Hard carbon (HC) is currently one of the most promising anode materials for sodium-ion batteries (SIBs). For commercial applications, HC anodes require a high initial Coulombic efficiency (ICE) and a high reversible capacity, which are closely related to a low open-pore volume and a high closed-pore volume in the HC structure. In parallel, HC requires production routes with lower energy consumption and smaller environmental footprints in order to support a circular economy. However, current HC production predominantly relies on conventional resistance-heated carbonization, in which heat is supplied externally and transferred indirectly to the material. This leads to high energy consumption and typically requires extreme carbonization temperatures to induce closed-pore formation. Therefore, additional chemical treatments or post-modification processes are often required, further increasing energy demand and environmental impact. These limitations collectively restrict the scalable and sustainable application of HC anodes.

This thesis aims to develop feasible and energy-efficient modification and carbonization processes for HC production to enhance material resource circularity. Accordingly, fundamental studies combining data-driven modeling, laboratory-scale experiments, and process simulations are conducted. The thesis is based on four different studies that together establish a systematic understanding of the process–structure–performance relationships in biomass-derived HC and propose an energy-efficient pore-engineering strategy enabled by bio-oil modification and induction heating carbonization (IC).

First, through comprehensive literature data analysis and machine-learning modeling, carbonization temperature and HC structure are identified as the dominant factors for HC electrochemical performance. Low open-pore structures and surface defect densities are found to be critical for achieving high ICE, while large interlayer spacing and closed-pore volumes are beneficial for a high plateau capacity. Importantly, the analysis reveals the limitation of conventional carbonization in simultaneously achieving low open porosity and promoting closed-pore formation.

To overcome these limitations, a sustainable bio-oil surface engineering strategy is developed to suppress open pores and surface defects. This approach reduces the specific surface area of HC from 28 to 9 m²/g and increases the ICE from 84.4% to 89.9%. By combining bio-oil surface engineering, a novel IC route is further developed. IC enables direct volumetric heating through eddy currents, which simultaneously minimizes open porosities and promotes closed-pore formation. As a result, optimal IC-derived HC exhibits open-pore volume below 0.003 cm³/g and closed-pore volume of up to 0.23 cm³/g, with an ultra-high ICE value exceeding 95%, and plateau capacity above 260 mAh/g.

Finally, energy analysis and life cycle assessment demonstrate that IC reduces the carbonization energy consumption by approximately 60% and lowers overall environmental impacts by approximately 35% compared with conventional routes. Overall, this thesis demonstrates that the combination of bio-oil modification and IC provides an energy-efficient and low-carbon pathway for producing high-performance biomass-derived HC anodes, supporting the sustainable development of next-generation sodium-ion batteries.

Hårt kol (HC) utgör för närvarande ett av de mest lovande anodmaterialen för natriumjonbatterier (SIB). För kommersiella tillämpningar krävs att HC-anoder uppvisar en hög initial Coulombisk verkningsgrad (ICE) och en hög reversibel kapacitet, vilka är nära kopplade till en HC-struktur med en låg öppen porvolym och en hög sluten porvolym. Parallellt kräver HC produktionsvägar med låg a energiförbrukningar och en reducerad miljöpåverkan för att stödja en cirkulär ekonomi. Emellertid baseras dagens HC-produktion huvudsakligen på konventionell resistansuppvärmd karbonisering, där värme tillförs externt och överförs indirekt till materialet. Detta leder till en hög energiförbrukning och kräver vanligtvis extrema karboniseringstemperaturer för att inducera bildning av slutna porer. Därför används ofta ytterligare kemiska behandlingar eller eftermodifieringsprocesser, vilket ytterligare ökar energibehovet och miljöpåverkan. Dessa begränsningar sammantaget hindrar den skalbara och hållbara tillämpningen av HC-anoder.

Denna avhandling syftar till att utveckla genomförbara och energieffektiva modifierings- och karboniseringsprocesser för HC-produktion för att förbättra materialresursernas cirkularitet. I detta syfte genomförs grundläggande studier som kombinerar datadriven modellering, laboratorieexperiment och processimuleringar. Avhandlingen baseras på fyra olika studier som tillsammans etablerar en systematisk förståelse av sambanden mellan process, struktur och prestanda i biomassabaserat HC samt föreslår en energieffektiv por-ingenjörsstrategi möjliggjord av bio-oljemodifiering och induktionsuppvärmd karbonisering (IC).

