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Hydrogels are often used to fabricate strain sensors; however, they also suffer from freezing at low temperatures and become dry during long-time storage. Encapsulation of hydrogels with elastomers is one of the methods to solve these problems although the adhesion between hydrogels and elastomers is usually low. In this work, using bovine serum protein (BSA) as the natural globulin model and glycerol/H

The boom in nanotechnology brings new insights into the development of artificial enzymes (nanozymes) with ease of modification, lower manufacturing cost, and higher catalytic stability than natural enzymes. Among various nanomaterials, two-dimensional (2D) nanomaterials exhibit promising enzyme-like properties for a plethora of bioapplications owing to their unique physicochemical characteristics of tuneable composition, ultrathin thickness, and huge specific surface area. Herein, we review the recent advances in several 2D material-based nanozymes, such as carbonaceous nanosheets, metal-organic frameworks (MOFs), transition metal dichalcogenides (TMDs), layered double hydroxides (LDHs), and transition metal oxides (TMOs), clarify the mechanisms of peroxidase (POD)-mimicking catalytic behaviors, and overview the potential bioapplications of 2D nanozymes.

Fiber supercapacitors (FSCs) that fulfill the necessities of high power/energy density, flexibility, robustness, and wearing comfort are prospective power sources for portable/wearable electronics. The efforts in this field remain to exploit high performance fibrous materials with combined advantages of suitable mechanical properties, high electrical conductivity, and enhanced specific capacitance. Herein, for the first time, we incorporate expanded molybdenum diselenides (MoSe2) into graphene fibers via the assistance of ethylenediamine. The presence of MoSe2 enables the as-fabricated hybrid fiber a 2.2-fold enhancement in volumetric capacitance (148.6 F cm−3) as well as good rate performance. The assembled FSC provides a capacitance of 22.8 F cm−3, an energy density of 1.2 mWh cm−3, and a maximum power density of 314.0 mW cm−3 in addition to excellent cycle stability. Notably, the flexible and mechanically steady FSCs display excellent processability under well-controlled conditions, including weaving into the fabric, and their electrochemical properties maintain unchanged under various bending angles. Furthermore, the FSCs are connected to steadily power LED lamp, illustrating the promising possibility as future wearable energy storage devices.

Flexible ammonium-ion battery-based self-powered wearable sensing devices can monitor various human motions sensitively and stably without an external power supply.

CoPi is used as an energy storage material in a two-electrode solar rechargeable device for the first time, which exhibits the highest working voltage among all previously reported devices.

Flexible all-in-one supercapacitors based on swelling-resistant microgel-reinforced hydrogel polymer electrolytes exhibit excellent mechanical stability, electrochemical performance and anti-freezing properties.

Electrochemical energy storage and conversion devices have greatly advanced our daily life in the past few decades because of the convenience and flexibility they provide. As one of the essential components of energy storage and conversion devices, electrode materials play a crucial role in overall device performances. Conventional material preparation methods, including hydrothermal, chemical vapor deposition, high temperature solid phase methods, etc., are often subject to harsh preparation conditions. Therefore, much simpler and more efficient preparation methods are still sought after by the research community. In recent years, ion exchange (IE) technology, as a novel method for syntheses of nanomaterials, has attracted a great deal of research attention for its great capability in precise structural design and simultaneous regulation of component compositions. Nevertheless, the links among reaction mechanisms, resulting products, and product application performances, have not been fully elaborated. Herein, this review systematically summarizes historical developments of the IE technology for preparation of nanomaterials and relevant reaction mechanisms from both kinetic and thermodynamic perspectives. A detailed summary of recent applications of the IE technology for preparation of a wide variety of nanomaterials and their applications in electrochemical energy storage and conversion devices, including supercapacitors, lithium/sodium-ion batteries, electrolytic water splitting, and hydrogen fuel cells, is presented. In-depth understanding of the IE technology provides better technical approaches for fabrication of high-performance electrode materials. In the final section, an outlook on the IE technology is offered.

