Lithium‐Metal Free Sulfur Battery Based on Waste Biomass Anode and Nano‐Sized Li₂S Cathode

The realization of a stable lithium‐metal free (LiMF) sulfur battery based on amorphous carbon anode and lithium sulfide (Li₂S) cathode is here reported. In particular, a biomass waste originating full‐cell combining a carbonized brewer's spent grain (CBSG) biochar anode with a Li₂S‐graphene composite cathode (Li₂S70Gr30) is proposed. This design is particularly attractive for applying a cost‐effective, high performance, environment friendly, and safe anode material, as an alternative to standard graphite and metallic lithium in emerging battery technologies. The anodic and cathodic materials are characterized in terms of structure, morphology and composition through X‐ray diffraction, scanning and transmission electron microscopy, X‐ray photoelectron and Raman spectroscopies. Furthermore, an electrochemical characterization comprising galvanostatic cycling, rate capability and cyclic voltammetry tests were carried out both in half‐cell and full‐cell configurations. The systematic investigation reveals that unlike graphite, the biochar electrode displays good compatibility with the electrolyte typically employed in sulfur batteries. The CBSG/Li₂S70Gr30 full‐cell demonstrates an initial charge and discharge capacities of 726 and 537 mAh g⁻¹, respectively, at 0.05C with a coulombic efficiency of 74%. Moreover, it discloses a reversible capacity of 330 mAh g⁻¹ (0.1C) after over 300 cycles. Based on these achievements, the CBSG/Li₂S70Gr30 battery system can be considered as a promising energy storage solution for electric vehicles (EVs), especially when taking into account its easy scalability to an industrial level.