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In practical pouch cell, LiNi0.5Mn0.3Co0.2O2/artificial graphite lithium ion battery using single-crystal LiNi0.5Mn0.3Co0.2O2 (S-NMC532) as cathode can have excellent cycle performance. However, single-crystal LiNi0.5Mn0.3Co0.2O2 inevitably suffers poor rate capability compared to the polycrystalline materials. Here, we systematically studied the relationship between microstructural characteristics and the practical rate performance, as well as explored the impedance change during the cycling process in the pouch cell. This work shows that the (001) plane microtexture of the electrode surface structure is a critical barrier for rate capability. Electron backscatter diffraction (EBSD), electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) are conducted on the cathodes. These analyses allow to conclude on the influence of the (001) plane microtexture on the electrode surface, which illustrates a diffusion resistance of lithium ions, and then, leading a high interfacial resistance. Thus, this work confirms the main cause of the inferior rate capability of S-NMC532 and offers guidance for developing a battery with high rate and ultralong cycling life.

WS2 with layered graphite-like structure as anode for sodium ion batteries has high specific capacity. However, the poor cycling performance and rate capability of WS2 caused by the low electronic conductivity and structure changes during cycles inhibit its practical application. Herein, metallic phase (1T) WxMo1−xS2 (x = 1, 0.9, 0.8 and 0.6) with high electronic conductivity and expanded interlayer spacing of 0.95 nm was directly prepared via a simple hydrothermal method. Specially, 1T W0.9Mo0.1S2 as anode for sodium ion batteries displays high capacities of 411 mAh g−1 at 0.1 A g−1 after 180 cycles and 262 mAh g−1 at 1 A g−1 after 280 cycles and excellent rate capability (245 mAh g−1 at 5 A g−1). The full cell based on Na3V2(PO4)2O2F/C cathode and 1T W0.9Mo0.1S2 anode also exhibits high capacity and good cycling performance. The irreversible electrochemical reaction of 1T W0.9Mo0.1S2 with Na ions during first few cycles results in the main products of W-Mo alloy and S. The strong adsorption of W-Mo alloy with polysulfides can effectively suppress the dissolution and shuttle effect of polysulfides, which ensures the excellent cycling performance of 1T W0.9Mo0.1S2.

In order to meet the challenges brought by the low ionic conductivity of solid-state electrolytes (SSEs) and the growth of lithium dendrites in all-solid-state lithium metal batteries (ASSLMBs), the composite polymer electrolytes (CPEs) constructed by the combination of three-dimensional (3D) porous ceramics framework and polymers have been widely studied. However, there are still many challenges to preparation of 3D high-strength porous ceramics framework by a simple way. Here, we designed a 3D interconnected porous Li1.3Al0.3Ti1.7(PO4)3 (LATP) framework using NaCl as the template, which not only provides the fast transport channels for Li+ but also serves as a physical barrier to suppress the growth of Li dendrites. Benefiting from the enhanced mechanical and ionic conductivity of the 3D interconnected porous LATP framework, Li/Li symmetric cells based on the prepared CPE can cycle over 1000 h at 0.2 mA cm−2, 0.2 mAh cm−2 and 2000 h at 0.1 mA cm−2, 0.1 mAh cm−2. Moreover, all-solid-state LFP/Li with this 3D CPE demonstrates long-term stability cycles at 1 C.

The development of dual-function anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) is exceedingly essential. Herein, with rationally designed hierarchical metal-organic framework (MOF)@MXene as a precursor, a novel sandwich-like CoP-NC@Ti3C2Tx composite has been successfully fabricated by the following phosphorization reaction. As anode material for LIBs, the CoP-NC@Ti3C2Tx composite exhibits remarkable electrochemical performance with high-rate capability (147.8 mAh g−1 at 2000 mA g−1; 245.6 mAh g−1 at 100 mA g−1) and ultralong cycling life (2000 cycles with a capacity retention over 100%). For SIBs, it delivers a discharge capacity of 101.6 mAh g−1 at a current density of 500 mA g−1 after 500 cycles. The well-designed sandwich-like composite effectively supports the easy access to electrolyte, facilitate the Li/Na ion transportation, and protect the active material from pulverization upon long cycling. In addition, the electrochemical reaction kinetics and Li-migration kinetics of the CoP-NC@Ti3C2Tx composite have been pioneeringly illuminated by pseudocapacitive behavior calculation and density functional theory (DFT) computations, respectively. This work sheds light on the rational design and development of MOF/MXene-derived dual-function anode materials for Li/Na-storage.

