Electrolytes For Solid-state Lithium Batteries Research Articles

Low-Cost, High-Strength Cellulose-based Quasi-Solid Polymer Electrolyte for Solid-State Lithium-Metal Batteries.

Solid-state lithium-metal batteries are considered as the next generation of high-energy-density batteries. However, their solid electrolytes suffer from low ionic conductivity, poor interface performance, and high production costs, restricting their commercial application. Herein, a low-cost cellulose acetate-based quasi-solid composite polymer electrolyte (C-CLA QPE) was developed with a high Li+ transference number ( ) of 0.85 and excellent interface stability. The prepared LiFePO4 (LFP)|C-CLA QPE|Li batteries exhibited excellent cycle performance with a capacity retention of 97.7 % after 1200 cycles at 1 C and 25 °C. The experimental results and Density Function Theory (DFT) simulation revealed that the partially esterified side groups in the CLA matrix contribute to the migration of Li+ and enhance electrochemical stability. This work provides a promising strategy for fabricating cost-effective, stable polymer electrolytes for solid-state lithium batteries.

Progress and Perspective of Glass-Ceramic Solid-State Electrolytes for Lithium Batteries

The all-solid-state lithium battery (ASSLIB) is one of the key points of future lithium battery technology development. Because solid-state electrolytes (SSEs) have higher safety performance than liquid electrolytes, and they can promote the application of Li-metal anodes to endow batteries with higher energy density. Glass-ceramic SSEs with excellent ionic conductivity and mechanical strength are one of the main focuses of SSE research. In this review paper, we discuss recent advances in the synthesis and characterization of glass-ceramic SSEs. Additionally, some discussions on the interface problems commonly found in glass-ceramic SSEs and their solutions are provided. At the end of this review, some drawbacks of glass-ceramic SSEs are summarized, and future development directions are prospected. We hope that this review paper can help the development of glass-ceramic solid-state electrolytes.

Cellulose acetate-promoted polymer-in-salt electrolytes for solid-state lithium batteries

Cellulose acetate-promoted polymer-in-salt electrolytes for solid-state lithium batteries

2-Dimensional g-C3N4 nanosheets modified LATP-based “Polymer-in-Ceramic” electrolyte for solid-state lithium batteries

Composite polymer electrolytes (CPEs) are gaining increasing interest due to their combined advantages of polymer and inorganic ceramic. “Polymer-in-Ceramic” (PIC) system containing a large portion of ceramic fillers (higher than 50 wt%), possesses superior safety, electrochemical and mechanical properties, which render it a promising strategy for mass production of inorganic ceramic electrolytes. However, the poor organic-inorganic interface compatibility between polymer and ceramic leads to severe agglomeration of ceramic fillers within the polymer electrolyte, resulting in cracks in the membrane that impedes the transportation of lithium ions. Thus, two-dimensional (2D) g-C3N4 nanosheets are introduced into the PIC-type electrolyte as a bridge between the organic and inorganic components to improve the homogeneity of the electrolyte membrane and build an effective transportation network. In this work, a PIC type g-C3N4/ Li1.3Al0.3Ti1.7(PO4)3(LATP)/Poly(vinylidene fluoride) (PVDF) electrolyte membrane with a thickness of 35.2 µm is prepared via a simple solution-casing method and delivers satisfactory all-around properties (a high conductivity of 5.9 × 10−4 S cm−1 at 25 ℃, a high lithium-ion transference number of 0.63 and superior thermal stability). To further evaluate its practicability, a solid-state lithium battery of LiNi0.8Mn0.1Co0.1O2|CPEs|Li is assembled and provides good cycling and rate performance at room temperature. This work proves the effectiveness of the 2D g-C3N4 nanosheets in resolving the agglomeration issue and optimizing the electrochemical properties of LATP-based polymer-in-ceramic electrolyte, which provides a universal strategy to modify the PIC-type solid-state electrolytes.

