Zinc metal anode has garnered a great deal of scientific and technological interest. Nevertheless, major bottlenecks restricting its large‐scale utilization lie in the poor electrochemical stability and unsatisfactory cycling life. Herein, a Janus separator is developed via directly growing vertical graphene (VG) carpet on one side of commercial glass fiber separator throughout chemical vapor deposition. A simple air plasma treatment further renders the successful incorporation of oxygen and nitrogen heteroatoms on bare graphene. Thus‐derived 3D VG scaffold affording large surface area and porous structure can be viewed as a continuation of planar zinc anode. In turn, the Janus separator harvests homogenous electric field distribution and lowered local current density at the interface of the anode/electrolyte, as well as harnesses favorable zincophilic feature for building‐up uniform Zn ionic flux. Such a separator engineering enables an impressive rate and cycle performance (93% over 5000 cycles at 5 A g−1) for Zn‐ion hybrid capacitors and outstanding energy density (182 Wh kg−1) for V2O5//Zn batteries, respectively. This strategy with large scalability and cost‐effectiveness represents a universal route to protect prevailing metal anodes (Zn, Na, K) in rechargeable batteries.

Printing is regarded as a revolutionary and feasible technique to guide the fabrication of versatile functional systems with designed architectures. 2D MXenes are nowadays attractive in printed energy storage devices. However, owing to the van der Waals interaction between the MXene layers, the restacking issues within the printed electrodes can significantly impede the ion/electrolyte transport and hence handicap the electrochemical performances. Herein, a melamine formaldehyde templating method is demonstrated to develop crumpled nitrogen‐doped MXene (MXene‐N) nanosheets. The nitrogen doping boosts the electrochemical performances of MXene via enhanced conductivity and redox activity. Accordingly, two types of MXene‐N inks are prepared throughout the optimization of the ink viscosity to fit the 2D screen printing and 3D extrusion printing, respectively. As a result, the screen printed MXene‐N microsupercapacitor delivers an areal capacitance of 70.1 mF cm−2 and outstanding mechanical robustness. Furthermore, the 3D‐printed MXene‐N based supercapacitor manifests an areal capacitance of 8.2 F cm−2 for a three‐layered electrode and readily stores a high areal energy density of 0.42 mWh cm−2. The approach to harnessing such versatile MXene‐N inks offers distinctive insights into the printed energy storage systems with high areal energy density and large scalability.

3D printing technology has stimulated a burgeoning interest to fabricate customized architectures in a facile and scalable manner targeting wide ranged energy storage applications. Nevertheless, 3D-printed hybrid capacitor devices synergizing favorable energy/power density have not yet been explored thus far. Herein, we demonstrate a 3D-printed sodium-ion hybrid capacitor (SIC) based on nitrogen-doped MXene (N-Ti3C2T x ) anode and activated carbon cathode. N-Ti3C2T x affording a well-defined porous structure and uniform nitrogen doping can be obtained via a sacrificial template method. Thus-formulated ink can be directly printed to form electrode architecture without the request of a conventional current collector. The 3D-printed SICs, with a large areal mass loading up to 15.2 mg cm–2, can harvest an areal energy/power density of 1.18 mWh cm–2/40.15 mW cm–2, outperforming the state-of-the-art 3D-printed energy storage devices. Furthermore, our SIC also achieves a gravimetric energy/power density of 101.6 Wh kg–1/3269 W kg–1. This work demonstrates that the 3D printing technology is versatile enough to construct emerging energy storage systems reconciling high energy and power density.

Potassium‐ion hybrid capacitors (KICs) reconciling the advantages of batteries and supercapacitors have stimulated growing attention for practical energy storage because of the high abundance and low cost of potassium sources. Nevertheless, daunting challenge remains for developing high‐performance potassium accommodation materials due to the large radius of potassium ions. Molybdenum diselenide (MoSe2) has recently been recognized as a promising anode material for potassium‐ion batteries, achieving high capacity and favorable cycling stability. However, KICs based on MoSe2 are scarcely demonstrated by far. Herein, a diatomite‐templated synthetic strategy is devised to fabricate nitrogen‐doped MoSe2/graphene (N‐MoSe2/G) composites with favorable pseudocapacitive potassium storage targeting a superior anode material for KICs. Benefiting from the unique biomorphic structure, high electron/K‐ion conductivity, enriched active sites, and the conspicuous pseudocapacitive effect of N‐MoSe2/G, thus‐derived KIC full‐cell manifests high energy/power densities (maximum 119 Wh kg−1/7212 W kg−1), outperforming those of recently reported KIC counterparts. Furthermore, the potassium storage mechanism of N‐MoSe2/G composite is systematically explored with the aid of first‐principles calculations in combination of in situ X‐ray diffraction and ex situ Raman spectroscopy/transmission electron microscopy/X‐ray photoelectron spectroscopy.

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Sodium ion batteries (SIBs) are considered the most promising battery technology in the post‐lithium era due to the abundant sodium reserves. In the past two decades, exploring new electrolytes for SIBs has generally relied on the “solid electrolyte interphase (SEI)” theory to optimize the electrolyte components. However, many observed phenomena cannot be fully explained by the SEI theory. Therefore, electrolyte solvation structure and electrode–electrolyte interface behavior have recently received tremendous research interest to explain the improved performance. Considering there is currently no review paper focusing on the solvation structure of electrolytes in SIBs, a systematic survey on SIBs is provided, in which the specific solvation structure design guidelines and their consequent impact on the electrochemical performance are elucidated. The key driving force of solvation structure formation, and the recent advances in adjusting SIB solvation structures are discussed in detail. It is believed that this review can provide new insights into the electrolyte optimization strategies of high‐performance SIBs and even other emerging battery systems.

Ammonium ions (NH 4 + ), as non-metallic charge carriers, have spurred great research interest in the realm of aqueous batteries. Unfortunately, most inorganic host materials used in these batteries are still limited by the sluggish diffusion kinetics. Here, we report a unique hydrogen bond chemistry to employ covalent organic frameworks (COFs) for NH 4 + ion storage, which achieves a high capacity of 220.4 mAh g −1 at a current density of 0.5 A g −1 . Combining the theoretical simulation and materials analysis, a universal mechanism for the reaction of nitrogen and oxygen bridged by hydrogen bonds is revealed. In addition, we explain the solvation behavior of NH 4 + , leading to a relationship between redox potential and desolvation energy barrier. This work provides a new insight into NH 4 + ion storage in host materials based on hydrogen bond chemistry. This mechanism can be leveraged to design and develop COFs for electrochemical energy storage.

The practical application of lithium-sulfur (Li-S) batteries is hindered by their poor cycling stabilities that primarily stem from the "shuttle" of dissolved lithium polysulfides. Here, we develop a nepenthes-like N-doped hierarchical graphene (NHG)-based separator to realize an efficient polysulfide scavenger for Li-S batteries. The 3D textural porous NHG architectures are realized by our designed biotemplating chemical vapor deposition (CVD) approach via the employment of naturally abundant diatomite as the growth substrate. Benefiting from the high surface area, devious inner-channel structure, and abundant nitrogen doping of CVD-grown NHG frameworks, the derived separator favorably synergizes bifunctionality of physical confinement and chemical immobilization toward polysulfides, accompanied by smooth lithium ion diffusions. Accordingly, the batteries with the NHG-based separator delivers an initial capacity of 868 mAh g with an average capacity decay of only 0.067% per cycle at 2 C for 800 cycles. A capacity of 805 mAh g can further be achieved at a high sulfur loading of ∼7.2 mg cm. The present study demonstrates the potential in constructing high-energy and long-life Li-S batteries upon separator modification.