Ionogel Electrolyte Research Articles

Blade-Coatable Hexagonal Boron Nitride Ionogel Electrolytes for Scalable Production of Lithium Metal Batteries

Solid-state electrolytes have attracted significant attention for rechargeable lithium-ion batteries due to their potential to enable higher energy density technologies and improve cell safety by removing volatile liquid electrolytes. However, existing solid-state electrolyte materials lack sufficient electrochemical performance or require expensive and time-consuming processing methods that have prevented their wide-scale adoption. Here, a blade-coatable hexagonal boron nitride ionogel electrolyte is introduced that exhibits high room temperature ionic conductivity (>1 mS cm–1), is stable against lithium metal anodes, and can be applied over a wide area in a thin (<40 μm) and crack-free film. Furthermore, this blade-coatable slurry has a tunable viscosity to enable its use in existing battery manufacturing infrastructure. The resulting blade-coated hBN ionogel electrolyte is employed in a lithium metal battery with a LiFePO4 cathode, exhibiting superlative rate capability at room temperature with a 78% capacity retention after 500 cycles at a rate of 1C.

Organic/inorganic hybrid quaternary ionogel electrolyte with low lithium-ion association and uniform lithium flux for lithium secondary batteries

High-energy-density lithium secondary batteries require high-voltage electrolyte. Ionic liquids with wide electrochemical window have been regarded as promising electrolyte candidate for high-safety electrochemical devices. However, the solvation state of lithium ions severely restricts the conductivity due to the sluggish kinetics of lithium-ion cluster. Moreover, the leakage risk also impedes its practical application. Here, we propose to mitigate the above issues by designing organic/inorganic hybrid quaternary ionogel electrolyte (PSIL). The key to our strategy is promoting the dissociation of Li (TFSI)2− cluster and increasing the percentage of free Li+ in the ionogel electrolyte. The amorphous matrix formed by PEO and SiO2 increases the interaction between Li+ and PEO, reducing the association of Li (TFSI)2− cluster. And then, the synergistic transportation of lithium ions by PEO and ionic liquid promises the high conductivity of PSIL. As a result, the ionogel electrolyte shows a high conductivity of 1.50 ×10−3 S•cm−1at 20 ℃. The impressive electrochemical performance with LiFePO4 cathode indicates the high compatibility with the electrode. The ex-situ SEM and molecular dynamic simulation both demonstrate the uniform transportation of lithium ions during the electrochemical process and indicate the successful design for the quaternary ionogel electrolyte.

Supramolecular Thixotropic Ionogel Electrolyte for Sodium Batteries.

Owing to the potential of sodium as an alternative to lithium as charge carrier, increasing attention has been focused on the development of high-performance electrolytes for Na batteries in recent years. In this regard, gel-type electrolytes, which combine the outstanding ionic conductivity of liquid electrolytes and the safety of solid electrolytes, demonstrate immense application prospects. However, most gel electrolytes not only need a number of specific techniques for molding, but also typically suffer from breakage, leading to a short service life and severe safety issues. In this study, a supramolecular thixotropic ionogel electrolyte is proposed to address these problems. This thixotropic electrolyte is formed by the supramolecular self-assembly of D-gluconic acetal-based gelator (B8) in an ionic liquid solution of a Na salt, which exhibits moldability, a high ionic conductivity, and a rapid self-healing property. The ionogel electrolyte is chemically stable to Na and exhibits a good Na+ transference number. In addition, the self-assembly mechanism of B8 and thixotropic mechanism of ionogel are investigated. The safe, low-cost and multifunctional ionogel electrolyte developed herein supports the development of future high-performance Na batteries.

Wearable Sensors Adapted to Extreme Environments Based on the Robust Ionogel Electrolytes with Dual Hydrogen Networks.

Nonvolatile ionogels are promising soft electrolyte materials for flexible electronics, but it is challenging to fabricate stable electrolytes with mechanical robustness. Here, through rationally optimizing the chemical structure of polymer matrix and ionic liquids, the high-performance ionogel electrolytes with mechanical robustness and stability were fabricated. There are double hydrogen bonding networks in the as-prepared ionogel electrolytes, one of which exists between the polymer chains while the other one existing between the polymer chains and ionic liquid molecules. By adjusting the content of the ionic liquid and the ratio of the two hydrogen bonding networks, the prepared ionogel electrolytes exhibit tunable properties with an elasticity of 1.3-30 kPa, a stretchability of more than 1800%, a fracture energy of 125.8-548.3 KJ m-3, and a coordinated self-healing efficiency of 6.2-37.9% to satisfy the needs of different application scenarios. The assembled wearable sensors based on the high-performance ionogel electrolytes can be attached to a part of the human body, detecting various motions and body temperature. Benefiting from the nonvolatile and hydrophobic properties of the ionogel electrolytes, the wearable sensors can be operated under extreme environments including high/low temperature (-15-100 °C) and high humidity (100% relative humidity). It is believed that this work provides prospects for the application of wearable electronic devices.