Recent Progress of Polymer Electrolytes for Solid-State Lithium Batteries

The critical challenges for lithium-ion batteries today are how to improve the energy densities and solve the safety issues, which can be addressed through the construction of solid-state lithium metal batteries with solid polymer electrolytes (SPEs). Significant efforts have been devoted to the design and synthesis of SPEs, in which their electrochemical windows and corresponding compatibilities with both electrodes are crucial, particularly when taking high-voltage transition metal oxides as cathodes. In this review, the SPEs with different electrochemical windows are summarized and categorized, including (i) anode stable SPEs with good lithium metal compatibilities, (ii) cathode stable SPEs with good oxidation resistances, (iii) multilayer SPEs simultaneously withstanding reduction of a lithium anode and oxidation at high voltage. The impacts of polymer molecular structures and compositions on the SPE properties and performance are discussed. The development of high-performance SPEs that can stabilize or form stable interfacial passivation layers with both cathodes and anodes simultaneously is the desired candidate of future applications.

Li4B10H10B12H12 as solid electrolyte for solid-state lithium batteries

The ionic conductivity of Li4B10H10B12H12 exceeds that of its parent compounds Li2B10H10 and Li2B12H12 by several orders of magnitude. It is stable against lithium metal and has been incorporated into solid-state batteries.

Polymer-based electrolytes for solid-state lithium batteries with a wide operating temperature range

Polymer-based electrolytes with regulated molecular structures demonstrate excellent temperature tolerance and are ideal for solid-state lithium batteries.

Polyhydroxy Urethanes and Carbonates Bearing Bio-Based Solid Electrolyte for Solid-State Lithium Batteries

With higher energy density, flexibility, safe operation at both room temperature as well as high temperature, solid-state batteries technology has been strongly looked upon as superior diversion from conventional liquid electrolytes-based lithium batteries. Among various other class of polymers, there is strong need to focus on sustainable and yet better alternatives other than most researched polyethylene oxide (PEO). Poly(hydroxyurethanes) (PHU) owing to their high degree of structural tunability can be interesting candidates for Solid polymer electrolyte (SPE). Here, we synthesized bio-based PHU networks by facile ring-opening polymerization of carbonated soybean oil (CSBO) without catalyst. The existence of polyether and polyester provides the PHU network with soft segments while urethane linkage with hard segments. The lower Tg with higher thermal stability widespread its application at elevated temperature without melting and significant degradation. PHU shows remarkable adhesive properties to the surface of metal speculating better interfacial contact and stability. The electrochemical investigations exhibited decent ionic conductivity (> 10-4 at 60o C), electrochemical stability window (ESW > 4.5 V vs. Li/Li+) and transport properties allowing it to be explored for high voltage cathodes. Lithium ferrophosphate (LiFePO4) cells with PHU also demonstrated promising charge-discharge (> 100 mAhg-1 at 60o C) with the li-metal anode. The attempt to develop bio-based batteries materials are much required added step toward green and clean energy for a sustainable future.

The Influence of Polar Functional Groups in Hot-Melt Extruded Polymer Blend Electrolytes for Solid-State Lithium Batteries

