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The evolution of mating signals is shaped by divergent roles and selective forces, which allow these signals to become multifunctional. Sexual dimorphism in mating signals can reflect this multifunctionality, where such dimorphism could contribute to both mate recognition and mate choice. Sexual dimorphism in mating signals is thought to arise due to divergent sex roles, driven by the interactions of several selective pressures. It has been suggested that, across taxa, both sexes can be choosy and result in sexual selection. However, whether sexual dimorphism in mating signals can predict its role in male courtship behaviour is still unclear. In this study, we used cuticular hydrocarbons (CHCs) in Drosophila species as a model to investigate the question, with CHCs serving as key chemical cues during courtship. This study investigates the relationship between CHC sexual dimorphism and its role in male courtship behaviour across 10 Drosophila species. Our results reveal variations in the degree of CHC sexual dimorphism across the test species. In addition, CHC detection was found to contribute to courtship initiation in most of the test species, but CHC sexual dimorphism did not predict male courtship behaviour. Notably, a longer courtship latency was observed following the loss of CHC detection, indicating that CHCs may convey information on mate quality. Our study suggests that sexual dimorphism in CHCs is not directly linked to its role in mating signal recognition and highlights the species-specific evolution of chemical signals in Drosophila courtship. 

Electrolytes play a critical role in the formation of stable solid electrolyte interphase (SEI) for Si anodes. This study investigates the impacts of five different electrolytes on the specific capacity and cycle stability of Si-based anodes and confirms the advantages of the second-generation (Gen2) electrolyte over the first-generation (Gen1) electrolyte in the first 200 cycles, beyond which the advantages of Gen2 electrolyte disappear. Addition of more FEC and VC additives to Gen2 electrolyte does not offer significant advantages in the cycle stability and specific capacities. However, very high FEC electrolytes with 20 wt% FEC and 80% dimethyl carbonate exhibits strong dependance on the lithiation cutoff voltage. This electrolyte results in durable SEI layers when the lithiation cutoff voltage is at 0.01 V vs Li/Li⁺. Furthermore, lowering the lithiation cutoff voltage from 0.1 V to 0.01 V vs Li/Li⁺has raised the specific capacity of Si-based anodes, leading to higher specific capacities than those of graphite anodes at the electrode level for 380 cycles investigated in this study. The understandings developed here provide unambiguous guidelines for selection of electrolytes to achieve long cycle stability and high specific capacity of Si-based cells simultaneously in the future. 

Silicon has the potential to be a high-performance anode material, but its practical application is impeded by huge volume expansion during lithiation. Many studies have revealed that the huge volume expansion problem can be mitigated by introducing engineered voids into Si/C core–shell structures. In this study, a Si/C core/shell structure with engineered voids, termed Si@void@C, is investigated for its specific capacity and cycle stability as a function of particle size and charge/discharge protocol. The study shows that finer Si@void@C particles result in higher specific capacities, but with little impact on the cycle stability. Further, lower and upper cutoff voltages in charge/discharge have a profound impact on the specific capacity and cycle stability. Importantly, cutoff voltages in formation cycles have long-lasting effects on the cycle stability, indicating the critical role of forming a robust solid electrolyte interphase (SEI) layer during formation cycles. Using a constant current charge followed by potentiostatic hold charge can further improve the cycle stability and minimize the sharp capacity decay in the first 20–40 cycles. With proper choices of charge/discharge protocols, the specific capacities of Si@void@C anodes at the electrode level are 66.8%, 38.2% and 22.7% higher than those of graphite anodes at the 1st, 300th and 500th cycles, respectively, proving that Si@void@C has promising potential to replace graphite anodes for practical applications in the future.