The transportation industry has shown rapid development in recent years. Electric vehicles (EVs) have developed rapidly because they can reduce environmental pollution and make the transportation system smarter. However, the uneven distribution of electric vehicle charging piles has led to the electric vehicle mileage anxiety problem. Vehicle-vehicle (V2V) energy mutual aid has become one of the key technologies to eliminate the mileage anxiety of EVs. The V2V technology not only enables the transmission of electricity between two EVs, alleviating the problems of insufficient battery range and uneven distribution of charging piles, but also significantly improves charging flexibility. In this paper, the topologies and control strategies of existing V2V devices are comprehensively discussed. Firstly, the working principles and application scenarios of the three main topologies, namely, isolated, non-isolated, and wireless transmission, are analyzed. Then, the advantages and disadvantages of the linear and non-linear control strategies are discussed, and optimization suggestions are given in combination with the different topologies. Further, this paper also extends the discussion on the development trend of V2X (vehicle-X) technology, including the application prospects of vehicle-vehicle (V2V), vehicle-home (V2H), vehicle-grid (V2G) cooperative control, and other application scenarios in the smart grid. Finally, the current status of the commercialization of V2V charging technology, commercialization solutions, and challenges are discussed.