Design of Nanocomposites for Lithium(Sodium) Ion Batteries
【摘要】：The nanocomposites show a number of attractive advantages of high electrical conductivity, buffering volume change, high chemical stability as well as reducing active material dissolution into electrolyte. As a result, they have been focusing on providing enhanced performance in lithium(sodium) ion batteries. However, developing a facile and versatility method toward uniform nanocomposites has been a considerable challenge due to the lack of the appropriate synthetic methods and/or effective reaction systems. Herein, we will present a rapid and general solvothermal approach as well as atomic layer deposition(ALD) technique to design some nanocomposites for lithium(sodium) ion batteries. As a demonstration, we fabricated crumpled reduced graphene oxide encapsulated VO_2 material(CG/VO_2). Note that vanadium based materials produced in previous studies were only in a rough manner to combine with rGO, such as anchoring onto the rGO surface, sandwiching between rGO, and uneven hybrid or mixture with rGO. Benefiting from this unique structure, therefore, the CG/VO_2 electrode served as sodium ion batteries anode exhibits a high reversible capacities of 214 m Ah g~(-1) at 4 A g~(-1)(321 Wh kg~(-1) and 4276 W kg~(-1)), and can stably operate for as long as 2,000 cycles with a capacity fade of 0.013% per cycle. More importantly, we can turn this CG/VO_2 into the crumpled reduced graphene oxide encapsulated three-dimensional V_2O_5 nano/microspheres(CG/V_2O_5) via simply sintering treatment. Meanwhile, the CG/V_2O_5 electrode can deliver reversible capacities of 289 m Ah g~(-1) at 100 m A g~(-1) and 163 m Ah g~(-1) at 5000 m A g-1(492 Wh kg~(-1) and 9840 W kg~(-1)), as well as capacity retention of about 94% after 200 cycles at 2000 m A g~(-1) in the potential range between 2.0 V and 4.0 V(vs. Li/Li~+). Most importantly, we have provided a chain of cogent evidence by coating on various electrode materials to confirm the generality of this proposed solvothermal synthesis method, which would open up a novel avenue to create more fascinating graphene-based functional materials for the multitudinous application domain. Using an ALD technique, we successfully uniformly deposited crystalline and amorphous SnO_2 on both sides of graphene nanosheets(GNS) to mitigate the main challenges of high volume change anodes, moreover, some functional coating layers were designed on cathode materials for lithium ion batteries. Our results demonstrated that ALD derived nanocomposites show superior advantages of increasing lithium ion battery performance.