A free-sealed high-voltage aqueous polymeric sodium battery enabling operation at −25°C

An increasing demand for electric vehicles and flexible electronics focuses attention on developing a safe, high-energy, and sustainable battery that can work under severe conditions. Emerging high-voltage aqueous batteries based on highly concentrated salts and molecular crowding electrolytes are likely to be hampered by their poor low-temperature performance because of a high freezing point and salting out at low temperature. Inspired by the antifreezing ionogel electrolyte for transport measurements at subzero temperatures, we design a water-in-ionogel electrolyte with a low salt-concentration (2m NaTFSI) and high operational voltage (3.0 V) by changing the hydrogen bonding and introducing fluoride additives for low-temperature operation. A full cell with a P2-type Na 2/3 Mn 2/3 Co 1/3 O 1.98 F 0.02 cathode and hard-carbon anode could deliver high energy densities of 109 and 23.4 Wh kg −1 at room temperature and −25°C. This eco-friendly aqueous polymeric battery could be free sealed and perform in water. This work opens an avenue for designing high-energy, free-sealed aqueous batteries for low-cost, sustainable energy storage, enabling subzero temperature operation. • F-containing water-in-ionogel electrolyte enables high-voltage, low-temperature operation • F doping endows Mn-based P2-type cathodes with enhanced hydrophilicity and rate performance • The fabricated aqueous polymeric sodium-ion battery enables subzero temperature operation • The free-sealed battery can work under severe condition with advantage in weight Rong et al. demonstrate that a water-in-ionogel (WIG) electrolyte with low salt concentration (2m NaTFSI) and high operational voltage (3.0 V) can rival the high voltage of typical “water-in-salt” and “molecular crowding” electrolytes. The WIG electrolyte, exhibiting superior antifreezing properties without salting out at low temperature and high stability against sodium metal, is a promising candidate for aqueous polymeric batteries.

Ternary Ionogel Electrolytes Enable Quasi‐Solid‐State Potassium Dual‐Ion Intercalation Batteries

Dual-Ion Batteries A novel battery concept reliant on a dual-ion intercalation mechanism is demonstrated in article 2100122 by Antonia Kotronia, Habtom Desta Asfaw, and co-workers. Using glass fiber fabrics infused with an ionogel electrolyte, a compact dual-ion battery (DIB) is demonstrated. The potassium-based salts used in the electrolyte make the DIB attractive for storing energy from renewable sources.

Novel poly(epichlorohydrin)-based matrix for monolithic ionogel electrolyte membrane with high lithium storage performances.

Based on gelling matrices and ionic liquids (ILs), monolithic ionogel electrolyte membranes (MIEMs) have become a research focus. However, further application is limited by lack of functional matrices. Herein, we proposed the introduction of an ionized polymer, i.e., polyether polymer with side-chain ionic groups obtained via the reaction of quaternary ammonium with uncrystallizable poly (epichlorohydrin) (PECH), as the matrix into the gels to balance the mechanical properties and the ionic conductivity. In combination with lithium bis-(fluorosulfonyl) imide (LiFSI) and 1-ethyl-3-methylimidazolium bis-(fluorosulfonyl)-imide (EMImFSI) via a solvent casting technique, a flexible MIEM was successfully prepared. The as-obtained MIEM exhibited good thermal stability (up to about 250 °C) and a high ionic conductivity of 1.21 mS cm−1 at 20 °C. Moreover, Li|LiFePO4 coin cells using this MIEM delivered high capacity (150.0 mA h g−1 at 0.2C) with good cycling stability, and an excellent C-rate response. This work discloses a novel and paramount route to exploit PECH-based MIEMs for Li storage, as well as energy storage systems beyond Li.

