{"id":1335,"date":"2016-09-08T14:36:49","date_gmt":"2016-09-08T17:36:49","guid":{"rendered":"https:\/\/www.nachodelatorre.com.ar\/mosconi\/?p=1335"},"modified":"2016-09-08T14:36:49","modified_gmt":"2016-09-08T17:36:49","slug":"una-nueva-bateria-doble-ionica-aluminio-grafito","status":"publish","type":"post","link":"https:\/\/www.fie.undef.edu.ar\/ceptm\/?p=1335","title":{"rendered":"Una nueva bater\u00eda doble i\u00f3nica Aluminio \u2013 Grafito"},"content":{"rendered":"

Un grupo de investigadores, con financiamiento de la National Natural Science Foundation of China y de otros organismos de ese pa\u00eds, ha desarrollado una bater\u00eda de ion doble, de bajo costo, a partir de aluminio y grafito. La bater\u00eda muestra una capacidad reversible de \u2248 100 mAh\/g y una retenci\u00f3n de la capacidad de 88% despu\u00e9s de 200 ciclos de carga-descarga. Se estima que una pila de grafito – aluminio lista para su comercializaci\u00f3n ofrecer\u00e1 una densidad de energ\u00eda de ~ 150 Wh\/kg a una densidad de energ\u00eda de \u2248 1200 W\/kg, que es aproximadamente un 50% m\u00e1s que las bater\u00edas de iones litio comerciales.<\/p>\n

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A novel low-cost aluminum\u2013graphite dual-ion battery<\/b> is reported. The battery shows a reversible capacity of \u2248100 mAh g\u22121<\/sup> and a capacity retention of 88% after 200 charge\u2013discharge cycles. A packaged aluminum\u2013graphite battery is estimated to deliver an energy density of \u2248150 Wh kg\u22121<\/sup> at a power density of \u22481200 W kg\u22121<\/sup>, which is \u224850% higher than most commercial lithium ion batteries.<\/p>\n<\/div>\n<\/section>\n

Lithium ion batteries based on cation intercalation have been powering the increasingly mobile society for decades.[1<\/a>] In a conventional lithium ion battery, the intercalation of lithium ions in both cathode (i.e., LiCoO2<\/sub>, LiFePO4<\/sub>) and anode (i.e., graphite, silicon) materials have been thoroughly studied, while the utilization of the anions in the electrolyte has drawn much less attention.[2<\/a>] In fact, the phenomenon of anion intercalate into graphite by chemical or electrochemical means was discovered and proposed as a possible positive electrode for batteries by R\u00fcdorff and Hofmann in 1938.[3<\/a>] However, the anion intercalation was achieved by using high concentration acid solution as electrolyte, this brought serious safety issue that hindered its application.[4<\/a>] In the 1990s, soon after the commercial application of lithium ion battery, Carlin et al. reported dual graphite intercalating molten electrolyte batteries that realized the application of anion intercalated graphite as positive electrode in batteries by using room temperature ionic liquids as electrolyte.[5<\/a>] In the following decades, continuous progresses have been made in anion intercalated graphite based dual carbon batteries, such as investigation of anion intercalation in non-aqueous electrolyte, in situ characterization of the staged anion intercalation process, and systematic study of the intercalation of different anions into graphite.[6<\/a>] However, due to electrolyte decomposition caused by the high positive potential of anion intercalated graphite (\u22485 V vs Li\/Li+<\/sup>) and exfoliation of graphite layers upon repeated ion\/solvent molecule intercalation\/deintercalation, reported dual-carbon batteries showed unsatisfied charge\u2013discharge reversibility.[7<\/a>]<\/p>\n

