Solid-state Polymer Electrolytes Research Articles

Multisalt chemistry in ion transport and interface of lithium metal polymer batteries

Solvent-free solid-state polymer electrolytes (SPE) that go beyond the barriers like intrinsic low ionic conductivity, slow ion dynamics, and unstable electrode-electrolyte interphase will be fundamental for realizing the next generation of safe and high-performance lithium metal batteries. Hereby, cross-linked solid polymer electrolyte (XSPE) networks based on multisalt chemistry are synthesized using photopolymerization reaction, which outshine the conventional single salt-based XSPEs. By introducing the multisalt chemistry, an enhanced Li+ ion transport (ionic conductivity and short residence time) via anion mediated transfer (AMT) and improved interfacial characteristics (e.g., stable Li|electrolyte interphase, smooth Li-deposition) are demonstrated. Furthermore, a three-times increase in Li+ ion transference number and nearly one order of magnitude increment in diffusion coefficient are achieved. Using theoretical calculations, we propose an AMT-based ion conduction pathway in multisalt-based XSPEs. Besides, the superior electrochemical performance of multisalt-based XSPEs compared to single salt-based polymer electrolytes in Li-metal polymer batteries (LMPB) using C-LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes are successfully demonstrated.

Application of a Modified Porphyrin in a Polymer Electrolyte with Superior Properties for All-Solid-State Lithium Batteries.

Porphyrins and their derivatives are a unique class of multifunctional and modifiable π-conjugated heterocyclic organic molecules, which have been widely applied in the fields of optoelectronic devices and catalysis. However, the application of porphyrins in polymer electrolytes for all-solid-state lithium-ion batteries (ASSLIBs) has rarely been reported. Herein, porphyrin molecules modified by polyether chains are used for composite solid-state polymer electrolytes (CSPEs) for the first time. The introduction of a modified porphyrin in an electrolyte can not only promote the electrochemical properties by constructing ordered ion channels via the intermolecular interaction between π-conjugated heterocyclic porphyrins, but also significantly improve the mechanical strength and interface contact between the electrolyte membrane and the lithium metal anode. Consequently, the all-solid-state batteries assembled by the modified porphyrin composite polymer electrolyte, LiFePO4 cathodes, and Li anodes deliver a higher discharge capacity of 158.2 mA h g-1 at 60 °C, 0.2 C, which remains at 153.6 mA h g-1 after 120 cycles with an average coulombic efficiency of ∼99.60%. Furthermore, the flexible porphyrin-based composite polymer electrolyte can also enable a Li || LiCoO2 battery to exhibit a maximum discharge capacity of 108.6 mA h g-1 at 60 °C, 0.1 C with an active material loading of 2-3 mg cm-2, which is unable to realize for the corresponding batteries with a pure PEO-based polymer electrolyte. This work not only broadens the application scope of porphyrins, but also proposes a novel method to fabricate CSPEs with improved electrochemical and mechanical properties, which may shed new light on the development of CSPEs for next-generation high-energy-density lithium-ion batteries.

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.

Cationic Cyclopropenium-Based Hyper-Crosslinked Polymer Enhanced Polyethylene Oxide Composite Electrolyte for All-Solid-State Li-S Battery.

The development of solid-state polymer electrolytes is an effective way to overcome the notorious shuttle effect of polysulfides in traditional liquid lithium sulfur batteries. In this paper, cationic cyclopropenium based cross-linked polymer was firstly prepared with the one pot method, and then the counter ion was replaced by TFSI− anion using simple ion replacement. Cationic cyclopropenium hyper-crosslinked polymer (HP) was introduced into a polyethylene oxide (PEO) matrix with the solution casting method to prepare a composite polymer electrolyte membrane. By adding HP@TFSI to the PEO-based electrolyte, the mechanical and electrochemical properties of the solid-state lithium-sulfur batteries were significantly improved. The PEO-20%HP@TFSI electrolyte shows the highest Li+ ionic conductivity at 60 °C (4.0 × 10−4 S·cm−1) and the highest mechanical strength. In the PEO matrix, uniform distribution of HP@TFSI inhibits crystallization and weakens the interaction between each PEO chain. Compared with pure PEO/LiTFSI electrolyte, the PEO-20%HP@TFSI electrolyte shows lower interface resistance and higher interface stability with lithium anode. The lithium sulfur battery based on the PEO-20%HP@TFSI electrolyte shows excellent electrochemical performance, high Coulombic efficiency and high cycle stability. After 500 cycles, the capacity of the lithium-sulfur battery based on PEO-20%HP@TFSI electrolytes keeps approximately 410 mAh·g−1 at 1 C, the Coulomb efficiency is close to 100%, and the cycle capacity decay rate is 0.082%.

