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Self‐direction has become an important skill in the 21st century. To cultivate learners with a high level of self‐direction, it is necessary to diagnose their self‐directed learning (SDL) ability. This study diagnosed and predicted learners' SDL ability based on their actual SDL behaviours. The study was performed in a self‐directed 3D design class lasting 90 minutes. A total of 193 middle school students participated in the study. The results of the Pearson correlation analysis (p < 0.001) showed that the reported perception of SDL ability was significantly correlated with SDL behaviours. The results of the hierarchical multiple linear regression analysis showed that the SDL behaviours explained 84.9% of the variance in SDL ability (adjusted R2 = 0.849, p < 0.001). Therefore, SDL behaviours had significant predictive effects on the reported perception of SDL ability. Moreover, based on the random forest algorithm, the study built an SDL ability prediction model with high performance (accuracy = 0.83, precision = 0.82, recall = 0.84) using SDL behaviours as features. The study provides evidence for the design of effective strategies to enhance SDL ability and promote SDL behaviours.Practitioner notesWhat is already known about this topicTo cultivate learners with a high level of self‐direction, it is necessary to diagnose their self‐directed learning (SDL) ability.SDL is a combination of internal personal attributes and external autonomous behaviours.Few studies have focused on diagnosing SDL ability based on learners' external SDL behaviours occurring during the learning process.What this paper addsThe reported perception of SDL ability was significantly correlated with SDL behaviours.SDL behaviours had significant predictive effects on the reported perception of SDL ability.Based on the random forest algorithm, the study built an SDL ability prediction model with high performance using SDL behaviours as features.Implications for practice and/or policyThe findings indicate that instructors could design effective strategies to promote SDL behaviours for the purpose of enhancing learners' SDL ability.The method and process of building an SDL ability prediction model might provide a reference for related research on ability prediction with behaviours. [ABSTRACT FROM AUTHOR]

The Co‐free Ni‐rich layered cathode materials with excellent structural stability and low‐cost in Ni‐rich family are emerging as the promising candidates for the next generation of high‐energy density cathodes. Previously, Mn is generally regarded as the structural stabilizer in Co‐free Ni‐rich cathodes, while the role of inevitable Li/Ni intermixing is underestimated. Herein, the study reveals that the real origin of the lattice oxygen/structure stability of Co‐free Ni‐rich cathodes is dominated more by Li/Ni intermixing than the widely accepted Mn. In the Li/Ni intermixing configuration, the intermixed Ni ions can suppress the oxidation of lattice oxygen by increasing the formation energy of oxygen vacancy and reducing charge compensation. Besides, the Li vacancy formed via the delithiation of intermixed Li in transition metal layer can serve as O2 capture sites. This dual stabilization mechanism is proposed and proved to be effectively in enhancing the reversibility of lattice oxygen and the stability of material structural. This work sheds light on the mechanism of stabilizing lattice oxygen through Li/Ni intermixing, which provides new insights for designing better batteries. [ABSTRACT FROM AUTHOR]

LiFePO4 is one of the most widely used cathode materials for lithium‐ion batteries, and the low‐temperature performance of LiFePO4‐based batteries has been widely studied in recent years. Herein, a 3.5 Ah pouch‐type full battery was assembled using LiFePO4 as the cathode and artificial graphite as the anode. For the LiFePO4‐based cathode, carbon‐coated aluminum foil was selected as the current collector, and a 0D–1D–2D multi‐scale conductive network was introduced into the electrode. Notably, both the carbon‐coated current collector and novel conductive network could significantly reduce the internal resistance of the LiFePO4‐based battery, thus improving its electrochemical dynamics and low‐temperature performance. This paper provides a theoretical basis for the development of low‐temperature LiFePO4‐based batteries. [ABSTRACT FROM AUTHOR]

