Flexible Lithium Research Articles

Highly reversible and safe lithium metal batteries enabled by Non-flammable All-fluorinated carbonate electrolyte conjugated with 3D flexible MXene-based lithium anode

Recognized as the most attractive and promising anode, Li metal has been pursued for its high specific capacity and lowest standard potential. However, the hazardous Li dendrite growth is one of the most challenging issues for LMB, which brings about fragile SEI formation, low CE, large volume change and even safety issues. To tackle these problems, we design a 3D flexible MXene based lithium metal anode to accommodate the volume changes, accelerate the charge transport and lower the specific current density. Moreover, nonflammable ternary all-fluorinated carbonate electrolyte system is proposed to construct stable interface by introducing LiF-rich SEI and address the safety concerns. With these synergetic effects, 3D Li-MXene anode in ternary all-fluorinated electrolyte shows significantly improved reversibility with high average CE at 94.5 % after 200 cycles. Full Li metal cell with LFP cathode, composited 3D anode and nonflammable electrolyte delivers high-capacity retention of 95.7 % at 300 mAh g−1 after 200 cycles and excellent rate ability. These results pave a new direction for developing high safety and high-performance Li metal batteries and can also be extended to other rechargeable metal-anode-based batteries such as Na/K/Mg/Ca et al.

Free-Standing Titanium Nitride Films as Carbon-Free Sulfur Hosts for Flexible Lithium–Sulfur Batteries

Free-Standing Titanium Nitride Films as Carbon-Free Sulfur Hosts for Flexible Lithium–Sulfur Batteries

Au-coated carbon fabric as Janus current collector for dendrite-free flexible lithium metal anode and battery

Composite lithium metal anodes with three-dimensional (3D) conductive fabric present great potential to be used in high-energy-density flexible batteries for next-generation wearable electronics. However, lithium dendrites at the top of the fabric anode increase the risk of separator piercing and, therefore, cause a high possibility of short circuits, especially when undergoing large mechanical deformation. To ensure the safe application of the flexible lithium metal batteries, we herein propose a 3D Janus current collector by a simple modification of the bottom side of carbon fabric (CF) with a lithiophilic Au layer to construct highly flexible, stable, and safe Li metal anodes. The Janus Au layer can guide an orientated deposition of Li to the bottom of the CF. The lithium dendrite problem can be largely alleviated due to the lithium-free interface between the anode and separator, and meanwhile, the porous upper skeleton of the CF also provides large space to buffer the volume expansion of lithium metal. The resulting composite lithium metal anode exhibits a significant improvement in the life cycle (∼two fold) compared to the traditional top deposition of lithium metal. More importantly, assembled full batteries using the Janus anode structure exhibit high stability and safety during severe mechanical deformation, indicating the opportunity of the orientated deposition strategy to be used in future flexible and wearable electronics.

Garnet ceramic fabric-reinforced flexible composite solid electrolyte derived from silk template for safe and long-term stable All-Solid-State lithium metal batteries

All-solid-state lithium batteries (ASSLBs) using solid electrolytes are considered the most promising candidate for next-generation lithium-ion batteries owing to their high energy density and safety. However, the low ionic conductivity and limited electrochemical windows of the solid electrolytes limit the practical applications of ASSLBs. Herein, we demonstrate a simple and scalable method to prepare a solid electrolyte consisting of Li7La3Zr2O12 (LLZO) ceramic fabric by using silk as the template to form a sandwich-structured garnet LLZO ceramic fabric composite solid electrolyte (LLZO CF-CSE). The flexible LLZO CF-CSE shows remarkable thermostability and electrochemical stability (wide electrochemical window of 5.1 V vs. Li+/Li). The lithium symmetrical battery fabricated using LLZO CF-CSE can stably cycle without short circuit for 700 h at 50 °C. The ASSLB based on LiFePO4 cathode delivers high reversible capacity and excellent cycle stability at 50 °C (149.3 mAh g − 1 after 100 cycles at 0.2 C, and 107.2 mAh g − 1 after 500 cycles at 1 C). In addition, the flexible lithium metal pouch battery operates safely and stably under extreme conditions. This work provides a novel strategy for designing ceramic electrolytes with unique structures and high-energy, safe, and long-term stable ASSLBs.