Interface charge transfer plays a key role in the performance of semiconductors for different kinds of solar energy utilization, such as photocatalysis, photoelectrocatalysis, photochromism and photo-induced superhydrophilicity. In previous studies, different mechanisms have been used to understand interface charge transfer processes. However, the charge transfer mechanism at the solid/liquid interface remains a controversial topic. Here, taking TiO2 as a model, we find and prove, via experiments, the new characteristic of photo-induced bipolarity of the surface layer (reduction faradaic layer and oxidation faradaic layer) on a semiconductor for the first time. Different from energy level positions in the classic surface states transfer mechanism, the potential window of a surface faradaic layer is located out of the forbidden band. Moreover, we find that the reduction faradaic layer and oxidation faradaic layer serve as electron and hole transfer mediators in photocatalysis, while the bipolarity or mono-polarity of the surface layer on a semiconductor depends on the applied potential in photoelectrocatalysis. The new characteristic of bipolarity can also offer new insights into the charge transfer process at the semiconductor/liquid interface for solar energy utilization.

Ultralong organic phosphorescence (UOP) crystals have attracted increased attention due to the distinct photophysical property of a long-lived lifetime. However, organic crystals are generally brittle, leading to a serious problem for their application in flexible technology. Herein, we report three types of elastic organic crystals (EOCs) with ultralong phosphorescence via introducing halogen atoms (Cl, Br, I) into π-conjugated phosphorescent molecules. Especially, the crystal containing iodine atoms displayed both excellent elasticity (ε = 3.01%) and high phosphorescent efficiency (ΦPh = 19.1%) owing to the strong halogen bonds. Taking advantage of its highly efficient UOP and excellent elasticity, we successfully used a DCz4I crystal for anti-counterfeiting application. These findings may provide guidance for the development of elastic crystals with afterglow and expand the scope of potential applications on flexible materials.

In this work, semi-crystalline nanocomposite hydrogels (i.e., PAAmA11A/GO gels) were synthesized by micellar copolymerization of acrylamide and N -acryloyl-11-aminoundecanoic acid (A11A) in the presence of a large amount of sodium dodecyl sulfonate (SDS) micelles and GO nanosheets. The resulting hydrogels (SMHs) not only demonstrated high strength and high toughness, but also exhibited good shape memory property. Because of near-infrared (NIR) light absorbability of GO nanosheets, shape recovery and shape of PAAmA11A/GO gels could be tuned by NIR irradiation. Moreover, bilayer hydrogels and trilayer hydrogels were also fabricated by the integration of shape-memorized PAAmA11A/GO gel and elastic hydrophobic associated hydrogel (E-gel). Based on the NIR-responsive shape memory property and layered structure, shape deformation of bilayer hydrogels and trilayer hydrogels was rather different from the single PAAmA11A/GO gel. Each kind of gel structure exhibited diverse and complex shapes via programmable NIR irradiation. More importantly, the shape morphing of NIR-SMHs-based hydrogels could mimic the hand and flower and be used as actuators.

The flexible strain sensor is of significant importance in wearable electronics, since it can help monitor the physical signals from the human body. Among various strain sensors, the foam-shaped ones have received widespread attention owing to their light weight and gas permeability. However, the working range of these sensors is still not large enough, and the sensitivity needs to be further improved. In this work, we develop a high-performance foam-shaped strain sensor composed of Ti3C2Tx MXene, multiwalled carbon nanotubes (MWCNTs), and thermoplastic polyurethane (TPU). MXene sheets are adsorbed on the surface of a composite foam of MWCNTs and TPU (referred to as TPU/MWCNTs foam), which is prefabricated by using a salt-templating method. The obtained TPU/MWCNTs@MXene foam works effectively as a lightweight, easily processable, and sensitive strain sensor. The TPU/MWCNTs@MXene device can deliver a wide working strain range of ∼100% and an outstanding sensitivity as high as 363 simultaneously, superior to the state-of-the-art foam-shaped strain sensors. Moreover, the composite foam shows an excellent gas permeability and suitable elastic modulus close to those of skin, indicating its being highly comfortable as a wearable sensor. Owing to these advantages, the sensor works effectively in detecting both subtle and large human movements, such as joint motion, finger motion, and vocal cord vibration. In addition, the sensor can be used for gesture recognition, demonstrating its perspective in human-machine interaction. Because of the high sensitivity, wide working range, gas permeability, and suitable modulus, our foam-shaped composite strain sensor may have great potential in the field of flexible and wearable electronics in the near future.

