Uncoordinated chemistry enables highly conductive and stable electrolyte/filler interfaces for solid-state lithium-sulfur batteries.

Composite-polymer-electrolytes (CPEs) embedded with advanced filler materials offer great promise for fast and preferential Li+ conduction. The filler surface chemistry determines the interaction with electrolyte molecules and thus critically regulates the Li+ behaviors at the interfaces. Herein, we probe into the role of electrolyte/filler interfaces (EFI) in CPEs and promote Li+ conduction by introducing an unsaturated coordination Prussian blue analog (UCPBA) filler. Combining scanning transmission X-ray microscope stack imaging studies and first-principle calculations, fast Li+ conduction is revealed only achievable at a chemically stable EFI, which can be established by the unsaturated Co-O coordination in UCPBA to circumvent the side reactions. Moreover, the as-exposed Lewis-acid metal centers in UCPBA efficiently attract the Lewis-base anions of Li salts, which facilitates the Li+ disassociation and enhances its transference number (tLi+). Attributed to these superiorities, the obtained CPEs realize high room-temperature ionic conductivity up to 0.36 mS cm-1 and tLi+ of 0.6, enabling an excellent cyclability of lithium metal electrodes over 4,000 h as well as remarkable capacity retention of 97.6% over 180 cycles at 0.5 C for solid-state lithium-sulfur batteries. This work highlights the crucial role of EFI chemistry in developing highly conductive CPEs and high-performance solid-state batteries.

Interfacial Plasticization Strategy Enabling a Long-Cycle-Life Solid-State Lithium Metal Battery.

The limited ionic conductivity and unstable interface due to poor solid-solid interface pose significant challenges to the stable cycling of solid-state batteries (SSBs). Herein, an interfacial plasticization strategy is proposed by introducing a succinonitrile (SN)-based plastic curing agent into the polyacrylonitrile (PAN)-based composite polymer electrolytes (CPE) interface. The SN at the interface strongly plasticizes the PAN in the CPE, which reduces the crystallinity of the PAN drastically and enables the CPE to obtain a low modulus surface, but it still maintains a high modulus internally. The reduced crystallinity of PAN provides more amorphous regions, which are favorable for Li+ transport. The gradient modulus structure not only ensures intimate interfacial contact but also favors the suppression of Li dendrites growth. Consequently, the interfacial plasticized CPE (SF-CPE) obtains a high ionic conductivity of 4.8 × 10-4 S cm-1 as well as a high Li+ transference number of 0.61. The Li-Li symmetric cell with SF-CPE can cycle for 1000 h at 0.1 mA cm-2, the LiFeO4 (LFP)-Li full-cell demonstrates a high capacity retention of 86.1% after 1000 cycles at 1 C, and the LiCoO2 (LCO)-Li system also exhibits an excellent cycling performance. This work provides a novel strategy for long-life solid-state batteries.

Transport Properties and Local Ions Dynamics in LATP-Based Hybrid Solid Electrolytes.

Hybrid solid electrolytes (HSEs), namely mixtures of polymer and inorganic electrolytes, have supposedly improved properties with respect to inorganic and polymer electrolytes. In practice, HSEs often show ionic conductivity below expectations, as the high interface resistance limits the contribution of inorganic electrolyte particles to the charge transport process. In this study, the transport properties of a series of HSEs containing Li(1+ x ) Alx Ti(2- x ) (PO4 )3 (LATP) as Li+ -conducting filler are analyzed. The occurrence of Li+ exchange across the two phases is proved by isotope exchange experiment, coupled with 6 Li/7 Li nuclear magnetic resonance (NMR), and by 2D 6 Li exchange spectroscopy (EXSY), which gives a time constant for Li+ exchange of about 50 ms at 60 °C. Electrochemical impedance spectroscopy (EIS) distinguishes a short-range and a long-range conductivity, the latter decreasing with LATP concentration. LATP particles contribute to the overall conductivity only at high temperatures and at high LATP concentrations. Pulsed field gradient (PFG)-NMR suggests a selective decrease of the anions' diffusivity at high temperatures, translating into a marginal increase of the Li+ transference number. Although the transport properties are only marginally affected, addition of moderate amounts of LATP to polymer electrolytes enhances their mechanical properties, thus improving the plating/stripping performance and processability.