Crocodile skin inspired rigid-supple integrated flexible lithium ion batteries with high energy density and bidirectional deformability

Flexible lithium ion batteries (FLIBs), considered as the most promising energy source for flexible planar electronic devices especially for portable phones and laptops, have attracted great attention. However, it is a critical challenge to achieve high energy density and high flexibility simultaneously. Herein, we demonstrate a novel and rational rigid-supple integrated FLIB inspired by crocodile skin. The thick, rigid parts for storing the most energy correspond to the osteoderm of crocodile skin, while the thin, supple parts are regarded as dermis of crocodile skin, providing outstanding bidirectional flexibility for planar flexible electronics. The fabricated battery, containing LiNi0.5Co0.2Mn0.3O2-based cathode and graphite-based anode, shows a record-setting volumetric energy density of 400.3 Wh L−1. More importantly, it can maintain stable electrochemical performance with 92.3% capacity retention and 0.038% capacity decay per cycle even undergo 30,000 times bending and after 200 charge/discharge cycles. Furthermore, the electrochemical property of the battery is confirmed by the tough dynamic bending test, including over 13,000 bidirectional bending times. Meanwhile, mechanical simulation results reveal its flexible mechanism. Accordingly, the reported bidirectional FLIB provides great promise for future practical applications in flexible devices.

Freestanding and Sandwich MXene-Based Cathode with Suppressed Lithium Polysulfides Shuttle for Flexible Lithium-Sulfur Batteries.

Flexible lithium-sulfur (Li-S) batteries with high mechanical compliance and energy density are highly desired. This manuscript reported that large-area freestanding MXene (Ti3C2Tx) film has been obtained through a scalable drop-casting method, significantly improving adhesion to the sulfur layer under the continuously bent. Titanium oxide anchored on holey Ti3C2Tx (TiO2/H-Ti3C2Tx) was also produced by the well-controlled oxidation of few-layer Ti3C2Tx, which greatly facilitates lithium ion transport as well as prevents the shuttling of lithium polysulfides. Therefore, the obtained sandwich electrode has demonstrated a high capacity of 740 mAh g-1 at 2 C and a high capacity retention of 81% at 1 C after 500 cycles. Flexible Li-S batteries based on this sandwich electrode have a capacity retention as high as 95% after bending 500 times. This work provides effective design strategies of MXene for flexible batteries and wearable electronics.

An integrate and ultra-flexible solid-state lithium battery enabled by in situ polymerized solid electrolyte

Searching for ultra-safe flexible electrolytes is crucial to the exploitation of flexible solid-state batteries and wearable devices. However, it is very challenging to simultaneously conquer the issues of the elastic electrolyte, including low ionic conductivity, inferior electrolyte/electrode interface compatibility, and unsatisfying cycling stability of the assembled cell. Herein, we developed an elastic PEL electrolyte using poly(butyl acrylate) cross-linked polyethylene glycol and EMIMTFSI with an ultrahigh elongation of 1000%. The PEL-0.1 electrolyte delivers an ionic conductivity of 1.19 × 10−4 S cm−1 and good flame resistance. The superior interface compatibility between electrodes and electrolyte is realized by the in situ polymerized PEL on cathode and contact stability towards metallic lithium, which facilitates the ion conduction in the solid-state cell and accommodate the electrode volume changes during the charge/discharge processes. The Li/PEL-0.1/Li cell can stable cycle for 300 h at 50 mV. The little difference in the impedance of the tabulate and wire-shaped solid-state batteries at various deformation states demonstrates the good shape conformability and feasibility of flexible PEL electrolyte. The integrated LiFePO4/PEL-0.1/Li batteries show excellent cycling stability at all the temperatures of 25 °C, 40 °C and 60 °C. A series of destructive operations on the working pouch cell confirms the superior safety and practicability of the designed electrolyte. The study proposed a promising ultrasafe and flexible electrolyte with outstanding electrochemical performance in the applications of the next-generation flexible solid-state lithium batteries and wearable devices.

