Designing Highly-safe Electrolyte Systems And A Applied Research For Lithium-sulfur Battery

With the development of the society,lithium batteries have been applied commercially in electronic products,such as mobile phone,computer,electric car etc.It puts forward further requirements on the energy density of lithium battery with new electric products(unmanned aerial vehicle electric and hybrid electric vehicle etc.)appeared.And it is urgent to develop novel batteries with higher energy density.Lithium-air battery,lithium-sulfur battery,sodium metal battery,magnesium battery,potassium battery and other kinds of high-performance batteries have also appeared,sequentially.Lithium-sulfur batteries have been regarded as the most promising high-energy electrochemical energy storage device owing to the abundant resources,environmental friendliness and high energy density.However,some challenges hinder their commercial applications(such as the combustion of electrolyte,the shuttling effect of polysulfides and the growth of lithium dendrites and so on).Basically,safety,power densities,and cycle life directly determine the applicability of Li-ion batteries(LIBs)in our daily life.Among all the problems,safety is the top priority considerations.Here,the present research illustrates the application of high-safety electrolyte in lithium sulfur battery from the perspective of improving the safety of lithium-sulfur battery.1.We proposed a new kind of wide-temperature electrolyte and research a novel flame-retardent electrolyte,sequentially.The electrolyte equiped 1 M LiDFOB/PC+1%FEC exhibits superior cycle performance and steady lithium plating/stripping behavior.It is also found that the electrolyte can enable the formation of effective SEI on Li metal anode and then suppress continuous generation of lithium dendrites.As a result,such electrolyte-based lithium-sulfur batteries delivered satisfactory battery performances in a wide range of temperatures(from-10℃ to 90℃)and further improves the safety performance of lithium-sulfur batteries.2.A novel kind of flame-retardant concentrated electrolyte(6.5 MLiTFSI/FEC)is considered for highly-safe and wide-temperature lithium-sulfur batteries.It was found that such concentrated electrolyte showed superior flame retardancy and high lithium-ion transference number(0.69).It is worth noting that the cell with 6.5 M LiTFSI/FEC exhibited high discharge specific capacity(839.1 mAh g-1)and superior cycle performance(capacity retention of 93%after 100 cycles)even at a high sulfur mass loading(2.5 mg/cm2).In addition,lithium-sulfur batteries with this flame-retardant concentrated electrolyte can also operate well in a wide range of temperatures(-10℃,25℃ and 90℃).