PurposeThis study aimed to examine the research hotspots and evolution paths in the field of health information behavior (HIB) in China and abroad, and conduct comparative analysis to better understand its development trajectory globally.Design/methodology/approachA keyword search of the relevant literature included in the China National Knowledge Infrastructure (CNKI) database and Web of Science (WoS) core collection database was conducted, using the visualized analysis tool CiteSpace V for bibliometric analyses.FindingsThe common research hotspots in China and abroad can be divided into related research on HIB, research on its influencing factors and health information research. Among these, health information-seeking behavior has been the focus of domestic and foreign scholars. From the subdivision perspective, the focus of Chinese and foreign research hotspots differs. In terms of evolutionary path, the initial stage of HIB research in China and abroad revolves around health information and health information-seeking behavior, followed by the influencing factors of HIB; however, the research breakthrough point is the reverse. Then, domestic and foreign research was conducted on different types of HIBs. Regarding the selection of research objects, Chinese and foreign research objects were increasingly diversified.Research limitations/implicationsThis study also has several limitations. First, the literature sample only selected the literature in the WoS and CNKI databases, and there may be many HIB-related works published in other databases. Therefore, future research should include other databases. Second, in terms of language, this study selected only Chinese and English literature, but in many countries, important research results on certain topics are usually published in native language, and future research should expand the language selection. Third, this study only conducted national and institutional collaboration network analysis, keyword co-occurrence analysis, cluster analysis and timeline chart analysis.Practical implicationsThe implication of practice can be divided into the following three points. (1) Analyzing the domestic and foreign literature on HIB and identifying highly cooperative institutions and countries in the field of HIB can reveal the research situation of HIB and help researchers establish new research networks in the future. (2) Analyzing the research hotspots and evolutionary paths of HIB at home and abroad is helpful for quickly understanding the development context of this field and grasping the emerging research directions such as HIB of people in close contact with patients, health information exchange behavior, health information avoidance behavior and health information discontinuation behavior, which can help researchers to explore the future research direction in this field, so as to determine the topic and fill the research gap. (3) Combining the analysis of HIB-related research at home and abroad is helpful for professionals to understand the characteristics and rules of HIB of users, consumers and other groups to further optimize and improve health information services.Originality/valueComparing and summarizing the research status of HIB in China and globally, and presenting the findings visually, will help researchers better grasp the research overview and hotspot changes in this field, as well as provide a follow-up reference.

MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The impressive electrochemical activity of MXene makes it one of the most potential electrode materials in rechargeable batteries and supercapacitors. However, single-component MXene electrodes are difficult to achieve high specific capacity, efficient ion/electron transport, and high stability compatibility in an electrochemical environment. Studies have shown that it is an effective method to introduce nanomaterials between MXene layers to construct heterostructures and to improve the electrochemical performance through the synergistic effect among the components in the heterostructures. The introduction of nanomaterials can effectively suppress the restacking of MXene nanosheets, shorten the diffusion path of ions and promote the electrolyte transport, which is beneficial to enhance the rate performance of MXene; moreover, the excellent mechanical flexibility of MXene can reduce the volume expansion of nanomaterials during charge/discharge, thereby effectively protecting the integrity of the electrode structure and improving the cycling stability. Therefore, in this review, combined with theoretical calculations, we summarize the recent advances of MXene heterostructures in terms of synthesis strategies and energy storage applications, including supercapacitors, metal-ions batteries (Li, Na, K, Mg, Zn, Al) and metal anode protection. Furthermore, potential challenges and application perspectives for MXene heterostructures are also outlined.