Single-Ion Conductive Polymer-Based Composite Electrolytes for High-Performance Solid-State Lithium Metal Batteries.

Flexible composite polymer electrolytes (CPEs) with inorganic electrolyte fillers dispersed in polymer electrolytes integrate the merits of the polymer and inorganic electrolytes and have attracted much attention in recent years. In order to increase the electrochemical performance, especially the low lithium (Li)-ion transference number in traditional dual-ion Li salt-containing CPEs, single-ion conductive CPEs are synthesized with a single-ion polymer conductor (SIPC) as the matrix and Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) particles as the active fillers. The single-ion conductive CPEs show a high Li-ion transference number (up to 0.96), high room-temperature (RT) ionic conductivity (>1.0 × 10-4 S cm-1 ), wide electrochemical stability window (>5.0 V, vs Li/Li+ ), and excellent long-term cycling stability with Li metal at RT (3200 h). Based on the SIPC-LLZTO CPE, the solid-state lithium metal batteries with LiFePO4 - and LiCoO2 -based cathodes deliver average discharge capacities of 159 mAh g-1 for 600 cycles and 119 mAh g-1 for 200 cycles at RT, respectively. This study sheds light on the design of high-performance CPEs for next-generation solid-state lithium metal batteries.

High-Strength MOF-Based Polymer Electrolytes with Uniform Ionic Flow for Lithium Dendrite Suppression.

The uneven formation of lithium dendrites during electroplating/stripping leads to a decrease in the utilization of active lithium, resulting in poor cycling stability and posing safety hazards to the battery. Herein, introducing a 3D continuously interconnected zirconium-based metal-organic framework (MOF808) network into a polyethylene oxide polymer matrix establishes a synergistic mechanism for lithium dendrite inhibition. The 3D MOF808 network maintains its large pore structure, facilitating increased lithium salt accommodation, and expands anion adsorption at unsaturated metal sites through its diverse large-space cage structure, thereby promoting the flow of Li+. Infrared-Raman and synchrotron small-angle X-ray scattering results demonstrate that the transport behavior of lithium salt ion clusters at the MOF/polymer interface verifies the increased local Li+ flux concentration, thereby raising the mobility number of Li+ to 0.42 and ensuring uniform Li+ flux distribution, leading to dendrite-free and homogeneous Li+ deposition. Furthermore, nanoindentation tests reveal that the high modulus and elastic recovery of MOF-based polymer electrolytes contribute to forming a robust, dendrite-resistant interface. Consequently, in symmetric battery systems, the system exhibits minimal overpotential, merely 35 mV, while maintaining stable cycling for over 1800 h, achieving low-overpotential lithium deposition. Moreover, it retains redox stability under high voltages up to 5.3 V.

Interfacial Interaction of Multifunctional GQDs Reinforcing Polymer Electrolytes For All-Solid-State Li Battery.

Solid-state polymer electrolytes are highly anticipated for next generation lithium ion batteries with enhanced safety and energy density. However, a major disadvantage of polymer electrolytes is their low ionic conductivity at room temperature. In order to enhance the ionic conductivity, here, graphene quantum dots (GQDs) are employed to improve the poly (ethylene oxide) (PEO) based electrolyte. Owing to the increased amorphous areas of PEO and mobility of Li+ , GQDs modified composite polymer electrolytes achieved high ionic conductivity and favorable lithium ion transference numbers. Significantly, the abundant hydroxyl groups and amino groups originated from GQDs can serve as Lewis base sites and interact with lithium ions, thus promoting the dissociation of lithium salts and providing more ion pathways. Moreover, lithium dendrite is suppressed, associated with high transference number, enhanced mechanical properties and steady interface stability. It is further observed that all solid-state lithium batteries assembled with GQDs modified composite polymer electrolytes display excellent rate performance and cycling stability.

Realizing Scalable Nano-SiO2-Aerogel-Reinforced Composite Polymer Electrolytes with High Ionic Conductivity via Rheology-Tuning UV Polymerization.

