Mobile energy storage technologies for boosting carbon neutrality

Carbon neutrality calls for renewable energies,and the efficient use of renewable energies requires energy storage mediums that enable the storage of excess energy and reuse after spatiotemporal reallocation.Compared with traditional energy storage technologies,mobile energy storage technologies have the merits of low cost and high energy conversion efficiency,can be flexibly located,and cover a largerange from miniature to large systems and from high energy density to high power density,although most of them still face challenges or technical bottlenecks.In this review,we provide an overview of the opportunities and challenges of these emerging energy storagetechnologies(induding rechargeable batteries,fuel cells,and electrochemical and dielectric capacitors).Innovative materials,strategies,and technologies are highlighted.Finally,the future directions are envisioned.We hope this review will advance the development of mobile energy storage technologies and boost carbon neutrality.

Robust,self-adhesive,and low-contact impedance polyvinyl alcohol/polyacrylamide dual-network hydrogel semidry electrode for biopotential signal acquisition

Herein,we fabricated a flexible semidry electrode with excellent mechanical performance,satisfactory self-adhesiveness,and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dual-network hydrogels(PVA/PAM DNHs)as an efficient saline reservoir.The resultant PVA/PAM DNHs showed admirable adhesive and compliance to the hairy scalp,facilitating the establishment of a robust electrode/skin interface for biopotential signal transmission.Moreover,the PVA/PAM DNHs steadily released trace saline onto the scalp to achieve the minimized potential drift(1.47±0.39 mV/min)and low electrode–scalp impedance(18.2±8.9 kΩ@10 Hz).More importantly,the application feasibility of real-world brain−computer interfaces(BCIs)was preliminarily validated by 10 participants using two classic BCI paradigms.The mean temporal cross-correlation coefficients between the semidry and wet electrodes in the eyes open/closed and the N200 speller paradigms are 0.919±0.054 and 0.912±0.050,respectively.Both electrodes demonstrate anticipated neuroelectrophysiological responses with similar patterns.This semidry electrode could also effectively capture robust P-QRS-T peaks during electrocardiogram recording.Considering their outstanding advantages of fast setup,user-friendliness,and robust signals,the proposed PVA/PAM DNH-based electrode is a promising alternative to wet electrodes in biopotential signal acquisition.

Enhancing energy storage efficiency in lead-free dielectric ceramics through relaxor and lattice strain engineering

Dielectric capacitors with high power density and fast charge-discharge speed play an essential role in the development of pulsed power systems.The increased demands for miniaturization and practicality of pulsed power equipment also necessitate the development of dielectric materials that possess high energy density while maintaining ultrahigh efficiency(η).In particular,ultrahigh efficiency signifies minimal energy loss,which is essential for practical applications but challenging to effectively mitigate.Here,we demonstrate a strategy of incorporating heterovalent elements into Ba(Zr_(0.1)Ti_(0.9))O_(3),which contributes to achieving relaxor ferroelectric ceramics and reducing lattice strain,thereby improving the comprehensive energy storage performance.Finally,optimal energy storage performance is attained in 0.85Ba(Zr_(0.1)Ti_(0.9))O_(3)-0.15Bi(Zn_(2/3)Ta_(1/3))O_(3)(BZT-0.15BiZnTa),with an ultrahighηof 97.37%at 440 kV/cm(an advanced level in the lead-free ceramics)and an excellent recoverable energy storage density(Wrec)of 3.74 J/cm^(3).Notably,the BZT-0.15BiZnTa ceramics also exhibit exceptional temperature stability,maintaining fluctuations in Wrec within∼10%andηconsistently exceeding 90% across the wide temperature range of−55℃ to 160℃,and under a high electric field of 250 kV/cm.All these features demonstrate that the relaxor and lattice strain engineering strategies have been successful in achieving high-performance lead-free ceramics,paving the way for designing high-efficiency dielectric capacitors with a wide temperature range.

Regulating local electric field to optimize the energy storage performance of antiferroelectric ceramics via a composite strategy

Electrostatic energy storage technology based on dielectrics is the basis of advanced electronics and high-power electrical systems.High polarization(P)and high electric breakdown strength(Eb)are the key parameters for dielectric materials to achieve superior energy storage performance.In this work,a composite strategy based on antiferroelectric dielectrics(AFEs)has been proposed to improve the energy storage performance.Here,AlN is selected as the second phase for the(Pb_(0.915)Ba_(0.04)La_(0.03))(Zr_(0.65)Sn_(0.3)Ti_(0.05))O_(3)(PBLZST)AFEs,which is embedded in the grain boundaries to construct insulating networks and regulate the local electric field,improving the Eb.Meanwhile,it is emphasized that AFEs have the AFE–FE and FE–AFE phase transitions,and the increase of the phase transition electric fields can further improve the recoverable energy density(Wrec).As a result,the Eb increases from 180 to 290 kV·cm−1 with a simultaneous increase of the phase transition electric fields,magnifying the Wrec to~144%of the pristine PBLZST.The mechanism for enhanced Eb and the phase transition electric fields is revealed by the finite element simulation method.Moreover,the PBLZST:1.0 wt%AlN composite ceramics exhibit favorable temperature stability,frequency stability,and charge–discharge ability,making the composite ceramics a promising candidate for energy storage applications.

