Identification and Mitigation of Generated Solid By-Products during Advanced Electrode Materials Processing

Abstract

A scalable, solid-state elevated-temperature process was developed to produce high-capacity carbonaceous electrode materials for energy storage devices via decomposition of a starch-based precursor in an inert atmosphere. In a separate study, it is shown that the fabricated carbonaceous architectures are useful as an excellent electrode material for lithium-ion, sodium-ion, and lithium-sulfur batteries. This article focuses on the study and analysis of the formed nanometer-sized by-products during the lab-scale synthesis of the carbon material. The material production process was studied in operando (that is, during the entire duration of heat treatment). The unknown downstream particles in the process exhaust were collected and characterized via aerosol and liquid suspensions, and they were quantified using direct-reading instruments for number and mass concentrations. The airborne emissions were collected using the Tsai diffusion sampler (TDS) for characterization and further analysis. Released by-product aerosols collected in a deionized (DI) water trap were analyzed, and the aerosols emitted from the post-water-suspension were collected and characterized. After long-term sampling, individual particles in the nanometer size range were observed in the exhaust aerosol with layer-structured aggregates formed on the sampling substrate. Upon the characterization of the released aerosol by-products, methods were identified to mitigate possible human and environmental exposures upon industrial implementation.

Environmental Impacts of Graphite Recycling from Spent Lithium-Ion Batteries Based on Life Cycle Assessment

“…52 Pyrolysis processes are also a significant impact driver not only given their energy-intensive character but also due to the release of volatile organic compounds (VOCs) from thermal decomposition, resulting in aerosol hydrocarbon formation with small average particle diameters and potential respiratory risks. 53 For instance, graphite readily oxidizes to form CO 2 at temperatures above 700 °C under an oxygen atmosphere. The residual electrolyte and organic binders present in graphite decompose and subsequently volatilize to form harmful gases such as hydrogen fluoride, volatile compounds including ethylene carbonate, propylene carbonate, or diethyl carbonate, and their decomposed products.…”

“…On the contrary, pyrometallurgical processes use large amounts of inert gases such as argon, contributing to eutrophication, ozone depletion, human carcinogenic toxicity, human noncarcinogenic toxicity, and ecotoxicity . Pyrolysis processes are also a significant impact driver not only given their energy-intensive character but also due to the release of volatile organic compounds (VOCs) from thermal decomposition, resulting in aerosol hydrocarbon formation with small average particle diameters and potential respiratory risks . For instance, graphite readily oxidizes to form CO 2 at temperatures above 700 °C under an oxygen atmosphere.…”