The development of applicable electrolytes is the key point for high-performance rechargeable magnesium batteries (RMBs). The use of liquid electrolyte is prone to safety problems caused by liquid electrolyte leakage. Polymer-based gel electrolytes with high ionic conductivity, great flexibility, easy processing, and high safety have been studied by many scholars in recent years. In this work, a novel porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane is prepared by a phase inversion method. By immersing porous PVDF-HFP membranes in MgCl2-AlCl3/TEGDME (Tetraethylene glycol dimethyl ether) electrolytes, porous PVDF-HFP based electrolytes (PPEs) are formed. The PPE exhibits a high ionic conductivity (4.72 × 10−4 S cm−1, 25 °C), a high liquid electrolyte uptake of 162%, as well as a wide voltage window (3.1 V). The galvanostatic cycling test of Mg//Mg symmetric cell with PPE reveals that the reversible magnesium ion (Mg2+) plating/stripping occurs at low overpotentials (~0.13 V). Excellent long cycle stability (65.5 mAh g−1 over 1700 cycles) is achieved for the quasi-solid-state RMB assembled with MoS2/C cathode and Mg anode. Compared with the liquid electrolyte, the PPE could effectively reduce the side reactions and make Mg2+ plating/stripping more uniformly on the Mg electrode side. This strategy herein provides a new route to fabricate high-performance RMB through suitable cathode material and polymer electrolyte with excellent performance.

All-solid-state lithium batteries (ASSLBs) employing sulfide electrolyte and lithium (Li) anode have received increasing attention due to the intrinsic safety and high energy density. However, the thick electrolyte layer and lithium dendrites formed at the electrolyte/Li anode interface hinder the realization of high-performance ASSLBs. Herein, a novel membrane consisting of Li6PS5Cl (LPSCl), poly(ethylene oxide) (PEO) and Li-salt (LiTFSI) was prepared as sulfide-based composite solid electrolyte (LPSCl-PEO3-LiTFSI) (LPSCl:PEO = 97:3 wt/wt; EO:Li = 8:1 mol/mol), which delivers high ionic conductivity (1.1 × 10−3 S cm−1) and wide electrochemical window (4.9 V vs. Li+/Li) at 25 °C. In addition, an ex-situ artificial solid electrolyte interphase (SEI) film enriched with LiF and Li3N was designed as a protective layer on Li anode (Li(SEI)) to suppress the growth of lithium dendrites. Benefiting from the synergy of sulfide-based composite solid electrolyte and ex-situ artificial SEI, cells of S-CNTs/LPSCl-PEO3-LiTFSI/Li(SEI) and Al2O3@LiNi0.5Co0.3Mn0.2O2/LPSCl-PEO3-LiTFSI/Li(SEI) are assembled and both exhibit high initial discharge capacity of 1221.1 mAh g−1 (135.8 mAh g−1) and enhanced cycling stability with 81.6% capacity retention over 200 cycles at 0.05 C (89.2% over 100 cycles at 0.1 C). This work provides a new insight into the synergy of composite solid electrolyte and artificial SEI for achieving high-performance ASSLBs.

Solid-state batteries (SSBs) have recently been revived to increase the energy density and eliminate safety concerns associated with conventional Li-ion batteries with flammable liquid electrolytes. To achieve large-scale, low-cost production of SSBs as soon as possible, it would be advantageous to modify the mature manufacturing platform, involving slurry casting and roll-to-roll technologies, used for conventional Li-ion batteries for application to SSBs. However, the manufacturing of SSBs depends on the development of suitable solid electrolytes. Inorganic–polymer composite electrolytes combine the advantages of inorganic and polymer solid electrolytes, making them particularly suitable for the mass production of SSBs. In this Review, we discuss the properties of solid electrolytes comprising inorganic–polymer composites and outline the design of composite electrolytes for realizing high-performance devices. We also assess the challenges of integrating the composite electrolytes into batteries, which will enable the mass production of SSBs. Inorganic–polymer composites have emerged as viable solid electrolytes for the mass production of solid-state batteries. In this Review, we examine the properties and design of inorganic–polymer composite electrolytes, discuss the processing technologies for multilayer and multiphase composite structures, and outline the challenges of integrating composite electrolytes into solid-state batteries.