Nanozymes as promising alternatives to natural enzymes have attracted enormous attentions for their high robustness, low cost, and tunable activity. Among various candidates, carbonaceous nanomaterials possess extra advantage features of designable surface properties and good biocompatibility. However, their peroxidase-like activity is typically moderate owing to the short half-life of radical hydroxyl (·OH), the poor catalytic activity and substrate affinity. Herein, we synthesize Fe,N-doped carbon (Fe,N-C-800) via pyrolyzing Fe-doped ZIF-8 (ZnFe-ZIF) in NH3 at 800 °C. Fe,N-C-800 shows excellent peroxidase mimic with outstanding substrate affinity and catalytic velocity superior to the advanced Fe single-atom catalyst. The excellent enzyme-like performance is ascribed to the synergistic contributions of Fe- and N-doping. Fe functions as catalytic center while pyrrolic N absorbs TMB (3,3’,5,5’-Tetramethylbenzidine) substrate and enhances the electron density of Fe sites, thereby shortening the migration distance of ·OH and further improving the catalytic activity. Based on Fe,N-C-800, disposable paper bioassays are fabricated and exhibit ultrasensitive detection of H2O2.

Flexible power supply systems for future wearable electronics desperately require high areal capacity (Ca) and robust cycling reliability due to the limited surface area of the human body. Transition metal sulfides are preferred as cathode materials for their improved conductivity and rich redox centers, yet their practical applications are severely hindered by the sluggish charge transport kinetics and unavoidable capacity decay due to the phase transformation during charge/discharge processes. Herein, we develop a site-selective transformation strategy for preparing tripod-like NiCo-sulfides@carbon (T-NCS@C) arrays on carbon cloth. The mass loading of active materials is balanced with charge (electron and ion) transport efficiency. The optimized T-NCS@C delivers a superior Ca of 494 μA h/cm2 (corresponding to 235 mA h/g) at 3 mA/cm2. Due to the protection of the carbon layer that is derived from transformed metal-organic framework (MOF) sheath, the T-NCS@C displays excellent stability with 92% retention over 5000 charge/discharge cycles. The flexible full cell adopting Fe2O3 as the anode and T-NCS@C as the cathode exhibits an improved Ea (areal energy density) of 389 μW h/cm2 at a Pa (areal power density) of 4.22 mW/cm2 together with robust cycling reliability.

Transition metal dichalcogenides (TMDs), particularly molybdenum diselenides (MoSe2), have the merits of their unique two-dimensional (2D) layered structures, large interlayer spacing (∼0.64 nm), good electrical conductivities, and high theoretical capacities when applied in lithium-ion batteries (LIBs) as anode materials. However, MoSe2 remains suffering from inferior stability as well as unsatisfactory rate capability because of the unavoidable volume expansion and sluggish charge transport during lithiation-delithiation cycles. Herein, we develop a simultaneous reduction-intercalation strategy to synthesize expanded MoSe2 (e-MoSe2) with an interlayer spacing of 0.98 nm and a rich 1T phase (53.7%) by rationally selecting the safe precursors of ethylenediamine (NH2C2H4NH2), selenium dioxide (SeO2), and sodium molybdate (Na2MoO4). It is noteworthy that NH2C2H4NH2 can effectively reduce SeO2 and MoO42- forming MoSe2 nanosheets; in the meantime, the generated ammonium (NH4+) efficiently intercalates between MoSe2 layers, leading to charge transfer, thus stabilizing 1T phases. The obtained e-MoSe2 exhibits high capacities of 778.99 and 611.40 mAh g-1 at 0.2 and 1 C, respectively, together with excellent cycling stability (retaining >90% initial capacity at 0.2 C over 100 charge-discharge cycles). It is believed that the material design strategy proposed in this paper provides a favorable reference for the synthesis of other transition metal selenides with improved electrochemical performance for battery applications.

Sensors are becoming increasingly significant in our daily life because of the rapid development in electronic and information technologies, including Internet of Things, wearable electronics, home automation, intelligent industry, etc. There is no doubt that their performances are primarily determined by the sensing materials. Among all potential candidates, layered nanomaterials with two-dimensional (2D) planar structure have numerous superior properties to their bulk counterparts which are suitable for building various high-performance sensors. As an emerging 2D material, MXenes possess several advantageous features of adjustable surface properties, tunable bandgap, and excellent mechanical strength, making them attractive in various applications. Herein, we particularly focus on the recent research progress in MXene-based sensors, discuss the merits of MXenes and their derivatives as sensing materials for collecting various signals, and try to elucidate the design principles and working mechanisms of the corresponding MXene-based sensors, including strain/stress sensors, gas sensors, electrochemical sensors, optical sensors, and humidity sensors. In the end, we analyze the main challenges and future outlook of MXene-based materials in sensor applications.

