Search

Flexible power supply devices provide possibilities for wearable electronics in the Internet of Things. However, unsatisfying capacity or lifetime of typical batteries or capacitors seriously limit their practical applications. Different from conventional heat-to-electricity generators, zinc ion thermoelectrochemical cells has been a competitive candidate for the self-power supply solution, but the lack of promising cathode materials has restricted the achievement of promising performances. Herein, we propose an attractive cathode material by rational heterostructure engineering of hydrated vanadium pentoxide. Owing to the integration of thermodiffusion and thermoextraction effects, the thermopower is significantly improved from 9.1 mV K− 1 to 25.3 mV K− 1. Moreover, an impressive normalized power density of 2.7 mW m− 2 K− 2 is achieved in the quasi-solid-state cells. In addition, a wearable power supply constructed by three units can drive the commercial health monitoring system by harvesting body heat. This work demonstrates the effectiveness of electrodes design for wearable thermoelectric applications.

This study demonstrates the promising potential of cathode microstructural engineering for high value-added energy conversion and storage.

Rechargeable aluminium-ion batteries (AIBs) are considered to be promising alternatives for current lithium-ion batteries (LIBs), since they can offer the possibilities of low cost with high energy-to-price ratios. Unlike in LIBs, the charge storage mechanism in AIBs involving different ionic species is far more complicated and remains largely unexplored, which impedes further screening and optimization of cathodes materials that can reversibly accommodate aluminium-based (complex) charge carriers with boosted cell performance. Here, we report a comprehensive study of the battery chemistry in metal selenide based cathode in AIBs from an integrated chemical and physical point of view. Various in situ and ex situ characterization techniques and theoretical calculations reveal that both Cl- and AlCl4- can act as the charge carriers in the FeSe2 cathode during the charge process, and the Al3+ can also be embedded into the host upon discharge process. Furthermore, using in situ magnetometry, the spin-polarized surface capacitance is observed in AIBs for the first time, which proves that Al3+ can serve as charge compensation in the formation of space charge zones with electrons. These innovative findings provide unprecedented insight into the charge storage mechanism of AIBs.

The designed NTCDI-COF with a triangular topological structure exhibits impressive electrochemical performance as a cathode material for lithium-ion batteries.

With the associated advantages of low costs and abundant resources, sodium-ion capacitors (SICs) present a suitable means for large-scale energy storage. However, their practical application is still significantly limited by the sluggish electrochemical reaction kinetics of battery-type anodes. Herein, the nitrogen-doped carbon-encapsulated Fe

Sodium-ion hybrid capacitors (SICs) are attracting increasing attention due to their high energy/power superiority and potentially low cost. However, the sluggish sodium-ion diffusion in the bulk o...

Nickel-rich layered oxides with excellent specific capacity and reasonable cost have extensively employed as cathode materials for higher energy density lithium-ion batteries (LIBs). However, side ...

Zinc ion hybrid supercapacitors (ZISCs), as one of emerging energy storage devices, have gained numerous attentions due to their high safety, satisfied energy/power output, low-cost and long-term durability. To construct a satisfying ZISC with good charge storage behavior, well-developed electrode structures and optimized electrolytes by effective strategies are highly demanded. However, current basic research is relatively far from its practical application, which has greatly deferred the large-scale production of ZISC and has become a key issue. Here, recent advances towards the ZISCs have been systematically summarized to meet such challenges, with a focus on the charge storage mechanism. In addition, insights into the development of electrodes and electrolytes are presented. It is worth believing that this review could be a medium for attracting more efforts to the early rise of ZISCs in terms of the sustainable material preparations and the advanced technique inventions.

