Featured
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Article
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Cation desolvation-induced capacitance enhancement in reduced graphene oxide (rGO)
Understanding local electrochemical processes can help improve electrochemical energy storage. Here, the authors report a charge storage mechanism in aqueous electrolyte for reduced graphene oxide using an electrochemical quartz crystal microbalance.
- Kangkang Ge
- , Hui Shao
- & Patrice Simon
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Article
| Open Access
Discovery of fast and stable proton storage in bulk hexagonal molybdenum oxide
Nanostructured electrode materials pose several challenges, including poor volumetric performance, severe side reactions, high costs, and complexity. Here, the authors develop a micrometer-sized bulk hexagonal molybdenum oxide with unconventional charge storage mechanism for fast and stable proton storage.
- Tiezhu Xu
- , Zhenming Xu
- & Laifa Shen
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| Open Access
Broad-high operating temperature range and enhanced energy storage performances in lead-free ferroelectrics
One of the key challenges in dielectric ceramics for energy storage lies in the comprehensive optimization of their properties. Here, the authors establish an equitable system considering performance and structure evolution in a lead-free ceramic capacitor, achieving a broad-high temperature performance.
- Weichen Zhao
- , Diming Xu
- & Di Zhou
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Laser maskless fast patterning for multitype microsupercapacitors
Miniature asymmetric supercapacitors have higher voltage and energy density but are often limited by a complex manufacturing process and difficulties in further miniaturization. Here, the authors demonstrate a maskless method for the patterned fabrication of submicron-scale symmetric and asymmetric supercapacitors.
- Yongjiu Yuan
- , Xin Li
- & Liangti Qu
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| Open Access
Heterogeneous intercalated metal-organic framework active materials for fast-charging non-aqueous Li-ion capacitors
Ideal anode materials for Li-ion capacitors must demonstrate safety and fast-charging properties. Here, the authors propose intercalated metal-organic frameworks for fast-charging Li-ion capacitors using a combined machine learning design and spray-dry synthesis.
- Nobuhiro Ogihara
- , Masaki Hasegawa
- & Naoyuki Nagasako
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Isolation of pseudocapacitive surface processes at monolayer MXene flakes reveals delocalized charging mechanism
MXenes are two-dimensional nanomaterials that can be used as supercapacitors to store electrical energy. Here, the authors isolated chemical response from a single MXene flake and provide a new understanding of the surface chemistry of MXenes.
- Marc Brunet Cabré
- , Dahnan Spurling
- & Kim McKelvey
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High-strength and machinable load-bearing integrated electrochemical capacitors based on polymeric solid electrolyte
High-strength composite materials for electrochemical energy storage is attractive for mobile systems. Here the authors demonstrate high-performance load-bearing integrated electrochemical capacitors, which show high strength, large capacitance, and good machinability.
- Jinmeng Zhang
- , Jianlong Yan
- & Hua Bai
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| Open Access
4D printing of MXene hydrogels for high-efficiency pseudocapacitive energy storage
2D MXene hydrogels are promising for diverse applications. Here, the authors report a universal 4D printing technology to manufacture MXene hydrogels with customizable geometry, high conductivity, and efficient pseudocapacitive energy storage ability.
- Ke Li
- , Juan Zhao
- & Valeria Nicolosi
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| Open Access
Aqueous hybrid electrochemical capacitors with ultra-high energy density approaching for thousand-volts alternating current line filtering
Filtering capacitors are essential to smooth high voltage alternating current lines but are typically limited to hundreds of volts. Here, the authors demonstrate an aqueous hybrid electrochemical capacitor that can exhibit an operating voltage of 1,000 V when assembled into a device of 670 units.
- Zhou Li
- , Xiaopeng Wang
- & Liangti Qu
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| Open Access
Giant energy-storage density with ultrahigh efficiency in lead-free relaxors via high-entropy design
Dielectric ceramics are widely used in advanced high/pulsed power capacitors. Here, the authors propose a high-entropy strategy to design “local polymorphic distortion” in lead-free ceramics, achieving high energy storage performance.