External pressure is widely applied to the fabrication and assembling of solid-state batteries, which can reduce grain sizes, enhance solid–solid contacts, and further increase the ionic conductivi...

The solid-state lithium battery is considered as an ideal next-generation energy storage device owing to its high safety, high energy density and low cost. However, the poor ionic conductivity of solid electrolyte and low interfacial stability has hindered the application of solid-state lithium battery. Here, a flexible polymer/garnet solid electrolyte is prepared with poly(ethylene oxide), poly(vinylidene fluoride), Li6.75La3Zr1.75Ta0.25O12, lithium bis(trifluoromethanesulfonyl)imide and oxalate, which exhibits an ionic conductivity of 2.0 × 10−4 S cm−1 at 55 °C, improved mechanical property, wide electrochemical window (4.8 V vs. Li/Li+), enhanced thermal stabilities. Tiny acidic OX was introduced to inhibit the alkalinity reactions between Li6.75La3Zr1.75Ta0.25O12 and poly(vinylidene fluoride). In order to improve the interfacial stability between cathode and electrolyte, an Al2O3@LiNi0.5Co0.2Mn0.3O2 based composite cathode framework is also fabricated with poly(ethylene oxide) polymer and lithium salt as additives. The solid-state lithium battery assembled with polymer/garnet solid electrolyte and composite cathode framework demonstrates a high initial discharge capacity of 150.6 mAh g−1 and good capacity retention of 86.7% after 80 cycles at 0.2 C and 55 °C, which provides a promising choice for achieving the stable electrode/electrolyte interfacial contact in solid-state lithium batteries.

Solid-state batteries (SSBs) with metallic lithium (Li) anodes are regarded as the next-generation energy storage devices with high energy and power densities. However, the issues of the Li dendrite growth and poor interfacial contact between the solid electrolyte and electrodes severely limit their wide practical applications. Therefore, it is of great importance to develop an electrolyte with high modulus to inhibit the growth of lithium dendrites and achieve a close contact with the electrodes. Herein, we fabricated a thin asymmetrical composite electrolyte (CPE), which integrates a ceramic-rich layer on the anode side and a polymer-rich layer on the cathode side by utilizing the natural settlement of Li6.28La3Zr2Al0.24O12 (LLZAO) during the in situ polymerization process. In such unique architecture, the rigid ceramic-rich layer is towards the Li metal and can effectively suppress the growth of Li dendrites, and the soft polymer-rich layer could wet the cathode to endow connected interface simultaneously. As a result, this asymmetric CPE possesses a high ionic conductivity of 8.43 × 10−4 S cm−1 and a wide electrochemical window up to 5.0 V at room temperature. The cycle of lithium symmetric cells renders a low charging voltage polarization and outstanding stability. Moreover, LiNi0.5Co0.2Mn0.3O2/Li batteries using this CPE exhibit excellent cyclic stability, superior rate capability, and a high initial discharge capacity of 149.1 mA h g−1 at room temperature.

All-solid-state lithium batteries (ASSLBs) based on sulfide solid-state electrolytes and high voltage layered oxide cathode are regarded as one of the most promising candidates for energy storage systems with high energy density and high safety. However, they usually suffer poor cathode/electrolyte interfacial stability, severely limiting their practical applications. In this work, a core-shell cathode with uniformly nanosized Li0.5La0.5TiO3 (LLTO) electrolyte coating on LiNi0.5Co0.3Mn0.2O2 (NCM532) is designed to improve the cathode/electrolyte interface stability. Nanosized LLTO coating layer not only significantly boosts interfacial migration of lithium ions, but also efficiently alleviates space-charge layer and inhibits the electrochemical decomposition of electrolyte. As a result, the assembled ASSLBs with high mass loading (9 mg cm−2) LLTO coated NCM532 (LLTO@NCM532) cathode exhibit high initial capacity (135 mAh g−1) and excellent cycling performance with high capacity retention (80% after 200 cycles) at 0.1 C and 25 °C. This nanosized LLTO coating layer design provides a facile and effective strategy for constructing high performance ASSLBs with superior interfacial stability.