The conventional cationic redox centers of transition-metal-based cathodes are reaching their theoretical capacity limit, which cannot match the ultra-high specific capacity contributed by the three-electron transfer reaction of an Al anode (2980 mA h g−1, 8056 mA h cm−3), severely restraining the development of high-energy rechargeable Al-ion batteries (RAIBs). In this work, we propose the multivalent cationic and anionic mixed redox chemistry of Sb2S3 as a promising way out of this problem. The energy storage is induced by the cumulative Sb-related cationic (Sb(+3) ⇔ Sb(+5)) and S-related anionic (S(−2) ⇔ S(0)) mixed 10-electron transfer reversible redox reaction during the charge/discharge process, which has been elucidated here by extensive electrochemical measurements and characterizations. Furthermore, excellent electrochemical performances are realized due to the carbon-based interlayer effectively blocking the charging products of the Sb-based cationic cluster (SbCl4+), by a dual defense mechanism that integrates the physical barrier of the porous structure and the powerful chemical adsorption ability of the oxygen groups. The Sb2S3 cathode could deliver a discharge specific capacity of 756 mA h g−1 at 100 mA g−1. The finding is that the joint multivalent cationic and anionic redox chemistry proposed in this work opens up new opportunities for designing high-performance electrodes for advanced rechargeable batteries. [ABSTRACT FROM AUTHOR]

Spinel LiNi0.5Mn1.5O4 (LNMO) is one potential cathode candidate for next-generation high energy-density lithium–ion batteries (LIBs). However, serious capacity decay from its poor structural stability, especially at high operating temperatures, shadows its application prospects. In this work, N-doped LNMO (LNMON) was synthesized by a facile co-precipitation method and multistep calcination, exhibiting a unique yolk–shell architecture. Concurrently, N dopants are introduced into a LNMO lattice, endowing LNMON with a more stable structure via stronger Ni–N/Mn–N bindings. Benefiting from the synergistic effect of the yolk–shell structure and N-doped engineering, the obtained LNMON cathode exhibits an impressive rate and the state-of-the-art cycling capability, delivering a high capacity of 103 mA h g−1 at 25 °C after 8000 cycles. Even at a high operating temperature of 60 °C, the capacity retention remains at 92% after 1000 cycles. The discovery of N dopants in improving the cycling capability of LNMO in our case offers a prospective approach to enable 5 V LNMO cathode materials with excellent cycling capability. [ABSTRACT FROM AUTHOR]

The lower electro-stripping/plating potential of Al3+/Al (−1.68 V) than that of H+/H2 seriously impedes the performance of rechargeable aqueous aluminum-ion batteries (AAIBs). Besides, the Al plate is easily corroded in aqueous electrolytes due to the typical acidic nature of aluminum salt solutions. Exploring appropriate aqueous electrolytes is indispensable to achieve a high-performance AAIB. In this work, we initiate an AlCl3/lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) electrolyte and find that the addition of an appropriate concentration of LiTFSI can efficiently hinder the hydrogen evolution and corrosion of Al anodes. The full AAIB composed of a vanadium potassium cathode and Al anode exhibits reversible charge/discharge behaviors in 0.5 M AlCl3@12 M LiTFSI electrolyte. Electrochemical and structural analyses reveal that the vanadium potassium cathode experiences a reversible Al3+, H+ and Li+ co-intercalation/de-intercalation process during cycling. The full AAIB manifests excellent performance in terms of large capacity (223 mA h g−1 at 1000 mA g−1), superior rate capability (more than 50% retention from 1000 to 6000 mA g−1) and outstanding cycling stability (maintains 64.6% after 300 cycles). Moreover, the soft-packed AAIB also manifests good cycling stability and desirable flexibility. The strategy reported in our manuscript may promote the development of rechargeable aluminum-ion batteries based on aqueous electrolytes. [ABSTRACT FROM AUTHOR]

