SEBASTIAN POHLMANN
CTO, UP Catalyst OÜ, Tallinn, Estonia

Abstract

Electrochemical energy storage technologies (Lithium & Sodium-ion, Lithium-Sulfur batteries) require a range of highly engineered carbon materials as active materials or conductive additives. With the overal demand for batteries expected at 5 TWh in 2030 (1), this article aims to give an overview on the challenge of sourcing these materials from sustainable processes as well as potential solutions. One solution in particular is to utilise CO2 as a feedstock to create valuable carbon materials while avoiding greenhouse gas emissions. The utilisation of CO2 is assessed from both technical and regulatory perspective, showcasing that a true carbon sink can be found in these materials.

Carbon materials for energy storage

Rechargable energy storage devices such as Lithium-ion batteries (LIBs) and Sodium-ion batteries (SIBs) store energy by moving Alkali-metal cations between their cathodes and their anodes. During the charging of these devices, ions are moved from cathode to anode, resulting in a current opposite to the stream of charged cations (2).

While the cathodes for these energy storage devices often comprise metal oxides or other crystal structures, their anodes are most often found to be made of carbon materials (3, 4, 5). In Lithium-ion batteries, Graphite is used (3, 4), while Sodium-ion batteries use non-graphitised carbons (Hard Carbons) (5). Other energy storage systems such as Lithium-Sulfur batteries use mixed carbon compounds (6). The reason for the use of carbon is found in the low potentials at which the Alkalimetal cations are stored in the material, allowing for overall higher cell voltages for the whole energy storage system (4). Lithiated Graphite as an example exhibits an electrochemical potential close to that of metalic Lithium, allowing for high cell voltages.
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