- Liang Chen
- , Shiqing Deng
- & Jun Chen
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| Open Access
Production of a hybrid capacitive storage device via hydrogen gas and carbon electrodes coupling
Conventional electric double-layer capacitors show limited energy content for energy storage applications. Here, the authors report an electrocatalytic hydrogen gas capacitor with improved specific energy, which can operate in pH-universal aqueous electrolyte solutions and a wide temperature range.
- Zhengxin Zhu
- , Zaichun Liu
- & Wei Chen
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Comment
| Open Access
Metrics and methods for moving from research to innovation in energy storage
Research activities are crucial for the advancement of energy storage technologies. However, not all the research lead to practical innovation. Here the author, focusing on supercapacitor devices, discusses the most challenging aspects to be considered to deliver practical innovation from fundamental research.
- Sebastian Pohlmann
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Article
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Mismatching integration-enabled strains and defects engineering in LDH microstructure for high-rate and long-life charge storage
Layered double hydroxides (LDH) are ideal for charge storage, however, the sluggish reaction dynamics are obstacle to their development. Here, triggered by mismatching integration of Mn sites, the authors configure wrinkled Mn/NiCo-LDH with strains and defects, where promoted mass & charge transport behaviors are realized.
- Wei Guo
- , Chaochao Dun
- & Jieshan Qiu
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| Open Access
Nanofluidic voidless electrode for electrochemical capacitance enhancement in gel electrolyte
Enhancing electrode capacitance without compromising one other metrics for solid-state supercapacitors is of high interest yet difficult to achieve. Here the authors demonstrate a strategy of using nanofluidic electrode with very low porosity to increase the electrochemical capacitance of gel-based solid state supercapacitor.
- Kefeng Xiao
- , Taimin Yang
- & Da-Wei Wang
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Nano-biosupercapacitors enable autarkic sensor operation in blood
The miniaturization of biocompatible microsystems that enable self-sufficiency and autarkic operations is ever increasing. Here, the authors demonstrate a robust integratable nano-biosupercapacitor with enhanced performance in complex biological fluids, thus enabling autarkic sensor operation in blood.
- Yeji Lee
- , Vineeth Kumar Bandari
- & Oliver G. Schmidt
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| Open Access
A multi-responsive healable supercapacitor
Self-healing property is important for supercapacitors when powering the electronics, but designing devices that possess a universal healing mechanism remains challenging. Here, the authors achieve an optically, electrically, and magnetically-responsive self-healing device with integrated configuration.
- Haili Qin
- , Ping Liu
- & Shu-Hong Yu
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Article
| Open Access
A seamlessly integrated device of micro-supercapacitor and wireless charging with ultrahigh energy density and capacitance
Miniaturized energy storage devices integrated with wireless charging bring opportunities for next generation electronics. Here, authors report seamlessly integrated wireless charging micro-supercapacitors with high energy density capable of driving a model electrical car.
- Chang Gao
- , Jiancheng Huang
- & Liangti Qu
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Article
| Open Access
A self-sustainable wearable multi-modular E-textile bioenergy microgrid system
Though energy-harvesting wearable systems have been reported in the literature, their system design imposes limitations that hinder their overall performance. Here, the authors report a system-level wearable e-textile microgrid system that relies solely on human activity for energy harvesting.
- Lu Yin
- , Kyeong Nam Kim
- & Joseph Wang
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| Open Access
Interstitial boron-doped mesoporous semiconductor oxides for ultratransparent energy storage
Realizing transparent supercapacitor is hindered by the trade-off between capacitance and transparency of the electrode material. Here, the authors report an interstitial doping strategy to boost the electrochemical activity of transparent conducting oxides while maintaining their optical feature.
- Jian Zhi
- , Min Zhou
- & Fuqiang Huang
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| Open Access
Laser photonic-reduction stamping for graphene-based micro-supercapacitors ultrafast fabrication
Microfabrication for cost-effective miniaturized energy storage devices remains a challenge. Here, the authors propose a spatially shaped femtosecond laser method, which is ultrafast, one-step, high resolution and large-scale, for use in patterning flexible high-performance micro-supercapacitors.
