A comprehensive review of sustainable recycling technologies and circular economy strategies for toy lithium battery waste

Lithium-ion batteries are increasingly used in toys and other small consumer products. The end-of-life of these batteries is raising concerns due to the presence of valuable metals and hazardous materials. This review gives an overview of the recycling and circularity of toy and small-format lithium-ion batteries with focus on their chemistry, collection, pre-treatment, recycling and material recovery. The review compares available recycling routes, mechanical, pyrometallurgical, hydrometallurgical and direct recycling processes. Hydrometallurgical methods can provide high metal recoveries, but most of the reported results are based on larger and more homogeneous battery feedstocks. Their performance on mixed and low-mass toy batteries are less well established. The review also covers practical issues associated with battery collection, sorting, transport and safe handling. These issues are particularly relevant for toys, since batteries are often discarded with household waste and may be difficult to remove from products. A review of existing reviews reveals little specific attention to toy batteries. The main gaps are lack of toy-scale recycling data, limited data on mixed chemistries and inadequate assessment of collection and economic feasibility. A PESTLE analysis also emphasises the importance of policy, infrastructure, market conditions and public participation in improving battery recovery. The review suggests that future work should address decentralised collection, safer product design, and improved sorting and recovery processes for small and mixed battery streams. A dedicated circularity framework for toy batteries is needed to improve resource recovery and minimise environmental risks from end-of-life management. Not applicable. This study did not involve any clinical trials.