A key challenge of developing highly reversible dual-graphite battery is to find a suitable electrolyte enabling both Li+<\/sup> intercalation into graphite negative electrode and anion intercalation into graphite positive electrode simultaneously. Conventional carbonate electrolytes were mainly composed of ethylene carbonate (EC), acyclic carbonate, and lithium salt. EC in the electrolyte is an important component for the formation of solid electrolyte interphase (SEI) and the protection of the negative graphitic electrode.[8<\/a>] Unfortunately, when applied in a dual-graphite battery, the EC molecules in the electrolyte can bind tightly with PF6<\/sub>\u2212<\/sup> anions, and prevent the intercalation of these anions into the interlayer spaces of graphite positive electrodes.[9<\/a>] Recently, with the developments of novel electrolyte formulas, several studies have reported significantly improved reversibility of dual-carbon batteries.[10<\/a>] Read et al. reported a reversible dual-graphite battery with simultaneous accommodation of Li+<\/sup> and PF6<\/sub>\u2212<\/sup> in graphitic structures enabled by a high voltage electrolyte based on fluorinated solvent and additive.[10a<\/a>] The battery demonstrated a reversible capacity of 60 mAh g\u22121<\/sup> and a capacity retention of 62% after 50 cycles at C\/7 rate. Rothermel et al. reported a dual-graphite battery based on a mixture of lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) and ionic liquid with SEI-forming additive. This electrolyte formula not only enabled stable TFSI\u2212<\/sup> intercalation into the graphite positive electrode, but also allowed highly reversible intercalation of Li+<\/sup> into the graphite negative electrode.[10b<\/a>] Under an upper cut-off potential of 5.0 V, the full graphite battery presented a capacity of 97 mAh g\u22121<\/sup> at a current rate of 10 mA g\u22121<\/sup>, and 50 mAh g\u22121<\/sup> at 500 mA g\u22121<\/sup>, which shed light on the potential application of dual-ion batteries as an environmentally friendly energy storage technology.<\/p>\n

Herein, we report a novel aluminum\u2013graphite dual-ion battery (AGDIB) in an ethyl\u2013methyl carbonate (EMC) electrolyte with high reversibility and high energy density. It is the first report on using an aluminum anode in dual-ion battery. The battery shows good reversibility, delivering a capacity of \u2248100 mAh g\u22121<\/sup> and capacity retention of 88% after 200 charge\u2013discharge cycles at 2 C (1 C corresponding to 100 mA g\u22121<\/sup>). To the best of our knowledge, performance of the battery is among the best of reported dual-ion batteries.<\/p>\n

Figure<\/b> 1<\/b><\/a>a schematically illustrates the initial and charged states of the AGDIB. Upon charging, PF6<\/sub>\u2212<\/sup> anions in the electrolyte intercalate into the graphite cathode, while the Li+<\/sup> ions in the electrolyte deposit onto the aluminum counter electrode to form an Al\u2013Li alloy. The discharge process is the reverse of the charge process, where both PF6<\/sub>\u2212<\/sup> anions and Li+<\/sup> ions diffuse back into the electrolyte. The Al counter electrode acts as both the anode and the current collector, which greatly benefits the specific energy density and volumic energy density of the AGDIB.[11<\/a>] Figure 1<\/a>b shows galvanostatic charge\u2013discharge curves of the AGDIB, exhibiting a typical profile of anion intercalation\/deintercalation into\/from graphite. The charge curve is mainly composed of three regions between 4.08 and 4.59 V (stage III), 4.59 and 4.63 V (stage II), and 4.63 and 5.0 V (stage I), each region corresponds to an anion intercalation stage of graphite, according to previous reports.[6e<\/a>] A dQ\/dV differential curve of the battery is shown in the inset of Figure 1<\/a>b. Peaks in the profile correspond to electrochemical processes in the AGDIB during charge\u2013discharge. Stage III contains three wide weak peaks, while stage II contains a strong peak and small shoulder peak. No obvious peak in stage I can be observed. Only three peaks are found in the discharge process, due to the diminish or disappear of two peaks during anion deintercalation process, as reported in previous report.[10b<\/a>] The AGDIB shows a working voltage range of 4.8\u20133.4 V with a middle working voltage of \u22484.2 V at 0.5 C current rate, which is much higher than most of those in commercial lithium ion batteries (\u22483.7 V).[12<\/a>] The relative high discharge voltage of the AGDIB enabled a single coin cell to light up two yellow LEDs (nominal voltage of \u22482.5 V) in series (Figure 1<\/a>b inset).<\/p>\n

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Figure\u00a01.<\/h4>\n