Multiscale control of MnO 2 growth via [WO 6 ]-perturbed [MnO 6 ] assembly toward a favorable balance between capacitance and rate performance

Although pseudocapacitive manganese dioxide (MnO 2 ) integrates the high-power merit of carbonaceous materials with the high-energy merit of battery-type materials, it still has a long way to go in achieving a more satisfactory balance of higher energy and power density, and in decoupling the relationship of structural characteristics with energy storage performance. To realize such goals, a bottom-up [WO 6 ]-perturbed [MnO 6 ] assembly strategy has been developed here due to their similar structure, yet mismatched lattice parameters. This facile protocol is capable of finely controlling the morphology and crystal structure of MnO 2 by adjusting its internal [WO 6 ] concentration. Therefore, the as-prepared W x –MnO 2 is treated as an ideal platform to scrutinize the correlations of the structure with the energy storage performance. The operando Raman spectra and finite element analysis have fully demonstrated the superiority of the locally ordered defects-enriched structure of W 0.02 –MnO 2 , which could reach a favorable balance between the ion diffusion equilibrium time and the number of active sites. As a result, the W 0.02 –MnO 2 is able to deliver a high capacitance of 292 F·g −1 at a current density of 1 A·g −1 and a remarkable rate performance with a 60% capacity retention at a current density of 50 A·g −1 . The further unveiled structure–performance relationship provides a guideline for the design of better pseudocapacitive energy storage devices. Graphical Abstract