Monolithic Task‐Specific Ionogel Electrolyte Membrane Enables High‐Performance Solid‐State Lithium‐Metal Batteries in Wide Temperature Range

AbstractMonolithic ionogel electrolyte membranes (IGEMs) based on gelling scaffolds and ionic liquids have aroused intensive interest because of their broad processing compatibility, nonflammability, and favorable thermal and electrochemical features. However, the absence of functional scaffolds that concurrently enable high mechanical strength and Li+ transportability of IGEMs constrains the battery power and safety. Herein, a task‐specific IGEM monolith featuring high Li+ conductivity and outstanding thermal stability is demonstrated, whereby electrospun positively charged poly(ionic liquid) nanofibers serve as a thermotolerant scaffold for the IGEM. Regulating the Li+ environment in the IGEM enables the shift from the sluggish vehicular to fast structural Li‐ion transport mode. With the unique IGEM, the solid‐state Li||LiFePO4 cells achieve improved rate capability and good cyclability in a wide temperature range from 0 to 90 °C. Furthermore, practical solid‐state Li||LiFePO4 pouch cells with a cathode capacity of ≈2 mAh cm−2 have also been demonstrated.

An all-in-one flexible supercapacitor based on redox ionogel electrolyte with high cycle performance

In this study, we prepare a kind of supercapacitor (SC) through all-in-one assembled method with redox-active ionogel electrolyte and carbon paper electrodes. The ionogel is compounded with poly (vinyl alcohol) (PVA), polyacrylamide (PAAM), lithium sulfate (Li2SO4), and 1-butyl-3-methylimidazolium bromide ionic liquid (BMIMBr IL). The device reveals outstanding long-term stability of 99.6% percent after 5000 times charge/discharge test in high current density, which is largely owed to the all-in-one method and low loss rate of ionogel that provides confined space, stable structure and good contact between electrodes and electrolytes interfaces. Due to the existence of double cross-link structure, ionogels exhibit excellent mechanical properties, which are proved by bending tests of flexible devices. Additionally, wide potential window of 1.6 V and pseudocapacitance provided by bromide ions redox reaction (Br- /Br3-) make the device have a relatively high area capacitance of 284.8 mF cm−2 in the activated carbon field. Moreover, the device also possesses a high energy density of 25.3 Wh kg−1 with the power density of 99.8 W kg−1 at 0.5 mA cm−2 current density.

Ternary Ionogel Electrolytes Enable Quasi‐Solid‐State Potassium Dual‐Ion Intercalation Batteries

A dual‐ion battery (DIB) is an emerging technology destined for use in stationary energy storage applications. Most DIB prototypes use expensive salt‐concentrated liquid electrolytes to ensure sufficient ion supply and an electrochemical stability window beyond 4.5 V, which is required for anion intercalation in graphite. Herein, the design of a compact quasi‐solid‐state potassium‐based DIB is introduced using ternary ionogel electrolytes (t‐IGEs) prepared from a potassium salt, an ionic liquid, and a poly(ionic liquid). Among a series of combinations, the t‐IGE with optimum mechanical property, thermal stability (&gt;200 °C), and electrochemical performance consists of 30% salt, 28% ionic liquid, and 42% poly(ionic liquid). With ionic conductivity ranging from 0.1 to 1 mS cm−1 at 30–100°C and an electrochemical stability window within 0.5–5.0 V versus K+/K, the t‐IGE is suited for practical MoS2–graphite KDIBs. Infusing the ionogel in plain‐weave glass fiber fabrics (≈40 μm thick) further enables the design of more compact KDIBs in which a significant reduction (≈64%) in electrolyte thickness is achieved. The cells are able to deliver specific capacities varying from 80 to 25 mAh g−1 at 10 to 160 mA g−1, with CEs ranging from ≈90% to 100%.

High‐Performance Ionic Thermoelectric Supercapacitor for Integrated Energy Conversion‐Storage

Converting low‐grade waste heat into usable electricity and storing it simultaneously requires a new technology that realize the directional migration of electrons or ions under temperature difference and enrichment on the electrodes. Although the urgent demand of energy conversion‐storage (ECS) has emerged in the field of wearable electronic, achieving the integrated bi‐functional device remains challenge due to the different mechanisms of electrical transportation and storage. Here, we report an ionic thermoelectric supercapacitor that relies on the synergistic functions of thermoelectricity and supercapacitor in the thermoelectric ionogel electrolyte and high‐performance hydrogel electrodes to enhance the ECS performance under a thermal gradient. The thermoelectric electrolyte is composed of polyacrylamide hydrogel and sodium carboxymethyl cellulose (PMSC), possessing cross‐linked network with excellent cation selectivity, while the ionic thermoelectric properties are further improved in the presence of NaCl. The corresponding Seebeck coefficient and ionic conductivity of the NaCl–PMSC electrolyte reach 17.1 mV K−1 and 26.8 mS cm−1, respectively. Owing to good stretchability of both gel‐based electrolyte and electrode, the full‐stretchable integrated ECS device, termed ionic thermoelectric supercapacitor, presents promising thermal‐charge storage capability (~1.3 mC, ΔT ≈ 10 K), thus holds promise for wearable energy harvesting.

