Abstract Separators in lithium-ion batteries are a key element in ensuring the safe and efficient operation of these energy storage devices. Their primary function is to physically separate the cathode and anode, thereby preventing short circuits, while allowing the passage of lithium ions through the electrolyte. Traditionally, polyolefin membranes such as polyethylene (PE) and polypropylene (PP) have been used, which offer good mechanical strength and chemical stability. However, their limited thermal resistance and tendency to shrink at higher temperatures pose a potential risk to battery safety (1). In response to these challenges, research is focused on developing advanced separators, including ceramic composites and multifunctional membranes, which combine high thermal stability with improved electrolyte wettability and ionic conductivity. Current trends also include the use of environmentally friendly materials such as cellulose and mineral composites, which offer more sustainable alternatives to traditional polymer separators (2). Life cycle assessment is a useful tool for businesses, product developers and decision-makers who want to better understand the overall environmental impacts of their activities. This way, they can more effectively design and implement changes towards more sustainable and greener alternatives. The life cycle of manually separated Li-ion battery separator made of PE, one side of which is coated with a layer of boehmite AlO(OH), is carried out. The material composition of separator has been verified using analytical methods, e. g. XRD, SEM-EDS and FTIR to understand the mechanical, chemical properties (1). The main goal of the ongoing research is to determine the material and related energy flows in the life cycle of PE/AlO(OH) separator and to define the strengths and weaknesses of this material. Based on pilot results supported by LCA software evaluation (Sphera), the effort is then made to optimize the existing separator or to propose material functional alternatives with a better life cycle and economic-ecological impact. This research is also connected to the question of whether and under what conditions the separator from used Li-ion battery can be effectively recycled and further processed into a secondary raw material usable either again in the battery industry or elsewhere (3).