Table 3.
Summary of GPEs systems mentioned in this work.
| Polymer Matrix | Salts | Salts Conc. sk. (Soaked) |
Ionic Conductivity (S/cm) | Ta (°C) |
Mechanical Strength (MPa) | Ref. No. | Battery Type |
Remarks |
|---|---|---|---|---|---|---|---|---|
| PVDF-HFP | Zn(TFSI)2/ ZnTf2 + IL EMIMTFSI |
0.2 M | 1.31∙10−3 | 25 | - | [138] | - | There is no visual difference between the membrane containing Zn salt and the membrane without Zn salt, which suggests homogeneous blending. Electrochemical stability window with anodic stability limit at 2.8 V vs. Zn2+/Zn and single phase behavior from −50 °C to 100 °C |
| PVDF-HFP | ZnTf2/ EMIMTf |
30% | 1.96∙10−3 | 30 | - | [139] | Zn-MnO2 | Inclusion of ILs inside the membranes is necessary to obtain GPEs with good electrical characteristics; poor results are obtained for IL-free GPEs. NMP residual is fundamental to rise the cation transport number |
| PVDF-HFP | ZnTf2/ TiO2 |
25%/ 5% |
3.4∙10−4 | 25 | - | [140] | Zn-ion | Cation transport due to the migration of Zn2+ ions has been enhanced, in the case of TiO2 up to 5 wt%, owing to the formation of a space charge region, which would provide an enhanced mobility of Zn2+ |
| PVDF-HFP/PEO | Zn(BF4)2/ [EMIM]BF4 |
25% | 16.9∙10−3 | 25 | 9.12 | [141] | Zn-ion | Reversibility and stability of metallic Zn in ILZE cell under fixed galvanostatic condition shows a dense and dendrite-free morphology, which contains no zinc oxides or Hydroxides(>3000 cycles). The solid hydrogen free Zn/cobalt ferricyanide battery shows over 30,000 cycles with 90% capacity retained at a ≈100% columbic efficiency and can work at wide temperature range of −20 to 70 °C. |
| PVA | LiCl/ZnCl2/ MnSO4 |
3 M LiCl/ 2 M ZnCl2/ 0.4 M MnSO4 |
0.897∙10−2 | / | / | [142] | Zn-MnO2 | The protective layer of PEDOT as well as the mild neutral electrolyte suppress the structural pulverization and dissolution of MnO2 and help the rechargeable Zn–MnO2 battery to exhibits a favorable capacity retention |
| PVA | KOH | 3 g | 30.3∙10−3 | 25 | - | [143] | Zn-air | Water plays a significant role in the transport of ions for the PVA–KOH GPE, which consists of a PVA polymer matrix and KOH aqueous electrolyte for mitigating ohmic polarization and promoting the resulting reaction kinetics |
| PVA | KOH | 12 M(sk.) | 0.34 | 20 | - | [51] | Zn-air | The Grotthuss mechanism significantly contributes to or is the central mechanism for hydroxyl anion transport through PVA-KOH channels. Confinement of Zn2+ close to Zn electrode by GPE makes necessary the OH– transport through the membrane as the only ionic species causing conductivity |
| PVA/TEAOH | KOH | 18 M | 30∙10−3 | - | - | [144] | Zn-air | Tetraethylammonium hydroxide (TEAOH) replaces KOH as the ionic conductor in the TEAOH−PVA electrolyte. A greatly improved shelf life of the TEAOH−PVA electrolyte is achieved compared to normal PVA-KOH. The special NR4+ structure of TEAOH is relatively stable because the positive charge of the TEA+ remains the same regardless of the pH of the environment. TEAOH is hygroscopic which binds the water in the polymer electrolyte more tightly. |
| PVA | KOH | 0.15 M | 3.33∙10–4 | - | - | [145] | Zn-air | Fiber-shaped zinc–air batteries are fabricated via a continuous method with a atomically thin mesoporous Co3O4 layers in situ coupled with N-rGO nanosheets as the bifunctional catalyst synthetized by high-yield method. The potential gap ∆E between Ej = 10 and E1/2 is generally used to assess the bifunctional activity of catalysts. The lower value of ∆E means better bifunctional activity. |
