Cardanol-Derived Epoxy Resins as Biobased Gel Polymer Electrolytes for Potassium-Ion Conduction

In this study, biobased gel polymer electrolyte (GPE) membranes were developed via the esterification reaction of a cardanol-based epoxy resin with glutaric anhydride, succinic anhydride, and hexahydro-4-methylphthalic anhydride. Nonisothermal differential scanning calorimetry was used to assess the optimal curing time and temperature of the formulations, evidencing a process activation energy of ∼65–70 kJ mol–1. A rubbery plateau modulus of 0.65–0.78 MPa and a crosslinking density of 2 × 10–4 mol cm–3 were found through dynamic mechanical analysis. Based on these characteristics, such biobased membranes were tested for applicability as GPEs for potassium-ion batteries (KIBs), showing an excellent electrochemical stability toward potassium metal in the −0.2–5 V voltage range and suitable ionic conductivity (10–3 S cm–1) at room temperature. This study demonstrates the practical viability of these biobased materials as efficient GPEs for the fabrication of KIBs, paving the path to increased sustainability in the field of next-generation battery technologies

Lignin as polymer electrolyte precursor for stable and sustainable potassium batteries

Potassium batteries show interesting peculiarities as large-scale energy storage systems and, in this scenario, the formulation of polymer electrolytes obtained from sustainable resources or waste-derived products represents a milestone activity. In this study, a lignin-based membrane is designed by crosslinking a pre-oxidized Kraft lignin matrix with an ethoxylated difunctional oligomer, leading to self-standing membranes that are able to incorporate solvated potassium salts. The in-depth electrochemical characterization highlights a wide stability window (up to 4 V) and an ionic conductivity exceeding 10−3 S cm−1 at ambient temperature. When potassium metal cell prototypes are assembled, the lignin-based electrolyte attains significant electrochemical performances, with an initial specific capacity of 168 mAh g−1 at 0.05 A g−1 and an excellent operation for more than 200 cycles, which is an unprecedented outcome for biosourced systems in potassium batteries

14C calibration in the 2nd and 1st millennia BC-Eastern Mediterranean radiocarbon comparison project (EMRCP)

We have measured additional known-age German oak samples in 4 intervals in the 2nd and 1st millennia BC to add to (and to replicate) parts of the international Northern Hemisphere radiocarbon calibration data set. In the 17th, 16th, and 12th centuries BC, our results agree well with IntCal04. In the 14th and 13th centuries BC, however, we observe a significant offset, with our results on average 27 yr older than IntCal04. The previously reported 14C offset between Anatolian juniper trees and central European oaks in the 9th and 8th centuries BC is smaller now, on the basis of our new measurements of German oak, but still evident. In the 17th and 16th centuries BC, the 14C ages from the Anatolian chronology agree well with IntCal04 and our new German oak data. \ua9 2010 by the Arizona Board of Regents on behalf of the University of Arizona

Polymer electrolytes for potassium batteries in the SYNERGY project framework

SYNERGY European project aims to strengthen the scientific and technical competences at the involved Portuguese institutions (PT Cluster) in the field of energy harvesting and micropower management, as a key component towards self-sustainable smart platforms on flexible substrates. Among the most in-vogue electrochemical energy technologies, the contribution from Politecnico di Torino also includes the development of advanced materials for potassium-based batteries. In this contribution, we present our recently started work focused on polymer electrolytes to replace unsafe and unstable liquid-state systems. Indeed, the high reactivity of alkali metals, like lithium and potassium, also interfacing with electrolytes, causes the unavoidable creation of the SEI layer, which is very likely to be fragile and heterogenous, causing the dendrites formation and eventually the failure of the cell. Gel polymer electrolytes (GPE) have been already proven to suppress dendrites growth thanks to their higher shear modulus. A BMA-co-PEGDA UV-cured system incorporating a plasticizer is here fully characterized and proposed as gel-polymer electrolyte for potassium-based batteries, showing outstanding ionic conductivity, excellent capacity retention in lab-scale cell prototypes and very good performances for more than 500 cycles

Preliminary studies on polymer electrolytes for potassium-based batteries

Future renewable energy integrated grid systems require rechargeable batteries with low cost, high safety and long cycle life. The much higher abundance of potassium compared to lithium in Earth crust indicates that rechargeable potassium batteries can represent an attractive replacement for lithium-ion counterparts. Rechargeable potassium batteries have gained tremendous attention during the past decade. However, the development of rechargeable potassium batteries is still in its infancy. In this talk, the main activities related to safe and quasi-solid polymer electrolytes investigated at the Electrochemistry Group @ PoliTO will be present. Two main approaches will be discussed, i.e. UV-curable formulations for sustainable and rapid preparation procedures and biosourced membranes coming from lignin or other sustainable biomasses

