Lithium-ion batteries (LIBs) have become indispensable power sources for portable electronic devices and electric vehicles, attributed to their superior characteristics, including high energy density and extended cycle life. However, the improper disposal of spent LIBs following their primary service life and subsequent cascade utilization poses substantial challenges, leading to significant resource waste and severe environmental contamination. Contemporary closed-loop recycling strategies for spent LIB cathode materials encompass three primary approaches: direct regeneration, pyrometallurgical processing, and hydrometallurgical treatment. These methodologies predominantly focus on recovering valuable metals from spent cathode materials for reintegration into battery manufacturing chains. Concurrently, extensive research has emerged investigating non-closed-loop valorization pathways for spent LIB cathode materials, exploring their transformation into high-value products beyond battery applications. Nevertheless, the current research landscape remains highly fragmented and compartmentalized, lacking comprehensive evaluation of both traditional closed-loop recycling and innovative non-closed-loop valorization strategies for the recovery of valuable metals from spent LIB cathode materials. This critical knowledge gap impedes the development of integrated assessment frameworks in terms of current achievements and future prospects across these divergent technological pathways. 

To address this deficiency, this review provides a systematic examination of the state-of-the-art closed-loop recovery processes for valuable metals from spent lithium iron phosphate (LFP) and ternary cathode materials (NCM/NCA). Furthermore, we comprehensively explore the potential for non-closed-loop transformation of valuable metals from spent LIB cathode materials into alternative applications, such as electrode materials for emerging energy storage systems, and functional materials for environmental remediation. From an industrial perspective, we present a comparative evaluation of process technologies and product performance characteristics of these two distinct recycling paradigms, analyzing their respective advantages, limitations, and scalability potential. The analysis encompasses multiple dimensions, including technical feasibility, economic viability, environmental sustainability, and industrial implementation challenges. We examine critical factors such as process complexity, energy consumption, chemical reagent usage, product purity, and market demand that influence the selection between closed-loop and non-closed-loop strategies. Special attention is given to emerging technologies that bridge both approaches, potentially offering synergistic benefits. 

Building upon this comprehensive analysis, we briefly outline the key challenges and emerging development trends associated with both closed-loop recycling and non-closed-loop valorization of spent LIB cathode materials. These insights cover technological innovations, regulatory frameworks, circular economy integration, and sustainability metrics that are expected to shape future recycling strategies. This systematic review serves as an essential reference for researchers, industry practitioners, and policymakers, providing crucial guidance for developing rational disposal strategies for spent LIB cathode materials while advancing sustainable solutions for the rapidly growing challenge of battery waste management in the transition toward electrified transportation and renewable energy systems.