Polymer electrolytes for lithium metal batteries have aroused widespread interest because of their flexibility and excellent processability. However, the low ambient ionic conductivity and conventional fabrication process hinder their large-scale application. Herein, a novel polyethylene-oxide-based composite polymer electrolyte is designed and fabricated by introducing nano-SiO2 aerogel as an inorganic filler. The Lewis acid-base interaction between SiO2 and anions from Li salts facilitates the dissociation of Li+. Moreover, the SiO2 interacts with ether oxygen (EO) groups, which weakens the interaction between Li+ and EO groups. This synergistic effect produces more free Li+ in the electrolyte. Additionally, the facile rheology-tuning UV polymerization method achieves continuous coating and has potential for scalable fabrication. The composite polymer electrolyte exhibits high ambient ionic conductivity (0.68 mS cm-1) and mechanical properties (e.g., the elastic modulus of 150 MPa). Stable lithium plating/stripping for 1400 h in Li//Li symmetrical cells at 0.1 mA cm-2 is achieved. Furthermore, LiFePO4//Li full cells deliver superior discharge capacity (153 mAh g-1 at 0.5 C) and cycling stability (with a retention rate of 92.3% at 0.5 C after 250 cycles) at ambient temperature. This work provides a promising strategy for polymer-based lithium metal batteries.

Regulating Lithium Plating/Stripping Behavior by a Composite Polymer Electrolyte Endowed with Designated Ion Channels.

The urgent demand for high energy and safety storage devices is pushing the development of lithium metal batteries. However, unstable solid electrolyte interface (SEI) formation and uncontrollable lithium dendrite growth are still huge challenges for the practical use of lithium metal batteries. Herein, a composite polymer electrolyte (CPE) endowed with designated ion channels is fabricated by constructing nanoscale Uio66-NH2 layer, which has uniformly distributed pore structure to regulate reversible Li plating/stripping in lithium metal batteries. The regular channels within the Uio66-NH2 layer work as an ion sieve to restrict larger TFSI- anions inside its channels and extract Li+ across selectively, which result in a high Li-ion transference number ( t Li + ${t_{{\rm{L}}{{\rm{i}}^{\bm{ + }}}}}$ ) of 0.6. Moreover, CPE provides high ion conductivity (0.245 mS cm-1 at room temperature) and expanded oxidation window (5.1 V) and forms a stable SEI layer. As a result, the assembled lithium metal batteries with CPE exhibit outstanding cyclic stability and capacity retention. The Li/CPE/Li symmetric cell continues plating/stripping over 500 h without short-circuiting. The Li/CPE/LFP cell delivers a reversible capacity of 149.3 mAh g-1 with a capacity retention of 99% after 100 cycles.

Engineering Two-Dimensional Metal-Organic Framework on Molecular Basis for Fast Li+ Conduction.

Metal-organic frameworks (MOFs) have been proposed as emerging fillers for composite polymer electrolytes (CPEs). However, MOF particles are usually served as passive fillers that yield limited ionic conductivity improvement. Building continuous MOF reinforcements and exploiting their active roles remain challenging. Here we demonstrate the feasibility of engineering fast Li+ conduction within MOF on molecule conception. Two-dimensional Cu(BDC) MOF is selected as an active filler due to its sufficient accessible open metal sites for perchlorate anion anchoring to release free Li+, verified by theoretical calculations and measurements. A novel Cu(BDC)-scaffold-reinforced CPE is developed via in situ growth of MOF, which provides fast Li+ channels inside MOF and continuous Li+ paths along the MOF/polymer interface for high Li+ conductivity (ambient 0.24 mS cm-1) and enables high mechanical strength. Stable cycling is achieved in solid-state Li-NCM811 full cell using the MOF-reinforced CPE. This molecule-basis Li+ conduction strategy brings new ideas for designing advanced CPEs.

Robust and high thermal-stable composite polymer electrolyte reinforced by PI nanofiber network.

To address the flammable and chemical unstable problems of liquid electrolyte, the solid electrolyte is a promising candidate to replace liquid electrolyte for solid-state batteries. Herein, a composite polymer electrolyte (CPE) of 3D polyimide (PI)-nanofiber membrane-incorporated polyethylene oxide (PEO)/lithium bis (triflu-romethanesulphonyl) imid (LiTFSI) is reported. Three advantages of the PI nanofiber network in the CPE include providing a continuous, rapid transport channel of lithium ions to improve the Li-ion conductivity, improving the mechanical properties and stability, and effectively inhibiting the dendrite growth of Li metal. The PI/PEO/LiTFSI CPE delivers an ionic conductivity of 4.2 × 10-4S cm-1at 60 °C, a wider electrochemical window to 5.4 V, and an excellent thermal stability, which result in the excellent electrochemical performance of LiFePO4full cells assembled with PI/PEO/LiTFSI CPE.

