of ≈550 mAh g^?1 in the low‐voltage region of ≈0.1 V versus Na⁺/Na, exhibiting high rate capabilities at a current rate of 1 A g^?1 and good cycling performance over 250 cycles. In addition, the PNA exhibits a high first Coulombic efficiency of ≈90%, achieving values above 99% during subsequent cycles. Furthermore, the feasibility of PNA usage is demonstrated by full‐cell tests with a reported cathode, which results in high specific energy and power values of ≈256 Wh kg^?1 and 471 W kg^?1, respectively, with stable cycling.     

ZIF‐8@ZIF‐67‐Derived Nitrogen‐Doped Porous Carbon Confined CoP Polyhedron Targeting Superior Potassium‐Ion Storage

Potassium ion batteries (KIB) have become a compelling energy‐storage system owing to their cost effectiveness and the high abundance of potassium in comparison with lithium. However, its practical applications have been thwarted by a series of challenges, including marked volume expansion and sluggish reaction kinetics caused by the large radius of potassium ions. In line with this, the exploration of reliable anode materials affording high electrical conductivity, sufficient active sites, and structural robustness is the key. The synthesis of ZIF‐8@ZIF‐67 derived nitrogen‐doped porous carbon confined CoP polyhedron architectures (NC@CoP/NC) to function as innovative KIB anode materials is reported. Such composites enable an outstanding rate performance to harvest a capacity of ≈200 mAh g^?1 at 2000 mA g^?1. Additionally, a high cycling stability can be gained by maintaining a high capacity retention of 93% after 100 cycles at 100 mA g^?1. Furthermore, the potassium ion storage mechanism of the NC@CoP/NC anode is systematically probed through theoretical simulations and experimental characterization. This contribution may offer an innovative and feasible route of emerging anode design toward high performance KIBs.     

Exploration of Advanced Electrode Materials for Approaching High‐Performance Nickel‐Based Superbatteries

The surging interest in high performance, low‐cost, and safe energy storage devices has spurred tremendous research efforts in the development of advanced electrode active materials. Herein, the in situ growth of zinc–iron layered double hydroxide (Zn–Fe LDH) on graphene aerogel (GA) substrates through a facile, one‐pot hydrothermal method is reported. The strong interaction and efficient electronic coupling between LDH and graphene substantially improve interfacial charge transport properties of the resulting nanocomposite and provide more available redox active sites for faradaic reactions. An LDH–GA||Ni(OH)₂ device is also fabricated that results in greatly enhanced specific capacity (187 mAh g^?1 at 0.1 A g^?1), outstanding specific energy (147 Wh kg^?1), excellent specific power (16.7 kW kg^?1), along with 88% capacity retention after >10 000 cycles. This approach is further extended to Ni–MH and Ni–Cd batteries to demonstrate the feasibility of compositing with graphene for boosting the energy storage performance of other well‐known Ni‐based batteries. In contrast to conventional Ni‐based batteries, the nearly flat voltage plateau followed by a sloping potential profile of the integrated supercapacitor–battery enables it to be discharged down to 0 V without being damaged. These findings provide new prospects for the design of high‐performance and affordable superbatteries based on earth‐abundant elements.     

Mechanochemical Synthesis of γ‐Graphyne with Enhanced Lithium Storage Performance

γ‐Graphyne is a new nanostructured carbon material with large theoretical Li⁺ storage due to its unique large conjugate rings, which makes it a potential anode for high‐capacity lithium‐ion batteries (LIBs). In this work, γ‐graphyne‐based high‐capacity LIBs are demonstrated experimentally. γ‐Graphyne is synthesized through mechanochemical and calcination processes by using CaC₂ and C₆Br₆. Brunauer–Emmett–Teller, atomic force microscopy, X‐ray photoelectron spectroscopy, solid‐state ¹³C NMR and Raman spectra are conducted to confirm its morphology and chemical structure. The sample presents 2D mesoporous structure and is exactly composed of sp and sp²‐hybridized carbon atoms as the γ‐graphyne structure. The electrode shows high Li⁺ storage (1104.5 mAh g^?1 at 100 mA g^?1) and rate capability (435.1 mAh g^?1 at 5 A g^?1). The capacity retention can be up to 948.6 (200 mA g^?1 for 350 cycles) and 730.4 mAh g^?1 (1 A g^?1 for 600 cycles), respectively. These excellent electrochemical performances are ascribed to the mesoporous architecture, large conjugate rings, enlarged interplanar distance, and high structural integrity for fast Li⁺ diffusion and improved cycling stability in γ‐graphyne. This work provides an environmentally benign and cost‐effective mechanochemical method to synthesize γ‐graphyne and demonstrates its superior Li⁺ storage experimentally.     

