A critical review on inconsistency mechanism, evaluation methods and improvement measures for lithium-ion battery energy storage systems

With the rapid development of electric vehicles and smart grids, the demand for battery energy storage systems is growing rapidly. The large-scale battery system leads to prominent inconsistency issues. This work systematically reviewed the causes, hazards, evaluation methods and improvement measures of lithium-ion battery inconsistency. From material to manufacture and usage, the process and conditions of each link affect battery consistency. The hazards of battery pack inconsistency include increasing system failure rate, reducing service performance and accelerating life decay. Inconsistency evaluation methods are summarized as statistics-based, machine learning-based and information fusion-based methods. Moreover, the improvement measures of battery inconsistency are reviewed from the aspects of the production process, sorting technology, topology optimization, equalization control and thermal management. In addition, the future works on challenges and prospects of battery inconsistency research are revealed, in hope of inspiring the efficient operation and maintenance of large-scale battery energy storage systems.