Aqueous zinc-ion batteries have been widely reported as promising candidates for energy storage, but the research on zinc-ion based supercapacitors or hybrid supercapacitors has received little attention and the energy storage mechanism is still controversial. Here, a high-performance zinc-ion hybrid supercapacitor is successfully demonstrated with biowaste-derived porous carbon and cheap zinc foil. Thanks to the bivalent characteristic of zinc and electric double layer capacitive nature of porous carbon, as-assembed hybrid supercapacitors can achieve high energy density of 147.0 ​Wh kg−1 at 136.1 ​W ​kg−1 and a maximum power density of 15.7 ​kW ​kg−1 at 65.4 ​Wh kg−1 together with outstanding cycling stability (92.2% capacity retention after 10000 cycles at a high current density of 10 ​A ​g−1). Most importantly, 61.6% of the initial capacity at 1 ​A ​g−1 can be remained even under a mass loading as high as 17 ​mg ​cm−2. Significantly, the phase composition of byproducts formed in Zn(CF3SO3)2 electrolyte have been confirmed by ex-situ experimental results and theoretical calculations. Besides, when appling optimized carbon cathode into quasi-solid-state hybrid supercapacitors with a unique anti-freezing hydrogel electrolyte, this device can well service at various bending states and relatively low temperature of −15 ​°C.

Accepted Manuscript version. The Published Journal Article is available on Journal of Solid State Chemistry, Volume 310, article number 123006 (DOI: https://doi.org/10.1016/j.jssc.2022.123006). Supplementary data available free of charge on the article webpage. © 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

Converting low-grade heat from environment into electricity shows great sustainability for mitigating the energy crisis and adjusting energy configuration. However, the thermally rechargeable devices suffer from poor Seebeck coefficient when a semiconductor or ionic electrolyte is typically employed. Breaking the convention of thermoelectric systems, we propose and demonstrate a new zinc ion thermogalvanic cell to generate electricity from low-grade heat via the thermo-extraction/insertion and thermodiffusion process of insertion-type cathode (VO2-PC) and stripping/plating behavior of Zn anode. Based on this strategy, a high thermopower of ~ 15 mV k− 1 and an excellent output power of 1.2 mW can be impressively obtained. Besides, a high specific capacity and a superior durability are originated from coupling of VO2-PC and Zn. This work with extraordinary energy conversion efficiency and satisfying energy storage capability will pave the way toward construction of thermoelectric setups with attractive property for high value-added utilization of low-grade heat.

Lithium ion capacitors combine the complementary advantageous characteristics of batteries and supercapacitors are expected to deliver both high energy and high power density. However, this technology suffers from the kinetics imbalance between battery electrode and capacitive electrode. Here, two dimensional T-Nb2O5/N-doped carbon nanosheets with a well-continuous ionic/electronic conducting network demonstrate superior rate capability of 142.3 mA h g−1 at 20 C (1 C = 200 mA g−1). A majority of charge storage in the T-Nb2O5/N-doped carbon nanosheets was proved to be intercalation pseudocapacitive processes by kinetic analysis, enabling fast charge storage performance. A lithium ion capacitor is based upon these T-Nb2O5/N-doped carbon nanosheets was successfully fabricated, demonstrating high energy density (70.3 W h kg−1) and high power density (16,014 W kg−1).

Summary: The application of conducting polymers (CPs) in energy storage systems is greatly limited by insufficient reversibility and stability. Here, we successfully incorporated functionalized dopants (Fe(CN)63− [FCN] and PO43− ions) in CPs matrixes to achieve a preferable electrochemical performance. A stable cation inserting/expulsing behavior of surface-doped polycarbazole (PCz) is demonstrated in our work, where doping levels and semiconductor properties of PCz are effectively controlled to adjust their redox properties and stability. With carbon nanotube (CNT) films as the substrate, the CNT/PCz:FCN composite is initially adopted as a free-standing catalytic electrode in Li-O2 cells. The molecule-level dispersed FCN dopants on the surface can work as bifunctional redox mediators on the charge-discharge process. Thus, this composite can not only achieve a low charge plateau of 3.62 V and a regular growth of capacities from 1,800 to 4,800 mAh/gCNT, but also maintain the most of charge voltages under 4.0 V for 150 cycles. : Catalysis; Energy Storage; Polymers Subject Areas: Catalysis, Energy Storage, Polymers