Progress in Solid Polymer Electrolytes for Lithium-Ion Batteries and Beyond.

Solid-state polymer electrolytes (SPEs) for high electrochemical performance lithium-ion batteries have received considerable attention due to their unique characteristics; they are not prone to leakage, and they exhibit low flammability, excellent processability, good flexibility, high safety levels, and superior thermal stability. However, current SPEs are far from commercialization, mainly due to the low ionic conductivity, low Li+ transference number (tLi+ ), poor electrode/electrolyte interface contact, narrow electrochemical oxidation window, and poor long-term stability of Li metal. Recent work on improving electrochemical performance and these aspects of SPEs are summarized systematically here with a particular focus on the underlying mechanisms, and the improvement strategies are also proposed. This review could lead to a deeper consideration of the issues and solutions affecting the application of SPEs and pave a new pathway to safe, high-performance lithium-ion batteries.

Exploring the Ion Solvation Environments in Solid-State Polymer Electrolytes through Free-Energy Sampling

The success of poly(ethylene oxide) (PEO) in solid-state polymer electrolytes for lithium-ion batteries is well established. Recently, in order to understand this success and to explore possible alternatives, we studied polyacetal electrolytes to deepen the understanding of the effect of the local chemical structure on ion transport. Advanced molecular dynamics techniques using newly developed, tailored interaction potentials have helped elucidate the various coordination environments of ions in these systems. In particular, the competition between cation–anion pairing and coordination by the polymer has been explored using free-energy sampling (metadynamics). At equivalent reduced temperatures, with respect to the polymer-specific glass-transition temperature, two-dimensional free-energy plots reveal the existence of multiple coordination environments for the lithium (Li) ions in these systems and their relative stabilities. Furthermore, we observe that the Li-ion movement in PEO follows a serial, stepwise pathway when moving from one coordination state to another, whereas this happens in a more continuous and concerted fashion in a polyacetal such as poly(1,3-dioxalane) [P(EO-MO)]. The implication is that interconversion between coordination states of the Li ions may be easier in P(EO-MO). However, the overarching observation from our free-energy analysis is that Li-ion coordination is dominated by the polymer (in either case) and contact-ion pairs are rare. We rationalize the observed higher increase in glass-transition temperature (Tg) with salt loading in polyacetals as due to intermolecular Li-ion coordination involving multiple polymer chains, rather than just one chain for PEO-based electrolytes. This interchain coupling in the polyacetals, resulting in the higher Tg, works against any gains due to variations in Li-ion coordination that might enhance transport processes over PEO. Further research is required to overcome the interdependence between local coordination and macroscopic properties to compete with PEO electrolytes at the same absolute working temperature.

A ketone-containing all-solid-state polymer electrolyte with rapid Li-ion conduction for lithium metal batteries

Solid-state polymer electrolytes (SPEs) have gained considerable attention in the application of all-solid-state lithium batteries (ASSLBs), but the low ionic conductivity at room temperature and inferior interfacial compatibility largely drag the practical development of SPEs. Herein, a ketone-containing poly(allyl acetoacetate) (PAAA) based polymer electrolyte is designed and prepared for the first time. The structure of ester and ketone groups provides PAAA polymers with not only strong dissociation of lithium salts but also weak coordination interactions with Li+ ions. Thus the prepared PAAA polymer electrolytes show excellent ion conductive behavior with ionic conductivity as high as 1.1 × 10-4 S cm−1 at 30 °C. Moreover, the PAAA polymer electrolytes still maintain superior viscoelasticity without compromising mechanical integrity. When assembling cells, the reduction-tolerant poly(ethylene oxide) (PEO) polymer electrolytes are employed as interlayers between the PAAA SPEs and lithium electrodes in order to improve interfacial stability. As a result, the hierarchical polymer electrolytes possess wide electrochemical window above 4.8 V, thus matching well with LiFePO4 or Li1.2Ni0.2Mn0.6O2 high-voltage cathode. The hierarchical structure does not affect interfacial contact, and the Li/PEO-PAAA-PEO/Li cells show low interfacial resistance and stable striping/plating behavior for at least 500 h at 0.2 mA cm−2 and 60 °C. This study enriches carbonyl-based polymer electrolytes by allying ketone with ester groups, and provides guidance for designing novel high-performance polymer electrolytes for practical application.

