Room-Temperature Solid-State Lithium Metal Batteries Using Metal Organic Framework Composited Comb-Like Methoxy Poly(ethylene glycol) Acrylate Solid Polymer Electrolytes

Solid polymer electrolyte with good thermal stability and flexibility is an excellent candidate for solid-state lithium metal batteries, while its low ionic conductivity caused by high crystallinity limits its application at ambient temperature. Here a metal organic framework (zeolitic imidazolate framework-8, ZIF-8) composited comb-like methoxy poly(ethylene glycol) acrylate polymer electrolyte (MCPE) with high ionic conductivity (9.96 × 10⁻⁵ S cm⁻¹ at 30 °C) is prepared by an in situ UV polymerization method. The as-prepared MCPE exhibits improved mechanical property due to the introduction of porous ZIF-8 nanofillers, which is beneficial to suppress the growth of lithium dendrites. Consequently, the LiFePO₄||MCPE||Li cells show a high capacity of 116 mAh g⁻¹ at 30 °C and 0.5 C, and maintain 89.4% of initial capacity after 150 cycles with the average Coulombic efficiency of 99.9%. These results demonstrate that the MCPE shows great potential in solid-state lithium metal batteries near room temperature.     

Preparation and performance of poly(ethylene oxide)-based composite solid electrolyte for all solid-state lithium batteries

Poly(ethylene oxide)-based solid electrolyte is attractive for using in all solid-state lithium batteries. However, the polymer has a certain degree of crystallization, which is adverse to the conduction of lithium ions. In order to overcome this drawback, a flexible composite polymer electrolyte (CPE) containing TiO₂ nanoparticles is elaborately designed and synthesized by tape casting method. The effects of different molar ratios of EO: Li and mass fraction of TiO₂ on the physical and electrochemical performances are carefully studied. The results show the CPE10 having 10 wt % TiO₂ has the lowest degree of crystallinity of 9.04%, the lowest activation energy of 8.63 × 10⁻⁵ eV mol⁻¹. Besides, the CPE10 shows a lower polarization and higher decomposition voltage. Thus, prepared all solid-state battery LiFePO₄/CPE10/Li shows a high initial capacity of 160 mAh g⁻¹ at 0.1 C, 134 mAh g⁻¹ at 0.5 C and higher capacity retention of 93.2% after 50 cycles at 0.5 C (1 C = 170 mAh g⁻¹). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47498.     

Enhanced Thermal Stability and Electrochemical Performance of Polyacrylonitrile/Cellulose Acetate-Electrospun Fiber Membrane by Boehmite Nanoparticles: Application to High-Performance Lithium-Ion Batteries

In this study, polyacrylonitrile/cellulose acetate (PAN/CA) composite nanofiber membranes with different boehmite contents are prepared by electrospinning. The physical and electrochemical properties of the composite nanofiber membrane as a separator in lithium batteries are investigated. In contrast to commercial polypropylene membrane (PP), the nanocomposite fiber membrane has a 3D network structure, higher porosity, higher thermal stability, higher electrolyte absorptivity, higher ionic conductivity, and better cycling performance. The PAN/CA composite membrane with 12 wt% boehmite has the highest ionic conductivity (1.694 mS cm⁻¹); the specific discharge capacity is 160 mAh g⁻¹ at 0.2 C discharge density and the highest capacity retention rate is 99.3% after 100 cycles. The cycle rate at 2 C has a higher capacity retention rate (88.75%). These results indicate that the PAN/CA/AlOOH composite nanofiber membrane can be expected to replace the commercial polyolefin membrane and behave as a high-performance separator for lithium-ion batteries.     

