High-Throughput Compatibility Screening of Materials for SF-Alternative Insulation.

With the annual global electricity production exceeding 30,000 TWh, the safe transmission of electric power has been heavily relying on SF, the most potent industrial greenhouse gas. While promising SF alternatives have been proposed, their compatibilities with materials used in gas-insulated equipment (GIE) must be thoroughly studied. This is particularly true as the emerging SF alternatives generally leverage their relatively higher reactivity to achieve lower global warming potentials (GWPs). Here, a high-throughput compatibility screening of common GIE materials was conducted with a representative SF alternative, namely, CFN (2,3,3,3-tetrafluoro-2-(trifluoromethyl)propanenitrile)/CO gas mixtures. In this screening, the insulation performance of CFN/CO gas mixtures, as an indicator of the CFN/materials compatibility level, was periodically monitored during the thermal aging with tens of materials from SF-insulated GIE, including desiccants/adsorbents, rubber, plastics, composites, ceramics, metals, etc. The identification of incompatible materials and the follow-up mechanism studies suggested that the acidity of materials represents the primary cause for CFN/materials incompatibility when CFN/CO gas mixtures are used as a drop-in replacement solution for existing SF-insulated apparatuses. Mitigation strategies tackling the acidity of materials were then proposed and validated. Additionally, the amphoteric characteristics of CFN were briefly discussed. This work provides insight into the materials incompatibility of SF alternatives, along with validated mitigation strategies, for the selection and design of materials used in future eco-friendly GIE.