Rational design of a pre-lithiated ionogel membrane with enhanced safety and electrochemical performances

Hard carbon is hard to be commercialized due to its low initial efficiency. The irreversible capacity loss usually consumes numerous lithium ions from the electrolyte, leading to an unexpected energy density attenuation. Therefore, effective pre-lithiation methods are extremely desired. Herein, a striking and simple pre-lithiated method was proposed through introducing lithium metal passivation powder into ionogel electrolyte as lithium source. Safety features and electrochemical performances of as prepared ionogel electrolyte were studied systemically. Notably, our work found that the incorporation of lithium metal powder could effectively improve the ionic conductivity, reduce the reactive activation energy, and supplement the lithium-ion loss of electrolyte. The pre-lithiated electrolyte could stand an ultra-high operating potential window of 4.2 V in lithium-ion capacitors. Moreover, our study reveals that the dissociation of the ionic clusters within the ionogel electrolyte favors the electrochemical performances at high temperature. Our optimized device delivered a maximum energy density of 138 Wh kg−1 and a maximum power density of 19339.4 W kg−1 at 60 °C. This simple pre-lithiation method will significantly benefit the rational fabrication of lithium-ion capacitors with high energy density and reasonable safety.

Highly conductive ionogel electrolytes based on N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide FSI and NaFSI mixtures and their applications in sodium batteries

The development of highly conductive and safe electrolytes for sodium-ion batteries is an emerging field beyond lithium battery technologies. In this work we have developed new ionogel electrolytes consisting of a binary mixture of an organic ionic plastic crystal, N-ethyl-N-methylpyrrolidiniumbis(fluorosulfonyl)imide (C2mpyrFSI), mixed with NaFSI supported on a mat of electrospun poly (vinylidene fluoride) nanofibers. The salt mixture near the eutectic composition (35 mol% NaFSI) was selected for further study after a detailed phase diagram analysis and ionogel electrolytes based on this were prepared. The ionic conductivity of the prepared ionogel composite reaches 2.6 × 10−3 S cm−1 at ambient temperature. This ionogel membrane possessed a relatively high Na-ion transference number of 0.44 at 50 °C and we demonstrate the performance of a Na metal full cell using a NaFePO4 cathode (1.75–4.0 V). The assembled cells show a good capacity retention with coulombic efficiency close to 100% at various C rates between C/20, C/10 and C/5, achieving 120 mAh g−1 at C/20. The long term charge/discharge performance is also demonstrated. Our study provides a feasible method to prepare highly conductive ionogel electrolytes for future Na-battery applications

(Invited) Fundamentals and Applications of Hexagonal Boron Nitride Ionogels

Ionogel electrolytes based on ionic liquids (ILs) and a gelling solid matrix are an attractive alternative to conventional liquid electrolytes for electronic and energy storage applications. In particular, ILs offer several advantages as an electrolyte including nonflammability, nonvolatility, high electrochemical stability, and high ionic conductivity. Moreover, combining ILs with a gelling solid matrix leads to a solid-state electrolyte that is sufficiently mechanically robust to replace both the liquid electrolyte and separator in a single component, thus allowing easier packaging, streamlined manufacturing, and minimal risk of leakage [1]. For ionogel electrolytes, hexagonal boron nitride (hBN) is an especially desirable solid matrix due to its excellent chemical and thermal stability in addition to its mechanical robustness [2]. This talk will address recent efforts to realize high-performance hBN/IL ionogel electrolytes using hBN that has been solution-exfoliated into two-dimensional nanosheets using ethyl cellulose (EC) stabilizing polymers [3]. In addition to the intrinsic advantages of hBN, EC-exfoliated hBN nanosheets significantly enhance both ionic conductivity (> 1 mS/cm) and mechanical strength (storage modulus > 1 MPa) compared to conventional hBN microparticles, providing additional competitive advantages for energy storage applications [4]. The high thermal stability of hBN/IL ionogel electrolytes also enables safe, high-rate operation (up to 10C charge/discharge rate) at high temperatures up to 175 °C, which represents the highest operating temperature to date for solid-state lithium-ion batteries. Since hBN ionogels can also be formulated into printable inks [5], they are particularly promising for printed devices including electrolyte-gated thin-film transistors, supercapacitors, and batteries.[1] A. C. M. de Moraes, et al., ACS Applied Materials & Interfaces, 12, 8107 (2020).[2] W. J. Hyun, et al., Advanced Energy Materials, 10, 2002135 (2020).[3] A. C. M. de Moraes, et al., Advanced Functional Materials, 29, 1902245 (2019).[4] W. J. Hyun, et al., ACS Nano, 13, 9664 (2019).[5] W. J. Hyun, et al., Faraday Discussions, DOI: 10.1039/C9FD00113A (2020).