Nanostructured TiO2 as anode material for potassium batteries

The development of solar energy conversion technologies energy must be coupled with efficient storage systems or solar fuels generators (like NH3). Nowadays, the most known batteries are lithium-ion ones (LIBs), that allowed the great success of portable electronic devices in the last decade. However, the low natural abundance of lithium threatens the further development of LIBs; consequently, the research moved toward post-lithium batteries, such as potassium-ion systems (PIBs). Due to the large atomic radius of potassium, some electrode materials that are commonly used in Li‐ion systems are not suitable for potassium batteries. Thus, anode and cathode materials that can tolerate the intercalation/deintercalation of K+, without suffering from the reorganization energy, are needed. Herein, we report the use of TiO2, in the form of both nanoparticles (NP) and nanotubes (NT), as anode material for PIBs. TiO2 NPs afforded a quite stable specific capacity, with a 87.4% retention efficiency after 200 charge/discharge cycles, when KFSI in DME was used as electrolyte. The Coulombic efficiency (CE) was remarkably high (> 98%), starting from the first cycles, suggesting the high reversibility of the insertion reaction. TiO2 NTs were synthesized by anodic oxidation of a Ti foil, in both the amorphous and the anatase phase and by varying the anodization time. In the best case, the specific capacity was 75 µAh/cm2, with a retention efficiency of 86.4% after 200 cycles and a CE of 98%. This preliminary work paves the way to a further development of nanostructured TiO2 as anode material in the PIB field

Nitrogen- and potassium-based technologies boosting the energy transition

The global energy and environmental context clearly highlights the need for new technologies capable of guaranteeing the conversion of renewable sources and the storage of the produced energy in a sustainable, safe and geographically balanced way. (Electro)chemical technologies and materials science are the basis of many of these strategies, and international decision-makers, being aware of them, have begun to promote suitable funding initiatives. In this contribution, three emerging scenarios currently under investigation at the Electrochemistry Group @PoliTO are presented. First, Li-N2 cells are proposed as a solution for the electrochemical N2 reduction reaction (E-NRR), leading to the irreversible Li3N formation and subsequent protonation into NH3. This represents a sustainable and renewable energy-powered process to replace the Haber-Bosch one and making NH3 as a viable green energy carrier, being easier transportable and safer than H2. Second, potassium batteries are presented as a viable alternative to Li-based ones for both stationary energy storage and E-NRR applications. They exploit potassium abundance, negative redox potential and weak Lewis acidity, leading to a truly promising technology to boost the energy transitions. Low-cost and/or biosourced cell components will be presented in the contribution. Third, our attempt to pushing these technologies towards higher TRLs in our laboratory will be presented, from both the fabrication and characterization aspects

Biobased polymer electrolytes for sustainable potassium batteries

Rechargeable batteries are a key technology in the world rush toward the energy transition. Li-ion batteries (LIBs) have reached unprecedent targets of performance and safety, nevertheless it is not logical to think that the LIB technology only is able to bear the world electrification, given the lithium scarcity (0.0017 wt% in the Earth crust) and its uneven distribution. It is therefore not surprising the increasing attention coming from the research community on potassium-based batteries. Potassium is abundant on Earth (2.09 wt%), evenly distributed, characterized by a very low standard equilibrium potential (-2.93 V vs. SHE with respect to -3.09 V vs. SHE of Li+/Li) and Lewis acidity (smaller solvated ions and thus faster conduction) [2]. K-ion batteries (KIBs) already proved to have all the requirements for large stationary storage systems. In this scenario and keeping in mind the sustainability of this technology, our groups work on the design, synthesis and characterization of fully biobased polymers for KIB electrolytes. In this contribution two gel polymer electrolytes are proposed. Primary, the first biosorced electrolyte successfully used in a KIB system is a lignin-based membrane resulted by crosslinking of pre-oxidized Kraft lignin matrix with PEGDGE [1]. Once the membrane is activated by soaking liquid electrolyte, the as obtained gel polymer electrolyte has been fully characterized showing suitable ionic conductivity exceeding 10-3 S cm-1, excellent chemical compatibility and tremendous ability at suppressing the growth of metal dendrites. The second electrolyte proposed for potential potassium-based application was crosslinked via ring-opening reaction of a cardanol-epoxidized resin with a cyclic succinic anhydride as curing agents. The samples showed excellent mechanical and thermal stability, a high electrolyte uptake ability, impressive electrochemical stability and outstanding ionic conductivities (up to 10-2 S cm-1)