Das, Mononita (2025) Development of Cellulose-Based Composite Separator Membranes for Energy Storage Devices. PhD thesis, Jadavpur University.

Full text not available from this repository. (Request a copy)

Abstract

The present thesis addresses the pressing challenge of developing sustainable, cost-effective, and safe alternatives to conventional polyolefin-based separators in lithium-ion batteries (LIBs).Commercial separators made of polypropylene (PP) or polyethylene (PE) suffer from low thermal stability, limited electrolyte wettability, and originate from non-renewable resources, which collectively limit their performance and raise safety concerns. In contrast, natural cellulose paper, with its fibrous network, abundant availability, and eco-friendly origin, provides a compelling base material for constructing next-generation battery separators. This work systematically investigates cellulose paper and its functional modification with ceramic fillers, hybrid systems, and natural clays to achieve a new class of paper-based composite separators with enhanced thermal safety, ionic transport, and electrochemical stability. Throughout the thesis, multiple strategies were explored to modify cellulose paper through scalable impregnation and coating processes. Inorganic fillers such as alumina (Al₂O₃), silica (SiO₂), and lithium-ion conducting garnets (LLZO) were incorporated to enhance structural reinforcement, electrolyte affinity, and interfacial stability. Organo–inorgano hybrid systems, derived from chelation of zirconium isopropoxide, were introduced to regulate lithium salt dissociation and optimize ionic conductivity. In parallel, montmorillonite (MMT) clay, a naturally abundant mineral with high ion-exchange capacity and strong flame-retardant properties, was employed to fabricate sustainable paper–clay separators. The combination of cellulose fibers with inorganic and hybrid domains gave rise to unique separators that demonstrated tunable porosity, controllable wettability, and robust thermal resistance. The structural and morphological studies confirmed that the fillers were uniformly distributed within the paper matrix, creating a hierarchical network that maintained flexibility while enhancing dimensional stability. Electrochemical investigations revealed that these modifications improved ionic conductivity, broadened the electrochemical stability window beyond 5.0 V versus Li/Li⁺, and reduced interfacial resistance compared to pristine paper and commercial PP separators. Full cell evaluations, particularly with NMC111 cathodes and MCMB anodes, validated the superior performance of optimized paper composites, which delivered higher discharge capacities, stable long-term cycling, and excellent coulombic efficiency. Notably, separators impregnated with XXIX MMT and LLZO outperformed the commercial PP membrane in both performance and safety metrics. A crucial highlight of this work is the significant improvement in thermal safety. Thermogravimetric analysis demonstrated higher char yields and delayed decomposition for the composite separators, while flame-resistance tests established their rapid self extinguishing ability. Unlike PP membranes, which undergo severe shrinkage and sustained combustion, the paper-based composites retained their morphology and functionality even after flame exposure. This was further corroborated by post-flame charge–discharge testing, where the clay-loaded paper separator maintained stable electrochemical behavior, demonstrating its reliability under extreme thermal stress. Beyond performance, this thesis emphasizes sustainability and scalability. The use of cellulose and montmorillonite clay, both low-cost and abundantly available, ensures that the developed separators can be manufactured on an industrial scale using aqueous processing routes without compromising environmental responsibility. By aligning material innovation with global energy and environmental needs, the research establishes paper–clay and paper–ceramic separators as strong contenders for next-generation LIBs, offering a safer, greener, and more economically viable alternative to existing synthetic plastic membranes. In summary, this thesis makes a comprehensive contribution to the design and development of cellulose-based composite separators for lithium-ion batteries. It demonstrates how the integration of natural polymers with functional inorganic fillers can overcome the limitations of current separators, achieving a synergistic balance between ionic transport, mechanical integrity, thermal stability, and cost-effectiveness. The findings not only enrich the scientific understanding of paper based hybrid separators but also pave the way for their practical application in sustainable and high-performance energy storage systems.

Item Type:	Thesis (PhD)
Subjects:	Engineering Materials
Divisions:	Fuel Cell and Battery
Depositing User:	Ms Upasana Sahu
Date Deposited:	12 Nov 2026 12:07
Last Modified:	12 Nov 2026 12:07
URI:	https://cgcri.csircentral.net/id/eprint/5849

Actions (login required)

View Item