Constructing a composite lithium anode with a rational structure has been considered as an effective approach to regulate and relieve the tough problems of a sparkling Li anode. However, the potential short circuits risk that Li deposition at the surface of the framework has not yet been resolved. Here, we present a simple regulating-deposition strategy to guide the preferentially bottom-up deposition/growth of Li. The triple-gradient structure of modified porous copper with electrical passivation (top) and chemical activation (bottom) shows significant improvements in the morphological stability and electrochemical performance. Meanwhile, the

Sodium-ion batteries are very promising in large-scale energy storage. The exploration of Na layered oxides as cathode materials for Na ion batteries usually consumes much resource, while the performances of Na layered oxides are dominated by their crystal structures. Therefore, it is highly desired to predict the stacking mode of the target oxides in advance: whether O3-type with higher ordered structure and stability, or P2-type with more Na content. For this purpose density functional theory computations do not work. Very recently, Hu's group and international collaborators have proposed a cationic potential to provide a very timely, effective, and accurate criterion to predict the stacking mode of Na layered oxides (Science, 370 (2020) 708–711). Under the guidance of the cationic potential phase map, Na layered oxides could be rationally designed. Here we would like to highlight the progress that novel Na layered oxides could be obtained with the combination of large specific capacity, high power density and good cycling stability.

In this study, highly pure Mo2CTx MXene was successfully synthesized from Mo2Ga2C by etching in hydrothermal conditions for 24 h at 140–180°C. The etching solutions were lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF) or ammonium fluoride (NH4F) mixed with hydrochloric acid (HCl). The temperature to obtain pure Mo2CTx MXene in NH4F + HCl solution was 140°C, lower than that in other etching solutions. The thickness of as-prepared monolayer Mo2CTx nanosheet was measured to be 1.5 ± 0.3 nm by atomic force microscope. From thermogravimetry and differential thermal analysis, Mo2CTx MXene was found to be stable in argon atmosphere at a temperature of up to 500°C. As the temperature increased, Mo2CTx MXene gradually transformed, and β-Mo2C/MoC/Mo3C2 was eventually formed to coexist with Mo2CTx MXene at 700°C. In air atmosphere, Mo2CTx MXene was stable at 200°C. At 590°C, Mo2CTx MXene was completely oxidized to MoO3.

Lithium–sulfur (Li–S) battery as a high-energy density electrochemical energy storage system has attracted many researchers’ attention. However, the shuttle effect of Li–S batteries and the challenges associated with lithium metal anode caused poor cycle performance. In this work, the organosulfide poly(sulfur-1,3-diisopropenylbenzene) (PSD) was prepared as cathode material and additive of P(VDF-HFP) polymer electrolyte (P(VDF-HFP)). It was verified that P(VDF-HFP) polymer electrolyte with 10% PSD (P(VDF-HFP)-10%PSD) showed a higher ionic conductivities than that of liquid electrolyte up to 2.27 × 10−3 S cm−1 at room temperature. The quasi-solid-state Li−S batteries fabricated with organosulfide cathode material PSD and P(VDF-HFP) based functional polymer electrolyte delivered good cycling stability (780 mAh g−1 after 200th cycle at 0.1 C) and rate performance (613 mAh g−1 at 1 C). The good cycling performance could be attributed to the synergistic effect of components, including the interaction between polysulfides and polymer main chain in the organosulfide cathode, the sustained organic/inorganic hybrid stable SEI layer formed by polymer electrolyte additive PSD, the improved cathode/electrolyte interface and the good affinity between P(VDF-HFP) based functional polymer electrolyte and Li metal surface. This strategy herein may provide a new route to fabricate high-performance Li–S batteries through the organosulfide cathode and functional polymer electrolyte.

