Thin-film Lithium Batteries Research Articles

In-operando observation of Li depth distribution and Li transport in thin film Li ion batteries

A quantitative assessment of Li transport is decisive for Li ion battery research. Here, we demonstrate in situ and in-operando depth profiling of the Li-inventory in lithium thin film batteries. We employ non-destructive coincidence elastic recoil detection analysis using different projectile ions in the MeV range to simultaneously quantify the lithium depth distribution in the whole stack with resolution better than 50 nm by simulations of experimental data. Experiments were performed while charging and discharging the stack. 5 MeV 7Li primary ions were employed to extract the Li depth distribution in an ∼3.6 μm thick Ti/LMO/LIPON/NbO/Ti thin film battery. To show the versatility of the approach, a coincidence experiment was also performed using 4 MeV He ions for an ∼3.4 μm thick Ti/LMO/LIPON/NbO/Ti battery. Our results illustrate, for example, lithium accumulation in the 90 nm thick NbO layer upon charging with +3 V. We could also show the transport of large amounts of Li from the LMO/LIPON interface to the LIPON/NbO interface upon overcharging with +5 V. Altogether, these experiments demonstrate the potential of the employed technique, enabling in-operando high resolution composition depth profiling of Li and other light elements (e.g., H, He, C, N, and O) in ultrathin all-solid state batteries.

Lithium Fluoride Coated Silicon Nanocolumns as Anodes for Lithium Ion Batteries.

Silicon (Si) films are promising anode materials in thin-film lithium batteries due to their high capacity of 3578 mAh g-1, but the huge volume expansion of lithiated Li15Si4 and the unstable solid electrolyte interphase (SEI) preclude their practical application. Here lithium fluoride (LiF) coated Si nanocolumns are fabricated by glancing angle evaporation to address the obstacle. The LiF coating can elevate the lithium ion diffusion coefficient (LDC) of Si electrodes upon the alloying reaction and reduce the LDC upon the SEI formation. The composition evolution of the outer SEI layer in the LiF/Si electrodes is studied by ex situ X-ray photoelectron spectroscopy. The modified surface and mitigated volume expansion enable the LiF/Si nanocolumns to exhibit superior rate capability and higher cycling stability compared with the pristine Si nanocolumns. This work demonstrates the positive effect of LiF coating for reducing the polarization and forming a robust SEI film on Si anodes.

Transparent Supercapacitor Display with Redox-Active Metallo-Supramolecular Polymer Films

The use of metallo-supramolecular polymer (MSP) as a thin-film based redox supercapacitor electrode material is reported for the first time. Fe(II)- and Ru(II)-based MSPs (polyFe and polyRu, respectively) were synthesized by complexation of appropriate metal salts with 4',4''-(1,4-phenylene)bis-2,2':6',2''-terpyridine and thin films of these polymers were prepared by a spray coating onto an indium tin oxide (ITO) glass substrate. A study of the energy-storage performances of the polyFe and polyRu films in a nonaqueous electrolyte system revealed volumetric capacitances of ~62.6 ± 3 F/cm3 for polyFe and 98.5 ± 7 F/cm3 for polyRu at a current density of 2 A/cm3. To improve the energy-storage performance over a wider potential range, asymmetric supercapacitor (ASC) displays were fabricated with suitable combinations of the MSPs as cathodic materials and Prussian blue as the anodic counter material in a sandwich configuration with a transparent polymeric ion gel as the electrolyte. The fabricated ASCs showed a maximum volumetric energy density (~10-18 mWh/cm3) that was higher than that of lithium thin-film batteries and a power density (7 W/cm3) comparable to that of conventional electrolyte capacitors, with superb cyclic stability for 10 000 cycles. To demonstration the practical use of the MSP, the illumination of an LED bulb was powered by a laboratory-made device. This work should inspire the development of high-performance thin-film flexible supercapacitors based on MSPs as active cathodic materials.

Directly integrated all-solid-state flexible lithium batteries on polymer substrate

Recently, all-solid-state lithium batteries have attracted great attention due to their safe operation without risk of explosion under high operating voltage. However, integrating all solid layers on flexible polymer substrate has been hampered by conflicts between the high crystallization temperature and the endurable temperature of the polymer substrate. In this work, we present a simple fabrication method for all-solid-state flexible lithium batteries that are directly integrated on a polymer substrate. Using excimer laser annealing technique, we are able to selectively crystalize the amorphous cathode layer grown on top of the polymer platform without any damage to the substrate. Our flexible battery is bendable up to a curvature radius of 9 mm without mechanical breakdown, and has an initial capacity of 20 μA h μm−1 cm−2 at a 0.2 C-rate. Our approach using laser annealing provides new opportunities for integrating all-solid-state lithium thin film batteries on a broader range of platforms.