The monitoring and prediction of the health status and the end of life of batteries during the actual operation plays a key role in the battery safety management. However, although many related studies have achieved exciting results, there are few systematic and comprehensive reviews on these prediction methods. In this paper, the current prediction models of remaining useful life of lithium-ion batteries are divided into mechanism-based models, semi-empirical models and data-driven models. Their advantages, technical obstacles, improvement methods and prediction performance are summarized, and the latest research results are shown by comparison. We highlight that the fusion models of convolution neural network, long short term memory network and so on, which have great practical application prospects because of their outstanding computing efficiency and strong modeling ability. Finally, we look forward to the future work in simplifying the model and improving its interpretability.

In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics, herein, 2D mesh-like vertical structures (NiCo2S4@Ni(OH)2) with a high mass loading of 2.17 mg cm−2 and combined merits of both 1D nanowires and 2D nanosheets are designed for fabricating flexible hybrid supercapacitors. Particularly, the seamlessly interconnected NiCo2S4 core not only provides high capacity of 287.5 μAh cm−2 but also functions as conductive skeleton for fast electron transport; Ni(OH)2 sheath occupying the voids in NiCo2S4 meshes contributes extra capacity of 248.4 μAh cm−2; the holey features guarantee rapid ion diffusion along and across NiCo2S4@Ni(OH)2 meshes. The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm−2 (246.9 mAh g−1) at 3 mA cm−2 and outstanding rate performance with 84.7% retention at 30 mA cm−2, suggesting efficient utilization of both NiCo2S4 and Ni(OH)2 with specific capacities approaching to their theoretical values. The flexible solid-state hybrid device based on NiCo2S4@Ni(OH)2 cathode and Fe2O3 anode delivers a high energy density of 315 μWh cm−2 at the power density of 2.14 mW cm−2 with excellent electrochemical cycling stability.

The major obstacle to developing nanozymes which are considered as promising alternatives to natural enzymes is their moderate performance, including poor affinity for substrates, low catalytic activity, and severe pH-dependence. To address these issues, herein, we synthesize ultrathin layered double hydroxide (LDH) nanosheets with a thickness of 1.4 nm and an average lateral size of 23 nm using a fast-precipitation method. Through the rational design of their compositions, it is found that NiMn LDHs exhibit the optimum peroxidase mimicking performance with excellent substrate affinity, high catalytic activity (a limit of detection (LOD) of 0.04 μM H2O2) and robustness in a wide pH range (from 2.6 to 9.0), which is superior to that of natural horseradish peroxidase (HRP). The main active centers are identified as Mn sites because of their strong Lewis acidity and low redox potential. Furthermore, a series of disposable paper bioassays based on NiMn LDH nanozymes are designed and used for the highly sensitive detection of H2O2 and ascorbic acid (AA).

In order to enhance the charge storage capability of carbonaceous fibers for wearable supercapacitors, efforts have been devoted to the incorporation of transition metal dichalcogenides (e.g., MoS2), nevertheless the improvement is moderate since the electrochemical properties of MoS2 severely depend on their crystal phase and interlayer spacing. Herein, a facile space-confined hydrothermal method is developed to synthesize graphene fibers embedded with expanded 1T-enriched MoS2 in a single-step. In such a fiber configuration, 1T phase enables MoS2 hydrophilicity and high electrical conductivity while expanded interlayer spacing facilitates fast ion intercalation/de-intercalation. The hybrid fibers exhibit significantly enhanced volumetric specific capacitance (CV) of 491.1 F cm-3 for single electrode and 44.6 F cm-3 for solid-state device, respectively, with good rate performance and excellent cycling stability.