Three-Dimensional-Percolated Ceramic Nanoparticles along Natural-Cellulose-Derived Hierarchical Networks for High Li+ Conductivity and Mechanical Strength.

Solid polymer electrolytes for safe lithium batteries are in general flexible and easy to process, yet they have limited ionic conductivity and low mechanical strength. Introducing nano/microsized fillers into polymer electrolytes has been proven effective to address these issues, while formation of a percolated network of fillers for efficient Li+ conduction remains challenging. In this work, composite polymer electrolyte with 3D cellulose/ceramic networks is successfully developed using natural cellulose fibers and Li+-conducting ceramic nanoparticles. Monodisperse ceramic nanofillers first form interconnected networks driven by the self-assembly of hybrid cellulose fibers. The hierarchical cellulose skeleton provides spatial guidance for ceramic fillers and firmly supports the whole structure. After polymer electrolyte infusion, the resultant hybrid electrolyte affords both 3D continuous Li+ pathways for high Li+ conductivity and sufficient mechanical strength for dendrite suppression. This cellulose-confined particle percolation approach enables efficient and strong solid electrolytes for lithium batteries.

Component-Interaction Reinforced Quasi-Solid Electrolyte with Multifunctionality for Flexible Li-O2 Battery with Superior Safety under Extreme Conditions.

High-performance flexible lithium-oxygen (Li-O2 ) batteries with excellent safety and stability are urgently required due to the rapid development of flexible and wearable devices. Herein, based on an integrated solid-state design by taking advantage of component-interaction between poly(vinylidene fluoride-co-hexafluoropropylene) and nanofumed silica in polymer matrix, a stable quasi-solid-state electrolyte (PS-QSE) for the Li-O2 battery is proposed. The as-assembled Li-O2 battery containing the PS-QSE exhibits effectively improved anodic reversibility (over 200 cycles, 850 h) and cycling stability of the battery (89 cycles, nearly 900 h). The improvement is attributed to the stability of the PS-QSE (including electrochemical, chemical, and mechanical stability), as well as the effective protection of lithium anode from aggressive soluble intermediates generated in cathode. Furthermore, it is demonstrated that the interaction among the components plays a pivotal role in modulating the Li-ion conducting mechanism in the as-prepared PS-QSE. Moreover, the pouch-type PS-QSE based Li-O2 battery also shows wonderful flexibility, tolerating various deformations thanks to its integrated solid-state design. Furthermore, holes can be punched through the Li-O2 battery, and it can even be cut into any desired shape, demonstrating exceptional safety. Thus, this type of battery has the potential to meet the demands of tailorability and comformability in flexible and wearable electronics.

Core-Shell Hybrid Nanowires with Protein Enabling Fast Ion Conduction for High-Performance Composite Polymer Electrolytes.

Incorporating nanofillers is one of the promising approaches for simultaneously boosting the ionic conductivity and mechanical properties of solid polymer electrolytes (SPEs). However, effectively creating faster ion-conduction pathways via nanofillers still remains a big challenge. Herein, core-shell protein-ceramic nanowires for more efficiently building fast ion-conduction networks in SPEs are reported. The core-shell protein-ceramic nanowires are fabricated via in situ growth of protein coating on the electrospun TiO2 nanowires in a subtly controlled protein-denaturation process. It is demonstrated that the core-shell protein@TiO2 nanowires effectively facilitate ion-conduction. As a result, the ionic conductivity, mechanical properties, electrochemical stability, and even Li+ transference number of the SPEs with core-shell protein@TiO2 nanowires are significantly enhanced. The contributions from the 1D morphology of the protein@TiO2 nanowires, and more importantly, the favorable protein structure for further promoting ion-conduction at the polymer-filler interfaces are analyzed. It is believed that the protein plays a pivotal role in dissociating lithium salts, which benefits from the strong interactions between protein and ions, making the protein serve as a unique "natural channel" for rapidly conducting Li+ . This study initiates an effective method of promoting ionic conductivity and constructing faster ion-conduction networks in SPEs via combining bio- and nanotechnology.

