Aleksander Piasecki

Premature failure of industrial lead–acid batteries can arise not only from conventional aging but also from atypical environmental exposure that changes the chemistry and morphology of corrosion products. This study presents a focused post mortem investigation of three industrial flooded lead–acid batteries that underwent premature failure shortly after building renovation, despite differing in manufacturer, nominal capacity, operational target, and service time. Corrosion products collected from electrolytes, bridges, and terminals were examined by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and complementary electrochemical testing of lead-based alloys in sulfuric acid. Raman spectra indicated mixtures of α- and β-PbO₂, PbSO₄, and trace PbS, whereas XRD identified the dominant crystalline phases as PbO₂ polymorphs, PbO, PbSO₄, and Pb₃O₄. The absence of a strong PbS signal in XRD is consistent with its low amount, poor crystallinity, and surface-localized occurrence. SEM images showed loose corrosion products rather than a dense protective layer. The combined evidence indicates an atypical, sulfide-associated corrosion pattern. External H₂S exposure is considered as one possible source of sulfur-containing species; however, no atmospheric H₂S measurements, renovation-material analyses, or controlled exposure tests were performed.

Lead–acid batteries remain widely used as backup power sources in distributed industrial infrastructure, where reliable State-of-Health (SoH) assessment is sometimes complicated by poorly documented service histories and uncontrolled environmental exposure. This study examines 12 field-deployed 12 V valve-regulated lead–acid (VRLA) batteries repres1enting six commercial models, withdrawn from medium-voltage grid-management devices after five years of service. Their condition was evaluated using temperature-dependent capacity testing, open-circuit voltage (OCV) measurements, and electrochemical impedance spectroscopy (EIS). The measurements revealed pronounced and highly non-uniform degradation. At −25°C, none of the tested battery types delivered more than 30% of their nominal capacity. More importantly, several batteries exhibiting apparently normal OCV values of 13.2–13.3 V retained only 10–30% of their nominal capacity during discharge, demonstrating that voltage measurements alone may substantially overestimate the availability of backup power. Advanced degradation was also manifested by non-linear discharge profiles and anomalous, physically non-interpretable impedance spectra, providing diagnostic information not evident from OCV measurements. These findings show that OCV-based screening alone is insufficient for reliable SoH assessment of aged VRLA batteries used in emergency power applications. For distributed industrial installations, practical monitoring protocols should therefore combine temperature-aware rapid electrical diagnostics, particularly impedance- or internal resistance-based screening, with periodic reference capacity tests and replacement criteria based on application-specific minimum-capacity requirements.

With the rising interest in hydrogen technologies as a pathway toward lower-carbon energy systems, there is a growing need for proton exchange membranes that can operate reliably in the 120–200 °C window. This second part of the review examines mixed phosphate–silicate networks, composites, and hybrid membranes designed to move beyond the limitations of the single-anion glasses discussed in Part I. Rather than listing compositions only, the present analysis is organized around a comparative framework that links network chemistry, hydration management, pore-space morphology, interfacial proton transport, and durability under thermal/humidity cycling. Mixed-anion lattices, sol–gel-derived porous glasses, polymer-assisted interpenetrating networks, ionic-liquid-modified systems, fully inorganic composites, and mechanochemically prepared hybrids are evaluated with respect to conductivity, humidity tolerance, structural stability, and device relevance. Particular attention is paid to strategies that attempt to decouple proton conductivity from simple water uptake by combining acidic-site engineering with mesostructural control. The literature shows that recent progress is real but uneven. Conductivity gains are often achieved through better retention of hydrated proton pathways or acid-rich interphases, yet these benefits remain constrained by pore collapse, acid migration, gas crossover, interfacial losses, or insufficient long-term validation in membrane–electrode assemblies. The review, therefore, closes with a cross-class benchmarking matrix and a synthesis-oriented guide intended to support more critical comparison of future intermediate-temperature membrane designs.

The accelerated deployment of hydrogen technologies is widely discussed as a pathway to mitigate climate change and reduce environmental pollution associated with fossil fuel use. In this context, intermediate-temperature proton-exchange membranes that operate in the 120–200 °C window, similar to the one characterizing liquid-acid PAFC systems (much larger in their power range), are sought as a bridge between low-temperature PFSA-based PEMFCs and low-temperature PCFs, thus combining reduced sensitivity to external humidification with solid-electrolyte handling. This Part I review surveys phosphate- and silicate-based glassy proton conductors as single-anion baseline matrices and organizes the literature around a mechanistic screening framework that links processing fingerprints—particularly sol–gel hydrolysis/condensation conditions, aging, drying, and thermal treatment—to pore architecture, hydration state, and the dominant proton-transport regime. Across both families, conductivity is governed by coupled variables: network chemistry (acidic site density and connectivity), water activity (RH), and microstructure-controlled percolation and retention. Reported σ values can arise from fundamentally different regimes, ranging from hopping-dominated transport supported by dense hydrogen-bond networks and proton-bearing groups to carrier-assisted, water-mediated transport in connected porosity, with distinct humidity dependence and stability implications. Accordingly, the review treats σ(T,RH) and activation energy together with hydration/porosity indicators as primary screening metrics, and it records missing durability and device-level information—chemical stability (hydrolysis and leaching/acid migration), mechanical robustness and cycling response, and current/power density where available—as explicit knowledge gaps. While substantial progress has been achieved within single-anion phosphate and silicate glasses, particularly through engineered acidity and microstructural control, most systems remain limited by hydration drift under gradients, thermal/humidity cycling stability, and electrode/electrolyte interfacial constraints when evaluated against intermediate-temperature membrane requirements. These conclusions establish a quantitative baseline and comparison rules for Part II, which will assess mixed-network, composite, and hybrid strategies designed to decouple conductivity from water-retention and durability trade-offs.