Following the COP26 Summit in November 2021, more than hundred countries pledged to reach zero-emission by 2070 at the latest and the major car manufacturers committed to selling only electric vehicles by 2040. Currently, lithium-ion batteries (LIBs) are among the most widely used storage systems because of their high energy and power densities and long lifespan.1 The early LIBs are composed of intercalation electrodes, electronically isolated by an ion-conducting organic liquid electrolyte. However, the use of liquid electrolytes presents some disadvantages – especially in regard to consumer safety – related to short-circuits and potential leakages of the flammable liquid solvent. Moreover, in the case of lithium metal batteries, the combination of a liquid electrolyte and a high-capacity lithium metal anode leads to the uncontrolled deposition of lithium during the reduction, forming dendrites between the electrodes. A promising way to avoid this instability and improve battery safety is to replace the liquid electrolyte with an ion-conducting solid electrolyte.2 Among them, solid polymer electrolytes (SPEs) represent one of the most attractive alternatives due to their capacity to effectively conduct ions and higher mechanical resistance than their liquid counterparts.3 An important criterion for selecting polymers for use in SPEs is their ability to dissolve lithium salts through polar functional groups. Salt dissolution results in the replacement of ion-ion interactions in the lithium salt, with ion-dipole interactions in the polymer. The transport mechanisms of these ion-conducting materials differ from those of liquid electrolytes. Cation transport in polymer involves two steps which are considered to be dissociated or not, depending on the model chosen (Arrhenius or Vogel-Fulcher-Tammann, respectively). The application of one of these models provides interesting information on the ionic mobility dynamics in SPEs and, in particular, on the interplay between ionic jumps and polymer chain mobility. In the Arrhenius model, ionic jumps occur between coordinating sites, without taking into account the influence of segmental relaxation. Conversely, the VTF equation implies a strong relationship between these parameters. According to previous studies, higher segmental motions in the amorphous phase of polymers mainly provide ionic transport, which explains the limited ionic conductivity of SPEs at ambient temperature (less than 10-5 S/cm).Another major limitation of SPEs is primarily related to their dual role as electrolyte and binder in composite electrodes, which requires contradictory requirements to be met. Indeed, SPEs must have both sufficient flexibility to allow good interfacial contact between the electrode components and sufficient rigidity to limit short circuits.Polymer blending has emerged as an economic and effective technique to develop new SPEs which may simultaneously combine properties of each polymer and control the intrinsic properties of the resulting blend by adjusting the formulation.4 Moreover, polymer blends can be obtained by a solvent-free processing method, which reduce SPE toxicity and production time (no solvent evaporation). However, polymer blending makes both the salt dissociation processes and the ionic transport more difficult to understand as both polymers can dissolve lithium salts with their polar functional groups. Each polymer has different ionic transport properties depending on its architecture and thermal properties. Currently, no systematic survey comparing the ability of polymers with various functional groups to dissolve lithium salts in blends has thus far been conducted.In this presentation, we will discuss the salt dissociation ability of polar functional groups in various polymer blend SPEs. These groups are limited to those that are most commonly present in SPEs : ether, nitrile, carbonate, ester, alcohol and amide.5 The blends presented have been obtained by extrusion, which allows the effect of solvents on salt/polymer interactions to be neglected. In this work, coupled FTIR, EDX and 7Li NMR analyses allow the interactions between LiTFSI and the polymer blends to be determined with a good degree of certainty. Our original study combines experimental and theoretical approaches to determine effects of polymers’ lithium salt solvating ability on polymer blend electrolyte properties and represents an advancement in understanding and optimizing polymer selection for SPEs, used in lithium-ion batteries. References Xie, W., Liu, X., He, R., Li, Y., Gao, X., Li, X., Peng, Z., Feng, S., Feng, X. and Yang, S. Journal of Energy Storage 2020, 32, 101837.Chen, R., Qu, W., Guo, X., Li, L. and Wu, F. Materials Horizons 2016, 3, 487-516.Gray, F. M. Solid polymer electrolytes, VCH New Tork 1991.Caradant, L., Lepage, D., Nicolle, P., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2020, 4943-4951.Caradant, L., Verdier, N., Foran, G., Lepage, D., Prébé, A., Aymé-Perrot, D. and Dollé, M. ACS Applied Polymer Materials 2021. Figure 1

Influence of Rutile and Anatase TiO2 Precursors on the Synthesis of a Li1.5Al0.5Ti1.5(PO4)3 Electrolyte for Solid-State Lithium Batteries

We report the effect of using rutile and anatase TiO2 as precursors in the synthesis of ceramic Li1.3Al0.3Ti1.7(PO4)3 (LATP) NASICON-type electrolyte for solid-state lithium batteries. Anatase TiO2 enables LATP crystallization at lower temperatures while rutile TiO2 leads to a purer and more crystalline LATP phase. We believe these findings are an important contribution towards the development of more effective and less expensive synthesis of Ti-based solid electrolyte materials.