Improving the Ionic Conductivity and Anode Interface Compatibility of LLZO/PVDF Composite Polymer Electrolytes by Compositional Tuning.

Utilizing aluminum-doped nano LLZO (Li6.28La3Zr2Al0.24O12) as the ceramic filler, we synthesized and optimized LLZO/PVDF/LiClO4 composite polymer electrolytes (CPEs) to achieve high ionic conductivity and good interfacial stability with metallic lithium. The research examines how the PVDF grade and the mass ratio of PVDF to LiClO4 affect the ionic conductivity, lithium metal compatibility, and overall performance of CPEs. The CPE using Kynar PVDF 741 and a PVDF-to-LiClO4 mass ratio of 2:1 emerged as superior, displaying a high ionic conductivity at room temperature (0.12 mS/cm), the lowest activation energy (0.247 eV), an extensive electrochemical stability window (approximately 4.9 V), and robust mechanical strength. In tests with lithium metal symmetric cells, the membrane facilitated over 1000 h of stable cycling at 0.1 mA cm-2 and 0.1 mAh cm-2. Furthermore, when integrated into full solid-state lithium-metal batteries with LiFePO4 cathodes, it sustained more than 80% capacity retention across 500 charge/discharge cycles at a rate of 0.5 C with constantly high Coulombic efficiencies above 99.8%, underscoring its exceptional durability and efficiency. This research provides a practical framework and benchmarks for developing LLZO/PVDF-based CPEs with high ionic conductivity and enhanced stability against lithium metals.

The Critical Role of Fillers in Composite Polymer Electrolytes for Lithium Battery.

With excellent energy densities and highly safe performance, solid-state lithium batteries (SSLBs) have been hailed as promising energy storage devices. Solid-state electrolyte is the core component of SSLBs and plays an essential role in the safety and electrochemical performance of the cells. Composite polymer electrolytes (CPEs) are considered as one of the most promising candidates among all solid-state electrolytes due to their excellent comprehensive performance. In this review, we briefly introduce the components of CPEs, such as the polymer matrix and the species of fillers, as well as the integration of fillers in the polymers. In particular, we focus on the two major obstacles that affect the development of CPEs: the low ionic conductivity of the electrolyte and high interfacial impedance. We provide insight into the factors influencing ionic conductivity, in terms of macroscopic and microscopic aspects, including the aggregated structure of the polymer, ion migration rate and carrier concentration. In addition, we also discuss the electrode-electrolyte interface and summarize methods for improving this interface. It is expected that this review will provide feasible solutions for modifying CPEs through further understanding of the ion conduction mechanism in CPEs and for improving the compatibility of the electrode-electrolyte interface.

Surface positive-charged modification of inorganic fillers to optimize lithium ion conductive pathways in composite polymer electrolytes for lithium-metal batteries.

The incorporation of inorganic fillers into composite polymer electrolytes (CPEs) is a common strategy to improve ionic conductivity. However, the high surface energy of inorganic fillers typically aggravates poor interfacial contact with polymer chains. Herein, we develop a surface positive-charge modification strategy for enhancing the intermolecular interaction of poly(ethylene oxide) (PEO) electrolytes with inorganic fillers and optimizing lithium ion (Li+) conductive pathways in CPEs. The SiO2 nanoparticles are coated with a polydopamine adhesive layer and then functionalized with a branched polyethyleneimine positively charged functional layer. Such surface modification not only effectively induces more amorphous structure into the PEO matrix but also promotes the dissociation of lithium salts and activates more free Li+ in the PEO to accelerate Li+ transport. The CPEs achieved a superior ionic conductivity of 6.12 × 10-5 S cm-1 at 30 °C. In addition, the modified fillers could induce the formation of a lithium fluoride (LiF)-rich solid-state interphase and correspondingly achieve excellent compatibility with Li metal. The Li symmetric battery using the as-prepared CPEs delivered stable Li plating/stripping performances over 3960 h under 0.2 mA cm-2. The resulting LiFePO4|Li battery has an excellent capacity retention of 92.8 % after 260 cycles at 0.5C and 60 °C.

Anionic Anchoring Enhanced Quasi Solid Composite Polymer Electrolytes for High Performance Lithium Metal Battery.