As an emerging post‐lithium battery technology, aluminum ion batteries (AIBs) have the advantages of large Al reserves and high safety, and have great potential to be applied to power grid energy storage. But current graphite cathode materials are limited in charge storage capacity due to the formation of stage‐4 graphite‐intercalated compounds (GICs) in the fully charged state. Herein, we propose a new type of cathode materials for AIBs, namely polycyclic aromatic hydrocarbons (PAHs), which resemble graphite in terms of the large conjugated π bond, but do not form GICs in the charge process. Quantum chemistry calculations show that PAHs can bind AlCl4− through the interaction between the conjugated π bond in the PAHs and AlCl4−, forming on‐plane interactions. The theoretical specific capacity of PAHs is negatively correlated with the number of benzene rings in the PAHs. Then, under the guidance of theoretical calculations, anthracene, a three‐ring PAH, was evaluated as a cathode material for AIBs. Electrochemical measurements show that anthracene has a high specific capacity of 157 mAh g−1 (at 100 mA g−1) and still maintains a specific capacity of 130 mAh g−1 after 800 cycles. This work provides a feasible "theory guides practice" research model for the development of energy storage materials, and also provides a new class of promising cathode materials for AIBs. [ABSTRACT FROM AUTHOR]

The rationally structural engineering is an efficient strategy to improve the comprehensive performance of potassium‐ion storage anode materials. In this paper, a hybrid with hollow FeS2 nanoparticles anchored into the 3D carbon skeleton (labeled as H‐FeS2@3DCS) is successfully constructed through two critical steps of in situ chemical deposition and anion‐exchange reaction strategies. In the former, the water‐soluble Na2CO3 crystals are used as hard templates for the preparation of 3DCS, while Fe3+‐containing aqueous solutions are utilized to remove the Na2CO3 templates. Interestingly, the intense collision between Fe3+ and CO32‐ in aqueous solution produces nanoscale Fe(OH)3 colloidal particles, which are firmly anchored into the pores of the carbon skeleton to form a "lotus‐seed"‐like nanostructure. In the latter case, a central void space is created inside the FeS2 nanoparticles due to the different diffusion rates of S‐anions and Fe‐cations during the subsequent sulfidation process. Thanks to this unique composition model, the H‐FeS2@3DCS hybrid not only alleviates the volume expansion efficiently by rationally hollow structure design, but also provides spacious "roads" (3D carbon skeleton) and "houses" (hollow FeS2 nanoparticles) for fast K‐ion transition and storage. As the anode of PIBs and PIHCs, the resultant H‐FeS2@3DCS electrode delivers an obviously enhanced K‐ions storage performance over state‐of‐the‐art. [ABSTRACT FROM AUTHOR]

Enhancing pseudocapacitance of Ti 3 C 2 T x MXene-based electrode materials induced by sufficient surface terminating groups (such as Ti–O bonding) becomes one promising way for fabricating high energy-density supercapacitors. However, most of terminating group activity cannot be excited well in the multilayer Ti 3 C 2 T x due to the layer stacking feature, which limits its further performance improvement. In this paper, a CQDs@Ti 3 C 2 T x hybrid material is synthesized by modifying few-layer Ti 3 C 2 T x MXene matrix with highly dispersed carbon quantum dots (CQDs). In this unique hybrid model, the Ti 3 C 2 T x MXene matrix with high conductivity and high specific surface area is just like the "paddy field", which not only promotes the charge rapid transfer, but also provides the high double layer capacitance by ion adsorption. More importantly, the CQDs act as "rice seedlings" firmly anchored to the Ti 3 C 2 T x matrix, and greatly stimulate the activity of the termination groups of Ti 3 C 2 T x. As expected, this hybrid achieves a harmonious coexistence of high conductivity and high pseudocapacitance. As a result, the CQDs@Ti 3 C 2 T x electrode delivers high reversible capacitances of 441.3 F g−1 at 1 A g−1 and 310.1 F g−1 at 20 A g−1, and a relatively stable cyclability with almost 100% capacitance retention after 10 000 cycles at 10 A g−1. A CQDs@Ti 3 C 2 T x hybrid is facilely designed, in which the activity of Ti–O bonding is excited well to enhance its pseudocapacitance. Consequently, this resultant CQDs@Ti 3 C 2 T x realizes a comprehensive energy storage ability. This strategy may provide a promising approach to fabricate high-performance MXene based electrode. [Display omitted] [ABSTRACT FROM AUTHOR]