Compared with other commercial cathode materials, the LiNi0.8Co0.1Mn0.1O2 cathode (NCM811) has high specific capacity and a relatively low cost. Nevertheless, the higher nickel content in NCM811 leads to an extremely unstable interface between the electrode and the electrolyte, resulting in inferior cyclic stability of the corresponding cell. Use of film-forming additives is regarded as the most feasible and economic approach to construct a stable interface on the NCM811 cathode. However, less effective electrolyte additives have been reported to date. Herein, we propose a valid film-forming electrolyte additive, 2,4,6-triphenyl boroxine (TPBX), for application in a high-voltage NCM811 cathode. Experimental and computational results reveal that the TPBX additive can be preferentially oxidized to generate a highly stable and conductive cathode electrolyte interface (CEI) layer on the NCM811 cathode, which efficiently suppresses the detrimental side reaction and improves the electrochemical performance eventually. In detail, the cyclic stability of the Li/NCM811 half-cell is enhanced from 57% (without additive) to 78% (with 5% TPBX) after 200 cycles at 1C between 3.0 and 4.35 V. At a high current rate of 15C, the TPBX-containing electrode delivers a capacity of about 135 mAh g-1, which is much higher than that of the electrode without the additive (80 mAh g-1). Interestingly, the TPBX is also reduced earlier than the ethylene carbonate (EC) solvent to form an ionically conductive solid electrolyte interface (SEI) film on the graphite anode. Due to the CEI layer on the cathode and the SEI film on the anode simultaneously formed by the TPBX additive, the cyclic performance of the graphite/LiNi0.8Co0.1Mn0.1O2 full cell is enhanced. Therefore, the incorporation of the TPBX additive into the electrolyte provides a convenient method for the commercial application of the high-energy-density NCM811 cathode in high-voltage lithium-ion batteries.

Upgrading the energy density and cycle life of current lithium ion batteries are urgently needed for developing advanced portable electronics and electric vehicles. Amorphous transition metal oxides (TMO) with inherent lattice disorders exhibit enormous potential as electrode materials for their high specific capacity, fast ion diffusion, and excellent cyclic stability, yet challenges remain in controllable synthesis. In this study, amorphous phase is induced into α-MoO3 crystal nanobelts at room temperature with the aid of Jahn-Teller effect via enhanced lattice distortion triggered by the accumulation of low-valent molybdenum centers. The optimized HI-MoO3-36h exhibits high reversible capacities of 886.0 at 0.1 A g−1 and 491.1 mAh g−1 at 1.0 A g−1, respectively, along with outstanding stability retaining 83.4% initial capacity after 100 cycles at 0.1 A g−1. The crystal engineering strategy proposed in this work is believed to be a salutary reference towards the synthesis of high-performance transition metal oxide anodes for energy storage applications.

Flexible pressure sensors have attracted great attention in health monitoring, human–machine interface, and soft robotics because of their simple device structure and easy to read signals. Two-dimensional (2D) materials (e.g., MXene) are promising candidates for constructing flexible pressure sensors due to their high conductivity and solution-based processability. Typically, during filtration, micrometer-sized MXene nanosheets are assembled into a thin membrane with plenty of wrinkles and folds in order to minimize the total energy. Herein, by taking advantage of this phenomenon, hydrazine hydrate is employed as a foaming agent to blow up the wrinkles and folds of MXene nanosheets in the membrane by gas species generated from the redox reactions, forming a porous foam. The as-prepared pressure sensor shows high sensitivity for a wide linear range (102.89 kPa−1 for 0–0.5 kPa and 2.86 kPa−1 for 2–10 kPa), low detection limit (1 Pa), fast response time (132 ms), and excellent durability (over 5000 cycles). As a detector, the MXene sensor can not only identify different sound signals and sound attributes by monitoring the vocal cord vibration but also distinguish various natural sounds transmitted through the air pressure waves caused by the sound transmission.

Two-electrode solar rechargeable device is one of the promising technologies to address the problem of solar energy storage in large scale. However, the mechanism of dark output voltage remains unclear and the low volumetric energy density also limits its practical applications. Herein, we report that a Si/CoOx/KBi(aq)/MnOx Faradaic junction device exhibits a photovoltage memory effect, that is, the dark output voltage can precisely record the value of the photovoltage in the device. To investigate the mechanism of the effect, we develop an open circuit potential method to real-time monitor the photo charge and dark discharge processes in the Faradaic junction device. This effect leads to minimized interface energy loss in the Faradaic junction device, which achieves much higher performances than the devices without the effect. Moreover, we realize a portable device with a record value of the dark volumetric energy density (∼1.89 mJ cm−3) among all reported two-electrode solar rechargeable devices. These results offer guidance to improve the performance of a solar rechargeable device and design other photoelectric devices for new applications.