| PVA | KOH/ SiO2 |
6 M/5% | 57.3∙10−3 | 25 | - | [146] | Zn-air | Porous PVA-based nanocomposite GPE containing 5 wt% SiO2 exhibits good ionic conductivity and electrolyte retention capability as well as good thermal and mechanical properties. SiO2 contribute to the electrolyte retention property due to the presence of high levels of bound water in the GPE formed through SiO2. |
| PVA/GA | KOH | 2% | 15∙10−3 | - | - | [147] | Zn-air | Battery components can be prefabricated as sheets of customized shape and size to fit space and energy needs for a variety of applications. |
| PVA/PEO | KOH | 8.3% | 0.3 | 25 | - | [148] | Zn-air | PEO was added to improve the mechanical properties of the electrolyte (0.83%). Aligned carbon nanotube (CNT) as sheets are materials that show conductivities of 102–103 S∙cm−1 and high tensile strengths in the order of 102–103 MPa. The number of CNT layer and the way CNT sheet electrode in rolled around hydrogel determines the performance of the battery. |
| PVA/PAA | KOH | 32% (sk.) | 0.301 | RT | - | [149] | Zn-air | Ionic conductivity of the alkaline PVA/PAA polymer electrolyte membrane increased as the PAA content increased. |
| PVA/PAA/ NAFION |
KOH | 6 M (sk.) | 6.6∙10−3 | RT | 39.4 | [150] | Zn-air | Nafion, can be suggested as a potential single cation conductor suppressing Zn(OH)42− crossover without deteriorating OH- conduction. Bicontinuous phases provide synergistic effects of blends. Into porous regions of the intermolecular condensed PVA/PAA nanofibres mat, Nafion is impregnated as an anion-repelling phase. |
| PVA/PAA/GO (PVAA–GO) |
KOH/ KI |
4 M KOH/ 2 M KI (sk.) |
0.155 | - | 67 | [151] | Zn-air | I− anions were employed as a soluble reaction modifier additive to reduce the charging potential alleviating degradation of the carbon-supported catalyst electrode. Hydrogen bonds of PVA have been partially replaced by hydrogen bonds among PVA, PAA, and GO. |
| PVA | KOH | - | 10∙10−3 | - | - | [152] | Zn/Ag | Cathode architecture with silver nanoparticle ink embedded into the conductive thread. Void spaces in the dendritic Zn deposit make it more flexible than compact Zn. batteries with 10 wt% KOH demonstrate stable capacity with lower silver migration. |
| PVA | Zn(CF3SO3)2 | 2 M | 12∙10−3 | - | - | [153] | Zn-ion | Freezing/thawing of PVA forms more crystalline microdomains, which serve as cross-links to achieve a porous network structure with pore size of 50–500 nm. When Zn(CF3SO3)2 is incorporated, gel fraction of free-moving PVA chain segments attract each other re-establishing hydrogen bonds and healing the fracture. |
| PAAM/ Zn-Alginate |
ZnSO4/ MnSO4 |
2 M ZnSO4 + 0.1 M MnSO4 |
43∙10−3 | - | - | [154] | Zn-MnO2 | Dual-crosslinked energy-dissipative hydrogel electrolyte endows the battery with outstanding flexibility and exceptional stability. Under heavy stress the covalently crosslinked PAAm network is deformed but maintain shape and strength of the hydrogel, whereas alginate network breaks, leading to effective energy dissipation. |
| PAAM | ZnSO4/ CoSO4 |
2 M ZnSO4/ 2 M CoSO4 |
0.12 | - | - | [155] | Zn/rich-Co3O4 | Highly reversible conversion reaction in Zn/Co(III) rich-Co3O4 system in mild aqueous electrolyte. The freeze-dried PAM hydrogel possesses interconnected macro-pores which allows ions to transfer freely in the electrolyte allow. Hence fast kinetic in the process of charge-discharge. High content of Co(III) in the Co(III) rich-Co3O4 leads to highly effective redox reaction. |