Solid-state polymer electrolytes with polypropylene separator-reinforced sandwich structure for room-temperature lithium ion batteries

Solid-state polymer electrolytes (SSPEs) for room-temperature lithium ion batteries (LIBs) usually suffer from the uncontrollable lithium dendrite propagation due to the mechanical weakness. Herein, through a facile double-side coating strategy, novel sandwich-like poly (vinylidene fluoride) (PVDF)-based electrolyte membranes that are mechanically reinforced by polypropylene (PP) separator are successfully developed for high-performance room-temperature solid-state LIBs. With a small amount of bound dimethylformamide (DMF) to serve as a plasticizer for the PVDF polymer host, the as-prepared PVDF/PP SSPEs achieve a high ionic conductivity of 1.53 × 10−4 S cm−1. The robust commercial PP separator can significantly improve the mechanical properties of the sandwich SSPEs, and more importantly it functions as physical obstacle here to restrain lithium dendrite growth during the repeated charge-discharge cycling. The solid-state batteries assembled with the PVDF/PP SSPEs, LiFePO4 (LFP) cathode and lithium anode thus exhibit dramatically enhanced cycling performance compared with the batteries based on blank PVDF SSPEs, delivering a high specific capacitance of 134 mAh g−1 and 97% capacity retention over 180 cycles under 0.3C at room temperature. Such high-performance PVDF/PP SSPEs with the facile and scalable fabrication, together with the low-cost and widely available raw materials, are highly promising electrolytes for room-temperature solid-state LIBs.

Defect-enriched hydroxyapatite induced by carboxylated chitosan as novel filler for pseudo solid-state supercapacitors

BackgroundThe severe crystalline region in pseudo solid-state polymer electrolyte needs to be addressed to improve the poor ionic conductivity performance. MethodsHydroxyapatite (HA) with rich defect, induced by carboxylated chitosan (CCS) via hydrothermal process is applied to serve as active filler for pseudo solid-state supercapacitor. Significant findingsCCS2 with high degree of carboxylation (DC) of 42.38% is introduced as defect inducing agents to generate CCS2-HA. CCS2-HA possesses small crystallinity index evaluated by FTIR and XRD. Moreover, the obvious structural defect of CCS2-HA in [301] orientation was observed from HRTEM. With CCS2-HA as defect-enriched filler, the crystallization temperature decreases from 75 to 65 °C. Meanwhile, the activation energy for the ionic conductivity decreases from 2.3 to 1.3 kJ/mol. Meanwhile, the loss tangent peak shifts to higher frequency with smaller intensity in the addition of CCS2-HA as active filler, showing the smaller relaxation time and less heat resistance than the pristine. CCS2-HA possessed rich defects to reduce crystalline region, increase amorphous region, enhance segmental motion, and assist short range ion migration for less internal resistance and heat dissipation as novel filler for superior solid-state energy storage devices.

Unique Carbonate-Based Single Ion Conducting Block Copolymers Enabling High-Voltage, All-Solid-State Lithium Metal Batteries.

Safety and high-voltage operation are key metrics for advanced, solid-state energy storage devices to power low- or zero-emission HEV or EV vehicles. In this study, we propose the modification of single-ion conducting polyelectrolytes by designing novel block copolymers, which combine one block responsible for high ionic conductivity and the second block for improved mechanical properties and outstanding electrochemical stability. To synthesize such block copolymers, the ring opening polymerization (ROP) of trimethylene carbonate (TMC) monomer by the RAFT-agent having a terminal hydroxyl group is used. It allows for the preparation of a poly(carbonate) macro-RAFT precursor that is subsequently applied in RAFT copolymerization of lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide and poly(ethylene glycol) methyl ether methacrylate. The resulting single-ion conducting block copolymers show improved viscoelastic properties, good thermal stability (Tonset up to 155 °C), sufficient ionic conductivity (up to 3.7 × 10–6 S cm–1 at 70 °C), and high lithium-ion transference number (0.91) to enable high power. Excellent plating/stripping ability with resistance to dendrite growth and outstanding electrochemical stability window (exceeding 4.8 V vs Li+/Li at 70 °C) are also achieved, along with enhanced compatibility with composite cathodes, both LiNiMnCoO2 – NMC and LiFePO4 – LFP, as well as the lithium metal anode. Lab-scale truly solid-state Li/LFP and Li/NMC lithium-metal cells assembled with the single-ion copolymer electrolyte demonstrate reversible and very stable cycling at 70 °C delivering high specific capacity (up to 145 and 118 mAh g–1, respectively, at a C/20 rate) and proper operation even at a higher current regime. Remarkably, the addition of a little amount of propylene carbonate (∼8 wt %) allows for stable, highly reversible cycling at a higher C-rate. These results represent an excellent achievement for a truly single-ion conducting solid-state polymer electrolyte, placing the obtained ionic block copolymers on top of polyelectrolytes with highest electrochemical stability and potentially enabling safe, practical Li-metal cells operating at high-voltage.