Template‐assistant design and fabrication of porous carbon electrode materials has experienced great progress throughout the past decades and yielded lots of successes via various gas or solid state templates. Nevertheless, liquid‐state templates are rather rare in preparing porous carbon materials to date. In this work, melting B2O3 beads are used as both templates and a B dopant, leading to unique B, N co‐doping hierarchically porous carbons containing a "bubble pool"‐like skeleton built of interconnected carbon nanobubbles. Notably, an interesting amending effect of doped B atoms on the N‐doped carbon network can be identified for the first time, which creates a "paddy field"‐like hybrid microstructure with the co‐existence of sp2 short‐range order and sp3 defective areas, leading to an ideal model of carbon materials with both good conductivity and high capacity. Together with the rich ion diffusing pathways and the structural integrity of the "bubble pool"‐like skeleton, the resultant electrode delivers a comprehensive K‐ion storage performance. Therefore, the findings demonstrate the unique pore‐making merits of liquid state templates, which may open the door for exploring porous carbons with more innovations of microstructures and functionalities for applications in energy storage and other fields. [ABSTRACT FROM AUTHOR]

High rate and good cycling capability are always difficult for sodium ion anode materials owing to the unstable electrode structure induced by reversibly intercalation of large‐sized sodium ions. In this paper, based on the unique nanotube arrays of crab shells, a novel space‐confined growth of MoS2 nanosheets in carbon nanotubes is reported to fabricate MoS2@carbon nanotube (MoS2@CT) with a semienclosed architecture. Due to the space‐confined effect, MoS2 sheets are nanosized with poor stacking feature, which are anchored on the inner surface of carbon tubes. The semienclosed architecture built of carbon nanotubes and abundant MoS2 nanosheets enhances the stability and integrity of the electrode structure during cycles. Thereby, the coupling effect of stable structure and MoS2 with fast kinetics achieves a comprehensive performance improvement of the MoS2@CT anode materials. Particularly for cycling capability, it delivers a capacity of 170 mAh g−1 after 10 000 cycles at a high current density of 10 A g−1, which is comparable for most previously reported cases. The assembled Na‐ion hybrid supercapacitors device delivers a high energy density of 82 Wh kg−1 at a power density of 2000 W kg−1 after 5000 cycles with an 89% retention. [ABSTRACT FROM AUTHOR]

The large volume expansion induced by K+ intercalation is always a big challenge for designing high‐performance electrode materials in potassium‐ion storage system. Based on the idea that large‐sized ions should accommodate big "houses," a facile‐induced growth strategy is proposed to achieve the self‐loading of MoS2 clusters inside a hollow tubular carbon skeleton (HTCS). Meantime, a step‐by‐step intercalation technology is employed to tune the interlayer distance and the layer number of MoS2. Based on the above, the ED‐MoS2@CT hybrids are achieved by self‐loading and anchoring the well‐dispersed ultrathin MoS2 nanosheets on the inner surface of HTCSs. This unique compositing model not only alleviates the mechanical strain efficiently, but also provides spacious "roads" (hollow tubular carbon skeleton) and "houses" (interlayer expanded ultrathin MoS2 sheets) for fast K+ transition and storage. As an anode of potassium‐ion batteries, the resultant ED‐MoS2@CT electrode delivers a high specific capacity of 148.5 mAh g−1 at 2 A g−1 after 10 000 cycles with only 0.002% fading per cycle. The assembled ED‐MoS2@CT//PC potassium‐ion hybrid supercapacitor device shows a high energy density of 148 Wh kg−1 at a power density of 965 W kg−1, which is comparable to that of lithium‐ion hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