All Solid-State Li/LLZO/LCO Battery Enabled by Alumina Interfacial Coating

Li7La3Zr2O12 (LLZO) garnet-type lithium-ion conductors are being investigated as a promising solid electrolyte for solid-state lithium batteries. To enable a functional all-solid-state configuration intensive investigations are needed to reduce the cathode/electrolyte interfacial resistance which contributes the most to cell performance loss. Among the commercial cathode materials investigated so far, LiCoO2 (LCO) is one of the most stable with garnet electrolytes as only a superficial reaction has been detected between the two materials. However, even this minor reaction would block the Li-ion transport through the interface, resulting in deteriorated cell performance. In this work, we demonstrate that a thin aluminum oxide layer (5 nm) can be an effective interlayer to impede the formation of a harmful interphase and enable facile Li-ion transfer between LCO and the LLZO garnet. Room-temperature-sputtered LCO thin films were employed to form an interface with the garnet electrolyte and annealed at 800 °C to reveal the effect of the interfacial reaction on the Li-ion transfer across the interface. An aluminum oxide layer was then introduced between LCO and the garnet electrolyte by sputtering a metallic aluminum layer which is then annealed together with the upper LCO layer in oxygen, or by direct atomic layer deposition of the oxide. Compared to the LCO/LLZO/Li cells without an aluminum oxide interlayer, those with the interlayer exhibited improved performance, i.e., a stable discharge capacity of up to 90 mAh/(g LCO) at a C/10 rate, a rate capability up to 1.68C and a stable galvanostatic cycling at 0.1C for over 100 cycles with a discharge capacity fade rate of 0.15% per cycle. It was determined that aluminum diffused into the LCO layer after preventing the initial detrimental reaction between LCO and the LLZO garnet from happening during high temperature annealing, suggesting that the coating does not have to remain a physically blocking layer during cycling to function.

Ultrahigh Elastic Polymer Electrolytes for Solid-State Lithium Batteries with Robust Interfaces.

Solid polymer electrolytes (SPEs) are promising for solid-state lithium batteries, but their practical application is significantly impeded by their low ionic conductivity and poor compatibility. Here, we report an ultrahigh elastic SPE based on cross-linked polyurethane (PU), succinonitrile (SN), and lithium bistrifluoromethanesulfonimide (LiTFSI). The resulting electrolyte (PU-SN-LiTFSI) exhibits an ionic conductivity of 2.86 × 10-4 S cm-1, a tensile strength of 3.8 MPa, and a breaking elongation exceeding 3000% at room temperature. A solid-state lithium battery using the electrolyte exhibits a high specific capacity of 150 mAh g-1 at 0.2C and a long cycling life of up to 700 cycles at 0.5C at room temperature, showing one of the best performances among its counterparts. The excellent performances are attributed to the fact that its ultrahigh elasticity, good ionic conductivity, tensile strength, and electrochemical stability contribute to robust electrode/electrolyte interfaces, thus greatly decreasing the charge-transfer resistance in charge/discharge processes. Our investigations provide a novel strategy to address the intrinsic interfacial issue of solid-state batteries.

Dual Interface Design of Ga-Doped Li7la3zr2o12/Polymer Composite Electrolyte for Solid-State Lithium Batteries

Dual Interface Design of Ga-Doped Li7la3zr2o12/Polymer Composite Electrolyte for Solid-State Lithium Batteries

A review on modified polymer composite electrolytes for solid-state lithium batteries

High performance modified polymer composite electrolytes are obtained by compounding polymers with other substances.

The multicomponent synergistic effect of a hierarchical Li0.485La0.505TiO3 solid-state electrolyte for dendrite-free lithium-metal batteries.