Nanocomposite polymer electrolytes for solid-state lithium-ion batteries with enhanced electrochemical properties

Solid-state polymer electrolytes (SPEs) have attracted significant attention owing to their improvement in high energy density and high safety performance. However, the low lithium-ion conductivity of SPEs at room temperature restricts their further application in lithium-ion batteries (LIBs). Herein, we propose a novel poly (ethylene oxide) (PEO)-based nanocomposite polymer electrolytes by blending boron-containing nanoparticles (BNs) in the PEO matrix (abbreviated as: PEO/BNs NPEs). The boron atom of BNs is sp²-hybridized and contains an empty p-orbital that can interact with the anion of lithium salt, promoting the dissociation of the lithium salts. In addition, the introduction of the BNs could reduce the crystallinity of PEO. And thus, the ionic conductivity of PEO/BNs NPEs could reach as high as 1.19 × 10⁻³ S cm⁻¹ at 60°C. Compared to the pure PEO solid polymer electrolyte (PEO SPEs), the PEO/BNs NPEs showed a wider electrochemical window (5.5 V) and larger lithium-ion migration number (0.43). In addition, the cells assembled with PEO/BNs NPEs exhibited good cycle performance with an initial discharge capacity of 142.5 mA h g⁻¹ and capacity retention of 87.7% after 200 cycles at 2 C (60°C).     

Polymer electrolyte lithium batteries rechargeability and positive electrode degradation: An AC impedance study

AC impedance measurements of polymer electrolyte-based, symmetrical composite cathode cells were used to probe the effects of the composite cathode composition and fabrication process upon its performance when used in polymer electrolyte-based thin film rechargeable lithium batteries. The relationship between cycling performance and AC impedance measurements were used to elucidate some of the reported failure mechanisms of rechargeable lithium polymer electrolyte batteries. The rapid initial capacity decay observed within the first few cycles of the polymer electrolyte/V₆O₁₃ based composite cathode is shown to be related to the properties of the composite cathode active material, while the slower capacity decay observed during subsequent cycles, under continuous cycling regimes, appears to be related to a loss of ionic and electronic contact in the composite cathode.     

Fabrication and properties of crosslinked poly(propylene carbonate maleate) gel polymer electrolyte for lithium‐ion battery

The poly(propylene carbonate maleate) (PPCMA) was synthesized by the terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride. The PPCMA polymer can be readily crosslinked using dicumyl peroxide (DCP) as crosslinking agent and then actived by absorbing liquid electrolyte to fabricate a novel PPCMA gel polymer electrolyte for lithium‐ion battery. The thermal performance, electrolyte uptake, swelling ratio, ionic conductivity, and lithium ion transference number of the crosslinked PPCMA were then investigated. The results show that the T_g and the thermal stability increase, but the absorbing and swelling rates decrease with increasing DCP amount. The ionic conductivity of the PPCMA gel polymer electrolyte firstly increases and then decreases with increasing DCP ratio. The ionic conductivity of the PPCMA gel polymer electrolyte with 1.2 wt % of DCP reaches the maximum value of 8.43 × 10⁻³ S cm⁻¹ at room temperature and 1.42 × 10⁻² S cm⁻¹ at 50°C. The lithium ion transference number of PPCMA gel polymer electrolyte is 0.42. The charge/discharge tests of the Li/PPCMA GPE/LiNi_1/3Co_1/3Mn_1/3O₂ cell were evaluated at a current rate of 0.1C and in voltage range of 2.8–4.2 V at room temperature. The results show that the initial discharge capacity of Li/PPCMA GPE/LiNi_1/3Co_1/3Mn_1/3 O₂ cell is 115.3 mAh g⁻¹. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Suppressing Li dendrite by a guar gum natural polymer film for high-performance lithium metal anodes

Lithium dendrites pose a major hurdle for enhancing the energy density of lithium metal batteries, and the artificial solid electrolyte interface layer offers a potential solution. In this work, a cost-effective and environmentally friendly guar gum film is applied to the artificial protective layer. The guar gum artificial solid electrolyte interface (SEI) layer formed naturally, enriched with  OH and  AOA groups, displayed exceptional electrochemical stability, and achieved an impressively high transference number of 0.88 for lithium-ion movement. In symmetric cells, the Li@GG-Cu anode displays remarkable cycling performance even during extended periods. This is evidenced by its ability to maintain a surface capacity of approximately 850 h (1 mA cm⁻², 1 mAh cm⁻²). In addition, when utilizing a complete cell setup comprising a LiFPO₄ cathode (weighing 1.5 mg cm⁻²) and anode coated with a guar gum film, the capacity retention of an impressive 96.2% showcases outstanding preservation of battery performance over time even after 700 cycles. This performance surpasses that of a lithium foil electrode (87.1%) and a copper anode with lithium deposition (0%). Our work exhibits a promising material for a novel configuration of artificial SEI, effectively stabilizing lithium metal anode.     