För det första identifieras, genom en omfattande litteraturanalys och maskininlärningsmodellering, karboniseringstemperatur och HC-struktur som de dominerande faktorerna som påverkar den elektrokemiska prestandan hos HC. Undertryckta öppna porstrukturer och låg ytdefekttäthet visar sig vara avgörande för att uppnå hög ICE, medan större interlagringsavstånd och hög sluten porvolym är gynnsamma för hög platåkapacitet. Analysen visar dessutom den inneboende begränsningen hos konventionell karbonisering när det gäller att samtidigt uppnå låg öppen porositet och främja bildning av slutna porer.

För att övervinna dessa begränsningar utvecklas en hållbar ytmodifieringsstrategi baserad på bio-olja för att minska andelen öppna porer och ytdefekter. Denna metod reducerar den specifika ytan hos HC från 28 till 9 m²/g och ökar ICE från 84,4 % till 89,9 %. Genom att kombinera bio-oljebaserad ytmodifiering utvecklas vidare en ny IC-process. IC möjliggör direkt volymetrisk uppvärmning via virvelströmmar, vilket samtidigt minimerar den öppen porositeten och främjar bildningen av slutna porer. Som ett resultat uppvisar en optimerat IC-framställd HC anod en öppen porvolym under 0,003 cm³/g och en sluten porvolym upp till 0,23 cm³/g, med mycket höga ICE-värden över 95 % samt platåkapaciteter över 260 mAh/g.

Slutligen visar energi- och livscykelanalyser att IC reducerar energiförbrukningen vid karbonisering med cirka 60 % och minskar den totala miljöpåverkan med cirka 35 % jämfört med konventionella processer. Sammantaget visar denna avhandling genom att använda kombinatione av en bio-oljemodifiering och en induktionsuppvärmd karbonisering är möjligt att åstadkomma en energieffektiv och koldioxidsnål väg för en produktion av högpresterande biomassabaserade HC-anoder, vilket stödjer en hållbar utveckling av nästa generations natriumjonbatterier.

The decarbonization of energy systems requires both clean fuel alternatives and sustainable materials for energy storage. This study explores catalytic graphitization of engineered pyrolysis bio-oil, a renewable, carbon-rich by-product of biomass conversion, to produce graphite for lithium-ion battery anodes and renewable hydrogen. Four engineered bio-oils derived from sawdust pyrolysis at 550 °C were evaluated at 1300 °C using reduced iron powder as a catalyst. Among these, heavy-phase filtered bio-oil (HFB) demonstrated superior graphitization efficiency, achieving a graphitization degree of 94.51% and generating a significant hydrogen yield of 5.25 g H<inf>2</inf>/100 g bio-oil. Compared to conventional synthetic graphite production, which relies on fossil coke and extreme temperatures (>2500 °C), this method significantly reduces energy demand and CO<inf>2</inf> emissions. A liquid–solid catalytic mechanism is proposed for the first time, enabling efficient carbon transformation and hydrogen release without the need for steam input. This work contributes to advancing circular bioeconomy strategies and highlights the role of biomass valorization in future sustainable energy systems.

Biomass-derived sulfur-containing hard carbons are promising anode candidates for sodium-ion batteries, but cross-study optimization remains difficult because reported electrochemical performance reflects both synthesis history and incomplete or non-uniform structural characterization. Here, we assembled a focused literature-derived dataset of 101 records from 16 journal articles and compared the predictive value of three information sources: precursor descriptors, process variables, and measured structural descriptors. We further introduced domain-knowledge-guided precursor descriptors to encode interpretable aspects of precursor chemistry and architecture, including lignin-related richness, polysaccharide contribution, volatile tendency, precursor-component coupling, and post-treatment category. In controlled feature-set comparisons, the model combining precursor and process descriptors achieved an R2 of 0.59, outperforming the conventional combination of process and structural descriptors (R2 = 0.57) and remaining close to the full-information setting (R2 ≈ 0.61). Model interpretation further showed that, when structural descriptors were removed, predictive reliance shifted toward precursor and process variables, indicating that accessible upstream descriptors retain a meaningful fraction of the formation-pathway information relevant to sodium storage. These results should be interpreted within this curated sulfur-containing literature space rather than as a universal predictor, but they demonstrate that domain-knowledge-guided precursor encoding can support low-characterization, screening-oriented prediction and experimental prioritization.

