Lithium-ion batteries have revolutionized the portable and stationary energy industry and are finding widespread application in sectors such as automotive, consumer electronics, renewable energy, and many others. However, their efficiency and longevity are closely tied to accurately measuring their SOC and state of health (SOH). The need for precise algorithms to estimate SOC and SOH has become increasingly critical in light of the widespread adoption of lithium-ion batteries in industrial and automotive applications. While the benefits of lithium-ion batteries are undeniable, the challenges related to their efficient and safe management cannot be overlooked. Accurate estimation of SOC and SOH is crucial for ensuring optimal battery management, maximizing battery lifespan, optimizing performance, and preventing sudden failures. Consequently, research and development of reliable algorithms for estimating SOC and SOH have become an area of growing interest for the scientific and industrial community. This review article aims to provide an in-depth analysis of the state-of-the-art in SOC and SOH estimation algorithms for lithium-ion batteries. The most recent and promising theoretical and practical techniques used to address the challenges of accurate SOC and SOH estimation will be examined and evaluated. Additionally, critical evaluation of different approaches will be highlighted: emphasizing the advantages, limitations, and potential areas for improvement. The goal is to provide a clear view of the current landscape and to identify possible future directions for research and development in this crucial field for technological innovation.

Catalyzed by the increasing interest in bi-directional electric vehicles, this paper delves into their significance and the challenges they encounter. Bi-directional electric vehicles not only serve as transportation but also function as essential electricity resources. Central to this energy revolution are On-Board Chargers (OBCs), which are pivotal in converting alternating (AC) energy into direct (DC) energy and vice versa. In this context, we explore the various circuit architectures of OBCs employed in bi-directional electric vehicles. We delve into the intricacies of rectifiers, switching converters, and the application of advanced control and filtering technologies. Our analysis extends to the implications of these circuit architectures on aspects such as voltage regulation capability, energy efficiency, and thermal management. Furthermore, we address the broader significance of these developments in the integration of bidirectional systems, which are driving advances in circuit architectures to better harness the energy flexibility of electric vehicles. We emphasize the critical role of bi-directional electric vehicles in the transition toward a smart and sustainable energy grid. To enhance accessibility for a diverse readership, we will provide concise definitions or explanations for technical terms used throughout the paper, ensuring that our work is approachable even for those who may not be experts in the field.