| PAAM PANa |
ZnSO4/ KOH-Zn(Ac)2 |
2 M ZnSO4/ 6 M KOH+ 0.2 M Zn(Ac)2 |
0.12/ ≈0.15 |
- | - | [156] | Zn-ion capacitor/Zn-air | U-shaped electrode is dual-functional with one part as a capacitor electrode and another part as an air electrode with two different electrolytes. The zinc-ion capacity maintains constant even overall 20,000 cycles. The high energy density of the zinc-air part could supply sufficient energy for zinc-ion capacitors. |
| PAM | KOH | 6 M(sk.) | 0.33 | - | - | [157] | Zn-air | The highly crosslinked PAM film was also found compatible with aqueous saline neutral pH GPE for flexible aluminum-air (Al-air) batteries. The optimal crosslinker (MBA) concentration was 0.2 mol% Catalyst powder was just simply spread onto PAM to form a catalyst layer in the side air-cathode. |
| PAM | KOH | 20% | 0.215 | - | - | [158] | Zn-air | The oxygen catalytic activity of MnO2/NRGO-Urea is much higher than that of MnO2/C and NRGO, suggesting the synergistic effect of MnO2 and NRGO |
| NFC/PAM | ZnSO4/ MnSO4 |
2 M ZnSO4/ 0.2 M MnSO4 (sk.) |
22.8∙10−3 | RT | - | [159] | Zn-MnO2 | With the addition of cellulose (NFC), a much larger and stable porous structure is formed. Sewing, enhance the shear tolerance of the battery. |
| EG-WAPUA/ PAM |
ZnSO4/ MnSO4 |
2 M ZnSO4/ 0.1 M MnSO4 |
14.6∙10−3 | −20 | [160] | Zn-MnO2 | The alcohols molecules must be anchored onto the polymer chains through covalent bonds to form a stable unified matrix to get anti-freezing hydrogel electrolytes. Covalent cross-linking bonding and physical hydrogen-bonding endows the synthesized hydrogel with excellent flexibility. Water molecules connect hydroxyl groups of the EG- waPUA and carbonyl groups of PAM chains firmly locking water molecules disrupting the formation of water crystal lattices. | |
| PAAM | ZnSO4 | 1 M ZnSO4 | 5.56∙10−3 | - | - | [161] | Zn/ PANI |
Vertically conducting PANI nanowires deposited on the CNT film with high crystallinity degree and uniform orientation, provides high electrical conductivity and substantial mechanical strength |
| PAM | ZnSO4/MnSO4 | 2 M ZnSO4/ 0.1 M MnSO4 |
1.73∙10−3 | RT | 0.27 | [162] | Zn-MnO2 | MnSO4 suppresses the dissolution of Mn2+ from MnO2 into electrolyte stabilizing the MnO2 cathode. Eco-flex silicone endows a superior waterproof performance to the flexible battery. Double-helix carbon nanotube (CNT) yarns are used as substrates. Roll-dip-coating and roll-electrodeposition continuous processes were used to produce the MnO2 yarn cathode and zinc yarn anode continuously. |
| PAA | KOH | 7.5 M | 0.36 | 65 | - | [163] | Zn-air | Solvodynamic radii of Zn(OH)42– calculated from the Stokes–Einstein equation had a range of values from 0.35 to 0.41 nm. For hydroxide ions, the thermochemical radius is 0.152 nm. Water retention is similar for PAA–KOH with 0.3, 0.5 and 0.7 mol% MBA. Higher crosslinking creates a denser network. When polymer structure then collapses, the network voids available for retaining water are minimized and water retention is decreased. Shape change on the Zn surface is also reduced with increasing MBA but ZAB cyclability is reduced. |
| PAA | KOH/ZnO | 8 M KOH/ Saturated |
55∙10−3 | - | - | [164] | Zn-MnO2 | Silver composite ink as current collector and nylon mesh embedded with electroactive inks show good flexibility avoiding cracks and delamination. The shear thinning behavior of the GPE can be used advantageously to allow printing with a lower pressure head |
