Not comparing like with like: a measurement-conditions audit of the solid polymer electrolyte literature
Year: 2026
Type: preprint
Abstract: Ionic conductivities of solid polymer electrolytes (SPEs) are routinely compared across publications as though they were measured the same way. We tested that assumption by building a measurement-conditions annotation layer over the largest open compilation of SPE conductivity data (16,009 measurements from 214 source papers), recording for each source study how the measurement was actually made. Fifty-eight papers spanning 1986–2020 and 20 journals were annotated across 59 fields, covering 11,394 measurements, or 71.2% of the compilation. Every condition was extracted twice independently and all substantive disagreements were adjudicated against the source PDFs. Three findings follow. First, 22.5% of the compilation’s measurements come from systems containing no polymer at all—salts in molecular solvents or ionic liquids, classified from the declared composition alone. These sit a median 2.6 orders of magnitude above solvent-free SPEs while being measured 35 řC cooler, and they inflate any pooled statistic drawn from the dataset. Second, refitting each formulation’s temperature series and extrapolating to 25 řC shows that among genuinely solvent-free polymer electrolytes, 50.1% reach 10−4 S cm−1 at the temperature reported but only 3.4% do so at 25 řC, a median loss of 2.54 orders; 97.5% of their best-reported values are taken at ≥60 řC. Pooling classes understates this attrition because liquid systems barely lose anything on cooling. Third, the conditions needed to reproduce or even recompute a conductivity are frequently absent: film thickness is not recoverable for 60.7% of papers, electrode area for 68.4%, per-point equilibration time for 77.2%, and only 5 of 57 papers report a measured residual water content.
Source: ChemRxiv
Author: Om Chaudhari
Institution: Indian Institute of Technology Bombay
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213987541