Preparation of single-ion conductor solid polymer electrolyte by multi-nozzle electrospinning process for lithium-ion batteries

In this work, a method for preparing solid polymer electrolytes with function of single ion conduction (SICs-SPEs) is developed and reported. A solid state ionic conduction path with three-dimensional interpenetrating network was constructed by multi-nozzle electrospinning technology and a followed hot pressed treatment. Here, two components of SICs-SPEs were chosen where one component is a single ion conducting lithium salt with polyanion structure, and the other component is a solid polymer electrolyte matrix with the function of conducting lithium ions in solid state. This stable three-dimensional interpenetrating network structure is beneficial to inhibit the separation of the two components. At the same time, the introduction of hydrophilic and hydrophobic silica (SiO2) reduces the crystallinity of polyethylene oxide (PEO) and promotes the dissociation of lithium ions, respectively, thereby the ionic conductivity of the prepared single-ion conductor solid polymer electrolyte can be increased to 5.4 × 10−5 S cm−1 at 60 °C, and the lithium-ion transference number (tLi+) can be increased to 0.96. This method can also adjust the performance of the solid state polymer electrolyte through balancing the ration of composition by controlling the number of spinning nozzle. It provides a practical way to develop functional solid polymer electrolyte by electrospinning technology with nozzle design.

Multifunctional polymer bottlebrush-based gel polymer electrolytes for lithium metal batteries

Solid-state polymer electrolytes (SPEs) are considered to be promising in solving the safety problems caused by the leakage of liquid electrolytes and the growth of lithium dendrite. However, the major challenge to realize practical applications is how to develop high-performance SPEs with superb interfacial contact, high ionic conductivity at room temperature, and mechanical robustness. Herein, a novel kind of multifunctional polymer bottlebrush (BC-g-PEGM)-based gel polymer electrolytes (BC-g-PEGM-GPEs) is designed and prepared. The as-obtained BC-g-PEGM-GPEs integrate features of BC backbone-strengthened nanonetwork, polymer brush-enhanced interfacial compatibility, and abundant lithium-ion conducting domains from polymer brushes. As a result, BC-g-PEGM-GPEs exhibit good mechanical properties (Young's modulus = 5.0 MPa, toughness = 316.7 KJ/m3) and high ionic conductivity of 2.7 × 10−4 S/cm at room temperature. The Li/Li symmetric batteries with BC-g-PEGM-GPEs show stable cycling over 1200 h at a current density of 0.5 mA/cm2. Furthermore, both Li/LiFePO4 and Li/Li4Ti5O12 batteries using BC-g-PEGM-GPEs exhibit desirable cycling stability and good rate performance at room temperature, suggesting that this new GPE system has great potential for practical applications in lithium metal batteries.

Agent molecule modulated low-temperature activation of solid-state lithium-ion transport for polymer electrolytes

Low-temperature activation of lithium-ion migration is crucial for enabling the practical application of solid-state polymer electrolytes for lithium-ion batteries. In this study, we perform a series of first-principle calculations and demonstrate that certain types of neutral molecules (so-called agent molecules) accelerate solid-state lithium-ion migration when mixed with lithium salts. We find that the intermolecular interaction in a selected agent-molecule/lithium-salt binary system is governed by the strong coupling between lithium and oxygen atoms. Upon the addition of agent molecules, the anionic species surrounding the lithium of lithium salts is replaced by the agent molecules. The resulting weakened Coulomb energy coupling between lithium and oxygen atoms is determined to be a key factor in enabling fast lithium-ion migration via facile dissociation of lithium salts and subsequent formation of ion-hopping sites in the form of lithium-free oxygen-cages. The structure-based interpretation of agent molecules suggests that neutral molecules with functional groups which enhance chemical resonance can be selected as potential agent molecules. We believe that the results obtained in this study serve as a theoretical basis for the future development of solid-state polymer electrolytes, particularly toward mitigating the dependence of lithium-ion transport on the movement of polymer chains.