Beyond conventional hybrid ion capacitors (HICs) based on porous carbon capacitive materials, the introduction of faradaic pseudocapacitance in HICs is an effective method to enhance energy density. Herein, we prepare methylene blue functionalized graphene (MB-X) composites taking advantage of electrostatic and extensive π-conjugated interaction. The test results confirm that the composites have high rate capability and excellent cycle stability on account of the synergistic effect between graphene and MB molecules. In order to improve the safety of HICs, an aqueous electrolyte is a promising candidate as long as the cell voltage can be efficiently increased. Therefore, we skillfully employ aqueous solutions with different pH values as asymmetric electrolytes to assemble HICs, where polyimide acts as the battery material and MB-X serves as the capacitive material. Thanks to the asymmetric electrolytes, the constructed aqueous HICs can operate at a cell voltage of 1.9 V, much larger than the decomposition voltage of water. Moreover, the flexible structure, and reversible and fast redox reactions of both the anode and cathode make the aqueous HICs display a maximum energy density of 48.6 W h kg−1 and a maximum power density of 19 kW kg−1, as well as a long-cycle lifetime with a decay of 0.00172% per cycle.

The Na-ion hybrid capacitor (NIC) has exhibited its potential applications for devices that need high energy and power densities with low cost. Nevertheless, due to their “Daniell-type” mechanism, conventional NIC devices require massive electrolytes to provide a good ionic conductivity during charging, which could decrease the packaged energy density. Herein, we report a novel “Rocking-Chair” Na-ion hybrid capacitor (RC-NIC) employing Na-ions as charge carriers, Na3V2O2(PO4)2F@PEDOT as the cathode material and activated carbon (AC) as the anode material. RC-NIC efficiently improves the energy density by minimizing the amount of electrolyte like secondary batteries because Na-ion is de-intercalated from the cathode while it is adsorbed to the anode during charging. The Na3V2O2(PO4)2F@PEDOT//AC (peanut shell derived carbon) RC-NIC delivers high energy density of ∼158 W h kg−1 and power density of ∼7000 W kg−1 based on the total mass of active materials in both electrodes, respectively, in the voltage window of 1.0–4.2 V. This is one of the highest energy densities among the previously reported NICs. This concept provides a new route to build sodium-ion hybrid capacitors that meet dual criteria of battery and supercapacitor characters.

Aqueous zinc ion hybrid supercapacitors (ZHSCs) have emerged and are regarded as promising candidates for energy storage due to their environmental friendlessness and cost‐effectiveness. However, the development of a satisfying positive electrode with high performance still poses challenges. Herein, a hierarchical porous carbon with a fast‐ion‐transport feature is rationally reported via a facile template modification strategy. By adjusting the content of the template, the physiochemical characteristics and microstructures of carbon can be reasonably optimized. As proof of concept, the produced carbon electrode can deliver a high specific capacitance of 294.8 F g−1 at a current density of 0.2 A g−1, long cycling stability with ≈100% capacitance retention over 20 000 cycles, and a maximum power density of 13.2 kW kg−1 at 30.8 W h kg−1. Significantly, a superior areal capacitance of 3390 mF cm−2 is offered with a mass loading of 21 mg cm−2. When coupled with a unique antifreezing hydrogel electrolyte, the constructed quasi‐solid‐state ZHSC can not only endure −15 °C, but also exhibits outstanding durability and an ultralow self‐discharging rate, demonstrating its potential prospect for extreme conditions. This work may bring light on the preparation of carbon materials and the fabrication of multifunctional devices.

Despite high specific capacity (3860 mAh g(-1)), the utilization of Li-metal anodes in rechargeable batteries are still hampered due to their insufficient cyclability. Herein, we report an anion-receptor-mediated carbonate electrolyte with improved performance and can ameliorate the solid electrolyte interphase (SEI) composition comparing to the blank electrolyte. It demonstrates a high average Coulombic efficiency (97.94%) over 500 cycles in the Li/Cu cell at a capacity of 1 mAh cm(-2). Raman spectrum and molecular modelling further clarify the screening effects of the anion receptor on the Li+-PF6- ion coupling that results in the enhanced ion dynamics. The X-ray photoelectron spectroscopy (XPS) distinguishes the disparities in the SEI components of the developed electrolyte and the blank one, which is rationalized by the molecular insights of the Li-metal/electrolyte interface. Thus, we prepare a 2.5 Ah prototype pouch cell, exhibiting a high energy density (357 Wh kg(-1)) with 90.90% capacity retention over 50 cycles. National Natural Science Fundation of ChinaNational Natural Science Foundation of China (NSFC) [U1802256, 21773118]; Key Research and Development Program in Jiangsu Province [BE2018122]; Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); Hubei Provincial Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [2020CFA093] K.S.H., C.Y.X., L.Y.W., Z.W.L., and X.G.Z. acknowledge the funding support from National Natural Science Fundation of China (U1802256, 21773118), the Key Research and Development Program in Jiangsu Province (BE2018122) and Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). G.F. acknowledges the support from Hubei Provincial Natural Science Foundation of China (2020CFA093). The computation is supported by High Performance Computing Platform of Nanjing University of Aeronautics and Astronautics.