| PANa | Zn(Ac)2/ KOH |
0.2 M Zn(Ac)2/ 6 M KOH |
0.17 | - | ≈0.15 | [165] | Zn/NiCo Zn–air | Electrostatic interactions between the acrylate ions along the PANa backbone and Zn2+ facilitated the formation of quasi-SEI eliminating zinc dendrites confirmed by SEM and TEM images of the Zn anode. PANa exhibited a tunable electrochemical performance depending on the concentration of water, OH− and/or Zn2+. The flexible quasi-SEI accommodated interface fluctuation during repeated charging/discharging without breakdown. |
| PANa | Zn(Ac)2/ KOH |
0.2 M Zn(Ac)2/ 6 M KOH(sk.) |
0.2 | - | - | [166] | Zn/NiCo | Resistance of CNT papers coated with Au foil drops from 31.1 to 0.8 Ω. Facilitating uniform electrodeposition of nickel cobalt hydroxide and zinc. PANa hydrogel was first pre-stretched to over 400% strain |
| PAA | Zn(Ac)2/ ZnO |
0.1–0.5 M Zn(Ac)2/ZnO | 0.28 | - | 0.047 | [167] | Zn-air | In aqueous electrolyte 6 M KOH, ZnO was found to be saturated at 0.5 M. The addition of 0.25 M ZnO reduces ionic conductivity of PAA–KOH. All the 0.25 M ZnO appears to be Zn(OH)42– in a highly alkaline solution (~6.5 M KOH). ZnO to reduce water activity and Zn corrosion. |
| P-(AM-co-AA) | Zn(Ac)2/ KOH |
0.2 M Zn(Ac)2/ 6 M KOH (sk.) |
0.148 | - | 0.052 | [168] | Zn-air | (Fe3C@N-doped carbons) as bifunctional non-noble-metal electro- catalyst at the air electrode with highly ordered graphitized structure. Abundant carboxylic acid groups (PAA) hinder packing of polymer chains, endowing PAA with amorphous properties. Silicone encapsulation slows down losses of water locked by GPE. |
| PAAK | KOH | 7.3 MKOH | 0.6 | 25 | - | [169] | Zn/Ni | The high solubility of Zn(OH)42− in alkaline solution results in the shape change of the zinc electrode, and the poor charge–discharge characteristics. |
| PANa | Zn(Ac)2/ KOH |
0.2 M Zn(Ac)2/ 6 M KOH (sk.) |
0.12 | 24 | - | [170] | Zn/Ni | PANa hydrogel soaked by concentrated ions can be easily stretched to 1400% in both cold (−20 °C) and hot (50 °C) environments. Concentrated ions reduce the freezing point of the hydrogel. Different ionic conductivity at different temperatures is substantiated by their microstructure, at −20 °C fewer micropores are observed and the micropores are smaller |
| PEO(H2O) | KOH | 30% | 5–10∙10−4 | RT | - | [171] | Zn/Ni, Zn/Cd |
Conductivity log(s) decreases almost linearly with 1000/T temperature, an Arrhenius-type behavior, which is often observed for semi-crystalline polymer. The presence, at high O/K ratios, of diffraction peaks not observed in the PEO nor in the KOH, suggests the existence of a different crystalline entity |
| PEO/ PVA(H2O) |
KOH | - | 4–5∙10−2 | RT | - | [172] | Zn-air | The surface morphology of film has a micro-porous structure consisting of many small pores with a dimension of about 0.1–0.2 µm. The cell with the solid polymer electrolyte has higher capacity and higher use of zinc on account of the much smaller pore size compared to PE/PP and cellulose separator. |
| PEO/PVdF | Zn(Ac)2/EMIMTFSI | 15% Zn(Ac)2/7% EMIMTFSI | 1.63∙10−4 | RT | - | [173] | - | PEO (90 wt%)/PVdF (10 wt%)]—15 wt% Zn (CF3SO3)2 IL 7 wt% (i.e., best conducting sample) shows by SEM the presence of uniformly distributed spherulites with numerous dark boundaries. Conductivity dependence vs. temperature exhibit curved plots, which is strongly associate with the segmental motion of polymer chain |
| PEO/PVDF-HFP/EC/PC | Zn(Tf)2/ ZnO |