Herein, ZIF-8 inorganic particles with different sized reinforced poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) solid composite polymer electrolytes (PVDF-HFP/10%ZIF-8) were prepared via a facile blade-coating approach, and free-standing quasi solid-state composite electrolytes (PVDF-HFP/10%ZIF-8(0.6)/Plasticizer, abbreviated as PH/10%ZIF-8(0.6)/P), were further obtained through the introduction of plasticizer. Optimized PH/10%ZIF-8(0.6)/P exhibited a high ionic conductivity of 2.8 × 10-4 S cm-1 at 30 °C, and superior Li+ transfer number of 0.89 with an ultrathin thickness (26 µm). Therefore, PH/10%ZIF-8(0.6)/P could effectively inhibit the growth of lithium dendrites, and the assembled Li/LiFePO4 cell delivered good cycling stability with a capacity retention rate of 89.1% after 100 cycles at 0.5 C.

Quasi-Solid-State Lithium-Sulfur Batteries Assembled by Composite Polymer Electrolyte and Nitrogen Doped Porous Carbon Fiber Composite Cathode.

Solid-state lithium sulfur batteries are becoming a breakthrough technology for energy storage systems due to their low cost of sulfur, high energy density and high level of safety. However, its commercial application has been limited by the poor ionic conductivity and sulfur shuttle effect. In this paper, a nitrogen-doped porous carbon fiber (NPCNF) active material was prepared by template method as a sulfur-host of the positive sulfur electrode. The morphology was nano fiber-like and enabled high sulfur content (62.9 wt%). A solid electrolyte membrane (PVDF/LiClO4/LATP) containing polyvinylidene fluoride (PVDF) and lithium aluminum titanium phosphate (Li1.3Al0.3Ti1.7(PO4)3) was prepared by pouring and the thermosetting method. The ionic conductivity of PVDF/LiClO4/LATP was 8.07 × 10-5 S cm-1 at 25 °C. The assembled battery showed good electrochemical performance. At 25 °C and 0.5 C, the first discharge specific capacity was 620.52 mAh g-1. After 500 cycles, the capacity decay rate of each cycle was only 0.139%. The synergistic effect between the composite solid electrolyte and the nitrogen-doped porous carbon fiber composite sulfur anode studied in this paper may reveal new approaches for improving the cycling performance of a solid-state lithium-sulfur battery.

High-Performance PEO-Based All-Solid-State Battery Achieved by Li-Conducting High Entropy Oxides.

A rock-salt-structured Li-conducting high entropy oxide was prepared and utilized as an active filler in a polyethylene oxide (PEO)-based solid-state composite electrolyte. X-ray diffraction and high-resolution transmission electron microscopy were adopted to analyze the crystal structure of the high entropy oxide containing 20% of Li ions (HL20). The HL20 was crystallized in the Fm3̅m space group with Li+ ions located at the center of the MO6 octahedra. The ionic conductivity of the composite membrane at 30 °C reaches 3.44 × 10-5 S cm-1. The inflection point of activation energy of the membrane with HL20 decreases by 5 °C compared with that of the pure PEO membrane. In the galvanostatic plating/stripping test, the Li||Li symmetric batteries could be cycled at a current density of 200 µA cm-2 for over 1200 h with an overpotential of 140 mV. The Li||LiFePO4 full battery could be charged/discharged at 0.5 C for 100 circles with a high capacity retention rate of 91%. Excellent rate performance is also achieved at lower temperatures and higher rates, showing the superiority of HL20 as an active filler. This work sheds light on the development of high entropy oxide as a new type of fast ionic conductor, promoting the practical application of all-solid-state batteries at a lower temperature.

2D Silicate Materials for Composite Polymer Electrolytes.

Two-dimensional (2D) silicate materials have become one of the promising candidates for constructing composite polymer electrolytes due to their advantages of low cost, high stability, good mechanical property, high ionic conductivity and potential to inhibit the growth of lithium dendrites. However, the application of 2D silicate materials in composite polymer electrolytes (CPEs) is still at the infancy stage and facing a lot of challenges. In this minireview, we summarize the structures and properties of 2D silicate materials that have been applied in CPEs, the processing methods of composite electrolytes based on 2D silicates, and the recent process of 2D silicate materials in CPEs. We hope this review could present a general overview of the 2D silicates for CPEs and promote the further study for potential applications.