A new neutron depth profiling spectrometer at the JCNS for a focused neutron beam

A new neutron depth profiling (NDP) spectrometer has been designed and built for the use at a high intensity focused cold neutron beam of the reflectometer MARIA at the Heinz Maier-Leibnitz Zentrum (MLZ, Germany). The extremely high neutron flux at the sample position of MARIA joined with the multiple charged particle detectors allows less than 10 s sampling rate and paves the way to study the kinetics of Li ions in thin-film microbatteries. The performance of the spectrometer with standard calibration samples and amorphous thin films is presented; possibilities to operando study the Li distribution inside thin-film rechargeable lithium batteries are discussed.

V2O5 Electrosynthesized in Metavanadate Solutions: The Physicochemical and Structural Properties and Specifics of Its Electrochemical Transformation in Redox Reactions with Lithium

V2O5 thin layers are electrodeposited on a stainless steel (Type 18N12Kh9T) anode from an aqueous metavanadate solution. The oxide deposits are subjected to thermal treatment at 300 or 500°C and tested in a redox reaction with lithium. The findings are compared to the behavior of similar deposits obtained from a vanadium oxysulfate solution. The use of prepared deposits in thin-film lithium batteries is discussed. The physicochemical and structural properties and surface morphology of synthesized materials are investigated using X-ray diffraction, IR absorption spectroscopy, atomic force microscopy, and thermal analysis. In comparison to coarse-grain deposits obtained in metavanadate solutions, deposits formed in vanadium oxysulfate solutions exhibit better adhesion to a substrate due to their branched structure. To use the V2O5 deposited from metavanadate solution in lithium batteries, new ways for modification of the deposit surface morphology must be developed. The coarse-grain structure of V2O5 can be broken if electrodeposition is carried out in the presence of Co2+ ions.

Flexible integrated metallic glass-based sandwich electrodes for high-performance wearable all-solid-state supercapacitors

The design and preparation of nanoporous metal (NPM)/metallic oxides (or hydroxides) electrodes with good flexibility as well as high energy storage performance has become a great challenge for applications in wearable electronic products. Herein, we report a novel strategy to synthesize flexible nickel oxide/hydroxide coated nanoporous nickel (np-NiOxHy@Ni) electrode containing metallic glass (MG) interlayer (np-NiOxHy@Ni/MG/np-NiOxHy@Ni sandwich) by one-step dealloying of Ni40Zr20Ti40 MG ribbons. Benefiting from the ductile MG interlayer, the sandwich-like electrode presents excellent flexibility, which has not been reported for other dealloyed porous ribbons. Electrochemical measurements show that the electrode is essentially a battery-type material while it also exhibits pseudocapacitive behavior. Due to an integrated sandwich structure and np-NiOxHy@Ni shell@core network, the electrode displays an enhanced capacitance of 778 F cm−3 at 1 A cm−3 in KOH solutions (achieves 3536.01 F cm−3 when just considering the volume of the dealloyed layer) and a remarkable rate performance (80.3 % retention when the current density increase by 128-fold), as well as an outstanding cycle stability (100 % capacitance retention after 8000 cycles). Furthermore, the cable-like all-solid-state flexible supercapacitor (CAFS) device assembled by this flexible electrode can bear a bending of 0–180° without significant performance change. The highest volumetric energy density of 28.52 mW h cm−3 with a power density of 0.10 W cm−3 is obtained, which far exceeds commercially available supercapacitors (<1 mW h cm−3) and thin-film lithium batteries (0.3–10 mW h cm−3). Moreover, a wearable system by the integration of the CAFS device with an electronic watch is achieved, which amazingly runs for more than 25 min. The introduction of MG into NPM composites greatly improves the flexibility, which harnesses the promise for applying dealloyed materials in advanced wearable devices.