The synthesis of highly nitrogen-doped hierarchical carbon spheres (NPCS) is reported. The NPCS with pomegranate-like nanostructure were prepared by the CaCO3 spheres template-induced self-activation route with dopamine as the carbon precursor. The template-induced self-activation mechanism was carefully investigated by controlling experiment conditions and thermogravimetric analyses combined with mass spectrometry. Under the optimized conditions, the as-prepared NPCS demonstrate large specific area (up to 1984 m2 g−1) and high level of nitrogen (N, 7.57%) doping. Electrochemical evaluations indicate that the energy density of NPCS-based EDLC devices can reach 6.2 and 14.4 Wh kg−1 in 6 M KOH electrolyte and aqueous concentrated electrolyte (5 M LiTFSI), respectively. This work provides a novel approach for preparing nanoporous carbon materials with hierarchical porosity and well-defined nanostructure.

Here, we report a facile and scalable strategy to prepare porous anatase TiO2 tablet consisted of nanoparticles, which is evolved from titanium-based metal–organic framework (MOF) template. After subsequent wet-chemical lithiation and post-annealing, porous Li4Ti5O12 nano-tablet is also obtained. When tested as anode materials for lithium ion batteries, both of them exhibit outstanding electrochemical performances. The capacity of the anatase TiO2 reaches up to 228 mAh g−1 at 0.1 A g−1. At the same time, Li4Ti5O12 delivers a high reversible capacity of 158 mAh g−1 at 0.1 A g−1, and excellent cycling stability of maintaining a capacity of 122 mAh g−1 after 1000 cycles at 1 A g−1 between 1.0 V and 2.5 V. The excellent electrochemical properties are attributed to their unique porous structure, which increases active sites to accommodate lithium ions and improve ionic diffusion.

Simultaneous integration of high power density, high energy density, long cycle life and superior safety in a single energy storage system is still a huge challenge. Addressing this issue requires the design of new energy storage systems with novel electrodes. Herein, we propose a novel electrochemical energy storage device called a quasi-solid-state Na-ion hybrid capacitor (QSS–NIC) based on surface oxygen-functionalized crumpled graphene (OCG) as both the negative and positive electrodes and a Na-ion conducting gel polymer as the electrolyte. The as-prepared OCG with dense and porous structure ensures abundant ion-accessible active sites and short ion diffusion path. The surface oxygen functional groups within OCG are favorable for high energy storage when applied as both battery-type negative electrodes and capacitor-type positive electrodes. Benefiting from the elaborate design of electrode materials and device configuration, the QSS–NIC achieves a high energy density of 121.3 W h kg−1, high power density of 8000 W kg−1 and a long cycling life of over 2500 cycles with a capacitance retention of ~ 86.7%. This work successfully demonstrates a proof of concept of quasi-solid-state Na-ion hybrid capacitors as a high performance energy storage device based on two graphene electrodes, which narrows the performance gap between conventional electrochemical capacitors and batteries.

MXenes, 2D transition metal carbides and nitrides, deliver competitive performance in sodium ion batteries because of metallic conductivity, hydrophilic surface and good mechanical stability. However, similar to other individual 2D materials, the electrochemical performance of MXenes was hindered by the modest capacity and the tendency of restacking. To overcome these limitations, construction heterolayered architecture with 2D high capacity SnS2 nanoplates is an effective strategy. The heterolayered electrode combined the metallic conductive of MXene and high redox activity SnS2 can achieve a synergistic enhancement. When used as anodes for sodium ion batteries, the MXene/SnS2 composite exhibited a great performance in term of capacity, rate capability, and cycling stability. A superior cycling could still obtain at extreme temperature that MXene/SnS2 5:1 electrode maintain a reversible capacity of 120 mAh g−1 after 125 cycles at 0 °C.

