Advanced materials and electrolyte for lithium-sulfur and lithium metal batteries

Yan-Bing He

Graduate School at Shenzhen, Tsinghua University 

Abstract: In recent years, how to improve the energy density and quick-charge property of lithium ion batteries has become the focus of the attention. Lithium-sulfur (Li-S) battery has a theoretical specific energy of 2500 Wh kg-1, more than ten times higher than that of conventional lithium-ion batteries, which is widely recognized as one of most promising systems for next-generation energy storage devices. However, commercial success of Li-S battery is limited because of a set of shortcomings, including low electronic conductivity of sulfur particles and their huge structural/volumetric changes (79%) during the cathodic reaction from S to Li2S. More importantly, lithium polysulfides formed as intermediates during the charge/discharge processes are highly soluble in liquid electrolyte (LE) and easily shuttle to the lithium metal anode and to be reduced to Li2S2 and Li2S, leading to the loss of active materials and the interfacial deterioration that greatly decrease the cycling stability of Li-S battery. The ability to suppress the dissolution of lithium polysulfides in liquid electrolyte (LE) is an important endeavor toward successful commercialization of lithium-sulfur (Li-S) batteries. We developed a pentaerythritoltetraacrylate (PETEA)-based gel polymer electrolyte (GPE) with an extremely high ionic conductivity (1.13×10-2 S cm-1), which can construct a robust integrated GPE/electrode interface and effectively immobilize the soluble polysulfides. We also designed and prepared V2O5-decorated carbon nanofiber interlayer, which not only can suppress the shuttle effect of lithium polysulfides through strong interaction between the well-decorated V2O5 component and polysulfies, but also greatly reduces the self-discharge of lithium–sulfur batteries. At last, a novel lithiated silicon–sulfur battery was developed using an optimized solid-like electrolyte to enhance safety and cycle Life.

Lithium metal anode is considered as “Holy Grail” because of its high capacity (3800 mAh g-1), low voltage (-3.04 V vs standard hydrogen electrode) and small density (0.53 g cm-3) as key factors to achieve high energy density of batteries such Li-S batteries, lithium metal batteries and solid state lithium ion batteries. However, several disadvantages, such as Li dendrite growth, dead Li formation, high reactivity and uncontrolled volume expansion, have limited the application of Li metal anode, especially the dendrites growth and volume expansion during Li stripping/plating process. We developed several methods to suppress the dendrites growth and volume expansion. It is found that the SiO2 hollow nanosphere-based composite solid electrolyte, 3D porous current collector, 3D cross-linked network polymer electrolyte can effectively suppress lithium dendrite growth and enhance cycle life of Li metal batteries.

 

Biography: Yan-Bing He received his Ph.D. degree from the Department of Applied Chemistry, Tianjin University in 2009. He worked as apost-doctoral fellow at Graduate School at Shenzhen, Tsinghua University from 2010 to 2012 and a visiting scholar at Hong Kong University of Science and Technology from 2012 to 2013. He is currently an associate professor of Graduate School at Shenzhen, PhD supervisor, Tsinghua University. His research interests mainly focus on lithium batteries and related materials. He has published 110 SCI papers, including Adv Mater, Adv Energy Mater, Adv MaterAdv Energy Mater, Angew Chem Int Ed, Energy Environ Sci, Nano Lett, Nano Energy, Chem Mater, ChemSusChem, Sci Rep, J Power Sources and etc., which have been cited 2300 times by others. As the first winner, he was awarded some academic awards, including Science and Technology Award of Guangdong Province (2nd class), the Nature Science Award of Shenzhen (2nd class) and Young talent of Guangdong Province Science and Technology Innovation.