With a low cost and high volumetric capacity, rechargeable magnesium batteries (RMBs) have been emerged as promising candidates for post-lithium ion batteries. The kinetically sluggish Mg2+ inserti...

Conventional lithium-ion batteries with liquid organic electrolytes generally suffer potential security risks concerning volatilization, flammability and explosion. Nonflammable and thin solid-state electrolytes particularly composite solid electrolytes (CSEs) that integrate the merits of different electrolyte systems have attracted increasing attention for advanced lithium batteries with improved energy density and high safety. In this work, a three-dimensional (3D) fiber-network-reinforced CSE, which consists of a mechanically robust, porous polyimide (PI) film as a host, Li6.75La3Zr1.75Ta0.25O12 (LLZTO) nanoparticles and poly (vinylidene fluoride) (PVDF) polymer matrix with bis-trifluoromethanesulfonimide lithium salt as electrolyte filler, is designed and fabricated. Such unique 3D CSE films with PI fiber network holding for uniform dispersion of LLZTO in PVDF show continuous lithium ion transfer pathways and effective prevention for lithium dendrite growth, consequently exhibiting improved mechanical property (high tensile strength of 11.5 ​MPa) and high cyclic stability (more than 1000 ​h of cycling for Li symmetric batteries). Furthermore, solid-state LiNi0.5Co0.2Mn0.3O2/Li pouch cells with the PI-PVDF/LLZTO CSE exhibit excellent cyclic stability (152.6 ​mA ​h ​g−1 with capacity retention of 94.9% at 0.1C after 80 cycles) at room temperature, and high functionality and safety (withstand harsh environments such as folding, cutting and nail penetration) in practical applications.

Bulk-type all-solid-state lithium batteries (ASSLBs) with high theoretical capacity and good safety are considered to be promising candidates as future energy storage devices. The ASSLBs with inorganic electrolytes usually have a thick electrolyte layer (more than 1 mm), which significantly reduces the cell-based energy density; therefore, a free-standing high-conductance electrolyte layer with a low thickness is essential for high-performance ASSLBs. In this work, we prepare free-standing 78Li2S–22P2S5 glass-ceramic (7822gc) composite solid electrolyte membranes reinforced with polymer electrolytes with a thickness of 120 μm through a liquid-phase method and systematically investigate the effects of solvents and polymer electrolytes on the microstructure and electrochemical properties of the 7822gc/polymer composite membranes. The sulfide/PEO and sulfide/PVDF composite electrolytes without lithium salt show an ionic conductivity of 2–4 × 10−4 S cm−1 at room temperature, while the conductivity of those with lithium salt is enhanced to 4–7 × 10−4 S cm−1. With such a high conductivity and low thickness, an ultra-high areal conductance of 59.0 mS cm−2 is obtained for the composite electrolyte membranes, which is ~2.7 times of that of pure 7822gc electrolyte pellets. All-solid-state lithium-sulfur batteries (ASSLSBs) with a sulfur/carbon nanotube composite cathode and a Li–In alloy anode are prepared. The cell-based energy density is as high as 87.0 Ah L−1. A discharge capacity of 725.1 mA h g−1 at 0.176 mA cm−2 after 100 cycles and a high capacity retention of 93.2% are achieved for the cells with 7822gc/polymer composite electrolyte membranes.

Bulk-type all-solid-state batteries (ASSBs) using sulfide solid electrolyte are considered as a promising alternative to commercial lithium-ion batteries owing to their high energy density and safety. However, cell energy density is often comparatively low due to use of a thick solid electrolyte separator and a lithium alloy as anode. For achieving high-performance ASSBs, creating a thin free-standing electrolyte with high-conductivity and good cycling stability against lithium anode is essential. In this work, we present Li6PS5Cl/poly(vinylidene difluoride) (LPSCl/PVDF) composite electrolytes prepared by a slurry method. The influence of the PVDF content on the microstructure, morphology, ionic conductivity and activation energy of the LPSCl/PVDF electrolytes is systematically investigated. Free-standing LPSCl/PVDF membranes with a thickness of 100–120 μm and a high ionic conductivity of about 1·10−3 S cm−1 at 25 °C are obtained. After adding PVDF to the LPSCl electrolyte, the cycling stability of the LPSCl electrolyte against lithium metal improves significantly. Therefore, LPSCl/PVDF composite electrolytes are promising candidates to be used in ASSBs. Keywords: Composite solid electrolyte, Li6PS5Cl, Poly(vinylidene difluoride)