Composite polymer electrolytes based on electrospun thermoplastic polyurethane membrane and polyethylene oxide for all‐solid‐state lithium batteries

To improve the electrochemical properties and enhance the mechanical strength of solid polymer electrolytes, series of composite polymer electrolytes (CPEs) were fabricated with hybrids of thermoplastic polyurethane (TPU) electrospun membrane, polyethylene oxide (PEO), SiO₂ nanoparticles and lithium bis(trifluoromethane)sulfonamide (LiTFSI). The structure and properties of the CPEs were confirmed by SEM, XRD, DSC, TGA, electrochemical impedance spectroscopy and linear sweep voltammetry. The TPU electrospun membrane as the skeleton can improve the mechanical properties of the CPEs. In addition, SiO₂ particles can suppress the crystallization of PEO. The results show that the TPU‐electrospun‐membrane‐supported PEO electrolyte with 5 wt% SiO₂ and 20 wt% LiTFSI (TPU/PEO‐5%SiO₂‐20%Li) presents an ionic conductivity of 6.1 × 10^?4 S cm^?1 at 60 °C with a high tensile strength of 25.6 MPa. The battery using TPU/PEO‐5%SiO₂‐20%Li as solid electrolyte and LiFePO₄ as cathode shows an attractive discharge capacity of 152, 150, 121, 75, 55 and 26 mA h g^?1 at C‐rates of 0.2C, 0.5C, 1C, 2C, 3C and 5C, respectively. The discharge capacity of the cell remains 110 mA h g^?1 after 100 cycles at 1C at 60 °C (with a capacity retention of 91%). All the results indicate that this CPE can be applied to all‐solid‐state rechargeable lithium batteries. © 2018 Society of Chemical Industry     

The Enhanced Performance of Polyethylene Composite Separators by the Modification of Lithium Salt@SiO2 Nanoparticles

Improving the dimensional thermal stability and electrochemical performance of polyethylene (PE) membrane is critical to enhance the safety performance of lithium-ion battery. In this paper, PE membranes are modified by lithium bis(trifuoromethanesulfonyl)imide (LiTFSI) solution and then coated with nano-SiO₂/polyvinyl alcohol solution to obtain composite membranes (PE@LnSiO₂, where n represents the concentration of LiTFSI solution). The obtained PE@L4SiO₂ (LiTFSI solution concentration is 4%) composite membrane possesses a thermal shrinkage rate of only 17% at 150 °C, which is far superior to that of the PE separator. The ionic conductivity of the composite membrane is 16.9 × 10⁻⁴ S cm⁻¹ at room temperature (RT), and the battery impedance decreases to 154 Ω, which is remarkably better than that of the PE membrane (188 Ω). The battery delivers a reversible discharge capacity of 164 mAh g⁻¹ at 0.2 C under RT after 250 cycles, and the coulomb efficiency remains above 99%. The battery also has a high discharge capacity of 132 mAh g⁻¹ at 2 C, which indicates that it has excellent rate performance. Therefore, this research successfully explores a simple method to effectively improve the dimensional thermal stability of PE separator, as well as the electrochemical and safety performance of lithium battery.     

Vanadium doped ceramic matrix Li6.7La3Zr1.7V0.3O12 enabled PEO-based solid composite electrolyte with high lithium ion transference number and cycling stability

Solid polymer electrolytes (SPEs) have attracted much attention because of their potential in improving energy density and safety. Vanadium doped ceramic matrix Li_6.7La₃Zr_1.7V_0.3O₁₂ (LLZVO) was synthesized by high-temperature annealing, and formed a composite electrolyte with polyethylene oxide (PEO). Compared with pure PEO electrolyte membrane, the composite electrolyte membrane exhibited better ionic conductivity (30 °C: 3.2 × 10^?5 S cm^?1; 80 °C: 3.6 × 10^?3 S cm^?1). The combination of LLZVO was beneficial to improve the lithium ion transference number (t_Li⁺) of SPE, which was as high as 0.81. The Li/SPE/LiFePO₄ battery shows good cycling ability, with a specific capacity of 142 mAh g^?1 after a stable cycle of 150 cycles. Meanwhile, the symmetrical lithium battery with composite electrolyte can work continuously for 1200 h without short circuit at the current density of 0.1 mA cm^?2 at 50 °C, and the capacity is 0.176 mAh. Vanadium doped ceramic matrix LLZVO as an active ionic conductor, improved the overall performance of solid electrolyte.     

