Superior performance of an ultrathin pyridinic-layered micro-structural porous silicon anode with a silicon content exceeding 99%

Abstract

Si-based materials have become the focus of current research efforts, emerging as leading candidates for next-generation lithium-ion battery anodes due to their exceptional theoretical capacities. However, the practical use of Si anodes is still constrained by substantial challenges, including low electrical conductivity, the severe volume expansion experienced by Si, and the limited Si contents of current anode formulations. To overcome these challenges, we developed a pyridinic-layered micro-sized porous silicon (m-PSi) anode by low-temperature thermolysis of poly(4-vinylpyridine). This pyridinic nitrogen at the layer enhances Li-ion and electron transport while increasing Li-ion storage by providing additional active sites. The resulting anode exhibited an impressive initial capacity of 3960 mAh g⁻¹, with a retention of 70.81% after 150 cycles; it also delivered a high-rate capacity of 2326.8 mAh g⁻¹ at 4 A g⁻¹ with a recovery rate of 90.4%. Full-cell testing revealed a retained capacity of 760 mAh g⁻¹ after 50 cycles at 0.1 A g⁻¹. Moreover, this pyridinic layer significantly restricted the volume expansion of the anode to 80%. Remarkably, this performance was achieved with a Si content exceeding 99% and is attributable to the covalently linked pyridinic layer that improves the structural integrity, Li-ion storage, and conductivity of the anode. The innovative interfacial design reported herein effectively addresses the key limitations of Si-based anodes, offering promising pathways for future technological advancements in energy storage.