Highly Conductive, Flexible, and Nonflammable Double-Network Poly(ionic liquid)-Based Ionogel Electrolyte for Flexible Lithium-Ion Batteries.

The solid-state lithium-ion battery is proposed as the ultimate form of battery and has rapidly become an updated attentive research field due to its high safety and extreme temperature tolerance. However, current solid-state electrolytes hardly meet the requirement in practical applications due to its low ionic conductivity, weak mechanical properties, and poor interfacial contact between the electrolyte and the electrode. In this work, we developed a double-network-supported poly(ionic liquid)-based ionogel electrolyte (DN-Ionogel) via a one-step method. Due to its compact cross-linking structure, the leakage-free DN-Ionogel electrolyte exhibits outstanding flexibility and favorable mechanical properties. In this ionogel electrolyte, the double network favors dissociation of lithium bis(trifluoromethanesulfony)imide (LiTFSI), further resulting in remarkable ionic conductivity (1.8 × 10-3 S/cm, room temperature), wide electrochemical window (up to 5.0 V), and high lithium-ion transference number (0.33). Furthermore, the cell (LiFePO4||DN-Ionogel||Lithium) delivers a discharge capacity as high as 150.5 mAh/g, stable cyclic performance (over 200 cycles), and superior rate behavior.

Intensified Energy Storage in High-Voltage Nanohybrid Supercapacitors via the Efficient Coupling between TiNb2O7/Holey-rGO Nanoarchitectures and Ionic Liquid-Based Electrolytes.

Obtaining a comprehensive understanding of the energy storage mechanisms, interface compatibility, electrode-electrolyte coupling, and synergistic effects in carefully programmed nanoarchitectural electrodes and complicated electrolyte systems will provide a shortcut for designing better supercapacitors. Here, we report the intrinsic relationships between the electrochemical performances and microstructures or composition of complex nanoarchitectures and formulated electrolytes. We observed that isolated TiNb2O7 nanoparticles provided both a Faradaic intercalation contribution and a surface pseudocapacitance. The holey graphenes partitioned by nanoparticles not only fostered the fast transport of both electrons and ions but also provided additional electrical double-layer capacitance. The charge contributions from the diffusion-controlled intercalation process and capacitive behaviors, double-layer charging, and pseudocapacitance, were quantitatively distinguished in different electrolytes including a formulated ionic-liquid mixture, various nanocomposite ionogel electrolytes, and an organic LiPF6 electrolyte. A steered molecular dynamics simulation method was used to unveil the underlying principles governing the high-rate capability of holey nanoarchitectures. High energy density and high rate capability in solid-state supercapacitors were achieved using the Faradaic contributions from the lithium-ion insertion process and its surface charge-transfer process in combination with the non-Faradaic contribution from the double-layer effects. The work suggests that practical high-voltage supercapacitors with programmed performances and high safety can be realized via the efficient coupling between emerging nanoarchitectural electrodes and formulated high-voltage electrolytes.

Lithium‐Ion Batteries: Layered Heterostructure Ionogel Electrolytes for High‐Performance Solid‐State Lithium‐Ion Batteries (Adv. Mater. 13/2021)

Ionogel electrolytes with a layered heterostructure are developed by Mark C. Hersam and co-workers in article number 2007864, using hexagonal boron nitride nanoplatelets and two imidazolium ionic liquids with different electrochemical stability windows. Compared with ionogels using the individual ionic liquids, the layered heterostructure ionogels provide broadened electrochemical stability windows while maintaining desirable ionic conductivity, suggesting a promising electrolyte strategy for high operating voltages and rate performance in solid-state lithium-ion batteries.