Synthesis and Characterization of Polyindole–NiO-Based Composite Polymer Electrolyte with LiClO4

There has been an increasing interest in synthesizing the novel composite polymer electrolyte (CPE) for use in lithium batteries in recent years. This paper describes the preparation and characterization of CPE containing lithium perchlorate based on polyindole–NiO nanocomposite. NiO nanoparticles were added to the monomer solution before the polymer formation in the presence of a surfactant to get the PInNiO nanocomposite. The thermal properties, surface morphology, and structural studies of the electrolyte were investigated by TGA, SEM, TEM, and XRD. An enhanced conductivity of 2.62 × 10^?4 S cm^?1 at 45°C for the composite polymer electrolyte was determined from impedance studies.     

Preparation of manganese monoxide@reduced graphene oxide nanocomposites with superior electrochemical performances for lithium-ion batteries

Manganese monoxide (MnO) nanowire@reduced graphene oxide (rGO) nanocomposites are synthesized using a simple hydrothermal method combined with a calcination process. The structural and morphological characterization of the composites indicates that the MnO nanowires homogeneously anchor on both sides of the cross-linked rGO. The nanocomposites exhibit a high surface area of 126.5?m² g^?1. When employed as an anode material for lithium-ion batteries, the nanocomposites exhibit a reversible capacity of 1195 mAh g^?1 at a current density of 0.1?A?g^?1, with a high charge-discharge efficiency of 99.2% after 150 cycles. The three-dimensional architecture of the present materials exhibits high porosity and electron conductivity, significantly shortening the diffusion path of lithium ions and accelerating their reaction with the electrolyte, which greatly improves the lithium-ion storage properties. These excellent electrochemical performances make the composite a promising electrode material for lithium-ion batteries.     

Polymer gel electrolytes containing sulfur-based ionic liquids in lithium battery applications at room temperature

Polymer gel electrolytes comprising a sulfur-based ionic liquid (IL), a lithium salt, and butyrolactone (GBL) as an additive hosted in PVdF-HFP matrix were prepared and characterized. The result shows that adding small amount of GBL to the polymer electrolytes can improve the cathodic stability of the electrolytes, which ensures the lithium plating/stripping in the redox process. Furthermore, cyclic voltammograms studies indicate that the polymer electrolytes have well reversible redox process. When the IL component reaches 75 wt%, the polymer electrolyte has higher ionic conductivity than the other samples and it is 6.32 × 10^?4 S cm^?1. The assembled batteries with the polymer electrolyte have better discharge capacity, and after 100 cycles, the discharge capacity of the battery still retains 148 mAh g^?1.     

Electrospun nanofiber polyacrylonitrile coated separators to suppress the shuttle effect for long-life lithium–sulfur battery

Polymeric coating on the separator with effective polysulfides diffusion inhibition can provide intimate contact between intermediate polysulfides and conductive layer of separator for high-energy lithium–sulfur (Li–S) batteries. Herein, polyacrylonitrile–poly(1,5-diaminoanthraquinone) (PAN/PDAAQ) and PAN-potassium functionalized graphene (PAN/K-FGF) nanofibers are synthesized via electrospinning method and act as effective separators for Li–S batteries to minimize polysulfides diffusion toward the anode. PAN/K-FGF coated separator shows capacity retention of 768 mAh g⁻¹ after 100 cycles at 1C. The capacity maintains at 419 mAh g⁻¹ after 500 cycles. PAN/PDAAQ nanofibers are coated on glass fiber separator functions as physical and chemical barrier for polysulfides diffusion. Therefore, the cell with PAN/PDAAQ coating on the separator demonstrates capacity retention of 881 mAh g⁻¹ after 100 cycles at 1C and small capacity decay rate of 0.11% per cycle resulted in 800 cycles at 1C. PAN/PDAAQ could define as an ideal separator material for Li–S batteries. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48606.     