Tunable surface pseudocapacitance assisted fast and flexible lithium storage of graphene wrapped NiO nano-arrays on nitrogen-doped carbon foams

Advanced materials incorporating battery-like high capacity and capacitor-like high rate capability hold promise for achieving both high energy and power density lithium ion batteries (LIBs). However, capacitive behavior for high capacity NiO anode has seldom been reported because the surface or near-surface fast faradic surface redox reactions highly depends on specific structure design. Herein, a flexible electrode that graphene wrapped NiO nanosheet arrays anchor on three-dimensional porous nitrogen-doped carbon foam (rGO@NiONCF) is fabricated. The rGO@NiONCF composite possesses a unique sandwich structure with 3D porous NCF as the inner conductive scaffold, ultrathin NiO nanosheet arrays as a middle layer, and rGO as the outer conductive buffer layer. The elaborated structure design endows rGO@NiONCF with enhanced electronic conductivity, sufficient electrolyte infiltration and restricted volume variation. As a result, the rGO@NiONCF electrode delivers high reversible capacity (1583 mAh g−1 at 0.1 A g−1) and superior cycling stability (maintains 607 mA h g−1 at 1 A g−1 after 500 cycles). Moreover, the enhanced surface capacitance adroitly facilitates an impressive fast charge and slow discharge performance. These results reveal that rational material design to encourage pseudocapacitance effect is a valuable roadmap for NiO-based battery towards more practical applications.

Quasi-solid electrolytes with tailored lithium solvation for fast-charging lithium metal batteries

Using quasi-solid electrolytes (QSEs) can make lithium metal batteries (LMBs) considerably safer. However, formulating QSEs with rate capabilities rivaling those of liquid electrolytes is extremely difficult. Herein, we develop a QSE characterized by safety, high conductivity above 2 × 10 −3 S cm −1 , and high lithium-ion transference number ( t Li + ) above 0.8. Computations and experiments reveal that these characteristics are achieved by adjusting the Li + solvation through a weak interaction with the polymer skeleton and strong coordination with NO 3 − . The further inclusion of fluoroethylene carbonate leads to the formation of a Li 3 N- and LiF-rich solid electrolyte interphase on the lithium metal. Consequently, QSE-based LMBs are capable of fast charging and high-power density, as well as stable and long cycling. By adjusting Li + solvation and lithium metal stability, this work rationally develops QSEs for fast-charging LMBs. • Quasi-solid electrolyte prepared with high-donor-number solvent and LiNO 3 • In-depth investigations on lithium solvation and ion transport by atomic simulations • Fast-charging lithium metal battery based on the QSE • Safe, flexible, and non-flammable pouch-type lithium metal battery Zhou et al. design a quasi-solid electrolyte with tailored lithium solvation and diffusion for fast-charging lithium metal batteries. The impact of the high-donor number solvent and LiNO 3 on solvation and charge-transfer mechanisms is studied experimentally and computationally.

Flexible self-charging lithium battery for storing low-frequency mechanical energy

Flexible self-charging power source, with admirable capability to harvest/store the energy generated by human motion, is considered as the most suitable power supply for next generation of wearable electronic devices. Herein, we demonstrated a flexible self-charging lithium battery for storing low-frequency tiny motion energy. The electrospinning polyvinylidene fluoride-trifluoro ethylene (P(VDF-TrFE)) porous membranes was adopted as a piezoelectric separator and a supporting layer of the electrode to fabricate a novel flexible self-charging power cell (SCPC). The flexible SCPC could be effectively charged by directly collecting movement energy through mechanical deformation. The SCPC sealed in flexible case could be charged via periodic tapping (6 N, 1 Hz), indicating a storage capacity of 0.092 μA h in 330 s. Compared with traditional self-charging batteries, the flexible SCPC can work effectively at lower frequency and pressure, and collect the tiny motion energy of human body to power wearable electronic devices. This work may provide an innovative way to develop new self-charging wearable electronic devices.

A flexible thin film lithium battery with a chemical vapor deposited organic complex cathode

Organic cathode materials have attracted significant research attention recently, yet their low electronic conductivity limits their application as solid-state cathodes in lithium batteries.

Ti-Doped Fe2o3/Carbon Cloth Anode with Oxygen Vacancies and Partial Rgo Encapsulation for Flexible Lithium Ion Batteries

Ti-Doped Fe2o3/Carbon Cloth Anode with Oxygen Vacancies and Partial Rgo Encapsulation for Flexible Lithium Ion Batteries

Mxene Enabled Binder-Free Feof Cathode with High Volumetric and Gravimetric Capacities for Flexible Lithium Ion Batteries

Mxene Enabled Binder-Free Feof Cathode with High Volumetric and Gravimetric Capacities for Flexible Lithium Ion Batteries

Lithium Storage Mechanism and Application of Micron‐Sized Lattice‐Reversible Binary Intermetallic Compounds as High‐Performance Flexible Lithium‐Ion Battery Anodes (Small 2/2022)

Lithium–Ion Batteries In article number 2105172, Jiaping Wang and co-workers propose lattice-reversible binary intermetallic compounds with zinc blende structure as a promising anode material for high-performance flexible lithium–ion batteries. The micron-sized indium antimonide/carbon nanotube electrodes with low volume expansion demonstrate outstanding cycle stability, rate performance, and flexibility.