Development of a composite electrolyte with high ionic conductivity, excellent electrochemical stability and preeminent mechanical strength is beneficial for suppressing Li-dendrite penetration and unstable interfacial reactions in solid-state Li-metal batteries. Herein, a novel composite electrolyte material comprising perovskite Li0.485La0.505TiO3 (LLTO), poly(ethylene oxide) (PEO), and a barium titanate (BTO)-polyimide (PI) composite matrix has been successfully fabricated. Benefiting from the well-defined ion channels, the resulting BTO-PI@LLTO-PEO-FEC-LiTFSI (BP@LPFL) exhibits excellent cycling stability, low interfacial resistance, enhanced mechanical strength, and high ionic conductivity. Particularly, BP@LPFL possesses an excellent ionic conductivity of 3.0 × 10-4 S cm-1 at room temperature and achieves a wide electrochemical window of 5.2 V (vs. Li+/Li). For Li-LiFePO4 batteries, such an ingenious structure yields a discharge capacity of 124 mA h g-1 at 0.1 C after 200 cycles at room temperature and delivers a discharge capacity of 165 mA h g-1 at 0.1 C after 110 cycles at 60 °C. Additionally, the symmetric Li cell remains stable after 700 h at a current density of 0.5 mA cm-2. Furthermore, ex situ X-ray photoelectron spectroscopy and ex situ scanning electron microscopy were used to verify the interface evolution. Besides, a flexible full battery is fabricated, which exhibits impressive performance. These properties presented here provide support for BP@LPFL as a feasible candidate electrolyte for solid-state lithium batteries.

Extrusion of Polymer Blend Electrolytes for Solid-State Lithium Batteries: A Study of Polar Functional Groups

Extrusion of Polymer Blend Electrolytes for Solid-State Lithium Batteries: A Study of Polar Functional Groups

Fast Li-ion transport pathways via 3D continuous networks in homogeneous garnet-type electrolyte for solid-state lithium batteries

Solid-state lithium batteries (SSLBs) using solid-state electrolytes (SSEs) have attracted much attention due to their satisfying safety and high energy density. Towards further practical development, insufficient room temperature ionic conductivity in garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZTO) SSEs (usually ˂1×10−3 S‧cm−1) remains a significant challenge and calls for a giant leap. In this work, a novel solid-state sintering strategy is employed by introducing La2O3 nanoparticles to promote the homogenous distribution of the grains and construct 3D continuous Li-ion transport networks along the grain boundaries. The La2O3 nanoparticles are regarded as the second phase to inhibit the abnormal grain growth (AGG) of LLZTO grains and reduce the voids defect to improve the relative density. The LaLiO2 Li-ion conductor is synthesized by combining the excess La2O3 nanoparticles and the gas Li2O, providing continuous ionic pathways and enhancing the Li-ion conductivity. The Li-ion conductivity reaches 1.12×10−3 S•cm−1 (64 % higher than the pure LLZTO electrolyte) with a relative density of 98.1 %. The results presented here show that SSLBs with LiFePO4 cathode achieve a superior stable cycling performance with a high discharge capacity of 128.8 mA•h•g−1 and a Coulombic efficiency over 99% after 600 long-term cycles (0.5 C) at room temperature. The work provides a feasible solid-state sintering approach to creating SSEs with high performances for future applications of SSLBs.

Oriented Attachment Strategy Toward Enhancing Ionic Conductivity in Garnet-Type Electrolytes for Solid-State Lithium Batteries.

Solid-state lithium batteries (SSLBs) based on garnet-type solid-state electrolytes (SSEs) have attracted much attention due to their high energy density and chemical stability. However, poor room-temperature ionic conductivity and low density of SSEs induced by conventional preparation routes limit their potential future applications. In this work, an oriented attachment strategy is employed to enhance the Li-ion conductivity and density of garnet-type SSE Li6.5La3Zr1.5Ta0.5O12 by introducing La2O3 nanoparticles. The oriented attachment of the ZrO2(Ta2O5) matrix mediates the epitaxial growth of the La-Zr(Ta)-O intermediate phase due to the addition of La2O3 nanoparticles. Continuous Li-ion transport pathways along grain boundaries are produced by the combination of residual La2O3 and gas Li2O. A densification interface is obtained when 10 wt % La2O3 is doped. The maximum value of Li-ion conductivity reaches 8.20 × 10-4 S·cm-1, with a relative density of 97.3%. SSLBs with a LiFePO4 cathode showing a stable cycling performance with a discharge capacity of 123.1 mA·h·g-1 and a Coulombic efficiency of 99.2% after 300 cycles (0.5C) at room temperature. This work is comparable to the state-of-the-art methodology, which provides a feasible approach to creating SSEs with high performances for SSLBs.