Hard carbon (HC) is currently the predominant anode material for sodium-ion batteries; however, its practical application is still limited by insufficient initial Coulombic efficiency (ICE) and plateau capacity. Meanwhile, conventional HC production relies on energy-intensive carbonization processes with considerable carbon emissions. Here, an induction heating carbonization strategy is developed for extruded biocarbon columns derived from biomass-based biochar and bio-oil, enabling simultaneous enhancement of electrochemical performance and production sustainability. Bio-oil combined with high-pressure extrusion suppresses open pores, whereas induction heating generates localized eddy currents and concentrated Joule heating that accelerate carbon rearrangement and promote closed pore formation. As a result, the closed-to-open pore volume ratio increases from 0.32 to 85.18, leading to improved ICE (95.0% vs. 84.4%) and plateau capacity ratio (77.6% vs. 64.7%) relative to conventional carbonized HC. Life-cycle assessment further indicates an approximately 35% reduction in global warming potential. Overall, this work presents an energy-efficient, low-emission route for producing high-performance HC anodes.

The efficient conversion of bamboo-derived biochar into high-quality syngas demands precise control of CO2 by-product pathways to optimize product selectivity and carbon utilization. Herein, we introduce a frequency-optimized microwave-assisted reforming strategy utilizing a solid-state microwave source spanning 2430–6000 MHz. An optimal frequency of approximately 4630 MHz was identified, delivering rapid heating rates up to 700 °C min−1, exceptional syngas yields of 167.9 mmol g−1 biochar consumed, and a nearly ideal H2/CO ratio (∼1.0). Detailed molecular dynamics simulations suggest that, under the microwave-heating scenario, CO2 exhibits a subtly different bond response and reaction evolution that are qualitatively consistent with enhanced progression of the Boudouard reaction in the present system. Comparative experiments demonstrate superior CO2 conversion (>99%) and substantially improved energy efficiency relative to conventional heating methods under equivalent bulk temperature conditions. Post-reaction characterization of the biochar indicates enhanced structural ordering, increased surface area (from 314 to 439 m2 g−1), and elevated dielectric properties, highlighting the simultaneous in-situ upgrading of biochar into a microwave-responsive carbon material. This study demonstrates that frequency-specific microwave technology enables more effective reaction regulation in the present biochar–reactor system while also promoting sustainable biochar valorization.

Over 90 million tonnes of textile waste are generated annually, yet its blended composition and chemical finishes limit conventional recycling. Here, cellulose-rich textile waste was converted into aromatic hydrocarbons by ZSM-5-catalyzed hydropyrolysis, which promoted deoxygenation and aromatization of textile-derived vapors. Across four real textile wastes, the process delivered aromatic hydrocarbon yields of 41.0%–56.0% with selectivity above 95%. A coupled LCA and TEA, built on an Aspen Plus process model, gave a cradle-to-gate GWP of 0.73 kg CO2-eq kg−1 aromatics with gray hydrogen (37% lower than fossil-based) and 0.59 kg CO2-eq kg−1 with green hydrogen. The gray-hydrogen route gave an MSP of US$0.68 kg−1, competitive with commercial mixed aromatics. These results show that hydrogen provenance governs the carbon footprint, whereas hydrogen price governs production cost, identifying low-cost low-carbon hydrogen as the decisive lever for scalable textile-waste-to-aromatics conversion.