Novel portable power sources featuring high flexibility, built-in sustainability and enhanced safety have attracted ever-increasing attention in the field of wearable electronics. Herein, a novel flexible self-charging sodium-ion full battery was feasibly fabricated by sandwiching a BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte film between an advanced Na3V2(PO4)3@C cathode and hard carbon anode. Besides the considerable flexibility and electrochemical storage performance, the as-designed device also delivers sound self-charging capability via various stress patterns, regardless of whether under static compression, repeated bending or continuous palm patting. Serially connected self-charging devices are able to drive several electronic devices with a good working state. Specifically, a unique theory of electromagnetic fields was successfully introduced to deduce the direct self-charging mechanism, where no rectifier was applied and the battery was charged by the built-in piezoelectric component. This work presents an innovative approach to achieve a new sustainable, safe and flexible sodium-ion battery for self-powered wearable electronics.

Aqueous zinc ion batteries (ZIBs) have attracted intensive attention due to their low cost, environmental friendliness and high safety. However, exploring suitable cathode materials and a deep understanding of their energy storage mechanisms remain a daunting challenge. In this work, a three-dimensional (3D) nest-like V6O13 structure is grown on carbon cloth (CC) as a free-standing ZIB cathode. Such interconnected V6O13 nanoneedles forming a 3D nest structure provide a large accessible surface area to the electrolyte and rapid channels for Zn2+ diffusion, and V6O13 with a V5+-rich state allows for more possibilities of multielectron reaction upon Zn (de)intercalation. As a result, an aqueous ZIB based on the V6O13/CC cathode and low-cost ZnSO4 electrolyte shows an ultrahigh capacity of 520 mA h g−1 (at a current density of 0.5 A g−1), desirable rate capability and cycle life (showing a stable capacity of 335 mA h g−1 over 1000 cycles). Moreover, the Zn2+ storage mechanism is deeply investigated based on experimental data and density functional theory simulation, and flexible solid-state ZIBs are established based on such a V6O13/CC cathode to reveal its high functional flexibility and excellent electrochemical performance, showing great potential applications in high-performance and safe electronic devices.

Potassium-ion batteries (KIBs) are currently being investigated as a potential alternative to lithium-ion batteries (LIBs) because of the natural abundance of K resources. Presently, it is crucial yet challenging to explore suitable anode materials for stable K-storage. Herein, a novel robust CoP–carbon composite with highly dispersed CoP nanoparticles (NPs) immobilized in natural cellulose nanofiber network (CNF)-derived carbon (denoted as CoP@CNFC) is synthesized via chemical bonding through a facile hydrothermal and subsequent in situ phosphidation approach. The designed structure can provide diverse merits, including fast reaction kinetics, sufficient active sites and effective accommodation for K+ insertion/extraction; thus, CoP@CNFC delivers desired electrochemical performance, including considerable reversible capacity, enhanced rate capability and excellent cycling stability. Additionally, the electrochemical reaction mechanism of CoP@CNFC was clearly revealed by ex situ characterizations and theoretical simulations of cyclic voltammetry (CV) and solid electrolyte interface (SEI) profiles based on first-principles calculations. The achieved deep elucidation of the reversible process of K+ insertion and extraction on the surface/interface of the active material during the discharge and charge states clearly highlights its significance for stable K-storage. This work promotes the facile design and deep understanding of nanostructured high-capacity electrodes of transition metal phosphates for rechargeable KIBs.