On the way to pursue advanced energy storage cells, an ingenious design and exquisite structure of electrode materials are key to success. In this work, we rationally prepared a unique mesocrystal TiO2 hollow sphere with a mesoporous shell by employing sulfonated-squid ink as templates. This is the first mesocrystal example with a hollow and porous sphere-like scaffold, which contributes to the synthetic coupling effect of SOx2− species and unique marine bio-templates. The specific combination of the 3D hierarchical porous architecture and mesocrystal nature not only offers large surface areas and rich porosity for the transfer of Na-ions during the electrochemical process, but also improves electronic conductivity and structural integrity owing to the little lattice mismatch of mesocrystals. As anode materials for sodium ion batteries, the obtained mesocrystal hollow TiO2 spheres exhibited a higher initial coulombic efficiency and sodium storage capacity (143 mA h g−1 at 2 A g−1), better rate performance and cycling stability (110 mA h g−1 after 1000 cycles at 1 A g−1) in an ether-based electrolyte than in an ester-based one, demonstrating a good match between the electrode materials and ether-based electrolyte. Therefore, these findings could open a new gate for rationally preparing new electrode materials for Na-ion batteries in new electrolyte systems. [ABSTRACT FROM AUTHOR]

In the pursuit of a lithium ion capacitor (LIC) with higher energy density and lower cost, the all-carbon symmetric-like LIC (ACS-LIC) has recently risen to prominence. In this article, we report a successful example of ACS-LIC synthesized by constructing both anode and cathode with one designed porous carbon material, prepared by a one-pot method and the cheap precursor methyl cellulose. By employing the salt crystal templates and N-doping, the as-obtained materials possess a unique interconnected porous carbon network with hierarchical pores and abundant active sites, showing low internal resistance, good wettability, high conductivity, and rich pseudocapacitance. The resultant NPC//NPC ACS-LIC device exhibited outstanding energy-power characteristics. Even at the super-large power density of 66 000 W kg−1, it can still achieve a high energy density of 70 W h kg−1. More importantly, the NPC//NPC ACS-LIC device demonstrates state-of-the-art cycling performance. After 10 000 cycles at 2 A g−1, the performance is retained at nearly 100%; even when tested at 10 A g−1, the device can still deliver 80.0% retention after 20 000 cycles, with only 0.001% fading per cycle, which is superior or at least comparable to the current state-of-the-art LICs. [ABSTRACT FROM AUTHOR]

Coatings with non-carbon films to improve the electrochemical performance of carbon materials have recently begun to gain attention. As one attempt in this field, we fabricated a thin TiO2/C composite film coated on porous biomass-derived biocarbon (PBC) (denoted as PBC@TC) by a facile sol–gel strategy. The experimental results exhibit an obvious Li+ storage capacity enhancement of the as-obtained PBC@TC sample compared with the uncoated sample, demonstrating the significant positive effect of the TiO2/C films on improving the electrochemical performance of the carbon matrix. Notably, the cycling stability of carbon materials can also be improved greatly by coating with this TiO2/C film, delivering an 86% capacity retention even after 10 000 cycles at 5 A g−1. When employed as anode materials in lithium ion capacitors (LICs), the resultant PBC@TC activate carbon LICs (PBC@TC//AC LICs) present an energy density of 130 W h kg−1 at a power density of 66.6 W kg−1 in a voltage range from 0 to 4 V, and a 90% capacity retention after 10 000 cycles at 5 A g−1. Therefore, besides chemical or physical activation and heteroatom doping, coating with TiO2/C films could be a new facile and green approach for improving lithium ion storage properties of carbon materials. Owing to the flexibility of the carbon matrix and film species, this strategy can be extended to other carbon matrix and non-carbon films, which could have potential for applications in exploring high-performance electrode materials. [ABSTRACT FROM AUTHOR]

Li-ion capacitors have been considered as next-generation advanced energy storage systems to meet the requirements of both high energy and high power due to the combination of rapid and long-term charge storage of supercapacitors and the high energy storage capacity of lithium ion batteries. Herein, we demonstrate the design of 2D nanostructured electrodes from low-cost biomass-kapok fiber for Li-ion capacitors: 2D carbon nanosheets with a high surface area and hierarchical porosity for the positive electrode, and 2D MnO/C nanocomposites with a large surface area and nanosized particles for the negative electrode. With the benefit of the structure of the Li-ion capacitor, the hybrid device can be operated at a high operating voltage of 4 V, exhibiting a high energy density of 100 W h kg−1 at 83 W kg−1, a high power density of 20 kW kg−1 at 30 W h kg−1 based on the active materials, and a capacity retention ratio of 70% after 5000 cycles. These results clearly demonstrate that biomass-derived electrodes are potential candidates for low-cost, fast and efficient energy storage systems in the future. [ABSTRACT FROM AUTHOR]