- Yongjiu Yuan
- , Lan Jiang
- & Tianhong Cui
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| Open Access
Maximizing ion accessibility in MXene-knotted carbon nanotube composite electrodes for high-rate electrochemical energy storage
Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. Here, the authors report a new type of MXene-carbon nanotube composite electrode that maximizes ion accessibility, resulting in high rate performance at low temperatures.
- Xiang Gao
- , Xuan Du
- & Ming Xu
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| Open Access
How to speed up ion transport in nanopores
Narrowing pores filled with an electrolyte usually slows down their charge-discharge dynamics. Here the authors demonstrate through molecular dynamics simulations and experiments with novolac-derived carbon electrodes how non-linear voltage sweeps can accelerate charging and discharging of subnanometer pores.
- Konrad Breitsprecher
- , Mathijs Janssen
- & Svyatoslav Kondrat
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Article
| Open Access
Adding salt to expand voltage window of humid ionic liquids
Water adsorbed on the electrode surface of electrochemical energy storage devices narrows the electrochemical windows. Combining atomistic simulations and cyclic voltammetry experiments the authors demonstrate an approach to expand the voltage window of humid ionic liquids based on the addition of lithium salt.
- Ming Chen
- , Jiedu Wu
- & Guang Feng
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| Open Access
Persistent and reversible solid iodine electrodeposition in nanoporous carbons
Iodide based energy storage is a potential candidate to improve performance of hybrid supercapacitors and batteries. Here, the authors revisit the previous understanding and show that electrochemical oxidation of iodide results in solid iodine deposits stabilized by the confinement of nanoporous carbons.
- Christian Prehal
- , Harald Fitzek
- & Qamar Abbas
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| Open Access
Energy storing bricks for stationary PEDOT supercapacitors
Fired brick is a universal building material, produced by thousand-year-old technology, which throughout history has seldom served any other purpose. Here, the authors show that bricks can store energy after chemical treatment to convert their iron oxide content into conducting polymer nanofibers.
- Hongmin Wang
- , Yifan Diao
- & Julio M. D’Arcy
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| Open Access
Single-site pyrrolic-nitrogen-doped sp2-hybridized carbon materials and their pseudocapacitance
A mixture of nitrogen species in carbon materials typically hinders the precise identification of electrochemically active nitrogen configurations for specific reactions. Here the authors show single-site pyrrolic-nitrogen-doped sp2-hybridized carbon materials and their pseudocapacitive properties.
- Kesong Tian
- , Junyan Wang
- & Yanglong Hou
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Article
| Open Access
Super-tough MXene-functionalized graphene sheets
Poor mechanical properties of reduced graphene oxide sheets hinder development of flexible energy storage systems. MXene functionalised graphene oxide with Ti-O-C bonding and additional crosslinking is here reported to dramatically increase toughness for flexible supercapacitors.
- Tianzhu Zhou
- , Chao Wu
- & Qunfeng Cheng
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| Open Access
Nanoelectrode design from microminiaturized honeycomb monolith with ultrathin and stiff nanoscaffold for high-energy micro-supercapacitors
Micro-supercapacitors are promising energy storage systems to power the future electronic devices. Here, the authors utilize honeycomb alumina nanoscaffold as a nanostructuring platform to design nanoelectrodes and construct micro-supercapacitors with impressive performance.
- Zhendong Lei
- , Long Liu
- & Yong Lei
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Article
| Open Access
Printable magnesium ion quasi-solid-state asymmetric supercapacitors for flexible solar-charging integrated units
Wearable self-powered electronics receive considerable attention, but development is hindered by bulky designs, energy storage systems, and safety issues. Here the authors demonstrate a flexible solar-charging integrated unit based on printed magnesium ion aqueous asymmetric supercapacitors.
- Zhengnan Tian
- , Xiaoling Tong
- & Zhongfan Liu
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| Open Access
Measurement of the combined quantum and electrochemical capacitance of a carbon nanotube
Contact between electrons in a nanotube and solvated ions in an electrolyte yield electric fields confined to small dimensions and electrostatics that are affected by quantum density of states. Here the authors measure quantum effects on capacitance in a reduced-dimension system in a liquid electrolyte.