Attachable micropseudocapacitors using highly swollen laser-induced-graphene electrodes

For powering wearable electronics, extensive research has been directed toward microscale flexible and stretchable energy-storage devices. Microsupercapacitors, though promising candidates, remain limited in terms of design flexibility, scalability, reusability, and compatibility with general substrates. This paper reports a high-performance sticker-type flexible microsupercapacitor using highly swollen reduced-graphene-oxide electrodes fabricated by an ultrashort-pulse laser to promote full active-site and durability of the electrodes. Our sticker-type flexible micropseudocapacitor provides a comparable volumetric energy density of 1.08 mWh cm−3 and 13 times higher volumetric power density of 83.5 mW cm−3 compared to conventional lithium thin-film batteries. Bio-inspired surface modifications are additionally applied to the reduced-graphene-oxide electrodes, which provides a six-fold increase (10.38 mF cm−2) of the areal capacitance. A 6 × 2 micropseudocapacitor array embedded in a sub-millimeter thin PDMS film adheres to safety goggles and successfully powers a μ-LED. The total capacitance of the array is maintained at ~97% of its original value after 200 repetitive attachments and detachments showing good durability. In addition, the sticker-type micropseudocapacitor array shows a stable performance under repeated deformation, and up to ~99% of capacitance retention after 200 bending cycles. This novel re-attachable flexible micropseudocapacitor will expedite the widespread use of flexible and wearable devices.

Annealing of LiCoO2 films on flexible stainless steel for thin film lithium batteries

Abstract

Integration of Ultrathin MoS2/PANI/CNT Composite Paper in Producing All-Solid-State Flexible Supercapacitors with Exceptional Volumetric Energy Density

Due to the expeditious expansion of wearable electronics, all-solid-state flexible supercapacitors are being contemplated as promising energy-storage devices. Through the successful preparation of large quantities of high-quality semiconducting-type thin molybdenum disulfide (MoS2) sheets suspended in water, the authors have developed an environmentally friendly and simple method to fabricate ternary flexible electrodes with MoS2, polyaniline (PANI), and carbon nanotubes (CNTs). The resulting MoS2/PANI/CNT all-solid-state supercapacitor can be easily integrated in series to power commercial light-emitting diodes without an external bias voltage. In addition, such a supercapacitor exhibits remarkable energy density (0.013 Wh cm–3) and power density (1.000 W cm–3), thus making it superior to commercially available lithium thin-film batteries (4 V/500 μA h) and 2.75 V/44 mF activated carbon electrochemical capacitors. These results demonstrate that the exfoliated MoS2-based composite is a promising material for the development of high-performance and low-cost energy-storage devices.

Scalable fabrication of printed Zn//MnO2 planar micro-batteries with high volumetric energy density and exceptional safety.

The rapid development of printed and microscale electronics imminently requires compatible micro-batteries (MBs) with high performance, applicable scalability, and exceptional safety, but faces great challenges from the ever-reported stacked geometry. Herein the first printed planar prototype of aqueous-based, high-safety Zn//MnO2 MBs, with outstanding performance, aesthetic diversity, flexibility and modularization, is demonstrated, based on interdigital patterns of Zn ink as anode and MnO2 ink as cathode, with high-conducting graphene ink as a metal-free current collector, fabricated by an industrially scalable screen-printing technique. The planar separator-free Zn//MnO2 MBs, tested in neutral aqueous electrolyte, deliver a high volumetric capacity of 19.3 mAh/cm3 (corresponding to 393 mAh/g) at 7.5 mA/cm3, and notable volumetric energy density of 17.3 mWh/cm3, outperforming lithium thin-film batteries (≤10 mWh/cm3). Furthermore, our Zn//MnO2 MBs present long-term cyclability having a high capacity retention of 83.9% after 1300 cycles at 5 C, which is superior to stacked Zn//MnO2 batteries previously reported. Also, Zn//MnO2 planar MBs exhibit exceptional flexibility without observable capacity decay under serious deformation, and remarkably serial and parallel integration of constructing bipolar cells with high voltage and capacity output. Therefore, low-cost, environmentally benign Zn//MnO2 MBs with in-plane geometry possess huge potential as high-energy, safe, scalable and flexible microscale power sources for direction integration with printed electronics.

Facile Development Strategy of a Single Carbon-Fiber-Based All-Solid-State Flexible Lithium-Ion Battery for Wearable Electronics.

Microsized and shape-versatile flexible and wearable lithium-ion batteries (LIBs) are promising and smart energy storage devices for next-generation electronics. In the present work, we design and fabricate the first prototype of microsized fibrous LIBs (thickness ≈ 22 μm) based on multilayered coaxial structure of solid-state battery components over flexible and electrically conductive carbon fibers (CFs). The micro coaxial batteries over the CF surface were fabricated via electrophoretic deposition and dip-coating methods. The microfiber battery showed a stable potential window of 2.5 V with an areal discharge capacity of ∼4.2 μA h cm-2 at 13 μA cm-2 of the current density. The as-assembled battery fiber delivered a comparable energy density (∼0.006 W h cm-3) with solid-state lithium thin-film batteries at higher power densities (∼0.0312 W cm-3). The fibrous batteries were also connected in parallel and in series to deliver large current and high voltage, respectively. The fibrous battery also retains up to 85% discharge capacity even after 100 charge-discharge cycles. Furthermore, these battery fibers performed well under both static and bending conditions, which shows the robustness of the battery fiber. Therefore, this type of fibrous microbattery can be used in advanced flexible and wearable microelectronics, bioelectronics, robotics, and textile applications.

