Cycling, lithium polymer batteries

This type of Li battery has already widely diffused in the electronic consumer market, however for automotive applications the presence of a liquid electrolyte is not considered the best solution in terms of safety, then for this type of utilization the so-called lithium polymer batteries appear more convenient. They are based on a polymeric electrolyte which permits the transfer of lithium ions between the electrodes [21]. The anode can be composed either of a lithium metal foil (in this case the device is known as lithium metal polymer battery) or of lithium supported on carbon (lithium ion polymer battery), while the cathode is constituted by an oxide of lithium and other metals, of the same type used in lithium-ion batteries, in which the lithium reversible intercalation can occur. For lithium metal polymer batteries the overall cycling process involves the lithium stripping-deposition at the anode, and the deintercalation-intercalation at the anode, according to the following electrochemical reaction, written for a Mn-based cathode ... 

Arie et al. [116] investigated the electrochemical characteristics of phosphorus-and boron-doped silicon thin-film (n-type and p-type silicon) anodes integrated with a solid polymer electrolyte in lithium-polymer batteries. The doped silicon electrodes showed enhanced discharge capacity and coulombic efficiency over the un-doped silicon electrode, and the phosphorus-doped, n-type silicon electrode showed the most stable cyclic performance after 40 cycles with a reversible specific capacity of about 2,500 mAh/g. The improved electrochemical performance of the doped silicon electrode was mainly due to enhancement of its electrical and lithium-ion conductivities and stable SEI layer formation on the surface of the electrode. In the case of the un-doped silicon electrode, an unstable surface layer formed on the electrode surface, and the interfacial impedance was relatively high, resulting in high electrode polarization and poor cycling performance. 

These polymer electrol5rtes were exploited in the late 1990s for the fabrication of large-sized, laminated battery modules based on cells formed by a lithium foil anode and a vanadium oxide cathode, developed jointly by Hydro Quebec in Canada and 3M company in the United States [7,8]. The battery module had very good performance in terms of energy density (155 Wh kg ) and cycle life (600 cycles at 80% depth of discharge (DOD)), and it was proposed as a power source for EVs, a very futuristic concept back in 1996. However, despite this and other successful demonstration projects, the lithium polymer battery project was abandoned and only very recently reconsidered for use in an EV produced in France [9]. 

The lithium-ion-polymer battery, which uses a cathode that contains lithium instead of cobalt, is likely to eventually replace lithium-ion. Lithium-ion-polymer batteries boast a longer life expectancy (over 500 charge-and-discharge cycles as opposed to around 400), much more versatility (they are flat and flexible and can be cut to fit almost any shape), and better safety (far less likely to vent flames while recharging). 

In this chapter, lithium secondary batteries using conductive polymers as positive electrodes are discussed with particular attention to the charge-discharge characteristics, discharge capacity, self-discharge, cycling life and so on. 

Fukami K, Sakka T, Ogata YH, Yamauchi T, TsubokawaN (2009) Multistep filling of porous silicon with conductive polymer by electropolymerization. Physica Status Solidi (a) 206 1259 Gao L, Mbonu N, Cao L, Gao D (2008) Label-lfee colorimetric detection of gelatinases on nanoporous silicon photonic films. Anal Chem 80 1468 Ge M, Rong J, Fang X, Zhou C (2012) Porous doped sdicon nanowires for lithium ion battery anode with long cycle life. Nano Lett 12 2318... 

LiCl, LijO, which precipitate on the electrode surface. Reduction of solvents is followed by the formation of both insoluble SEI components like Li COj and partially soluble semicarbonates and polymers. The voltage at which the SEI is formed depends on the type of carbon, the catalytic properties of its surface (ash content, type of crystallographic plane, basal-to-edge plane ratio), temperature, concentration and types of solvents, salts and impurities, and on the current density. Eor lithium-ion battery electrolytes, is typically in the range 1.7-0.5 V vs Li reference electrode, but the SEI continues to form down to 0 V. In some cases, p is less than 100% during the first few cycles. This means that the completion of SEI formation may take several charge-discharge cycles. 

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