- Jinfeng Li
- & Peter J. Burke
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| Open Access
Arbitrary waveform AC line filtering applicable to hundreds of volts based on aqueous electrochemical capacitors
AC to DC conversion is important for renewable power sources, and requires suitable filtering capacitors. Here the authors report a series-connected configuration of aqueous hybrid electrochemical capacitors for alternate current line filtering of arbitrary waveforms in wide frequency and voltage ranges.
- Mingmao Wu
- , Fengyao Chi
- & Liangti Qu
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Article
| Open Access
Layer-by-layer self-assembly of pillared two-dimensional multilayers
Layer-by-layer self-assembly method using small molecules holds promise to precisely combine atomically thin materials and enable fabrication of pillared structures with superior device performance. Here, the authors report controlled synthesis of supercapacitor electrodes based on 2D Ti3C2Tx MXene multilayers with a volumetric capacitance of 583 F/cm3.
- Weiqian Tian
- , Armin VahidMohammadi
- & Mahiar M. Hamedi
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| Open Access
A polymer-direct-intercalation strategy for MoS2/carbon-derived heteroaerogels with ultrahigh pseudocapacitance
Methods to fabricate layered materials are often associated with harsh conditions and complicated manipulations. Here the authors report a polymer-direct-intercalation strategy to synthesize composite heteroaerogels consisting of molybdenum sulfide/carbon nanosheets for high-capacitance supercapacitors.
- Nan Feng
- , Ruijin Meng
- & Jinhu Yang
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Article
| Open Access
Negative dielectric constant of water confined in nanosheets
Confinement within nanospace could significantly alter the properties of chemical species. Here the authors report the negative dielectric constant of water confined in nanosheets that can enhance the capacitance of electric-double layer capacitor electrodes.
- Akira Sugahara
- , Yasunobu Ando
- & Atsuo Yamada
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| Open Access
Size-dependent stability of ultra-small α-/β-phase tin nanocrystals synthesized by microplasma
Key features of tin, including electronic band structure and opto-electronic properties, are influenced by the crystal structure. Here the authors report a microplasma process for the synthesis of ultra-small tin nanocrystals in which the crystal structure is dependent on crystallite size.
- Atta Ul Haq
- , Sadegh Askari
- & Davide Mariotti
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Article
| Open Access
Ultrastretchable and superior healable supercapacitors based on a double cross-linked hydrogel electrolyte
Healable and stretchable energy storage devices are gaining interest for wearable electronics and smart textiles. Here the authors report a nanocomposite hydrogel with high stretchability, ionic conductivity, and healing capability for use in a supercapacitor that can stretch 900% after healing.
- Huili Li
- , Tian Lv
- & Tao Chen
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| Open Access
Highly twisted supercoils for superelastic multi-functional fibres
The development of electrically conductive fibres is attractive for wearable electronics, but performance should be maintained upon deformation and tensile strain. Here the authors fabricate flexible, stretchable, carbon nanotube-coated spandex fibres for supercapacitors and artificial muscles.
- Wonkyeong Son
- , Sungwoo Chun
- & Changsoon Choi
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Article
| Open Access
Minimizing the electrosorption of water from humid ionic liquids on electrodes
Ionic liquid electrolytes can impart increased operational voltage and energy density in supercapacitors, but water may diminish performance. Here the authors show that the hydrophilicity/hydrophobicity of ionic liquids can influence electrosorption of water and ultimately the supercapacitor performance.
- Sheng Bi
- , Runxi Wang
- & Guang Feng
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Article
| Open Access
Silicon as a ubiquitous contaminant in graphene derivatives with significant impact on device performance
Silicon-based contaminants are ubiquitous in natural graphite, and they are thus expected to be present in exfoliated graphene. Here, the authors show that such impurities play a non-negligible role in graphene-based devices, and use high-purity parent graphite to boost the performance of graphene sensors and supercapacitor microelectrodes.
- Rouhollah Jalili
- , Dorna Esrafilzadeh
- & Gordon G. Wallace
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Article
| Open Access
Microfluidic-spinning construction of black-phosphorus-hybrid microfibres for non-woven fabrics toward a high energy density flexible supercapacitor
Supercapacitors that exhibit flexibility and deformability are attractive for wearable devices; however achieving high energy density remains challenging. Here the authors report a non-woven fabric based on black phosphorus and carbon nanotubes for use in a supercapacitor with notable performance.
