Algae‑Based Hard Carbon as a Sustainable Replacement for Graphite Anodes in Lithium‑Ion Batteries

Abstract

Graphite is the dominant anode material in commercial lithium‑ion batteries owing to its high reversibility and excellent cycling stability. However, its limited theoretical capacity of 372 mah g⁻¹ and environmental concerns associated with graphite mining motivate the search for more sustainable and higher‑capacity alternatives. Biomass‑derived hard carbons, particularly algae‑based hard carbons, have emerged as promising candidates due to their renewable origin, tunable porosity, and rich surface chemistry. This paper reviews the synthesis routes, structural characteristics, lithium‑storage mechanisms, electrochemical performance, advantages, and current limitations of algae‑derived hard carbon anodes. Reported studies indicate that optimized algae‑based hard carbons can deliver reversible capacities exceeding those of graphite and offer improved rate capability and low‑temperature behaviour, while reducing dependence on mined or fossil‑based carbons. Nevertheless, significant initial irreversible capacity loss, relatively low electronic conductivity, and challenges in large‑scale, reproducible production still hinder practical implementation. Addressing these issues through surface engineering, heteroatom doping, and process optimization will be crucial to realize algae‑derived hard carbon as a viable sustainable replacement for graphite in next‑generation lithium‑ion batteries.​