Among many kinds of batteries, lithium-ion batteries have become the focus of research interest for electric vehicles (EVs), thanks to their numerous benefits. However, there are many limitations of these technologies. This paper reviews recent research and developments of lithium-ion battery used in EVs. Widely used methods of battery sorting are presented. The characteristics and challenges of estimating battery’s remaining useful life (RUL) and state-of-charge (SOC) are critically reviewed, along with a discussion of the strategies to solve these issues. A new method of sorting retired lithium-ion batteries and estimating the RUL and SOC of the retired lithium-ion batteries is proposed.