Ultrathin Ti3C2Tx nanosheets modified separators for lithium–sulphur batteries

Currently, among the various emerging energy storage systems, the lithium–sulphur (Li-S) battery is expected to be one of the next-generation lithium secondary batteries with high efficiency. However, the practical application of Li-S batteries still faces many obstacles. To solve the shuttle effect of lithium polysulphides, ultrathin Ti₃C₂T_x nanosheets were prepared through the in-situ acid etching method and applied to separator modification to suppress the shuttle effect of lithium polysulphides. Ultrathin Ti₃C₂T_x nanosheets with enlarged interlayer spacing accelerated the migration of Li⁺. The abundant termination groups on the surface of Ti₃C₂T_x played the role of the lithium polysulphide capture centre. When the mass loading of separator modification materials was set as 0.025 mg cm⁻², the as-prepared battery exhibited a reversible specific capacity as high as 780 mAh g⁻¹ after 200 cycles at 0.2 C, and the single-cycle capacity decay rate was only 0.09%.     

Preparation and properties of a novel green solid polymer electrolyte for all-solid-state lithium battery

Solid polymer electrolyte (SPE)-based lithium batteries have easy processing and safety for energy vehicles and storage. However, the preparation process of SPEs mostly used a lot of organic solvents, which will threaten human living space and body health. Herein, a novel green solid polymer electrolyte (ionic liquid type waterborne polyurethane, IWPUS) without no organic solvents was prepared from hybrids of ionic liquid-based waterborne polyurethane (IWPU) and LiClO₄. The structure and properties of IWPUS were investigated by IR, SEM, XRD, TGA, ion conductivity test. The results showed that Li⁺ of LiClO₄ could coordinate with  CO and  C O C in the polyurethane matrix. LiClO₄ had been well dispersed in IWPU. The conductivity of IWPUS increased with the increase of LiClO₄ content. The higher conductivity of IWPUS with 20% LiClO₄ at 80°C was 1.8 × 10⁻⁴ s•cm⁻¹. IWPUS based on ionic liquid-based waterborne polyurethane would be promised to become an environmentally friendly candidate for all solid-state lithium ion batteries.     

Overcoming the abnormal grain growth in Ga-doped Li7La3Zr2O12 to enhance the electrochemical stability against Li metal

Li₇La₃Zr₂O₁₂ (LLZO) solid electrolyte is a promising candidate for next generation batteries. In the LLZO family with various doping elements, Ga-doped LLZO (Ga-LLZO) delivers the highest Li-ion conductivity of higher than 1 × 10⁻³ S cm⁻¹. However, Ga-LLZO ceramics always contain lots of overgrown huge grains after sintering, resulting in short-circuiting as applied with Li anode in batteries. Hence a simple two-step sintering strategy is developed to prepare fine-grained Ga-LLZO ceramics with good electrochemical properties. Pellets with the composition of Li_6.4Ga_0.2La₃Zr₂O₁₂ deliver pure garnet phase, uniform fine grains, high relative density of 97.3% and conductivity of 1.24 × 10⁻³ S cm⁻¹ at 27 °C after sintering at 1150 °C for 1 min and 1000 °C for 3 h. In addition, those fine-grained Ga-LLZO exhibit improved stability against molten Li. The Li/Ga-LLZO/Li symmetric cells show a critical current density of 0.7 mA cm⁻², and a stable cycling of over 600 h at 0.4 mA cm⁻² at 27 °C. The Li/Ga-LLZO/LiFePO₄ full cells deliver reversible capacity of 150 mAh g⁻¹, showing negligible decay after 50 cycles. These results bring the Ga-LLZO electrolytes one step closer to practical application in solid-state batteries.     

