Coherence in the Ferroelectric A3ClO (A = Li, Na) Family of Electrolytes

Energy harnessing and storage from surface switching with a ferroelectric electrolyte

In the quest for innovative energy solutions suitable for mobile, stationary and digital applications, ferroelectric topological insulators (FETIs)1 emerge as promising candidates. These materials combine topologically protected states with spontaneous and switchable polarization. This study reveals emergent phenomena in FETI-electrolytes through experiments and simulations, specifically in the A3-2xBaxClO family (where A = Li, Na or K, and x = 0 or 0.005). Here, it is shown that surface oscillations of the potential (V), temperature, and mass may synchronize with the bulk's oscillations, and be harnessed and stored in the form of electrical energy either in a sole FETI or in a battery-type cell presenting a panoply of applications from wireless batteries to transistors, memories, sensors, and selective catalysts.

Distinctive Electric Properties of Group 14 Oxides: SiO2, SiO, and SnO2

The oxides of group 14 have been widely used in numerous applications in glass, ceramics, optics, pharmaceuticals, and food industries and semiconductors, photovoltaics, thermoelectrics, sensors, and energy storage, namely, batteries. Herein, we simulate and experimentally determine by scanning kelvin probe (SKP) the work functions of three oxides, SiO2, SiO, and SnO2, which were found to be very similar. Electrical properties such as electronic band structure, electron localization function, and carrier mobility were also simulated for the three crystalline oxides, amorphous SiO, and surfaces. The most exciting results were obtained for SiO and seem to show Poole-Frankel emissions or trap-assisted tunneling and propagation of surface plasmon polariton (SPP) with nucleation of solitons on the surface of the Aluminum. These phenomena and proposed models may also describe other oxide-metal heterojunctions and plasmonic and metamaterials devices. The SiO2 was demonstrated to be a stable insulator interacting less with the metals composing the cell than SnO2 and much less than SiO, configuring a typical Cu/SiO2/Al cell potential well. Its surface charge carrier mobility is small, as expected for an insulator. The highest charge carrier mobility at the lowest conduction band energy is the SnO2's and the most symmetrical the SiO's with a similar number of electron holes at the conduction and valence bands, respectively. The SnO2 shows it may perform as an n-type semiconductor.

Cork: Enabler of sustainable and efficient coaxial structural batteries

Structural batteries aim to advance to 'massless' energy storage units. Here we report an electrode-less coaxial battery with a cork-internal shell, CFRP(+)/cork/Cu/Na_2.99Ba_0.005ClO/Al(-), where CFRP is carbon fiber reinforced polymer. The cell may, alternatively, solely have a cork external shell cork/Cu(+)/Na_2.99Ba_0.005ClO/Al(-). Cork is a cellular material with a negative CO₂ footprint, light, elastic, impermeable to gases or liquids, and an excellent thermal insulator. Cork was used tandemly with a CFRP shell, working as the positive current collector to enhance the structural batteries' properties while allowing a giant electrostatic performance in conjunction with the Na⁺ solid-state ferroelectric injected between the Al negative collector and the cork. Cork was shown a polar dielectric. This 'minimalist' cell may perform without copper making the cells even more sustainable. Neither cells contain traditional electrodes, only one or two current collectors. The cells perform from 0 to >50 °C. The maximum capacity of the cork/Cu(+)/Na_2.99Ba_0.005ClO/Al(-) cells is ∼110 mAh.cm^-2 (outer shell) with <I> ≈ 90 μA cm^-2, <V> ≈ 0.90 V, V_max ≈ 1.1-1.3 V, I_max ≈ 108 μA cm^-2, and a constant resistance discharging life (>40 days). The novel family of cells presented may also harvest waste heat and thermal energy at a constant temperature as their potential and current increase with temperature. Conversely, rising potentials boost the cells' temperature, as expected from pyroelectrics, as shown herein.

Combating Li metal deposits in all-solid-state battery via the piezoelectric and ferroelectric effects

All-solid-state Li-metal batteries (ASSLBs) are highly desirable, due to their inherent safety and high energy density; however, the irregular and uncontrolled growth of Li filaments is detrimental to interfacial stability and safety. Herein, we report on the incorporation of piezo-/ferroelectric BaTiO₃ (BTO) nanofibers into solid electrolytes and determination of electric-field distribution due to BTO inclusion that effectively regulates the nucleation and growth of Li dendrites. Theoretical simulations predict that the piezoelectric effect of BTO embedded in solid electrolyte reduces the driving force of dendrite growth at high curvatures, while its ferroelectricity reduces the overpotential, which helps to regularize Li deposition and Li⁺ flux. Polarization reversal of soft solid electrolytes was identified, confirming a regular deposition and morphology alteration of Li. As expected, the ASSLBs operating with LiFePO₄/Li and poly(ethylene oxide) (PEO)/garnet solid electrolyte containing 10% BTO additive showed a steady and long cycle life with a reversible capacity of 103.2 mAh g^-1 over 500 cycles at 1 C. Furthermore, the comparable cyclability and flexibility of the scalable pouch cells prepared and the successful validation in the sulfide electrolytes, demonstrating its universal and promising application for the integration of Li metal anodes in solid-state batteries.

An All-Solid-State Coaxial Structural Battery Using Sodium-Based Electrolyte

The transition to a sustainable society is paramount and requires the electrification of vehicles, the grid, industry, data banks, wearables, and IoT. Here, we show an all-solid-state structural battery where a Na⁺-based ferroelectric glass electrolyte is combined with metallic electrodes/current collectors (no traditional cathode present at fabrication) and thin-ply carbon-fiber laminates to obtain a coaxial multifunctional beam. This new concept aims to optimize the volume of any hollow beam-like structure by integrating an electrochemical system capable of both harvesting thermal and storing electrical energy while improving its mechanical performance. The coaxial cell is a coaxial cable where the dielectric is ferroelectric. The electrochemical results demonstrated the capability of performing three-minute charges to one-day discharges (70 cycles) and long-lasting discharges (>40 days at 1 mA) showing an energy density of 56.2 Wh·L^-1 and specific energy of 38.0 Wh·kg^-1, including the whole volume and weight of the structural cell. This is the highest specific energy among safe structural cells, while no Na⁺-based structural cells were found in the literature. The mechanical tests, instead, highlighted the coaxial cell capabilities to withstand severe inelastic deformation without compromising its functionalities, while increasing the flexural strength of the hosting structure. Moreover, the absence of alkali metals and liquid electrolytes together with its enhanced thermal properties makes this coaxial structural battery a valid and safe alternative as an energy reservoir for all the applications where traditional lithium-ion batteries are not suitable.