As a promising alternative to lithium-ion batteries (LIBs), rechargeable sodium-ion batteries (SIBs) are attracting enormous attention due to the abundance of sodium. However, the lack of high-performance sodium anode materials limits the commercialization of SIBs. In this work, the dual enhancement of SnS2/graphene anodes in sodium storage is achieved through S-compositing and Co doping via an innovative one-step hydrothermal reaction at a relatively low temperature of 120 °C. The as-prepared 7% Co-SnS2/S@r-G composite consisting of 15.4 wt % S and 1.49 atom % Co shows both superior cycling stability (over 1000 cycles) and rate capability, giving high reversible specific capacities of 878, 608, and 470 mAh g-1 at 0.2, 5, and 10 A g-1, respectively. More encouragingly, the full-cell also exhibits an outstanding long-term cycling performance under 0.5 A g-1, which delivers a reversible capacity of 500 mAh g-1 over 200 cycles and still retains a high reversible capacity of 432 mAh g-1 over 400 cycles. The enhancement mechanism is attributed to the favorable three-dimensional structure of the composite, Co doping, and S-composition, which can induce a synergistic effect.

It is a challenge to realize high strength, toughness, and energy storage, as well as excellent capacitive self-recovery, fatigue-resistant, and self-healing performances simultaneously in a single all-in-one supercapacitor aiming for wearable electronics. Herein, based on the self-crosslinking and molecular template, a supramolecular poly(vinyl alcohol)/poly (

Thanks to their light-weight, wearing comfort, and amenability to be woven into textiles, solid-state fiber supercapacitors (FSCs) have been considered as promising energy storage devices for wearable electronics. Carbon fibers (CFs) have the merits of both superior mechanical strength and conductivity, excellent flexibility, doped by heteroatoms, good knittability/weavability, and most importantly have already been produced in ton-scale in form of continuous tows; however, their applications in FSCs are limited to current collectors or conductive scaffolds as a result of the inert surface composed of highly compacted and well-aligned graphitic sheath. Inspired by Cattail’s unique compact core-fluffy sheath structure, herein, we develop an electrochemical method to directly transform CFs into high performance electrode by controllably swelling the well-aligned graphitic sheath without disturbing the core fiber of interlinked randomly-orientated carbon nanocrystals. Compared to pristine CFs, the obtained fiber electrode delivers more than two-order improved capacitance (87.2 F cm−3 at 1.0 A cm−3) with excellent rate capability and cycling stability, enabling the as-fabricated solid-state supercapacitor much enhanced energy density. The scalability of our method is demonstrated, which is believed to be compatible with the state-of-art commercial processing techniques, thus holds great promise for future development of electronic-textiles.

It has been demonstrated that the incorporation of Ni into metal oxide-based gas sensors often enhances the sensing performance by increasing the catalytic and heterojunction effects. However, it remains unclear how these two effects work either individually or synergistically in gas sensing. Herein, a series of Ni-doped In2O3 nanotubes (NIO NTs) with different doping concentrations were synthesized through a traditional electrospinning technique. The as-prepared NIO NTs were uniform, with length of micron scale, an average diameter of approximately 70 nm, and a tube wall thickness of approximately 10 nm. Following their incorporation into gas sensors, the NIO NTs often showed improved sensing properties (including excellent response and selectivity) for ethanol vapor compared to the pristine In2O3 NTs. Specifically, at 100 ppm ethanol and 220 °C, the response of NIO-7 NTs (7 mol% Ni) was approximately four-fold higher than that of pristine In2O3 NTs (49.74 vs. 13.39). The gas sensing test results indicated that the improved sensing performance was due to the formation of a heterojunction between In2O3 and NiO, as well as to the catalysis effects of Ni3+ ions. Additionally, simulation results indicated that the improved gas selectivity could be due to the Ni doping-induced change in surface adsorption energies of the tested gases.

