The integration of diverse capabilities into a waste-free biorefinery has laid the foundation for solving tricky contractions in the holistic utilization of biomass. Promoting multiple uses of industrial wastewater and residual lignin from traditional hydrothermal biorefineries became an urgent problem that needed to be addressed. A green and tandem approach was proposed to simultaneously produce carbon dots (CDs), fermentable sugars and a lithium-sulfur (Li-S) cell installed in lignin from eucalyptus using an L-cysteine-catalyzed hydrothermal pretreatment. The overall yield of xylooligosaccharides (XOS) reached up to 50.16% (w / w) xylan extracted directly from the wood framework in a moderately acidic hydrothermal environment, including 22.03% XOS with a low degree of polymerization (DP 2‒6). The graphite N, S-doped CDs with light blue fluorescence, which originated mainly from the irregular conjugation of xylan, lignin and L-cysteine, had an average diameter of 4.7 nm, which was restricted to a quasi-spherical shape. The correct relief of amorphous ingredients and unruly intercellular structure can be attributed to autohydrolysis with the help of amino acids, which promotes the enzymatic digestibility of well-preserved cellulose from 15.1% to 82.4%. Cellulose-enzymatic lignin (CEL), which is capable of high levels of β-aryl ether and hydroxyl groups, was converted into a hierarchically structured heteroatom-doped biochar with exposed active sites (N, S, O-induced intrinsic defect and surface state) using a. synthesizes dual template. It may serve as an available candidate for molten sulfur host to install a Li-S cathode that maintained 582 mA hg − 1 at 1 C after 300 cycles, with average coulomb efficiency and capacity drop per cycle being 93.79%, respectively 0.098%. With the advent of bioethanol tech, the all-round trail offers a graceful prelude to boosting revenue for the waste-free biorefinery that inspired the applicable products from biomass waste streams, including unified CDs and rechargeable Li-S cells.