Effect of Pore Structures on the Electrochemical Performance of Porous Silicon Synthesized from Magnesiothermic Reduction of Biosilica

Two kinds of porous silicon（PS） were synthesized by magnesiothermic reduction of rice husk silica（RHS） derived from the oxidization of rice husks（RHs）. One was obtained from oxidization/reduction at 500 ℃ of the unleached RHs, the other was synthesized from oxidization/reduction at 650 ℃ of the acidleached RHs. The structural difference of the above PS was compared： the former had a high pore volume（PV, 0.31 cm3/g） and a large specific surface area（SSA, 45.2 m^2/g）, 138 % and 17 % higher than the latter, respectively. As anode materials for lithium ion batteries, the former had reversible capacity of 1 400.7 m Ah/g, 987 m Ah/g lower than the latter; however, after 50 cycles, the former had 64.5 % capacity retention（907 m Ah/g）, which was 41.2 % higher than the latter（555.7 m Ah/g）. These results showed that the electrochemical performance of PS was significantly affected by its pore structures, and low reduction temperature played the key role in increasing its porosity, and therefore improving its cycling performance.

Status quo on recycling of waste crystalline silicon for photovoltaic modules and its implications for China's photovoltaic industry

As a clean and efficient renewable energy source,solar energy has been rapidly applied worldwide.The growth rate of China's installed capacity ranks first in the world.However,the life span of photovoltaic(PV)modules is 25 to 30 years,and the rapid development of installed capacity indicates that a large number of PV modules will be decommissioned in the future.Therefore,the ongoing treatment of the scrapped PV waste cells in the near future requires urgent plans and countermeasures.Proper recycling and disposal of decommissioned PV modules is a practical requirement for the sustainable development of the country and industry.Crystalline silicon(c-Si)solar cells currently occupy 85%-90%of the market share,and some scholars have begun to seek the utilization pathways of the waste Si in and outside the PV industry.In this paper,the research status of the separation and recycling process of crystalline Si PV modules is reviewed,and the recycling ways of crystalline silicon are particularly focused on.In addition,the current bottlenecks in the PV recycling industry in China are analyzed and some suggestions on the sustainable development of the PV industry are proposed.

Lithiation-enhanced charge transfer and sliding strength at the silicon-graphene interface:A first-principles study

The application of silicon as ultrahigh capacity electrodes in lithiumion batteries has been limited by a number of mechanical degradation mechanisms including fracture, delamination and plastic ratcheting, as a result of its large volumetric change during lithiation and delithiation. Graphene coating is one feasible technique to mitigate the mechanical degradation of Si anode and improve its conductivity. In this paper, first-principles calculations are performed to study the atomic structure, charge transfer and sliding strength of the interface between lithiated silicon and graphene. Our results show that Li atoms segre- gate at the （lithiated） Si-graphene interface preferentially, donating electrons to graphene and enhancing the interfacial sliding resistance. Moreover, the interfacial cohesion and sliding strength can be further enhanced by introducing single-vacancy defects into graphene. These findings provide insights that can guide the design of stable and efficient anodes of silicon/graphene hybrids for energy storage applications.