Engineering coordination compounds, e.g., prussian blue (PB) and its analogues (PBAs), with designable complex nanostructures via chemical etching holds great opportunities for improving energy storage performances by adjusting topological geometry, selectively exposing active sites, tuning electronic properties and enhancing accessible surface area. Unfortunately, it remains ambiguous particularly on site-selective and anisotropic etching behaviors. Herein, for the first time, we propose that two distinct regions are formed inside NiCo PBA (NCP) cubes due to the competition between classical ion-by-ion crystallization and non-classical crystallization based on aggregation. Such a unique structure ultimately determines not only the etching position but also the anisotropic pathway by selectively exposing unprotected Ni sites. According to this principle, complex PBA architectures, including nanocages, open nanocubes (constructed by six cones sharing the same apex), nanocones, and chamfer nanocubes can be intentionally obtained. After thermal annealing, NCP nanocones are converted to morning glory-like porous architectures composed of NiO/NiCo2O4 heterostructures with a mean particle size of 5 nm, which show improved rate performance and cycling stability.

Human voice recognition systems (VRSs) are a prerequisite for voice-controlled human-machine interfaces (HMIs). In order to avoid interference from unexpected background noises, skin-attachable VRSs are proposed to directly detect physiological mechanoacoustic signals based on the vibrations of vocal cords. However, the sensitivity and response time of existing VRSs are bottlenecks for efficient HMIs. In addition, water-based contaminants in our daily lives, such as skin moisture and raindrops, normally result in performance degradation or even functional failure of VRSs. Herein, we present a skin-attachable self-cleaning ultrasensitive and ultrafast acoustic sensor based on a reduced graphene oxide/polydimethylsiloxane composite film with bioinspired microcracks and hierarchical surface textures. Benefitting from the synergetic effect of the spider-slit-organ-like multiscale jagged microcracks and the lotus-leaf-like hierarchical structures, our superhydrophobic VRS exhibits an ultrahigh sensitivity (gauge factor, GF = 8699), an ultralow detection limit (ε = 0.000 064%), an ultrafast response/recovery behavior, an excellent device durability (10 000 cycles), and reliable detection of acoustic vibrations over the audible frequency range (20-20 000 Hz) with high signal-to-noise ratios. These superb performances endow our skin-attachable VRS with anti-interference perception of human voices with high precision even in noisy environments, which will expedite the voice-controlled HMIs.

High voltage LiNi0.5Mn1.5O4 material is a promising cathode for lithium ion battery, but the unsatisfied cycle stability hinders its further development in higher energy density battery. Amorphous terpolymer poly(butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)), which possesses good affinity with carbonated liquid electrolyte and high adhesion ability, is used together with traditional poly(vinylidene fluoride) (PVDF) binder to improve the cyclic performance of LiNi0.5Mn1.5O4 cathode. The retention ability of discharge capacity is 92% for Li/LiNi0.5Mn1.5O4 coin cell after 300 cycles at 1C rate when the cathode uses the co-binders of PVDF and P(BMA-AN-St) (2:1 in weight), compared with 55% capacity retention for the cathode fabricated with PVDF binder alone. From the physical and electrochemical characterizations of the cycled electrode, it is found that the introduced terpolymer enhances the liquid electrolyte uptake ability of LiNi0.5Mn1.5O4 cathode and the adhesion strength inside the particles by building a better interconnected conductive structure. Furthermore, the improved cycle stability of co-binder based cathode is contributed to the passivating layer formed by the terpolymer on the surface of LiNi0.5Mn1.5O4 particles, which effectively suppresses the decomposition of liquid electrolyte at high voltage and maintains the structural integrity of active material in the repeated intercalation/de-intercalation process.

Despite red phosphorous (P)-based anodes hold great promise for advanced lithium-ion batteries due to their high theoretical capacity, their practical application is hindered by poor electronic conductivity and drastic volume changes during charge-discharge processes. In order to tackle these issues, herein, a facile grinding method was developed to embed sub-micro- and nano-sized red P particles in N,P-co-doped hierarchical porous carbon (NPHPC). Such a unique structure enables P@NPHPC long-cyclic stability (1120 mA h g−1 after 100 cycles at 100 mA g−1) and superior rate performance (248 mA h g−1 at 6400 mA g−1). It is believed that our method holds great potential in scalable synthesis of P@carbon composites for future practical applications.