Self-standing oxygen-deficient α-MoO3-x nanoflake arrays as 3D cathode for advanced all-solid-state thin film lithium batteries

Compared with the planar two-dimensional (2D) all-solid-state thin film batteries (TFBs), three-dimensional (3D) all-solid-state TFBs with interdigitated contact between electrode and electrolyte possess great advantage in achieving both high energy and power densities. Herein, we report a facile fabrication of vertically aligned oxygen-deficient α-MoO3-x nanoflake arrays (3D MOx) using metal Mo target by direct current (DC) magnetron sputtering. By utilizing the 3D MOx cathode, amorphous lithium phosphorus oxynitride solid electrolyte, and lithium thin film anode, 3D solid-state TFBs have been successfully fabricated, exhibiting high specific capacity (266 mAh g−1 at 50 mA g−1), good rate performance (110 mAh g−1 at 1000 mA g−1), and excellent cycle performance (92.7% capacity retention after 1000 cycles) in comparison with the 2D TFBs using the planar MOx thin film as cathode. The superior electrochemical performance of the 3D TFBs can be attributed to the 3D architecture of the cathode, maximizing the cathode/electrolyte interface while retaining the short Li+ diffusion length. The charge/discharge measurements of the 3D MOx cathode in liquid electrolyte, however, exhibit fast capacity fading, demonstrating the advantage of using transition metal oxide as cathode in solid-state batteries.

Research progress of all solid-state thin film lithium Battery

Compared with the traditional liquid lithium-ion battery, all solid-state lithium battery can significantly improve its safety, specific energy, specific power and cycle performance. With the development of smart society, the integration of devices has become a trend, and the corresponding energy supply system has gradually attracted attention. Among them, all solid-state thin film lithium battery is a better smart device energy unit. The deposition techniques of all solid-state thin film lithium battery are compatible with the micro-nano techniques of the micro-devices, which is conducive to the integration of the micro-devices and the micro-energy sources. This article first introduced the advantages and key issues of all solid-state thin film lithium batteries. Next, the deposition techniques of all solid-state thin film lithium batteries are introduced. Finally, the latest advances in all solid-state thin film lithium batteries are introduced, including flexible all-solid-state Thin-film lithium-ion batteries and three-dimensional structure of all-solid-state lithium-ion batteries.

2D mesoporous MnO2 nanosheets for high-energy asymmetric micro-supercapacitors in water-in-salt gel electrolyte

Two-dimensional (2D) mesoporous nanosheets as electrodes present a critical materials platform for dramatically boosting the performance of planar micro-supercapacitors (MSCs) due to their unique features of interconnected porous network, enriched nanopore arrays, and high specific surface area. However, efficient strategies for constructing such complicated mesoporous architectures are very limited. Here, we developed a supramolecular bottom-up self-assembly strategy for direct synthesis of ultrathin mesoporous manganese dioxide (m-MnO2) nanosheets for high-energy all-solid-state planar asymmetric MSCs (AMSCs). The m-MnO2 nanosheets exhibited ultrathin thickness of 10 nm, uniformly interconnected network of mesopores with size of 5–15 nm, high surface area of 128 m2 g−1, and remarkably enhanced capacitance of 243 F g−1 at 1 mV s−1 in comparison with non-mesoporous MnO2 nanosheets (123 F g−1). Further, all-solid-state AMSCs were assembled based on m-MnO2 nanosheets as positive electrode, porous VN nanosheets as negative electrode, and electrochemically exfoliated graphene as conductive agent and metal-free current collector in “water-in-salt” gel electrolyte. Importantly, our all-solid-state AMSCs operated stably at 2.0 V and offered impressive energy density of 21.6 mWh cm−3, outperforming most reported MnO2 based MSCs, and two times higher than lithium thin-film batteries (≤10 mWh cm−3). Also, they presented long-term cycling stability with 90% capacity retention after 5000 cycles, outstanding flexibility without observable capacitance decay under different bending angles, and facile serial and parallel interconnection for creating high-voltage and high-capacitance integrated bipolar cells. Therefore, our proposed strategy will open many opportunites for patterning novel 2D mesoporous metal oxide nanosheets for high-performance microscale electrochemical energy storage devices.

