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Medientyp:
E-Artikel
Titel:
Lithium Titanium Sulfide Thin Film Cathodes for All-Solid-State Lithium-Ion Batteries: Taking Advantage of a Dual Cation and Anion-Based Redox Process
Beschreibung:
<jats:p>The significant growth of both the number and the kinds of portable electronic systems, generally battery-powered has triggered the race for the development of high-performance microprocessors and systems on chips using low power consumption integrated circuits. As a consequence, the energy supply of such optimized components can also be ensured today by miniaturized power sources such as Li microbatteries. The latter have the advantage of being manufactured by vacuum deposition process also widely used in the microelectronics industry [1]. Nevertheless to be considered as an electronic components, the microbattery need to sustain temperature higher than 230°C for the reflow soldering to attach the component to the PCB . As Li metal anode melts at 181°C, Li microbatteries are not tolerant to such high temperature. For this reason we have manufactured Li-ion all-solid-state thin films batteries based on Si at the negative electrode and a new lithiated titanium oxysulfide as a cathode [2]. Lithium titanium sulphide thin films were synthesized by sputtering of LiTiS<jats:sub>2</jats:sub> targets. Three different methods including chemical lithiation, solid state synthesis or spark plasma sintering steps were used to prepare the targets in-house and were found to influence the final composition of the films [3]. Due to the high reactivity of titanium, incorporation of some oxygen into the LiTiS<jats:sub>2</jats:sub> film is inevitable. The limited oxygenation of the films that occurs, favours the occurrence of the S<jats:sup>2-</jats:sup>/(S<jats:sub>2</jats:sub>)<jats:sup>2-</jats:sup> redox process at the expense of the Ti<jats:sup>3+</jats:sup>/Ti<jats:sup>4+</jats:sup> one during the battery operation. Finally, a perfect reversibility of both electrochemical processes is highlighted, whatever the initial oxygen content. All-solid-state lithium microbatteries using these amorphous lithiated titanium disulphide thin films and operated between 1.5-3.0 V/Li<jats:sup>+</jats:sup>/Li deliver a greater capacity (210-270 mAh g<jats:sup>-1</jats:sup>) than LiCoO<jats:sub>2</jats:sub>, with a perfect capacity retention (-0.0015 % cycle<jats:sup>-1</jats:sup>). Excellent electrochemical performances in terms of capacity value and cycling stability were also obtained in all-solid state Li-ion cells with Si as a negative electrode. After three successive solder-reflow processes (thermal treatment at 260°C), the capacity, the cycle life as well as the voltage profile remained unchanged. Finally, Li<jats:sub>1.2</jats:sub>TiO<jats:sub>0.5</jats:sub>S<jats:sub>2.1 </jats:sub>is confirmed as a new interesting lithiated positive material for thin film lithium and lithium-ion microbatteries. Moreover, as its synthesis does not require any thermal treatment (contrary to the well-known LiCoO<jats:sub>2</jats:sub>), is well-adapted to thermally sensitive substrates such as flexible polymers foils. </jats:p>
<jats:p>References: </jats:p>
<jats:p>[1] B. Fleutot, B. Pecquenard, F. Le Cras, B. Delis, H. Martinez et al., <jats:italic>J. Power Sources</jats:italic>, 196 (2011) 10289 </jats:p>
<jats:p>[2] F. Le Cras, B. Pecquenard, V. Dubois, V.P. Phan et al., <jats:italic>Adv. </jats:italic>
<jats:italic>Energy Mater.</jats:italic>, 5 (2015) 1501061 </jats:p>
<jats:p>[3] V. Dubois, B. Pecquenard, S. Soulé, H. Martinez, F. Le Cras, <jats:italic>submitted</jats:italic>
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