Flexible Solid Flow Electrodes for High-Energy Scalable Energy Storage

Abstract

Flow batteries allow independent scaling of power and energy and permit lowcost materials for large-scale energy storage. However, they suffer from low-energy densities or poor scalability when a solid electrode is used in hybrid systems (zinc or lithium metals). Breaking the convention of pumping fluids, we propose and demonstrate a new flow battery invention that transports active material via rotation of flexible electrode belts made from high-energydensity solid electrode materials (flexible solid flow electrode). Using this strategy, we demonstrated a fully scalable aqueous solid-liquid hybrid flow battery using a lithium titanium phosphate (LTP) flexible anode belt coupled with lithium iodide (LiI) catholyte. This strategy of the circulating flexible solid electrode can be readily applied to existing solid-liquid hybrid flow batteries (e.g., Zn-I 2 , Zn-Br 2 , Li-I 2 , Li-polysulfide, etc.) and allows many types of solid electrode materials in a flow battery platform without constraints in solubility or scalability.

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

“…Stable cycling performance was achieved in each slug with a total volumetric capacity of 50 Ah L −1 , which is consistent with the performance at the single static mode. It is also noticeable that the charge capacity of the first slug is larger than that of other three slugs, which is mainly caused by the charge migration resulting from sharp changes of the SOC at the boundaries between slugs [60] . Likewise, the discharge capacity of the 4th slug is smaller than that of other three slugs as expected.…”

Redox Flow Batteries: Materials, Design and Prospects

“…In order to overcome the solubility limitations of conventional electrolytes, one possible alternative is to use a semi-solid electrolyte [259,260]. This approach means that the active species are a suspension (instead of solution) and therefore can react without being dissolved in the electrolyte.…”

“…This approach means that the active species are a suspension (instead of solution) and therefore can react without being dissolved in the electrolyte. The electrodes are usually carbon paper and/or suspended porous materials (conducting additive) since graphite felt would be clogged by the suspended species [259,260]. This configuration is represented in Figure 10.…”

“…This configuration is represented in Figure 10. Since the concentration of these redox species is not limited by the solubility threshold, it is possible to achieve higher energy densities both with inorganic or organic redox species [59,259,260,[262][263][264][265][266][267]. Additionally, the semi-solid RFB can be either aqueous [268,269] or non-aqueous, such as the one represented in Figure 11.…”

Membrane‐Free Zn/MnO2 Flow Battery for Large‐Scale Energy Storage

“…In addition, another scale up strategy that transports active material via rotation of carbon felt electrode is applied for this novel redox flow battery, in which we design a hexagonal substrate for the decoupling of energy and power demonstration (Figure S22a, Supporting Information) . The cathode of the rotating cell was built by pasting six 1 cm 2 carbon cathodes (6.35 mm in thickness, the same as the one used in the normal cell) onto six sides of a stainless steel hexagon rotator, with 2 cm in length and 1.5 cm in width for each side.…”