Boosting lithium batteries under harsh operating conditions by a resilient ionogel with liquid-like ionic conductivity

New chemistries are being developed to increase the capacity and power of rechargeable batteries. However, the risk of safety issues increases when high-energy batteries using highly active materials encounter harsh operating conditions. Here we report on the synthesis of a unique ionogel electrolyte for abuse-tolerant lithium batteries. A hierarchically architected silica/polymer scaffold is designed and fabricated through a facile soft chemistry route, which is competent to confine ionic liquids with superior uptake ability (92.4 wt%). The monolithic ionogel exhibits high conductivity and thermal/mechanical stability, featuring high-temperature elastic modulus and dendrite-free lithium cycling. The Li/LiFePO4 pouch cells achieve outstanding cyclability at different temperatures up to 150 °C, and can sustain cutting, crumpling, and even coupled thermal–mechanical abuses. Moreover, the solid-state lithium batteries with LiNi0.60Co0.20Mn0.20O2, LiNi0.80Co0.15Al0.05O2, and Li1.2Mn0.54Ni0.13Co0.13O2 cathodes demonstrate excellent cycle performances at 60 °C. These results indicate that the resilient and high-conductivity ionogel electrolyte is promising to realize high-performance lithium batteries with high energy density and safety.

High-stable, outstanding heat resistance ionogel electrolyte and the poly(3,4-ethylenedioxythiophene) electrodes with excellent long-term stability for all-solid-state supercapacitor

• The high-stable ionogel electrolyte (PAAm/IL-X) was prepared. • The PAAm/IL-X can be operated in a wide temperature range from 0 °C to 90 °C. • The conductivity of the prepared ionogel was up to 23 mS cm −1 at 90 °C. • The PEDOT/CC electrode displayed excellent electrochemical performance. • The capacitance performance of the device ASSC-X was increased by 5% at 90 °C. Supercapacitors (SCs), a type of energy storage devices, have dragged an attention worldwide due to its high electrochemical performance for various applications. However, the use of liquid electrolyte in SCs spresents several drawbacks on packaging and security. Therefore, the preparation of SCs using solid electrolytes is a feasible method. Here, we report an ionogel electrolyte (PAAm/IL-X) which composed of polyacrylamide (PAAm) network and ionic liquid 1-vinyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([VMIM][TFSI]). The introduction of ionic liquid ([VMIM][TFSI]) improves the thermal stability and conductivity of the electrolyte. The conductivity of the prepared ionogel is up to 23 mS cm −1 at 90 °C, which still retained 71% even after 20 days at room temperature. It is noted that the thermal decomposition temperature of PAAm/IL-X was above 220 °C. In addition, the poly(3,4-ethylenedioxythiophene/carbon cloth (PEDOT/CC) electrode prepared by electroplating method exhibits excellent electrochemical performance. The specific capacitance can reach 157.8 F g −1 , and the capacitance retention rate is 93% after 3000 GCD. All-solid-state supercapacitor (ASSC-X) is assembled using PAAm/IL-X electrolyte and PEDOT/CC electrodes. The energy density of ASSC-X can reach 14.22 Wh kg −1 satisfying the require of energy density for commercial devices. Interestingly, its capacitance performance of the device ASSC-X was increased by 5% at 90 °C. These high electrochemical properties indicate the potential of PAAm/IL-X as an electrolyte/separator for safe SCs.

UV curable ionogel for all-solid-state supercapacitor

An ionogel electrolyte with polyurethane acrylate (PUA) and 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) is proposed as an all-solid-state supercapacitor operating at 4 V. The ionogel-based electrolyte is manufactured by using a solvent-free in-situ polymerization method. The ratio of EMITFSI to PUA is optimized by maintaining the free-standing membrane and high ionic conductivity. The supercapacitor, which comprises 25 wt% PUA and 75 wt% EMITFSI, exhibits the highest specific capacitance of 150.88 F g−1 at 0.1 A g−1. It also possesses a high specific energy density (93.93 W h kg−1) without sacrificing specific power density (2000.96 W kg−1) at 0.5 A g−1. Furthermore, the ionogel-applied supercapacitor maintains 99% of its specific capacitance (Cs) after 1000 cycles and exhibits remarkable flexibility while maintaining 92% of its Cs after bending 100 times.