A Novel Potassium‐Ion‐Based Dual‐Ion Battery

In this work, combining both advantages of potassium‐ion batteries and dual‐ion batteries, a novel potassium‐ion‐based dual‐ion battery (named as K‐DIB) system is developed based on a potassium‐ion electrolyte, using metal foil (Sn, Pb, K, or Na) as anode and expanded graphite as cathode. When using Sn foil as the anode, the K‐DIB presents a high reversible capacity of 66 mAh g^?1 at a current density of 50 mA g^?1 over the voltage window of 3.0–5.0 V, and exhibits excellent long‐term cycling performance with 93% capacity retention for 300 cycles. Moreover, as the Sn foil simultaneously acts as the anode material and the current collector, dead load and dead volume of the battery can be greatly reduced, thus the energy density of the K‐DIB is further improved. It delivers a high energy density of 155 Wh kg^?1 at a power density of 116 W kg^?1, which is comparable with commercial lithium‐ion batteries. Thus, with the advantages of environmentally friendly, cost effective, and high energy density, this K‐DIB shows attractive potential for future energy storage application.     

Interfacial Engineering Coupled Valence Tuning of MoO3 Cathode for High‐Capacity and High‐Rate Fiber‐Shaped Zinc‐Ion Batteries

Aqueous Zn‐ion batteries (ZIBs) have garnered the researchers' spotlight owing to its high safety, cost effectiveness, and high theoretical capacity of Zn anode. However, the availability of cathode materials for Zn ions storage is limited. With unique layered structure along the [010] direction, α‐MoO₃ holds great promise as a cathode material for ZIBs, but its intrinsically poor conductivity severely restricts the capacity and rate capability. To circumvent this issue, an efficient surface engineering strategy is proposed to significantly improve the electric conductivity, Zn ion diffusion rate, and cycling stability of the MoO₃ cathode for ZIBs, thus drastically promoting its electrochemical properties. With the synergetic effect of Al₂O₃ coating and phosphating process, the constructed Zn//P‐MoO_3?x@Al₂O₃ battery delivers impressive capacity of 257.7 mAh g^?1 at 1 A g^?1 and superior rate capability (57% capacity retention at 20 A g^?1), dramatically surpassing the pristine Zn//MoO₃ battery (115.8 mAh g^?1; 19.7%). More importantly, capitalized on polyvinyl alcohol gel electrolyte, an admirable capacity (19.2 mAh cm^?3) as well as favorable energy density (14.4 mWh cm^?3; 240 Wh kg^?1) are both achieved by the fiber‐shaped quasi‐solid‐state ZIB. This work may be a great motivation for further research on molybdenum or other layered structure materials for high‐performance ZIBs.     

Na2Ti6O13 Nanorods with Dominant Large Interlayer Spacing Exposed Facet for High‐Performance Na‐Ion Batteries

As the delegate of tunnel structure sodium titanates, Na₂Ti₆O₁₃ nanorods with dominant large interlayer spacing exposed facet are prepared. The exposed large interlayers provide facile channels for Na⁺ insertion and extraction when this material is used as anode for Na‐ion batteries (NIBs). After an activation process, this NIB anode achieves a high specific capacity (a capacity of 172 mAh g^?1 at 0.1 A g^?1) and outstanding cycling stability (a capacity of 109 mAh g^?1 after 2800 cycles at 1 A g^?1), showing its promising application on large‐scale energy storage systems. Furthermore, the electrochemical and structural characterization reveals that the expanded interlayer spacings should be in charge of the activation process, including the enhanced kinetics, the lowered apparent activation energy, and the increased capacity.     

Polypyrenes as High‐Performance Cathode Materials for Aluminum Batteries

The pressing need for low‐cost and large‐scale stationary storage of electricity has led to a new wave of research on novel batteries made entirely of components that have high natural abundances and are easy to manufacture. One example of such an anode–electrolyte–cathode architecture comprises metallic aluminum, AlCl₃:[EMIm]Cl (1‐ethyl‐3‐methylimidazolium chloride) ionic liquid and graphite. Various forms of synthetic and natural graphite cathodes have been tested in recent years in this context. Here, a new type of compelling cathode based on inexpensive pyrene polymers is demonstrated. During charging, the condensed aromatic rings of these polymers are oxidized, which is accompanied by the uptake of aluminum tetrachloride anions (AlCl₄^?) from the chloroaluminate ionic liquid. Discharge is the fast inverse process of reduction and the release of AlCl₄^?. The electrochemical properties of the polypyrenes can be fine‐tuned by the appropriate chemical derivatization. This process is showcased here by poly(nitropyrene‐co‐pyrene), which has a storage capacity of 100 mAh g^?1, higher than the neat polypyrene (70 mAh g^?1) or crystalline pyrene (20 mAh g^?1), at a high discharge voltage (≈1.7 V), energy efficiency (≈86%), and cyclic stability (at least 1000 cycles).     