Self‐Healing and Flexible Ionic Gel Polymer Electrolyte Based on Reversible Bond for High‐Performance Lithium Metal Batteries

The low ionic conductivity, poor interface contact, and low safety of the electrolytes are the main problems in the practical application in flexible lithium metal batteries. A new type of chemical crosslinked ionic gel polymer electrolyte (IGPE) with good self‐healing ability and excellent electrochemical properties is designed based on polyoxyethylenebis(amine), and 1,3,5‐benzenetricarboxaldehyde in the presence of ionic liquid through a one‐step reaction. The interaction between ionic liquid and polymer with the ether oxygen atom of EO chains improves the stability of IGPE and the crystallinity decreased significantly due to the incorporation of ionic liquid. The IGPEs show good self‐healing, film flexibility, and high ionic conductivity even at −25 °C. They also possess high thermal stability, wide electrochemical stability window, and good interfacial compatibility. The Li/IGPE‐50/LiFeO4 battery with IGPE‐50 as an electrolyte is studied and the high discharge capacity of 154.8 mAh g−1 is obtained at 0.1 C with 99.6% of coulombic efficiency, and remains 132.8 mAh g−1 on the 50th cycle. Ionic liquid combined with polymers based on dynamic reversible bonds can optimize the electrochemical performance of IGPEs, and improve its safety and stability, which is very useful for flexible lithium metal batteries.

Ultra-flexible and foldable gel polymer lithium–ion batteries enabling scalable production

Flexible lithium–ion batteries are an emerging and promising technology for next-generation flexible devices; however, some potential problems, such as potential safety hazards of organic liquid electrolytes, severe capacity loss caused by poor adhesion between electroactive materials and current collectors, and the unscalable production of flexible current collectors, prevent flexible batteries from being used in practice. This study demonstrates a safety reinforced ultra-flexible and foldable lithium–ion battery using LiCoO2 (LCO) as the cathode, Li4Ti5O12 (LTO) as the anode, a high-quality carbon nanotubes film as a flexible current collector, and a novel porous composite as the gel polymer electrolyte. The flexible battery exhibits superior electrochemical performance compared to other flexible batteries reported, with a capacity retention rate of 93% after 150,000 cycles of mechanical bending. The gravimetric energy density of the flexible electrodes is 1.6 times higher than that of standard electrodes using metal foils as current collectors. More importantly, the flexible battery offers extreme safety performance and performs very well under various severe conditions, such as repeated folding and punching. These results demonstrate the promising potential of flexible batteries for many wearable applications and offer a new platform for the scalable production of flexible and wearable energy storage technologies.

Rational Design of Li-Wicking Hosts for Ultrafast Fabrication of Flexible and Stable Lithium Metal Anodes.

The ever-increasing development of flexible and wearable electronics has imposed unprecedented demand on flexible batteries of high energy density and excellent mechanical stability. Rechargeable lithium (Li) metal battery shows great advantages in terms of its high theoretical energy density. However, the use of Li metal anode for flexible batteries faces huge challenges in terms of its undesirable dendrite growth, poor mechanical flexibility, and slow fabrication speed. Here, a highly scalable Li-wicking strategy is reported that allows ultrafast fabrication of mechanically flexible and electrochemically stable Li metal anodes. Through the rational design of the interface and structure of the wicking host, the mean speed of Li-wicking reaches 10 m2 min-1 , which is 1000 to 100000 fold faster than the reported electrochemical deposition or thermal infusion methods and meets the industrial fabrication speed. Importantly, the Li-wicking process results in a unique 3D Li metal structure, which not only offers remarkable flexibility but also suppresses the dendrite formation. Paring the Li metal anode with lithium-iron phosphate or sulfur cathode yields flexible full cells that possess a high charging rate (8.0mA cm-2 ), high energy density (300-380Wh kg-1 ), long cycling stability (over 550 cycles), and excellent mechanical robustness (500 bending cycles).

Flexible Tellurium-Based Electrode for High-Performance Lithium-Tellurium Battery.

