Protection of lithium anodes by fibrous silica nanospheres.

Jinxin Fan,Yu Luo,Keliang Jiang,Cheng Wang

doi:10.1039/c9ra09481d

Abstract

Lithium metal (anode) has attracted significant attention for use in lithium-metal batteries due to its high energy density, but its practical application is still hindered by the dendrite growth during the battery charging process. Here, fibrous silica nanospheres were prepared via a direct hydrothermal reaction and coated on a separator to form a composite electrode with lithium sheets. Upon using this composite electrode in a symmetrical cell, the charge and discharge curves became more stable and the overpotential was alleviated compared with that of the bare lithium metal electrode. Meanwhile, the coulombic efficiency obtained from the Li‖Cu cell remained above 95.9% after 200 cycles at 0.5 mA h cm−2. The validity of using this composite electrode in the Li‖LFP (LiFePO4, lithium iron phosphate) cells was also evaluated. The results show that the composite electrode can help restrict the growth of lithium dendrites and the accumulation of dead lithium.

Highlights

With the rapid development of portable electronic devices, electric vehicles and renewable energy, high-energy-density batteries are highly demanded.[1,2,3,4,5,6,7] Currently, the capacity of lithium-ion batteries (LIBs) with the traditional graphite anode has reached its limit and it is highly necessary to search for high-capacity anode materials
Compared with solid nanometer silicon coatings, in which solid silicon nanospheres were coated on separators to help suppress the formation of Li dendrites,[40,41] our FSNS/Li composite electrode has at least four advantages (Scheme 1): (1) the thickness of the FSNS coating is about 5 mm, and it is thinner than previously reported coatings ($20 mm).[40,41] (2) Fibrous silica nanospheres have a larger speci c surface area and can enable more functional groups to participate in the reaction to guide the uniform deposition of lithium ions
The porous structure of FSNSs provided enough place for free lithium ion redeposition to inhibit the growth of lithium dendrites and the accumulation of dead lithium

Summary

Introduction

With the rapid development of portable electronic devices, electric vehicles and renewable energy, high-energy-density batteries are highly demanded.[1,2,3,4,5,6,7] Currently, the capacity of lithium-ion batteries (LIBs) with the traditional graphite anode has reached its limit and it is highly necessary to search for high-capacity anode materials. Compared with solid nanometer silicon coatings, in which solid silicon nanospheres were coated on separators to help suppress the formation of Li dendrites,[40,41] our FSNS/Li composite electrode has at least four advantages (Scheme 1): (1) the thickness of the FSNS coating is about 5 mm, and it is thinner than previously reported coatings ($20 mm).[40,41] (2) Fibrous silica nanospheres have a larger speci c surface area and can enable more functional groups to participate in the reaction to guide the uniform deposition of lithium ions.

Materials

Preparation of porous silica sphere coating

Electrochemical measurements

Characterization of materials

Results and discussion

Conclusions