Rationally Designed PEGDA-LLZTO Composite Electrolyte for Solid-State Lithium Batteries.

A novel composite electrolyte is rationally designed with a polyethylene glycol diacrylate (PEGDA) polymer and a garnet-type fast lithium-ion conductor (Li6.4La3Zr1.4Ta0.6O12, LLZTO) for solid-state lithium batteries. The LLZTO ceramic phase is incorporated into the PEGDA polymeric matrix as nanoparticles. The ionic conductivity of the composite is further optimized with a succinonitrile plasticizer. The solid composite membranes are synthesized via a tape casting process followed by a UV curing procedure. The resulting solid-state composite electrolyte delivers a room-temperature Li+-ion conductivity of 3.1 × 10-4 S cm-1 and can sustain an electrochemical polarization potential up to 4.6-4.7 V (vs Li+/Li). The compositing approach harnesses the advantages of both polymeric PEGDA and ceramic LLZTO. In addition to enhancing the ionic conductivity, the LLZTO ceramic filler can suppress Li dendrites. The polymeric phase of PEGDA facilitates good interfacial contact between the solid electrolyte and the electrodes. The solid-state cells fabricated with the composite solid electrolyte, lithium-metal anode, and LiNi0.8Mn0.1Co0.1O2 (NMC 811) cathode show long cyclability.

Garnet Nb-Doped Li7La3Zr2O12 Ceramic Electrolyte and Its Composite Electrolyte for Solid-State Lithium Batteries

Lithium ion batteries (LIBs) have world-widely emerged as energy storage devices for electronic products, electric vehicles, energy storage systems and special purpose devices. LIBs are increasingly expected to be provided with a shorter battery charging time, a longer battery life and the better battery security for industrial development and social demand. However, most conventional LIBs with active organic liquid electrolytes have suffered from several issues, especially high safety risk and low energy density. Therefore, continuously improving conventional LIBs and designing new-type lithium batteries are extremely urgent. Solid-state lithium batteries (SSLBs) are recognized as the promising candidates of next generation lithium batteries with good safety and high energy density. Solid-state electrolytes (SSEs) as the most critical component in SSLBs largely lead the future battery development. To obtain the SSEs with good overall performance is a prerequisite to realize the potential of SSLBs. Garnet Li7La3Zr2O12 (LLZO) ceramic SSEs have the great potential for SSLBs, owing to high ionic conductivity, wide stable potential window and good electrochemical stability against lithium metal. However, so far, LLZO ceramic SSEs still suffer from critical issues of poor air stability and hard machinability, greatly limiting their practical application. Hence, in this work, the cubic garnet Nb-doped LLZO, Li6.5La3Zr1.5Nb0.5O12, ceramic electrolyte is synthesized by a simple sol-gel process. Stability and mechanical properties of as-synthesized Li6.5La3Zr1.5Nb0.5O12 ceramics are explored in detail. Directly polishing and assembling Li6.5La3Zr1.5Nb0.5O12 ceramic pellets in analog batteries are applied to investigate electrochemical behaviours. In addition, the flexible composite membrane composed of Li6.5La3Zr1.5Nb0.5O12 particles and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix is successfully prepared through tape casting method. The composite membrane shows good machinability. When the composite membrane as electrolyte is applied in the lithium metal cell, good electrochemical performances are exhibited. The composite membrane integrating hard inorganic Li6.5La3Zr1.5Nb0.5O12 ceramics with soft polymer achieves a gain effect of “1+1 > 2”. This work may be helpful for next forward-looking studies of garnet LLZO family SSEs and their extensions.