In situ formed uniform and elastic SEI for high-performance batteries

The solid electrolyte interphase (SEI) is one of the most important components of a battery, and plays a crucial role in the battery performance. Here, a uniform and elastic SEI was constructed by in situ electro-polymerization (ISEP-SEI) of ionic liquid electrolytes. The excellent uniformity of ISEP-SEI and its excellent contact with the substrate could passivate the electrode surface effectively. At the same time, the superior elasticity of ISEP-SEI could enable the electrode to sustain a large number of volume changes during cycling and maintain its structural integrity. Both these features are essential for building high-performance batteries. With ISEP-SEI, the potassium metal symmetric batteries stably cycled for 5000 h with only a piece of separator and no special treatment of the potassium metal surface. Moreover, a Prussian Blue (PB) cathode matched with potassium metal operated for more than 3000 cycles at 1000 mA g(-1). The graphite anode, which does not cycle stably in traditional electrolytes, can be operated for more than 1000 cycles after an ISEP-SEI formed on its surface. Importantly, the flame-retardant ionic liquid guaranteed the batteries' safety. The electrochemical performance of full batteries, PB||K batteries at high temperatures, and lithium batteries with ISEP-SEI have also been explored.

Automated summary

The solid electrolyte interphase (SEI) serves a crucial role in battery performance, and a uniform and elastic SEI was constructed using in situ electro-polymerization (ISEP-SEI) of ionic liquid electrolytes. ISEP-SEI exhibited excellent uniformity, effectively passivating the electrode surface, and maintained structural integrity during cycling due to its superior elasticity. This technology enabled stable cycling of potassium metal symmetric batteries for 5000 hours and improved the performance and stability of other battery components.