Electrochemical Injection Oxygen Vacancies in Layered CaMnO for Boosting Zinc-Ion Storage.

Manganese-based compounds have emerged as attractive cathode materials for zinc-ion batteries owing to their high operating voltage, large specific capacity, and no pollution. However, the structural collapse and sluggish kinetics of manganese-based compounds are major obstacles that hinder their practical applications. Here, a kind of novel layered CaMnO with a low ion diffusion barrier and high structural stability has been achieved through an electrochemical charging process with in situ injecting oxygen vacancies. This greatly increases the electrochemical active area and improves the Zn ions diffusion coefficient by 2 orders of magnitude, which significantly enhances the reaction kinetics, pseudocapacitance properties, and capacity. As a result, the cathode containing oxygen vacancies present an impressive reversible capacity of 368 mAh g, an unprecedented energy density of 512 Wh kg, and superior capacity retention of 92.3% at a high current density of 5 A g after 3000 cycles. This work unveils an effective method for vacancy regulation of electrode materials, paving a new way to improve the electrochemical performance of zinc-ion batteries.