Chunli Wang,Lianshan Sun,Bingbing Tian,Yong Cheng,Limin Wang
As important ingredients in lithium-ion battery, the Coulombic efficiency and power density greatly impact the electrochemical performances. Although recent literatures have reported nano-porous materials to enhance the specific capacities, intrinsic drawbacks such as poor initial Coulombic efficiency and low volumetric capacity could not be avoided. Herein, we propose a strategy to prepare carbon supported MoO 2 spheres used for lithium-ion battery with high volumetric capacity density. A high initial Coulombic efficiency of 76.5% is obtained due to limited solid electrolyte interface film formed on the exposed surface. Meantime, the sample with an optimal carbon content and a proper structural strength reveals a higher reversible capacity of 956 mA h g −1 than the theoretical capacity of crystalline MoO 2 (838 mA h g −1 ) and a high capacity retention ratio of 96.4% after 100 cycles at 0.5 A g −1 . And an effective compaction capacity density (under 5 MPa) of 670 mA h cm −3 of the spheres proves its potential value in practical applications.
Flow battery is a promising energy storage technology for facilitating utilization of renewable resources. While new types of flow batteries have been explored toward high energy density, hampering the power density due to high electrolyte viscosity and sluggish reaction kinetics. Discovery of an aqueous electrolyte with multi-electron transfer reaction is thus favorable for both high energy and power densities due to its multiple charge stored at the same concentration. Both criteria are crucial to improve the flexibility of cell design and widen the application potential. Herein, bismuth is pioneered as negative electrolyte (negolyte) for hybrid flow battery owing to its three-electron reaction and the significantly increased solubility in methanesulfonic acid. In conjunction with cerium electrolyte, a volumetric energy density of 90 Wh L −1 is achieved and simultaneously a high power density of 295 mW cm −2 at 90% state-of-charge is demonstrated using low-cost carbon electrode. Furthermore, a high volumetric capacity of 120 Ah L −1 is reached via adopting graphite felt, which is 100% of the theoretical specific capacity of 1.5 M bismuth negolyte.
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