From the point of second use of electric vehicle batteries in power systems

we introduced the background

research progress

and commercialization level of the application

and summarized present researches and demonstration projects worldwide. After analyzing the process and cost structure of the second use

on the basis of the test data of retired battery’s secondary cycle

we obtained the relationship between the battery’s capacity retention and cycle number through fitting

and proposed an assessment method of cost competitiveness for second use battery energy storage system on the basis of equal benefit convert. Furthermore

the method was applied to calculate three typical applications for example

and the impact of subsidies on the cost competitiveness of retired battery energy storage system was discussed thoroughly. The results show that

compared with conventional batteries in energy storage systems

retired electric vehicle batteries with capacity retention more than 0.6 have cost competitiveness in applications of shifting peak load and stabilizing distributed power output fluctuations

and if the capacity retention reaches 0.8

they can be even cost-competitive in standby power applications.