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Owing to the significant latent heat generated at constant temperatures, phase change fibers (PCFs) have recently received much attention in the field of wearable thermal management. However, the phase change materials involved in the existing PCFs still experience a solid–liquid transition process, severely restricting their practicality as wearable thermal management materials. Herein, we, for the first time, developed intrinsically flexible PCFs (polyethylene glycol/4,4′‐methylenebis(cyclohexyl isocyanate) fibers, PMFs) through polycondensation and wet‐spinning process, exhibiting an inherent solid‐solid phase transition property, adjustable phase transition behaviors, and outstanding knittability. The PMFs also present superior mechanical strength (28 MPa), washability (>100 cycles), thermal cycling stability (>2000 cycles), facile dyeability, and heat‐induced recoverability, all of which are highly significant for practical wearable applications. Additionally, the PMFs can be easily recycled by directly dissolving them in solvents for reprocessing, revealing promising applications as sustainable materials for thermal management. Most importantly, the applicability of the PMFs was demonstrated by knitting them into permeable fabrics, which exhibit considerably improved thermal management performance compared with the cotton fabric. The PMFs offer great potential for intelligent thermal regulation in smart textiles and wearable electronics. [ABSTRACT FROM AUTHOR]

Li‐rich cathode materials (LRMs) are regarded as the key cathode candidates for next‐generation lithium‐ion batteries(LIBs) because of their high specific capacity and environmental friendliness. However, LRMs encounter poor cyclability and low initial coulombic efficiency (ICE) hindering their practical application. Herein, a general near‐surface in situ reconstruction strategy is proposed of constructing the Li/O dual vacancies and spinel‐carbon dual coating layers on the surface of LRMs concurrently to improve Li+ storage performance. The as‐prepared LRMs exhibit a greatly strengthened specific capacity of 283 mAh g−1 with an enhanced ICE of 94% and long‐term cyclability of 91% retention after 200 cycles compared with the pristine LRMs (212 mAh g−1 with an ICE of 65%, 76% retention after 200 cycles). Furthermore, it is theoretically revealed that O vacancies (Ov) prefer to occur at the interface of the C2/m and R3¯$\bar{3}$m phases to mitigate lattice stress, rather the O sites in individual C2/m or R3¯$\bar{3}$m phase with more coordinated atoms. Besides, Li ions exhibit lower migration energy from C2/m phase to R3¯$\bar{3}$m phase with the Ov located at the lattice interface. Therefore, this strategy opens a new avenue in the design perspective of the LRMs' near‐surface for high‐energy‐density LIBs. [ABSTRACT FROM AUTHOR]

Sulfide solid‐state electrolytes (SSEs) with superior ionic conductivity and processability are highly promising candidates for constructing all‐solid‐state lithium metal batteries (ASSLMBs). However, their practical applications are limited by their intrinsic air instability and serious interfacial incompatibility. Herein, a novel glass‐ceramic electrolyte Li3.12P0.94Bi0.06S3.91I0.18 was synthesized by co‐doping Li3PS4 with Bi and I for high‐performance ASSLMBs. Owing to the strong Bi‒S bonds that are thermodynamically stable to water, increased unit cell volume and Li+ concentration caused by P5+ substitution with Bi3+, and the in situ formed robust solid electrolyte interphase layer LiI at lithium surface, the as‐prepared Li3.12P0.94Bi0.06S3.91I0.18 SSE achieved excellent air stability with a H2S concentration of only 0.205 cm3 g−1 (after 300 min of air exposure), outperforming Li3PS4 (0.632 cm3 g−1) and the most reported sulfide SSEs, together with high ionic conductivity of 4.05 mS cm−1. Furthermore, the Li3.12P0.94Bi0.06S3.91I0.18 effectively improved lithium metal stability. With this SSE, an ultralong cyclability of 700 h at 0.1 mA cm−2 was realized in a lithium symmetrical cell. Moreover, the Li3.12P0.94Bi0.06S3.91I0.18‐based ASSLMBs with LiNi0.8Mn0.1Co0.1O2 cathode achieved ultrastable capacity retention rate of 95.8% after 300 cycles at 0.1 C. This work provides reliable strategy for designing advanced sulfide SSEs for commercial applications in ASSLMBs. [ABSTRACT FROM AUTHOR]

The rapid advancement in the miniaturization, integration, and intelligence of electronic devices has escalated the demand for customizable micro‐supercapacitors (MSCs) with high energy density. However, efficient microfabrication of safe and high‐energy MXene MSCs for integrating microelectronics remains a significant challenge due to the low voltage window in aqueous electrolytes (typically ≤0.6 V) and limited areal mass loading of MXene microelectrodes. Here, we tackle these challenges by developing a high‐concentration (18 mol kg−1) "water‐in‐LiBr" (WiB) gel electrolyte for MXene symmetric MSCs (M‐SMSCs), demonstrating a record high voltage window of 1.8 V. Subsequently, additive‐free aqueous MXene ink with excellent rheological behavior is developed for three‐dimensional (3D) printing customizable all‐MXene microelectrodes on various substrates. Leveraging the synergy of a high‐voltage WiB gel electrolyte and 3D‐printed microelectrodes, quasi‐solid‐state M‐SMSCs operating stably at 1.8 V are constructed, and achieve an ultrahigh areal energy density of 1772 μWh cm−2 and excellent low‐temperature tolerance, with a long‐term operation at −40°C. Finally, by extending the 3D printing protocol, M‐SMSCs are integrated with humidity sensors on a single planar substrate, demonstrating their reliability in miniaturized integrated microsystems. [ABSTRACT FROM AUTHOR]