N-doping can endow carbon materials with high electrochemical activity. Besides the widely validated sp 2 -hybridized nitrogen doping, sp -hybridized nitrogen (sp - N) atoms are also expected to be new active sites. However, both sp - N atoms and cyano (CN) groups containing sp - N are rarely produced in carbon materials presently. In this work, the first cyano groups-modified carbon materials are synthesized firstly via an interesting struggle between the chemical etching of KOH and the catalytic graphitization of Co nanoparticles in carbon frameworks. The theoretical calculations and experimental results manifest that the stronger electronegativity of CN groups renders carbon materials a higher electrochemical activity. As K+ storage anodes, the CN−modified carbon materials exhibit an obvious boost in potassium storage performance in both ester- and ether-based electrolytes. Therefore, as a new N doping form, the successful introduction of CN groups into carbon materials opens a door for exploring sp -N doped carbon materials for applications in energy storage and other fields. [Display omitted] • The first cyano-modified carbon materials are prepared. • As K+ storage anodes, the CN-modified carbon exhibits the impressive performance. • The storage mechanism of CN was explored by theoretical calculation and test. [ABSTRACT FROM AUTHOR]

Co-free Ni-rich layered oxides are considered a promising cathode material for next-generation Li-ion batteries due to their cost-effectiveness and high capacity. However, they still suffer from the practical challenges of low discharge capacity and poor rate capability due to the hysteresis of Li-ion diffusion kinetics. Herein, based on the regulation of the lattice magnetic frustration, the Li/Ni intermixing defects as the primary origin of kinetic hysteresis are radically addressed via the doping of the nonmagnetic Si element. Meanwhile, by adopting gradient penetration doping, a robust Si-O surface structure with reversible lattice oxygen evolution and low lattice strain is constructed on Co-free Ni-rich cathodes to suppress the formation of surface dense  barrier layer. With the remarkably enhanced Li-ion diffusion kinetics in atomic and electrode particle scales, the as-obtained cathodes (LiNixMn1-xSi0.01O2, 0.6 ≤ x ≤ 0.9) achieve superior performance in discharge capacity, rate capability, and durability. This work highlights the coupling effect of magnetic structure and interfacial chemicals on Li-ion transport properties, and the concept will inspire more researchers to conduct an intensive study., (© 2024 Wiley‐VCH GmbH.)

High-potential Mn 3+ /Mn 2+ redox couple (>1.3 V vs SHE) in a static battery system is rarely reported due to the shuttle and disproportionation of Mn 3+ in aqueous solutions. Herein, based on reversible stripping/plating of the Sn anode and stabilized Mn 2+ /Mn 3+ redox couple in the cathode, an aqueous Sn-Mn full battery is established in acidic electrolytes. Sn anode exhibits high deposition efficiency, low polarization, and excellent stability in acidic electrolytes. With the help of H + and a complexing agent, a reversible conversion between Mn 2+ and Mn 3+ ions takes place on the graphite surface. Pyrophosphate ligand is initially employed to form a protective layer through a complexation process with Sn 4+ on the electrode surface, effectively preventing Mn 3+ from disproportionation and hindering the uncontrollable diffusion of Mn 3+ to electrolytes. Benefiting from the rational design, the full battery delivers satisfied electrochemical performance including a large capacity (0.45 mAh cm -2 at 5 mA cm -2 ), high discharge plateau voltage (>1.6 V), excellent rate capability (58% retention from 5 to 30 mA cm -2 ), and superior cycling stability (no decay after 30 000 cycles). The battery design strategy realizes a robustly stable Mn 3+ /Mn 2+ redox reaction, which broadens research into ultrafast acidic battery systems.