Exploring the Ion Solvation Environments in Solid-State Polymer Electrolytes through Free-Energy Sampling

Lithium-ion batteries are high energy density power sources that find uses in the automobile industry for electric cars and various portable devices like smartphones, laptops etc. There are strong motivations for developing solid-state electrolytes due to safety concerns associated with the combination of flammable liquid electrolytes and cell shorting due to lithium dendrite growth in current technology. A major issue with solid electrolytes is their low conductivity, which limits the power density (rate of charge/discharge), and possible loss of electrical contact due to anode shrinking. Lithium salts dissolved in poly(ether-acetals) are prime candidates for such electrolytes but the major challenge in improving the performance of these batteries is that the exact mechanism of the motion of the Li+ ions in such systems is not yet well understood. Our goal is to understand the underlying structural differences in the lithium coordination environments in these different systems and how this would affect the movement of the lithium ion from one coordination cage to another. This insight will allow us to suggest new compositions for electrolytes with improved performance for battery applications.Molecular dynamics simulations using newly developed, accurate interaction potentials have helped elucidate possible mechanisms for various transport properties in these systems. The presence of a second coordination shell around the Li ion, observed in some of these systems, seems to distort the first coordination shell, creating a more open cage structure that may help facilitate transport in these polymers. Furthermore, this distorted coordination may also assist in the formation of a lower coordination transition state while the Li ions jump from one cage to another during diffusion. This may be similar to the pathways followed in solid-state transport - either during topotactic intercalation, as ions move from interstitial to interstitial site; or within materials with solid-solid phase transitions related to thermally induced rotations of complex anions. Free energy calculations further elucidate the relative stability of these different Li-ether coordination environments and the possible pathways to move between them (See figure 1 for example). Furthermore, to understand the associated correlations of glass transition temperature in these systems with microscopic chemical details like the polymer backbone chemistry, ion clustering and coordination, we study the trends in these different systems with extensive statistics from long time molecular dynamics simulations at different temperatures and compositions. Figure 1

(Student Battery Slam Best Presentation Award Winner) “Water-in-Salt” Polymer Electrolyte for Li-Ion Batteries

Lithium ion batteries (LIBs) have been widely applied in multitudinous energy storage systems due to their high energy density, long cycle stability and high energy efficiency. While the public concern over the safety of LIBs increases rapidly with our reliance on this technology in our daily life, for which the nonaqueous and highly flammable electrolyte should bear most of the responsibility. Aqeuous rechargeable lithium ion batteries resolve several challenges of conventional LIBs. However, the electrochemical stability window of aqueous electrolytes is less than 2.0 V, beyond which the electrolysis of H2O with the hydrogen evolution reaction at anode (H2 generated) and oxygen evolution reaction at cathode (O2 generated). Recently, the ground-breaking of “water-in-salt” electrolyte (WiSE) successfully expanded the ESW of water to 3.0 V. To further enhance the energy density of WiSE based batteries, the cathodic limitation of 1.9 V needs to further reduced, and a high Coulombic efficiency (CE) of > 99.9% at a matched areal capacities of cathode/anode is required for a long-term cycling. Here, we designed a solid-state aqueous polymer electrolyte (SAPE) by incorporating WiSE with UV-curable methacrylic polymer. The abundant hydrophilic groups of the polymer stabilized water molecules due to the sluggish water mobility in SAPE and formed a water-less thin passivation interphase between anode and electrolyte. In addition, by pre-coating a strongly basic water-free solid polymer electrolyte on the surface of anode, an artificial passivation interphase was formed. A robust SEI was formed on the surface of anode and the water reduction reaction is suppressed in our electrolyte system. Also, an extended electrochemical stability window of 3.86 V is achieved at 12 mol kg-1 aqueous polymer electrolyte, enabling the 3 V full cells cycled with an unprecedented high initial CE of 90.5% and average CE of 99.97%. The SAPE exhibits intrinsic safety and tolerance of drastic mechanical abuse, the flexible full cell with supper robustness can be widely used for low-cost and high-safety flexible electronic devices. Moreover, the UV-cured polymerization process possesses the merit of facile and high efficiency, and the whole process have the potential to be practical used in a large scale. Overall, this newly developed reduced salt concentration WiSE not only reduces the cost of aqueous electrolyte, but also opens up another perspective on future directions and guidance for the design of aqueous electrolyte for high-energy-density Li-ion batteries in practical applications.

