The vanadium redox flow battery (VRFB) is an attractive alternative to lead acid or lithium battery technologies, offering higher energy capacity better suited for static storage at larger scales.
Vanadium batteries provide extended service life, no discernible degradation of electrodes or electrolytes after thousands of rapid charge-discharge cycles, superior safety from no combustibles and good operability across a wide range of ambient temperatures. Permitting is simplified as vanadium electrolyte is classified as a non-toxic fluid per UN regulations. VRFB has a low incremental cost for increased storage duration and the vanadium contained is completely reusable and recyclable.
A remaining obstacle to widespread adoption of VRFB is the price volatility from supply-demand cycles of ferro alloys.
X GROUP is refining a ground-breaking process for producing battery grade electrolyte directly off its ion exchange platform. The most important differentiator of the new process is high-purity vanadyl sulphate (V4+) solution produced at elevated concentrations in a liquid-only flowsheet, i.e. without precipitation of vanadium oxides conventionally required. The flowsheet thereby eliminates several costly steps which promises compelling cost advantage compared to other methods.
This X GROUP process has advanced through several important milestones:
2020 - Confirmation of ion exchange chromatography whereby vanadium is selectively adsorbed from dilute solutions, achieving eluates of >99.5% purity on metal oxide basis. Read more:
2021 - Confirmation of favourable desorption economics in a low-cost ion exchange stripping circuit.
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2022 – A breakthrough development of novel reductive desorption, whereby vanadyl sulphate is produced at 3 molar concentrations and 99.5% metal oxide purity.
2023 – Further refinement of reductive desorption, adding precipitation of hydrated vanadium dioxide of 99.8% metal oxide purity.
Ongoing work is focused on electrolytic reduction of vanadyl sulphate, aiming for the 50/50 ratio of V3+ and V4+ speciation required for preparation of battery-ready VRFB electrolyte.
It is expected that these process refinements, together with independent review, will be finalised by mid-2023 whereafter commercial rollout may follow.