1 M Zn(Tf)2/ 10% |
3∙10−3 | 30 | - | [174] | - | Raman shows that ZnO nanoparticles are present in the gelled polymer matrix as a separate phase. The temperature dependence σ vs. 1/T of the ionic conductivity of nanocomposite films showed VTF behavior. The gel electrolyte system EC–PC–Zn(Tf)2 immobilized in PVdF-HFP offers an acidic character. |
| PE/PVDF-HFP/EC/ PEGDME |
Zn(Tf)2/ Zn(TFSI)2 |
0.5 M Zn(TFSI)2 | 4.7∙10−4 | 25 | - | [175] | - | (PEGDMEs), methyl capped short-chain PEO possess excellent thermal and chemical stability. Blending PEGDME with a small amount of EC has large beneficial effects on the ionic conductivity. It is likely that a solid electrolyte interface (SEI) film forms at the surface of zinc, as in the case of lithium |
| PEO-PPO-PEO Pluronic Hydrogel (PHE) | ZnSO4/ Li2SO4 |
0.25 M ZnSO4/ 0.25 M Li2SO4 |
6.33∙10−3 | 25 | - | [176] | Zn/LMO Zn/LFP |
Perfect wetting of the electrodes, especially in the low temperature range. High initial open-circuit voltage (1.60 V) of the Zn/LMO cell, close to the thermodynamic voltage (1.71 V). Li+—intercalation/de-intercalation processes on the cathode side upon cycling. After crack due to bending or By a cooling-recovery procedure, PHE reversibly turned into its fluid phase rewetting the electrode in situ in 5 min. |
| Starch | KOH | 6 M | 4.34∙10−3 | RT | - | [177] | - | - |
| Cellulose/PAA/ gelatin |
KOH | 0.4% | 0.097 | RT | - | [178] | - | Pristine NFC hydrogel had 10−6–10−7 S/cm−1. With KOH NFC hydrogel became brittle, and not stable. Adding PAA and gelatin, more stable GPEs are attained. |
| QA-functionalized nanocellulose/ GO |
KOH | 1 M (sk.) | 58.8∙10−3 | 70 | - | [179] | Zn-air | According to the XRD results and activation energies, two types of ion transport including Grotthuss mechanism and vehicle mechanism exist. The water uptake of the QAFCGO membrane and performance stability in a zinc-air battery is higher than those of the A201 membrane. |
| Cellulose nanofibres | ZnCl2/ NH4Cl |
2 M ZnCl2/ 3 M NH4Cl |
16.4∙10−3 | - | - | [180] | Zn-ion | Graphite papers as flexible substrates for anodes. Superior battery performance related to the nanostructured PANI grown on lens paper. The nanostructured PANI facilitates electron and ion transport as well as its use during electrochemical process. |
| Functionalized DMOAP Cellulose nanofibres | KOH | 1 M | 21.2∙10−3 | - | - | [181] | Zn-air | Superior hydroxide-ion conduction and water retention of the membrane as well as low anisotropic swelling. Improved cycling stability of the battery, compared to commercial alkaline AEM (A201). Self-purging of carbonates in zinc-air batteries in CO2 rich atmosphere. |
| BC/PVA | Zn(Ac)2/ KOH |
6.0 M KOH/0.2 M Zn(Ac)2 | 80.8∙10−3 | RT | 0.951 | [182] | Zn-air | High crystallinity, high purity, and high hygroscopicity of bacterial cellulose (BCs). Load-bearing percolating dual network, these BC/PVA composite membranes exhibit superior mechanical strength and toughness. |
| Gelatin/Borax | ZnSO4/ MnSO4 |
4∙10−2 mol ZnSO4 4∙10−3 mol MnSO4 |
20∙10−3 | - | - | [183] | Zn-ion | Shape memory wire battery Zn-ion battery (SMWB) using Nitinol (NT). Twined yarns of SS/MnO2/PANI and Nitinol/Zn. Gelatin/Borax GPE showed similar performance respect to the liquid one. |
| Gelatin | KOH | 0.1 M | 3.1∙10−3 | - | - | [184] | Zn-air | Nonprecious metal catalyst (NPMC) based on silk fibroin for metal/nitrogen/carbon (M/N/C) with high catalytic activity for the ORR. Cable-type flexible ZAB with a spiral zinc anode. |
