In this study, lamellar-structured, vertically aligned silicon@reduced graphene oxide frameworks (VA-Si@rGO) are developed for binder-free, high-arealcapacity lithium ion battery (LiB) anodes. First, SiO 2 /rGO frameworks with unidirectional pores are constructed via the gelation of SiO 2 /graphene oxide sol and subsequent freeze-casting. Afterwards, the sturdy constructed frameworks are maintained during a series of processes, namely magnesiothermic reduction, acid etching, and thermal carbon coating, which result in carboncoated VA-Si@rGO. The electrode exhibits a high specific capacity, reversibility, and cycle stability, which are attributed to its unique inner porous structure, high Si yield, and uniform carbon layers. A high areal capacity of approximately 9 mAh cm −2 could be achieved by increasing the initial sol concentration up to 23.5 wt%. Furthermore, even at a high current density of 3 mA cm −2 , the electrode delivered a high areal capacity of approximately 6 mAh cm −2 and exhibited excellent stability with a high capacity retention of 68% after the 150th cycle.
Li-argyrodite phase Li 6 PS 5 Cl is a promising solid electrolyte (SE) with potential applications in all-solid-state batteries (ASSBs). Conventional SE synthesis methods such as high-energy ball-milling and solid-state synthesis require a significant amount of energy. Consequently, in recent years, several studies have been conducted on developing liquid phase methods for mass-producing SEs. One such liquid phase method uses tetrahydrofuran (THF, an aprotic solvent) and ethanol (EtOH, a protic solvent) to synthesize Li 6 PS 5 Cl. However, the synthesized SE contains impurities that are generated by reactions between EtOH and PS 4 3À . In this study, we present a novel one-pot liquid phase method for synthesizing Li 6 PS 5 Cl using THF. The synthesized SE had a high ionic conductivity (2.03 mSÁcm À1 ) and low electronic conductivity (7.44 Â 10 À8 SÁcm À1 ). Notably, it had few impurities and was essentially composed of a single phase. Furthermore, an ASSB cell composed of LiNbO 3coated LiNi 0.6 Mn 0.2 CoO 2 (NMC622)/Li 6 PS 5 Cl/Li-In, which contained the synthesized SE, exhibited a high discharge capacity of 156 mAhÁg À1 . Therefore, the liquid phase method proposed herein can be used to synthesize SEs, and can help realize mass production and commercialization.
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