- Xingjiang Wu
- , Yijun Xu
- & Su Chen
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Article
| Open Access
Salt concentration and charging velocity determine ion charge storage mechanism in nanoporous supercapacitors
To improve supercapacitor performance, mechanisms of operation should be understood. Here the authors identify parameters controlling ion charge storage mechanisms and show that charging initially implies a non-equilibrium ion configuration followed by charge-neutral equilibration.
- C. Prehal
- , C. Koczwara
- & O. Paris
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Article
| Open Access
High energy flexible supercapacitors formed via bottom-up infilling of gel electrolytes into thick porous electrodes
The development of high performance flexible solid supercapacitors calls for an effective approach to infill gel electrolytes into porous electrodes. Here the authors report a bottom-up method to address this technical challenge, which leads to enhanced areal capacitance and durability.
- Xiangming Li
- , Jinyou Shao
- & Paul V. Braun
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Article
| Open Access
Bioinspired leaves-on-branchlet hybrid carbon nanostructure for supercapacitors
One way to improve the performance of supercapacitors is to use hybrid carbon nanomaterials. Here the authors show a bioinspired electrode design with graphene petals and carbon nanotube arrays serving as leaves and branchlets, respectively. The structure affords excellent electrochemical characteristics.
- Guoping Xiong
- , Pingge He
- & Timothy S. Fisher
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Article
| Open Access
Flexible supercapacitor electrodes based on real metal-like cellulose papers
With ligand-mediated layer-by-layer assembly between metal nanoparticles and small organic molecules, the authors prepare metallic paper electrodes for supercapacitors with high power and energy densities. This approach could be extended to various electrodes for portable/wearable electronics.
- Yongmin Ko
- , Minseong Kwon
- & Jinhan Cho
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Article
| Open Access
Hierarchical porous carbons with layer-by-layer motif architectures from confined soft-template self-assembly in layered materials
2D nanomaterials are promising capacitive energy storage materials, but their tendency to restack hinders electrolyte transport. Here, Yamauchi and colleagues introduce 2D ordered mesoporous carbons in between MXene layers, and metal removal affords all-carbon porous 2D–2D heterostructures in which restacking is prevented.
- Jie Wang
- , Jing Tang
- & Yusuke Yamauchi
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Article
| Open Access
Atomic-level energy storage mechanism of cobalt hydroxide electrode for pseudocapacitors
Developing high-performance hybrid energy storage devices requires improved understanding of the mechanism that governs the electrochemical reactions. Here, the authors show the atomic-level working process of cobalt hydroxide electrode for pseudocapacitors.
- Ting Deng
- , Wei Zhang
- & Teófilo Rojo
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Article
| Open Access
The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets
Two-dimensional solids are of interest for energy storage due to their large accessible surface area, enabling rapid charge/discharge. Here, the authors quantify the point defects in oxide nanosheets, demonstrating that intentional introduction of charged point defects improves the charge storage behaviour.
- Peng Gao
- , Peter Metz
- & Scott T. Misture
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Article
| Open Access
Improvement of system capacitance via weavable superelastic biscrolled yarn supercapacitors
Carbon nanotube yarns with high loadings of pseudocapacitive material are desirable, e.g., for emerging wearable technologies. Here authors make biscrolled yarns with high loadings of MnO2nanoparticles confined in carbon nanotube galleries, demonstrating very high linear and areal capacitances.
- Changsoon Choi
- , Kang Min Kim
- & Seon Jeong Kim
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Article
| Open Access
Wearable energy-smart ribbons for synchronous energy harvest and storage
Flexible materials for harvesting and storing energy are desirable for wearable electronics, but efficiency is still an issue. Here, the authors demonstrate a flexible and weavable ribbon which integrates a solar cell and supercapacitor via a shared electrode for efficient energy harvesting and storage.
- Chao Li
- , Md. Monirul Islam
- & Jayan Thomas
Monolithically integrated micro-supercapacitors with high areal number density produced by surface adhesive-directed electrolyte assembly