Organic Multiple Redox Semi-Solid-Liquid Suspension for Li-Based Hybrid Flow Battery

Magnetic Field-Enhanced Performance of Superparamagnetic LiMn2 O4 -Based Composite Slurry Electrode for Semisolid Flow Battery

Semisolid flow batteries are expected to be applied to large-scale energy storage fields due to the combination of the high energy density of rechargeable batteries and the flexible design of flow batteries. However, electronic conductivity, specific capacity, and viscosity of slurry electrodes are generally mutually restrictive. Here, a new concept of semisolid flow batteries based on magnetic modification slurry electrode is proposed and the electrochemical performance of the semisolid electrode is expected to be improved by close contact and enhanced electronic conductivity between the active particles with the aid of external magnetic field. This concept is further demonstrated using superparamagnetic LiMn2 O4 -Fe3 O4 -carbon nanotube composite as semisolid cathode. It achieves a capacity of 113.7 mAh g-1 at a current density of 0.5 mA cm-2 with the aid of external magnetic field (about 0.4 T), which is about 21% higher than that without external magnetic field. Simulation study also reveals this improvement mainly resulted from the increase of the conductive paths of electrons after the rearrangement of the active particles under the external magnetic field. It is believed that this strategy gives a new and effective method for controlling the viscosity and electronic conductivity of the slurry electrodes and related flowable electrochemical energy storage systems.

High-capacity polysulfide-polyiodide nonaqueous redox flow batteries with a ceramic membrane

Nonaqueous redox flow batteries (NRFBs) have been regarded as promising large-scale electrochemical energy storage technology due to the wider solvent stable potential windows and greater selection of materials. However, the application of NRFBs is greatly limited considering the low capacity and high cost of active materials. In this work, we design and demonstrate a high-capacity polysulfide (PS)-polyiodide (PI) NRFB in Li-ion based 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) (v/v ∼ 1 : 1) organic electrolyte. The high solubility and low cost of PS (5 M) and PI (4 M) can achieve the high capacity and high applicability of NRFBs, which is attractive for realizing large-scale stationary energy storage. The highest volumetric capacity of 28 Ah L^-1 based on a full cell is achieved with 1.5 M PS-4 M PI. The high coulombic efficiency (∼100%) and capacity retention (>99%) for 100 cycles in the PS-PI system is demonstrated by using a Li-ion conducting ceramic membrane. Voltage control is applied for both PS and PI to avoid the formation of irreversible solid Li₂S and I₂, which ensures the high stability of battery reaction. In situ UV-vis spectroscopy reveals the high reversibility of PS and PI in DOL/DME. A continuous flow mode test of the PS-PI system is also demonstrated to realize >300 hours stable cycling performance which implies good applicability for a long-term process. The successful demonstration of this high-capacity PS-PI nonaqueous system provides a new direction to promote the application of NRFBs in more fields.