| κ-carrageenan/ rice paper |
ZnSO4/ MnSO4 |
2 M ZnSO4/ 0.1 M MnSO4 |
33.2∙10−3 | RT | - | [185] | Zn-ion | After 300 bending cycles, 95% capacity was retained. |
| PNiPAM/CMC | Zn(Tf)2 | 0–30% | 0.17∙10−3 | RT | 35.6 | [186] | Zn-ion | PNiPAM suppress dendrite formation. Most CMC/PNiPAM blend exhibited better mechanical properties than that of CMC. Thermo-responsive macromolecular transition from a hydrophilic to a hydrophobic structure at 30–35 °C |
| PVA/chitosan/ EC |
NH4NO3 | 40% | 1.6∙10−3 | RT | - | [187] | Zn/H+ battery |
Conductivity–temperature plot is Arrhenian type. Proton battery. ZnSO4 added to zinc anode. |
| Chitosan/PDDA/GA | KOH | 2 M | 24∙10−3 | RT | 25.30 | [188] | Zn-air | Glutareldehide crooslinking. Good stability in 8 M KOH at 80 °C. Used in fuel cell, capacitor, and zinc-air battery. |
| Guar ammonium salt/GA/PCL | KOH | 2 M | 0.123 | 90 | [189] | Zn-air | Low anisotropic swelling degree, outstanding mechanical strength, and excellent thermal stability. Binary cross-linking strategy to prepare highly conductive alkaline anion polymer electrolyte. Discharge time and capacity are superior to that the A201 membrane | |
| Gelatin/ NaAlginate/GA (GAME) |
ZnSO4 | 2 M ZnSO4 | 3.7∙10−2 | 2.14 | 2.14 | [190] | Zn-ion | Good interfacial contact between electrodes and GAME. 3D cross-linked IPN network with rich functional groups provides good ionic conductivity. Elasticity and toughness for a better resistance to Zn dendrite attack. |
| Poly ε-caprolactone | Zn(Tf)2 | 25% | 8.8∙10−6 | 25 | - | [191] | Zn-MnO2 | PCL (polycaprolactone) becomes a smoother one due to the addition of salt as observed from SEM. Good electrochemical stability window of 3.7 V with an excellent reversibility |
| PAN/PC/EC | Zn(Tf)2 | ≈0.6 M | 2.7∙10−3 | 27 | - | [192] | Zn-ion | The mass ratio of (PC-EC) to PAN is approximately 5:1. The logσ vs. 1/T relationship follows an Arrhenius-type behavior at all compositions. |
| Silica | Li2SO4/ ZnSO4 |
2 M Li2SO4/ 1 M ZnSO4 |
60∙10−3 | RT | - | [193] | Zn/LiMn2O4 | The required quantities of silica materials are in the range of 4–15 wt%. 10–12% higher cyclability compared with the performance of the batteries using the conventional liquid. |
| Fumed silica | ZnSO4 | 2 M ZnSO4 | 8.1∙10−3 | RT | - | [194] | Zn-ion | Zn dendrite growth is thoroughly eliminated. |
| Gelatin/PAM | ZnSO4/ MnSO4 |
2 M ZnSO4/ 0.1 M MnSO4 |
1.76∙10−2 | RT | 7.76 | [12] | Zn-ion | Flexible ZIB can be tailored to any desired shape to meet the demands of high-level integration. ZIB did not catch fire even after being exposed to fire for more than 5 min. Reliable power source that can work under a variety of severe conditions, such as being bent, hammered, punctured, cut, sewed, washed in water, and set on fire |
| Gelatin | ZnSO4/ MnSO4 |
2 M ZnSO4/ 0.1 M MnSO4 |
5.68∙10−3 | RT | 1.25 | [12] | ||
| Gelatin | ZnSO4/ Li2SO4 |
0.5 M ZnSO4/ 0.5 M Li2SO4 |
6.1∙10−3 | - | 0.11 | [87] | Zn/LiMn2O4 | In situ coating of the GHE on the electrodes. Solidifies into a strong film, provides mechanical strength to suppress Zn dendrite formation. Fast cooling rate leads to more orderly localized gelatin molecules and a more robust electrolyte |
| Xanthan gum | ZnSO4/ MnSO4 |
3 M ZnSO4/ 0.1 M MnSO4 |
16.5∙10−3 2.5∙10−3 |
−8 °C | - | [64] | Zn-ion | A high-salt tolerant, water-soluble polysaccharide. Conductivity at −8 °C, suggesting its ability of working at low temperatures. Gum electrolyte has a long-term stability. |