Recent Developments in Electrochemical Lignin Depolymerization Using Flow Systems: A Mini Review

Lignin, the second most abundant biopolymer, remains critically underutilized despite annual availability of 50 million tons. Electrochemical flow depolymerization combines energy‐efficient hydrogen production with selective lignin upgrading, offering a promising pathway to unlock this renewable aromatic feedstock. This mini‐review provides the first systematic analysis of flow‐based anodic lignin depolymerization studies, categorizing them into three strategic objectives: (1) oxygen evolution reaction (OER) substitution achieving cell voltage reductions of 0.2–0.45 V and 20%–40% energy savings, (2) nonselective fragmentation yielding oligomeric intermediates with molecular weight reductions up to 87%, and (3) selective monomer production up to 8 wt%. Critical deficiencies limiting industrial translation include incomplete lignin characterization, heterogeneous reactor descriptions, absence of standardized analytics, and prevalence of semibatch over continuous operation. Six research priorities are defined: (1) transition to continuous single‐pass or CSTR configurations with integrated product separation, (2) standardized test protocols and reference lignins with unified analytical methods, (3) comprehensive reactor design specifications, (4) development of stable noble metal‐free electrodes, (5) integration of continuous downstream separation technologies, and (6) systematic technoeconomic and life cycle assessments versus petrochemical benchmarks. This roadmap advances electrochemical lignin valorization from laboratory toward industrial readiness, essential for circular carbon economy strategies and chemical industry defossilization.