Self-Standing 3D Cathodes for All-Solid-State Thin Film Lithium Batteries with Improved Interface Kinetics.

3D all-solid-state thin film batteries (TFBs) are proposed as an attractive power solution for microelectronics. However, the challenge in fabricating self-supported 3D cathodes constrains the progress in developing 3D TFBs. In this work, 3D LiMn2 O4 (LMO) nanowall arrays are directly deposited on conductive substrates by magnetron sputtering via controlling the thin film growth mode. 3D TFBs based on the 3D LMO nanowall arrays and 2D TFBs based on the planar LMO thin films are successfully fabricated using a lithium phosphorous oxynitride (LiPON) electrolyte and Li anode. In comparison, the 3D TFB significantly outperforms the 2D TFB, exhibiting large specific capacity (121 mAh g-1 at 1 C), superior rate capability (83 mAh g-1 at 20 C), and good cycle performance (over 90% capacity retention after 500 cycles). The superior electrochemical performance of the 3D TFB can be attributed to the 3D architecture, which not only greatly increases the cathode/electrolyte interface and shortens the Li+ diffusion length, but also effectively enhances the structural stability. Importantly, the vertically aligned nanowall array architecture of the cathode can significantly mitigate disordered LMO formation at the cathode surface compared to the 2D planar thin film, resulting in a greatly reduced interface resistance and improved rate performance.

Modifications of Solid Interfaces in All Solid-State Thin Film Lithium Batteries

The development of smart devices requires matching energy units, so the research on micro-energy has attracted attention. The all solid-state thin film lithium battery is a better smart energy unit, which not only improves the safety of the lithium battery, but also improves the energy density and cycle performance of lithium battery. All solid-state thin film lithium batteries can adopt the physical deposition technique and is compatible with MEMS technology, which is favorable for the preparation of the self-powered smart device. The solid interface is a key issue that limits the performance of all solid-state thin film lithium batteries. This paper reviews a brief research on modification of solid interface in all solid-state thin film lithium batteries.

Efficient and scalable synthesis of highly aligned and compact two-dimensional nanosheet films with record performances

It is crucial to align two-dimensional nanosheets to form a highly compact layered structure for many applications, such as electronics, optoelectronics, thermal management, energy storage, separation membranes, and composites. Here we show that continuous centrifugal casting is a universal, scalable and efficient method to produce highly aligned and compact two-dimensional nanosheets films with record performances. The synthesis mechanism, structure control and property dependence of alignment and compaction of the films are discussed. Significantly, 10-μm-thick graphene oxide films can be synthesized within 1 min, and scalable synthesis of meter-scale films is demonstrated. The reduced graphene oxide films show super-high strength (~660 MPa) and conductivity (~650 S cm−1). The reduced graphene oxide/carbon nanotube hybrid-film-based all-solid-state flexible supercapacitors exhibit ultrahigh volumetric capacitance (407 F cm−3) and energy density (~10 mWh cm−3) comparable to that of thin-film lithium batteries. We also demonstrate the production of highly anisotropic graphene nanocomposites as well as aligned, compact films and vertical heterostructures of various nanosheets.

Functional Scanning Force Microscopy for Energy Nanodevices.

Energy nanodevices, including energy conversion and energy storage devices, have become a major cross-disciplinary field in recent years. These devices feature long-range electron and ion transport coupled with chemical transformation, which call for novel characterization tools to understand device operation mechanisms. In this context, recent developments in functional scanning force microscopy techniques and their application in thin-film photovoltaic devices and lithium batteries are reviewed. The advantages of scanning force microscopy, such as high spatial resolution, multimodal imaging, and the possibility of in situ and in operando imaging, are emphasized. The survey indicates that functional scanning force microscopy is making significant contributions in understanding materials and interfaces in energy nanodevices.

Insight Into the Formation of Lithium Alloys in All-Solid-State Thin Film Lithium Batteries

Solid-state thin-film batteries utilise electrode and electrolyte components which are nanometres or micrometres thick, enabling the production of novel devices with new form factors. Here, in situ X-ray diffraction is used to carry out the first study of a solid-state thin-film lithium-ion battery containing a solid-state LiPON electrolyte and Bi negative electrode. The structure-electrochemistry relationships in the Li-Bi system are revealed and details of cell construction, data collection, and data analysis is presented to guide for research.