Pre-lithiation carbon anodes mitigating potassium loss for high-performance potassium-ion energy storage devices†

Abstract

Pre-potassiation technologies, which serve to provide additional potassium sources and/or mitigate potassium loss during cycling, are capable of enhancing the energy density and cycling life of potassium-ion capacitors (PICs) and potassium-ion batteries (PIBs). However, many reported pre-potassiation strategies involve using highly chemically reactive potassium sources, such as metallic potassium or K-containing additives, which increase both the cost and production risks. Herein, we propose a novel potassium-ion compensation strategy to meet the demand for high-performance potassium-ion full cells without using any high chemical reactivity potassium sources. This strategy is based on the foundation that a pre-lithiation carbon anode with a preformed solid-electrolyte-interphase (SEI) layer can effectively mitigate potassium loss without hindering the K⁺ diffusion from the electrolyte to the electrode during cell operation. PICs based on pre-lithiation carbon anodes, including soft carbon, hard carbon, and graphite, show better capacitive performance than those based on pre-potassiation carbon counterparts. This versatile strategy is also applicable to high-performance PIBs. We believe that this design principle, which incorporates mature pre-lithiation technologies into potassium-ion energy storage systems, has the potential to resolve some of the challenges with immature pre-potassium technologies.