A rechargeable battery needs to provide stable and fast charge/discharge cycling over a wide temperature range (−40 °C ≤ T ≤ 60 °C). A large market and cost considerations may require the use of a Na-ion battery rather than a Li-ion battery because of the greater availability of sodium.[2] Prussian Blue (PB) has shown the advantage of a small volume change upon Na+ ions insertion/extraction, a high theoretical specific capacity, and favorable rate capability at ambient-temperature. In this work, we have systematically studied the electrochemical performance of PB materials from ambient to extreme temperatures. 1) We have suppressed the defects and interstitial water content in PB crystal by controlling the crystal nucleation and growth speed. The developed “high-quality” PB crystal presents improved cycle stability and Coulombic efficiency. 2) We used a “double-protective” method to synthesize “Na-rich” PB crystals, increasing the energy density of PB and making it more promising for practical use. 3) We demonstrate a fast and stable electrochemical cycling of PB at −25 °C by nucleating its cubic nanoparticles on carbon nanotubes to form a robust composite material (Figure 1). 4) We demonstrate a stable electrochemical cycling of PB at elevated temperature up to 70 oC with 92% capacity retention over 150 cycles by an in-situ activation method. Our work enriches the knowledge of develop all-climate Na-ion batteries and could also be applied to develop other advanced electrode materials.

Prussian blue cathode material for Na-ion batteries: From ambient to extreme temperatures

ACS Spring Meeting 2021

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