The selective conversion of plastic waste into benzene and toluene (BT) offers a promising route for producing Liquid Organic Hydrogen Carriers (LOHCs). This approach supports both carbon recycling and long-distance hydrogen storage. However, conventional catalytic pathways suffer from limited selectivity and frequent reliance on noble-metal catalysts for hydrogen-assisted deoxygenation. Here, we present a metal-free catalytic strategy that transforms Polyphenylene Oxide (PPO), an engineering thermoplastic with an aromatic-rich backbone, into high-purity BT aromatics under 0.2 MPa hydrogen pressure. A range of zeolite catalysts with varied topologies and acidities (HZSM-5, SAPO-34, USY, HSSZ-13, HZSM-11) were systematically evaluated. HZSM-5 exhibited the highest BT selectivity (>88 %) with minimal polyaromatic byproducts. Mechanistic studies reveal that moderate Brønsted acidity and medium-pore confinement in HZSM-5 play key roles. These features facilitate efficient ether bond cleavage and selective hydrogen-assisted Direct Deoxygenation (DDO) of methylated phenolic intermediates. Structure–activity correlations highlight the importance of pore architecture and acidity. Proper design promotes monoaromatic formation while suppressing side reactions. This work establishes a scalable, metal-free platform for converting oxygenated plastic waste into LOHC molecules. The strategy offers integrated solutions for plastic upcycling and clean hydrogen energy systems.

A continuous pyrolysis combined with an in-line biochar-catalytic reforming of the pyrolysis vapor was investigated in a comprehensive system consisting of an auger reactor and a downstream fixed-bed reactor. The effect of the weight hourly space velocity (WHSV), particle size and morphology of biochar, and the pressure drop of the biochar bed on the catalytic performance were discussed in this study. Results showed that lower WHSV, which allows longer residence time, led to higher syngas yield and increased H2+CO proportion. The use of the smallest biochar particles (0.6-1 mm) produced the highest syngas and H2 yields, correlating with the greatest pressure drops. Spherical and rounded biochar particle shape enhanced syngas and H2 yields, as well as H2+CO proportions, due to improved heat and mass transfer. A maximum of 12 mmol H2/g-biomass was achieved, with a dry gas yield of 0.68 Nm3/kg, comprising 39 vol % H2 and 27 vol % CO, at the use of pelletized biochar with a WHSV of 0.51. The used biochar demonstrated stable catalytic performance as a reforming catalyst in a 100-min test period.

Syngas is vital for sustainable energy conversion, but conventional steam-carbon reforming suffers from slow heat transfer and temperature gradients, which promote secondary oxidation and water-gas shift reactions, leading to CO2 formation. Here, a variable-frequency microwave approach was applied using lignin charcoal (LC) as the receptor. Among four tested frequencies, 5525 MHz performed best, reaching 814 degrees C within 80 s at 100 W, with uniform heating and producing CO2-free syngas. Simulations show that 5525 MHz provides superior electric field symmetry, dielectric loss density, and energy utilization efficiency. Spent LC analysis reveals enhanced defects and polarization, sustaining strong microwave absorption. These findings highlight the decisive role of microwave frequency in controlling temperature, energy distribution, and syngas selectivity, offering a prom-ising strategy for low-carbon syngas production.

Bamboo residues represent an abundant, renewable biomass feedstock that can be converted into hard carbon-an emerging anode material for sodium-ion batteries. This study presents a detailed techno-economic analysis of hard carbon production from bamboo residues across China's ten most bamboo-rich provinces. Regional feedstock availability was estimated from provincial production statistics, while average transportation distances were derived using a square-root-area-based approximation method. The process includes hydrothermal pretreatment, acid washing, carbonization, graphitization, and ball milling. Material and energy inputs were estimated for each stage, and both capital and operating expenses were evaluated using a discounted cash flow model assuming a 15% internal rate of return. The resulting minimum selling price of bamboo-derived hard carbon ranges from 14.47 to 18.15 CNY/kg. Assuming 10% of bamboo residues can be feasibly collected and processed, these ten provinces could collectively support an annual hard carbon production capacity of approximately 1.04 million tons. The results demonstrate that bamboo residues are a strategically distributed and underutilized resource for producing cost-competitive hard carbon at scale, particularly in provinces with existing bamboo industries and supply chains.