Li4Ti5O12 with long cycling life has been deemed to be one of the most promising anode materials for lithium ion battery. Nevertheless, poor electronic conductivity impedes its application for energy storage. Meanwhile MXene possesses high electrical conductivity and moderate electrochemical energy storage. Herein, we develop a novel strategy for the in-situ synthesis of layered-stacked Li4Ti5O12-MXene composite. The synergistic effect of Li4Ti5O12 and MXene greatly improved the electrochemical properties of Li4Ti5O12-MXene composite. At a high current density of 10 A g− 1, a high discharge capacity of 116 mAh g− 1 can be achieved. Moreover, a high discharge capacity of 178 mAh g− 1 after 500 cycles can be maintained at a current density of 5 A g− 1. This work demonstrates a scalable route to assemble MXene-derived Ti-based materials for high-performance electrochemical energy storage applications.

Although the soluble redox mediator (RM) has been effectively applied in Li–O2 batteries, parasitic reactions between the lithium anode and RM+ can result in poor cycle performance. Herein, we proposed a nonelectroactive surfactant (sodium dodecyl sulfate, SDS) that could adsorb on the hydrophobic carbon surface and form a stable anionic layer upon charge, which can effectively suppress the diffusion of oxidized RM+ and facilitate charge transfer at the electrode–solution interface. To coordinate with SDS, a new RM named 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) was adopted due to its oxidation process following after in situ formation of the anionic layer. Moreover, as a bifunctional mediator, PTIO cannot only get a low charge plateau but also greatly enhance the discharge capacity when applied in Li–O2 batteries. The electrochemical results demonstrated that the cycling performance, energy efficiency, and discharge capacity were significantly improved owing to the synergistic effect ...

There is an urgent need but it is still a huge challenge to integrate high energy and power density with high safety in a single energy storage device. Addressing this issue largely depends on design of new energy storage systems with novel electrode architectures. Herein, a novel electrochemical energy storage device called a quasi-solid-state Na-ion capacitor (QSS-NIC) is designed based on a 3D self-supported Na2Ti3O7 nanoribbon array/graphene foam (NTO/GF) anode and graphene foam (GF) cathode, and a Na-ion conducting gel polymer as the electrolyte and separator, without any binders, conducting additives or metal current collectors. Benefiting from the unique 3D self-supported cathode and anode, the GF//NTO/GF configuration achieves a high energy density of 70.6 W h kg−1 and high power density of 4000 W kg−1 on the basis of the mass of both electrodes, and a prominent cycling stability over 5000 cycles (capacitance retention ∼73.2%). This work successfully demonstrates a proof of concept of QSS-NIC as a high performance energy storage device based on two self-supported electrodes, which could provide a feasible approach to bridge the performance gap between capacitors and Na-ion batteries.

Lithium ion capacitors (LICs), which combine the merits of both lithium ion batteries and supercapacitors, have recently attracted considerable attention. However, LICs generally use different materials and synthesis routes for the cathode and anode, resulting in a complicated process and high production cost, from an energy storage device perspective. In addition, the current collector interface structure design plays a key role in the electrochemical process. Herein, we have designed and fabricated a novel LIC with similar-symmetric architecture in both electrodes. The nitrogen-doped porous carbon microspheres (NPCM) derived from the hierarchical assembly of polyimide nanosheets as the anode material showed excellent lithium storage properties. The cathode material (NPCM-A) obtained by the activation of NPCM led to an ultrahigh specific surface area (2007 m2 g−1) and excellent capacitance characteristics. Benefiting from the unique superstructure and 3D porous array current collectors, the novel LIC achieved a high energy density of 95.08 W h kg−1 and could retain 48.2 W h kg−1 even at a high power density of 15 kW kg−1 on the basis of mass of both electrodes. Moreover, the LIC achieved 80.1% capacity retention after 5000 ultra-long cycles, corresponding to fading of 0.004% per cycle.

