ABSTRACT
Rechargeable Li-air (O2) batteries have attracted a great deal of attention because of their high theoretical energy density and been regarded as a promising next-generation energy storage technology. Among numerous obstacles to Li-air (O2) batteries preventing their use in practical applications, water is a representative impurity for Li-air (O2), which could hasten the deterioration of the anode and accelarate the premature death of cells. Here, we report an effective in situ high-current pretreatment process to enhance the cycling performance of Li-O2 batteries in a wet tetraethylene glycol dimethyl ether-based electrolyte. With the help of certain levels of H2O (from 100 to 2000 ppm) in the electrolyte, adequate Li2O formed on the lithium anode surface after high-current pretreatment, which is necessary for a robust and uniform solid electrolyte interphase layer to protect Li metal during the long-term discharge-charge cycling process. This in situ high-current pretreatment method in a wet electrolyte is shown to be an effective approach for enhancing the cycling performance of Li-O2 batteries with a stable Li metal anode and promoting the realization of practical Li-air batteries.
ABSTRACT
Rechargeable lithium-oxygen (Li-O2) batteries (LOBs) with extremely high theoretical energy density have been regarded as a promising next-generation energy storage technology. However, the limited cycle life, undesirable corrosion, and safety hazards are seriously limiting the practical application of the lithium metal anode in LOBs. Here, we demonstrate a rational design of the Li-Al alloy (LiAlx) anode that successfully achieves ultralong cycling life of LOBs with stable Li cycling. Through in situ high-current pretreatment technology, Al atoms accumulates, and a stable Al2O3-containing solid electrolyte interphase protective film formed on the LiAlx anode surface to suppress side reactions and O2 crossover. The cycling life of LOB with the protected LiAlx anode increases to 667 cycles under a fixed capacity of 1000 mA h g-1, as compared to 17 cycles without pretreatment. We believe that this in situ high-current pretreatment strategy presents a new vision to protect the lithium-containing alloy anodes, such as Li-Al, Li-Mg, Li-Sn, and Li-In alloys for stable and safe lithium metal batteries (Li-O2 and Li-S batteries).
ABSTRACT
The electrode-electrolyte interface stability is a critical factor influencing cycle performance of All-solid-state lithium batteries (ASSLBs). Here, we propose a LiF- and Li3N-enriched artificial solid state electrolyte interphase (SEI) protective layer on metallic lithium (Li). The SEI layer can stabilize metallic Li anode and improve the interface compatibility at the Li anode side in ASSLBs. We also developed a Li1.5Al0.5Ge1.5(PO4)3-poly(ethylene oxide) (LAGP-PEO) concrete structured composite solid electrolyte. The symmetric Li/LAGP-PEO/Li cells with SEI-protected Li anodes have been stably cycled with small polarization at a current density of 0.05 mA cm-2 at 50 °C for nearly 400 h. ASSLB-based on SEI-protected Li anode, LAGP-PEO electrolyte, and LiFePO4 (LFP) cathode exhibits excellent cyclic stability with an initial discharge capacity of 147.2 mA h g-1 and a retention of 96% after 200 cycles.
ABSTRACT
In an animal body, coronary arteries cover around the whole heart and supply the necessary oxygen and nutrition so that the heart muscle can survive as well as can pump blood in and out very efficiently. Inspired by this, we have designed a novel heart-coronary arteries structured electrode by electrospinning carbon nanofibers to cover active anode graphene/silicon particles. Electrospun high conductive nanofibers serve as veins and arteries to enhance the electron transportation and improve the electrochemical properties of the active "heart" particles. This flexible binder free carbon nanofibers/graphene/silicon electrode consists of millions of heart-coronary arteries cells. Besides, in the graphene/silicon "hearts", graphene network improves the electrical conductivity of silicon nanopaticles, buffers the volume change of silicon, and prevents them from directly contacting with electrolyte. As expected, this novel composite electrode demonstrates excellent lithium storage performance with a 86.5% capacity retention after 200 cycles, along with a high rate performance with a 543 mAh g-1 capacity at the rate of 1000 mA g-1.
