Hierarchically Designed Germanium Microcubes with High Initial Coulombic Efficiency toward Highly Reversible Lithium Storage

Germanium has been investigated intensively for its high specific capacity and tough nature, which make it a promising candidate anode for high energy lithium-ion batteries. However, the rational design of a germanium electrode with enhanced electrochemical performances is still a big challenge. Herein, we designed and synthesized germanium microcubes with a hierarchical structure directly on titanium foil via a simple hydrogen reduction method. An ultrahigh initial Coulombic efficiency of 91.8% was acquired due to the high crystallinity of germanium for reversible lithium insertion and extraction, less adverse side reaction for irreversible lithium loss, and unique hierarchical structure for easier electrolyte penetration. In addition, the Li₂CO₃-predominated solid electrolyte interface contributes significantly to the excellent cycling and rate performances of the anode. Both half and full cell performances demonstrate that germanium has potential applications in high-performance lithium-ion batteries

Insights into Magneto-Optics of Helical Conjugated Polymers

Materials with magneto-optic (MO) properties have enabled critical fiber-optic applications and highly sensitive magnetic field sensors. While traditional MO materials are inorganic in nature, new generations of MO materials based on organic semiconducting polymers could allow increased versatility for device architectures, manufacturing options, and flexible mechanics. However, the origin of MO activity in semiconducting polymers is far from understood. In this paper, we report high MO activity observed in a chiral helical poly-3-(alkylsulfone)­thiophene (<b>P3AST</b>), which confirms a new design for the creation of a giant Faraday effect with Verdet constants up to (7.63 ± 0.78) × 10⁴ deg T^–1 m^–1 at 532 nm. We have determined that the sign of the Verdet constant and its magnitude are related to the helicity of the polymer at the measured wavelength. The Faraday rotation and the helical conformation of <b>P3AST</b> are modulated by thermal annealing, which is further supported by DFT calculations and MD simulations. Our results demonstrate that helical polymers exhibit enhanced Verdet constants and expand the previous design space for polythiophene MO materials that was thought to be limited to highly regular lamellar structures. The structure–property studies herein provide insights for the design of next-generation MO materials based upon semiconducting organic polymers