Sodium-ion capacitors (SICs), designed to attain high energy density, rapid energy delivery, and long lifespan, have attracted much attention because of their comparable performance to lithium-ion capacitors (LICs), alongside abundant sodium resources. Conventional SIC design is based on battery-like anodes and capacitive cathodes, in which the battery-like anode materials involve various reactions, such as insertion, alloying, and conversion reactions, and the capacitive cathode materials usually depend on activated carbon (AC). However, researchers have attempted to construct SICs based on battery-like cathodes and capacitive anodes or a combination of both in recent years. In this Minireview, charge storage mechanisms and material design strategies for SICs are summarized, with a focus on the battery-like anode materials from both inorganic and organic sources. Additionally, the challenges in the fabrication of SICs and future research directions are discussed.

Graphene, conducting polymers and their hybrids have more superiority and potential as electrode materials for supercapacitors. Neverthless, graphene encountered challenges to guarantee adequate interactions with conducting polymers while maintaining a high level of naked surface for the permeability with electrolytes. To tackle this challenge, developing functionalized or new structured graphene hybrids and their controllable preparation novel strategy is urgent and a focus strategy. Here, SiO2/graphene/polyaniline (SGP) is fabricated through the cross-dimensional assembling of two-dimensional graphene with zero-dimensional SiO2 and polyaniline successively. SiO2 is chosen as a functional connection layer between electrodes and electrolytes, and between hydrophobic graphene and polyaniline for aqueous supercapacitors. Hydrophilic SiO2 not only enhanced the interfacial interactions and ion exchanges at the electrolyte/electrode interface, but also suppressed the stacking between graphene and polyaniline, and among graphene layers. As a result, both the electric double layer capacitance of graphene and pseudocapacitance of polyaniline are better utilized with the aid of SiO2. SGP shows a capacitance retention of 90% after 3500 cycles and improved electrochemical performances, higher than graphene/polyaniline based on both three-electrode and two-electrode cell configurations. These findings demonstrate that SiO2 embeded graphene hybrids is an effective strategy to promote the overall electrochemical properties for supercapacitors.

High voltage LiNi0.5Mn1.5O4 (LMNO) spinel cathode has been attracting high interest due to its high energy density and cobalt-free chemistry. However, high temperature (50 °C) cycling behavior is not very good because of the electrolyte decomposition, metal dissolutions, and the formation of gas products. To improve the high-temperature cycling behavior of the LMNO spinel cathode, vanadium doping was employed. For this purpose, pristine LMNO, LiNi0.45Ti0.1Mn1.45O4, and LiNi0.4V0.1Mn1.5O4 cathode materials were synthesized and their elevated temperature cycling behavior was compared. After 200 cycles, the 10% V-doped LMNO still has an excellent cycling performance of 99.5 mAh g−1 (capacity fade is 6.55%) at 50 °C and 1C-rate compared to 28.8 mAh g−1 pristine LMNO (capacity fade is 70.4%), and 84 mAh g−1 LiNi0.45Ti0.1Mn1.45O4 capacity retention (capacity fade is 25.6%), respectively. These results showed that the V-doped LMNO design is the proper solution for high-temperature durability.

Summary The application of conducting polymers (CPs) in energy storage systems is greatly limited by insufficient reversibility and stability. Here, we successfully incorporated functionalized dopants (Fe(CN)63− [FCN] and PO43− ions) in CPs matrixes to achieve a preferable electrochemical performance. A stable cation inserting/expulsing behavior of surface-doped polycarbazole (PCz) is demonstrated in our work, where doping levels and semiconductor properties of PCz are effectively controlled to adjust their redox properties and stability. With carbon nanotube (CNT) films as the substrate, the CNT/PCz:FCN composite is initially adopted as a free-standing catalytic electrode in Li-O2 cells. The molecule-level dispersed FCN dopants on the surface can work as bifunctional redox mediators on the charge-discharge process. Thus, this composite can not only achieve a low charge plateau of 3.62 V and a regular growth of capacities from 1,800 to 4,800 mAh/gCNT, but also maintain the most of charge voltages under 4.0 V for 150 cycles., Graphical Abstract, Highlights • A controllable electrochemical method to introduce redox-active anions in CP matrixes • Doping levels and semiconductor properties of CPs can be effectively controlled • Surface-doped CPs have better redox properties and electrochemical stability • The PCz doped by functionalized dopants shows a good catalytic effect, Catalysis; Energy Storage; Polymers

Spinel Li