Zinc doped Fe2O3 hierarchical particles for stable all-solid-state Ni-Co/Fe battery

Fast growing demands in clean energy storage devices and wearable electronics trigged the developments of all-solid-state batteries. Here, we report the synthesis of Zinc doped Fe2O3 hierarchical particles (Zn-Fe2O3 HPs) with enhanced electrochemical performance. The capacity reaches 124 mAh g−1 at 2 A g−1 after annealing treatment at 400 °C. A good cycling stability has been achieved after 1500 cycles. Interestingly, morphology evolution of active materials during the cycling test has been observed. Furthermore, all-solid-state Ni-Co/Fe batteries have been assembled using annealed Zn-Fe2O3 HPs as positive electrode, Ni and Co layered double hydroxides (NiCo-LDHs) as positive electrode and polybenzimidazole doped with KOH (PBI-KOH) as solid-state polymer electrolyte and separator. The device delivers a high specific capacity of about 72 mAh g−1 at 0.5 A g−1 based on the total mass of active materials in two electrodes. More importantly, the device shows a good cycling stability after 6000 cycles. These features endow the PBI based all-solid-state Ni-Co/Fe battery a very competitive energy storage system candidate for the wearable electronics.

Polyethylene Oxide-Based Solid-State Composite Polymer Electrolytes for Rechargeable Lithium Batteries

Solid-state polymer electrolytes are considered to be the most promising electrolytes for next-generation high-energy rechargeable lithium batteries due to the advantages of high safety, good mecha...

Solid-State Polymer Electrolyte Solves the Transfer of Lithium Ions between the Solid–Solid Interface of the Electrode and the Electrolyte in Lithium–Sulfur and Lithium-Ion Batteries

The use of secondary batteries has been on the rise in recent years, especially solid-state batteries. However, security issues have become a major challenge in practical applications. Both lithium...

Use of Solid-State NMR Spectroscopy for the Characterization of Molecular Structure and Dynamics in Solid Polymer and Hybrid Electrolytes.

Solid-state NMR spectroscopy is an established experimental technique which is used for the characterization of structural and dynamic properties of materials in their native state. Many types of solid-state NMR experiments have been used to characterize both lithium-based and sodium-based solid polymer and polymer–ceramic hybrid electrolyte materials. This review describes several solid-state NMR experiments that are commonly employed in the analysis of these systems: pulse field gradient NMR, electrophoretic NMR, variable temperature T1 relaxation, T2 relaxation and linewidth analysis, exchange spectroscopy, cross polarization, Rotational Echo Double Resonance, and isotope enrichment. In this review, each technique is introduced with a short description of the pulse sequence, and examples of experiments that have been performed in real solid-state polymer and/or hybrid electrolyte systems are provided. The results and conclusions of these experiments are discussed to inform readers of the strengths and weaknesses of each technique when applied to polymer and hybrid electrolyte systems. It is anticipated that this review may be used to aid in the selection of solid-state NMR experiments for the analysis of these systems.

Cyclopropenium Cationic-Based Covalent Organic Polymer-Enhanced Poly(ethylene oxide) Composite Polymer Electrolyte for All-Solid-State Li-S Battery.

Cyclopropenium cationic-based covalent organic polymer (iCP@TFSI) was successfully prepared through the SN2 reaction and ion replacement process, which can be incorporated into the PEO/LiTFSI matrix as a filler. The obtained solid-state polymer electrolytes were utilized for an all-solid-state lithium-sulfur (Li-S) battery. Padding iCP@TFSI into the PEO matrix not only has a positive influence on both the ionic conductivity and the mechanical capacity of solid-state polymer electrolytes but also increases the stability of the lithium metal anode, which essentially improves the overall cycling ability of all-solid-state Li-S batteries. Among the membranes attained, the PEO-10%iCP@TFSI electrolyte displays the best ionic conductivity up to 1.2 × 10-3 S·cm-1 at 80 °C. The symmetrical lithium battery exhibits higher cycle stability (600 h) due to the higher mechanical properties related to more stable lithium metal interfaces. The Li-S battery based on the PEO-10%iCP@TFSI electrolyte exhibits excellent electrochemical performance with better Coulombic efficiency and outstanding cycling stability. Its capacity is maintained at 490 mAh·g-1 after 500 cycles at 1 C with a 0.032% decay rate each cycle, and the Coulombic efficiency is close to 100% during the whole cycling.