Low Volume‐Expansion, Insertion‐Type Layered Silicate Hierarchical Structure For Superior Storage Of Li, Na, K

Abstract

Abstract A hierarchical structure is successfully synthesized by coating polypyrrole (PPy) on the surface of carbon/saponite superlattice (denoted as PPy@C/SAP), and applied as low volume‐expansion insertion‐type anode for Li, Na, K storage.The synergistic effect of metal Ni, Fe doping, carbon/silicate superlattice, abundant oxygen vacancies and PPy coating leads to a good electronic conductivity and large current discharging capability. As a Si‐based material, PPy@C/SAP has excellent storage capability for Li (659 mAh g −1 after 1000 cycles at 2 A g −1 and 550 mAh g −1 after 1000 cycles at 5 A g −1 ), Na (maximum specific capacity of 533 and 327 mAh g −1 after 50 cycles) as well as K (236 mAh g −1 after 100 cycles). XPS, XANES, XRD, FTIR, HRTEM, SEM are used to detect the hybrid mechanism (bulk insertion and surface conversion) with a volume expansion as low as 9%. Insertion reaction driven by valence state change of Ni, Fe, Si (Ni 0 ⇔Ni 2+ , Fe0⇔Fe 3+ , Si 2+ ⇔Si 4+ ) in laminates and conversion reactions between LiOH/Li 2 CO 3 and LiH/Li 2 C 2 catalyzed by Ni° contribute to the high performance. In the whole electrochemical process, layered structure is retained while the conversion reactions of LiOH (prodeced by laminates dehydroxylation) and Li 2 CO 3 (electrolyte decomposition) cause the dynamic evolution of solid ectrolyte interphase. This study develops a promising Si‐based anode material for lithium ion batteries, sodium ion batteries and potassium ion batteries, which is significant for designing long cycle life rechargeable batteries.