Low-dimensional nanomaterials have attracted considerable attention for next-generation flexible energy devices owing to their excellent electrochemical properties and superior flexibility. Herein, uniform Tellurium nanotubes (Te NTs) were prepared through a facile hydrothermal method, and then a flexible and freestanding electrode was fabricated with Te NTs as active materials and a small amount of nanofibrillated celluloses (NFCs) as a flexible matrix through a vacuum filtration method without adding extra conductive carbon or a binder. The resulting Te-based electrode exhibits a high volumetric capacity of 1512 mAh cm−3 at 200 mA g−1, and delivers admirable cyclic stability (capacity retention of 104% over 300 cycles) and excellent rate performance (833 mAh cm−3 at 1000 mA g−1), which benefits from the unique structure and intrinsically superior conductivity of Te NTs. After bending 50 times, the Te-based electrode delivers a desirable volumetric capacity of 1117 mAh cm−3, and remains 93% of initial capacity after 100 cycles. The results imply that the Te-based electrode exhibits excellent electrochemical properties and superior flexibility simultaneously, which can serve as a potential candidate for the flexible lithium batteries.

Collectively Exhaustive MXene and Graphene Oxide Multilayer for Suppressing Shuttling Effect in Flexible Lithium Sulfur Battery

AbstractThe shuttling effect of lithium polysulfide (LiPS), which leads to the gravest capacity degradation, is one of the critical problems to hindering the commercialization of lithium–sulfur batteries (LSBs). Here, collectively exhaustive Ti3C2Tx MXene and graphene oxide (GO) multilayers are reported to suppress the shuttling effect by utilizing both physical inhibition of micro/mesoporous and chemical absorption of surface functional groups. The abundant surface functional groups of GO and MXene attract the positively charged lithium ion (Li+) and eject the negatively charged polysulfides (Sn2–) through electrostatic affinity and repulsion. A simple approach using vacuum filtration is utilized to encapsulate elemental sulfur (S8) between GO and MXene film (GSM), acting as a permselective separator and functionalized current collector, respectively. The functionally antagonistic GSM directly plays a role in a cathode for LSBs and exhibits a specific capacity of 1425 mAh g–1 at 0.1C in the initial cycle. The abundant functional groups, which can chemisorb the LiPSs, result in a high cyclic retention of ≈85.1% after 500 cycles. Furthermore, a flexible LSB is demonstrated with a PEO‐LiTFSI electrolyte based on the flexibility of the exceptionally thin GSM due to the 2D nanomaterials, MXene and graphene oxide.

Six-armed and dicationic polymeric ionic liquid for highly stretchable, nonflammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte for flexible and safe lithium batteries

Solid-state polymer electrolytes (SPEs) with outstanding flexibility and self-healing capacity are appealing for utilization in reliable and wearable electronic devices. Herein, a highly stretchable (extensibility > 1500% and stress > 490 kPa), non-flammable and notch-insensitive intrinsic self-healing SPE based on six-armed poly(N,N,N-trimethyl-N-((2-(dimethylamino)ethyl methacrylate)-7-propyl)-ammonium dual bis(trifluoromethanesulfonyl) imides), imidazole-based ionic liquid (EMIM–TFSI) and LiTFSI is fabricated. The multi-armed structure in combination with the multiple charged center endow the six-armed dicationic polymeric ionic liquid (DPIL-6) with significantly strengthened ionic attractions and Van der Waals' force among the polymer segments, thus conferring the DPIL-6 derived SPE (DPIL-6-SPE) with prominent self-healing ability (recovery time < 2 h, 25 ℃). Moreover, DPIL-6-SPE presents a superior adhesion strength (weight loading > 200 g) towards lithium electrode, signifying excellent interfacial compatibility. Compared with the counterpart of monocationic polymeric ionic liquid derived SPE (MPIL-6-SPE), the multiple cationic center in DPIL-6-SPE facilitates the dissociation of lithium salt and liberates more Li+ from trapping with TFSI-, thereby resulting in a superior ionic conductivity (over 10-5 S cm−1 at room temperature) and lithium ion transference number (0.46). The as-assembled LiFePO4/DPIL-6-SPE/Li battery can deliver a high discharge capacity of 152.6 mAh g−1 at 0.1C, and its capacity retention rate reaches 94% after 50 cycles with a coulombic efficiency of 96%. In particular, the mechanical properties and conductivity of DPIL-6-SPE can fully recover after repeated damage, conferring the derived soft-pack battery stable powering capacity upon multi-angle bending and folding. The design of multi-armed and multiple charged PILs provides new avenues for developing flexible electronic devices with self-healing capacity.