Ultrahigh Rate Performance of Hollow Antimony Nanoparticles Impregnated in Open Carbon Boxes for Sodium‐Ion Battery under Elevated Temperature

Antimony is a competitive and promising anode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, the poor rate capability and fast capacity fading greatly restrict its practical application. To address the above issues, a facile and eco‐friendly sacrificial template method is developed to synthesize hollow Sb nanoparticles impregnated in open carbon boxes (Sb HPs@OCB). The as‐obtained Sb HPs@OCB composite exhibits excellent sodium storage properties even when operated at an elevated temperature of 50 °C, delivering a robust rate capability of 345 mAh g^?1 at 16 A g^?1 and rendering an outstanding reversible capacity of 187 mAh g^?1 at a high rate of 10 A g^?1 after 300 cycles. Such superior electrochemical performance of the Sb HPs@OCB can be attributed to the comprehensive characteristics of improved kinetics derived from hollow Sb nanoparticles impregnated into 2D carbon nanowalls, the existence of robust Sb? O? C bond, and enhanced pseudocapacitive behavior. All those factors enable Sb HPs@OCB great potential and distinct merit for large‐scale energy storage of SIBs.     

Flexible Membrane Consisting of MoP Ultrafine Nanoparticles Highly Distributed Inside N and P Codoped Carbon Nanofibers as High‐Performance Anode for Potassium‐Ion Batteries

Rechargeable potassium‐ion batteries (PIBs) have attracted tremendous attention as potential electrical energy storage systems due to the special merit of abundant resources and low cost of potassium. However, one critical barrier to achieve practical application of PIBs has been the lack of suitable electrode materials. Here, a novel flexible membrane consisting of N, P codoped carbon nanofibers decorated with MoP ultrafine nanoparticles (MoP@NPCNFs) is fabricated via a simple electrospinning method combined with the later carbonization and phosphorization process. The 3D porous CNF structure in the as‐synthesized composite can shorten the transport pathways of K‐ions and improve the conductivity of electrons. The ultrafine MoP nanoparticles can guarantee high specific capacity and the N, P co‐doping could improve wettability of electrodes to electrolytes. As expected, the free‐standing MoP@NPCNF electrode demonstrates a high capacity of 320 mAh g^?1 at 100 mA g^?1, a superior rate capability maintaining 220 mAh g^?1 at 2 A g^?1, as well as a capacity retention of more than 90% even after 200 cycles. The excellent rate performance, high reversible capacity, long‐term cycling stability, and facile synthesis routine make this hybrid membrane promising anode for potassium‐ion batteries.     

3D Interconnected and Multiwalled Carbon@MoS2@Carbon Hollow Nanocables as Outstanding Anodes for Na‐Ion Batteries

Currently, the specific capacity and cycling performance of various MoS₂/carbon‐based anode materials for Na‐ion storage are far from satisfactory due to the insufficient structural stability of the electrode, incomplete protection of MoS₂ by carbon, difficult access of electrolyte to the electrode interior, as well as inactivity of the adopted carbon matrix. To address these issues, this work presents the rational design and synthesis of 3D interconnected and hollow nanocables composed of multiwalled carbon@MoS₂@carbon. In this architecture, (i) the 3D nanoweb‐like structure brings about excellent mechanical property of the electrode, (ii) the ultrathin MoS₂ nanosheets are sandwiched between and doubly protected by two layers of porous carbon, (iii) the hollow structure of the primary nanofibers facilitates the access of electrolyte to the electrode interior, (iv) the porous and nitrogen‐doping properties of the two carbon materials lead to synergistic Na‐storage of carbon and MoS₂. As a result, this hybrid material as the anode material of Na‐ion battery exhibits fast charge‐transfer reaction, high utilization efficiency, and ultrastability. Outstanding reversible capacity (1045 mAh g^?1), excellent rate behavior (817 mAh g^?1 at 7000 mA g^?1), and good cycling performance (747 mAh g^?1 after 200 cycles at 700 mA g^?1) are obtained.     

A High‐Energy and Long‐Life Aqueous Zn/Birnessite Battery via Reversible Water and Zn2+ Coinsertion

Aqueous rechargeable Zn/birnessite batteries have recently attracted extensive attention for energy storage system because of their low cost and high safety. However, the reaction mechanism of the birnessite cathode in aqueous electrolytes and the cathode structure degradation mechanics still remain elusive and controversial. In this work, it is found that solvation water molecules coordinated to Zn²⁺ are coinserted into birnessite lattice structure contributing to Zn²⁺ diffusion. However, the birnessite will suffer from hydroxylation and Mn dissolution with too much solvated water coinsertion. Through engineering Zn²⁺ primary solvation sheath with strong‐field ligand in aqueous electrolyte, highly reversible [Zn(H₂O)₂]²⁺ complex intercalation/extraction into/from birnessite cathode is obtained. Cathode–electrolyte interface suppressing the Mn dissolution also forms. The Zn metal anode also shows high reversibility without formation of “death‐zinc” and detrimental dendrite. A full cell coupled with birnessite cathode and Zn metal anode delivers a discharge capacity of 270 mAh g^?1, a high energy density of 280 Wh kg^?1 (based on total mass of cathode and anode active materials), and capacity retention of 90% over 5000 cycles.