High-performance na 0.44 mno 2 slabs for sodium-ion batteries obtained through urea-based solution combustion synthesis

One of the primary targets of current research in the field of energy storage and conversion is the identification of easy, low-cost approaches for synthesizing cell active materials. Herein, we present a novel method for preparing nanometric slabs of Na 0.44 MnO 2 , making use of the eco-friendly urea within a solution synthesis approach. This kind of preparation greatly reduces the time of reaction, decreases the thermal treatment temperature, and allows the obtaining of particles with smaller dimensions compared with those obtained through conventional solid-state synthesis. Such a decrease in particle size guarantees improved electrochemical performance, particularly at high current densities, where kinetic limitations become relevant. Indeed, the materials produced via solution synthesis outperform those prepared via solid-state synthesis both at 2 C, (95 mA h g −1 vs. 85 mA h g −1 , respectively) and 5 C, (78 mA h g −1 vs. 68.5 mA h g −1 , respectively). Additionally, the former material is rather stable over 200 cycles, with a high capacity retention of 75.7%.