Fluoride passivation of ZnO electron transport layers for efcient PbSe colloidal quantum dot photovoltaics

Lead selenide(PbSe)colloidal quantum dots(CQDs)are suitable for the development of the next-generation of photovoltaics(PVs)because of efcient multiple-exciton generation and strong charge coupling ability.To date,the reported high-efcient PbSe CQD PVs use spin-coated zinc oxide(ZnO)as the electron transport layer(ETL).However,it is found that the surface defects of ZnO present a difculty in completion of passivation,and this impedes the continuous progress of devices.To address this disadvantage,fuoride(F)anions are employed for the surface passivation of ZnO through a chemical bath deposition method(CBD).The F-passivated ZnO ETL possesses decreased densities of oxygen vacancy and a favorable band alignment.Benefting from these improvements,PbSe CQD PVs report an efciency of 10.04%,comparatively 9.4%higher than that of devices using sol-gel(SG)ZnO as ETL.We are optimistic that this interface passivation strategy has great potential in the development of solution-processed CQD optoelectronic devices.

Sb_(2)Se_(3) film with grain size over 10μm toward X-ray detection

Direct X-ray detectors are considered as competitive next-generation X-ray detectors because of their high spatial resolution,high sensitivity,and simple device configuration.However,their potential is largely limited by the imperfections of traditional materials,such as the low crystallization temperature of α-Se and the low atomic numbers of α-Si and α-Se.Here,we report the Sb_(2)Se_(3) X-ray thin-film detector with a p-n junction structure,which exhibited a sensitivity of 106.3 μC/(Gyair·cm^(2))and response time of<2.5 ms.This decent performance and the various advantages of Sb_(2)Se_(3),such as the average atomic number of 40.8 and μτ product(μ is the mobility,and τ is the carrier lifetime)of 1.29×1O^(-5) cm^(2)/V,indicate its potential for application in X-ray detection.

Fabrication and characterization of ZnO/Se1‑xTex solar cells

Selenium(Se)element is a promising light-harvesting material for solar cells because of the large absorption coefcient and prominent photoconductivity.However,the efciency of Se solar cells has been stagnated for a long time owing to the suboptimal bandgap(>1.8 eV)and the lack of a proper electron transport layer.In this work,we tune the bandgap of the absorber to the optimal value of Shockley-Queisser limit(1.36 eV)by alloying 30%Te with 70%Se.Simultaneously,ZnO electron transport layer is selected because of the proper band alignment,and the mild reaction at ZnO/Se_(0.7)Te_(0.3) interface guarantees a good-quality heterojunction.Finally,a superior efciency of 1.85%is achieved on ZnO/Se_(0.7)Te_(0.3)solar cells.

Rapid thermal evaporation for cadmium selenide thin-film solar cells

Cadmium selenide(CdSe)belongs to the binary II-VI group semiconductor with a direct bandgap of~1.7 eV.The suitable bandgap,high stability,and low manufacturing cost make CdSe an extraordinary candidate as the top cell material in silicon-based tandem solar cells.However,only a few studies have focused on CdSe thin-film solar cells in the past decades.With the advantages of a high deposition rate(~2µm/min)and high uniformity,rapid thermal evaporation(RTE)was used to maximize the use efficiency of CdSe source material.A stable and pure hexagonal phase CdSe thin film with a large grain size was achieved.The CdSe film demonstrated a 1.72 eV bandgap,narrow photoluminescence peak,and fast photoresponse.With the optimal device structure and film thickness,we finally achieved a preliminary efficiency of 1.88%for CdSe thin-film solar cells,suggesting the applicability of CdSe thin-film solar cells.

From narrow-bandgap GeSe to wide-bandgap GeS solar cells

Ge-based binary chalcogenides including GeSe and GeS have recently emerged as promising photovoltaic absorber materials owing to their attractive optoelectronic properties such as suitable bandgaps of 1.14 eV(GeSe) for singlejunction solar cells and 1.7 eV(GeS) for tandem solar cells as top cells and indoor photovoltaics(IPVs).

Filter-free self-power CdSe/Sb_(2)(S_(1-x),Se_(x))_(3)nearinfrared narrowband detection and imaging

Accurate and clear bioimaging is crucial in the field of medical diagnosis.High-quality bioimaging requires to avoid the effects of ambient light as well as the absorption of biological tissues.Nearinfrared(NIR)narrowband detectors located at wavelength from 650 to 900 nm can meet these requirements;thus,they are the potential solution.In this work,we construct a filter-free and self-power NIR narrowband photodetector based on the structure of n-CdSe/p-Sb_(2)(S_(1-x),Se_(x))_(3)heterojunction,and achieve a narrow spectral response at 735 nm with a full width at half-maximum of 35.3 nm in the detector.Further,the imaging characteristics of the NIR narrowband detector are explored,verifying the ability to narrowband detection and imaging.This filter-free and self-power NIR narrowband detector shows considerable promise in real-life applications.