Resin-silica composite nanoparticle grafted polyethylene membranes for lithium ion batteries

To avoid the peeling-off of ceramic nanoparticles (NPs) from polyolefin membranes usually occurred in commercially available ceramic NPs coated polyolefin separators for lithium batteries, we propose a simple one-pot in-situ reaction method to modify commercial polyethylene (PE) separators by surface grafting 3-Aminophenol/formaldehyde (AF)/silica (SiO₂) composite NPs. The AF/SiO₂ composite NPs form self-supporting connected pores on the modified layer of the separator surface, which ensures the transportation of Li⁺. Moreover, the PE@AF/SiO₂ separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO₂ layer and AF/SiO₂ composite NPs, resulting in higher lithium ion transference number (= 0.62) and ionic conductivity (σ = 0.722 mS cm⁻¹). More importantly, the discharge capacity, capacity retention rate and coulombic efficiency (136.2 mA h g⁻¹, 87.9% and 99%, respectively) after 200 cycles of Li|NMC half batteries with PE@AF/SiO₂ separators, are all more excellent than that with the pure PE separator (125 mA h g⁻¹, 83.1% and 85%, respectively). Our results show that the PE@AF/SiO₂ separators obtained by this modification method have higher electrochemical stability in the lithium battery system.     

Synthesis of lithium rich layered oxides with controllable structures through a MnO2 template strategy as advanced cathode materials for lithium ion batteries

The electrochemical performance of lithium ion batteries depend largely on the structural properties of electrode materials. In this work, we propose an approach to synthesize lithium-rich layered oxides (LLOs) materials using a manganese dioxide (MnO₂) template strategy, which could control the structure and particle size of final products via choosing different MnO₂ templates. Through precisely optimizing, we successfully prepare cross-linked nanorods (CLNs) and agglomerate microrods (AMs) Li_1.2Ni_0.15Co_0.1Mn_0.55O₂ cathode materials by using carbon-decorated MnO₂ nanowires and MnO₂ nanorods as templates, respectively. The lithium ion battery based on the CLNs exhibits excellent performance, delivering a high capacity of 286.2 mAh g⁻¹ at 0.1 C and 237.5 mAh g⁻¹ at 1 C. In addition, the device remains 98% and 89% of its initial capacity after 50 cycles at 0.1 C and 100 cycles at 1 C, respectively. The remarkable electrochemical performance can be mainly attributed to the cross-linked nanorods structure which can provide relatively shorter lithium ion diffusion length, larger reaction surface and more internal cavity. This universal structure engineering strategy may shed light on new material structures for high performance lithium-rich layered oxide cathode materials.     

Boosting lithium-ion transport capability of LAGP/PPO composite solid electrolyte via component regulation from ‘Ceramics-in-Polymer’ to ‘Polymer-in-Ceramics'

The design and regulation of the ion transport channels in the polymer electrolyte is an important means to improve the lithium ion transport behavior of the electrolyte. In this work, we for the first time combined the high ionic conductive inorganic ceramic electrolyte Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) with flexible polypropylene oxide (PPO) polymer electrolyte to synthesize a high-filling LAGP/PPO composite solid electrolyte film and regulated the ion transport channels from ‘Ceramics-in-Polymer’ mode to ‘Polymer-in-Ceramics' mode by optimizing the ratio of LAGP vs. PPO. The results reveal that when the LAGP content <40%, the electrolyte belongs to ‘LAGP-in-PPO’, and then changes to ‘PPO-in-LAGP’ when the LAGP content exceeds 40%. Compared with ‘LAGP-in-PPO’, the ‘PPO-in-LAGP’ shows better comprehensive properties, especially for the 75% LAGP-filled PPO electrolyte, the room-temperature ionic conductivity is as high as 3.46 × 10^?4 Scm^?1, the ion migration number and voltage stable window reach 0.83 and 4.78 V respectively. This high-filled composite electrolyte possesses high tensile stress of 40 MPa with a strain of 46% and withstands working environment up to 200 °C. The NCM622/Li solid-state battery composed of this electrolyte also presents good rate and cycle performances with a capacity retention of 80% after 230 cycles at 0.3C because of its high ion transport capability and good inhibition of lithium dendrites. This composite structural design is expected to develop high-performance solid-state electrolytes suitable for high-voltage solid-state lithium batteries.