Structure and conductivity enhanced treble-shelled porous silicon as an anode for high-performance lithium-ion batteries

A porous silicon anode prepared by dealloying a Sr-modified Al–Si eutectic alloy for lithium ion batteries

Silicon has been considered to be one of the most promising anode materials for next generation lithium ion batteries due to its high theoretical specific capacity. However, its huge volume expansion during the lithiation/delithiation process that can result in rapid capacity fading and low conductivity present significant challenges for application. In this study, the morphology of Si in an Al–Si eutectic alloy was modified by Sr, and porous Si was then produced by dealloying the precursor. Profiting from the unique structure, the Si anode exhibits an excellent reversible capacity of 405 mA h g⁻¹ at 0.5 A g⁻¹ after 100 cycles and a fantastic first cycle coulombic efficiency of 83.74%. Furthermore, the porous silicon modified by Sr delivers a stable capacity of 594.8 mA h g⁻¹ even at a high current density of 2 A g⁻¹ after 50 cycles, suggesting a good rate capability.

With a porous coralloid structure, the silicon anode prepared by dealloying the Sr-modified Al–Si eutectic alloy exhibits excellent cycle and rate performances.

Recovery of porous silicon from waste crystalline silicon solar panels for high-performance lithium-ion battery anodes

A low-cost and easy-available silicon (Si) feedstock is of great significance for developing high-performance lithium-ion battery (LIB) anode materials. Herein, we employ waste crystalline Si solar panels as silicon raw materials, and transform micro-sized Si (m-Si) into porous Si (p-Si) by an alloying/dealloying approach in molten salt where Li⁺ was first reduced and simultaneously alloyed with m-Si to generate Li-Si alloy at the cathode. Subsequently, the as-prepared Li-Si alloy served as the anode in the same molten salt to release Li⁺ into the molten salt, resulting in the production of p-Si by taking advantage of the volume expansion/contraction effect. In the whole process, Li⁺ was shuttled between the electrodes in molten LiCl-KCl, without consuming Li salt. The obtained p-Si was applied as an anode in a half-type LIBs that delivered a capacity of 2427.7 mAh g^-1 at 1 A g^-1 after 200 cycles with a capacity retention rate of 91.5% (1383.3 mAh g^-1 after 500 cycles). Overall, this work offers a straightforward way to convent waste Si panels to high-performance Si anodes for LIBs, giving retired Si a second life and alleviating greenhouse gas emissions caused by Si production.