Newsgroup: it.scienza.chimica
Titolo: Batterie LiFePO4

Lo sapevate? Nuove batterie al fosfato di litio e ferro(II)
ricaricano in 10-20 secondi!
 
http://tinyurl.com/cfzuof
  (CdS)
   la velocità resa possibile da un rivestimento di fosfato di litio
     Batteria turbo, ricarica in dieci secondi
   Scoperta del Mit: può trovare applicazione in telefonini, portatili,
   ma anche nelle auto elettriche, entro tre anni
 
http://www.nature.com/nature/journal/v458/n7235/abs/nature07853.html
   Battery materials for ultrafast charging and discharging
  "The storage of electrical energy at high charge and discharge rate is
  an important technology in today's society, and can enable hybrid and
  plug-in hybrid electric vehicles and provide back-up for wind and solar
  energy. It is typically believed that in electrochemical systems very
  high power rates can only be achieved with supercapacitors, which trade
  high power for low energy density as they only store energy by surface
  adsorption reactions of charged species on an electrode material.
  Here we show that batteries which obtain high energy density by storing
  charge in the bulk of a material can also achieve ultrahigh discharge
  rates, comparable to those of supercapacitors. We realize this in
  LiFePO4 , a material with high lithium bulk mobility by creating a
  fast ion-conducting surface phase through controlled off-stoichiometry.
  A rate capability equivalent to full battery discharge in 10-20 s
  can be achieved."
  Full Text:
 
http://www.nature.com/nature/journal/v458/n7235/pdf/nature07853.pdf
  "The ability to charge and discharge batteries in a matter of seconds
  rather than hours may make possible new technological applications
  and induce lifestyle changes. Such changes may first take place in the
  use of small devices, where the total amount of energy stored is small.
  Only 360 W is required to charge a 1 Wh cell phone battery in 10 s
  (at a 360C charging rate). On the other hand, the rate at which very
  large batteries such as those planned for plug-in hybrid electric
  vehicles can be charged is likely to be limited by the available power:
  180 kW is needed to charge a 15 kWh battery (a typical size estimated
  for a plug-in hybrid electric vehicle) in 5 min.
   Electrode materials with extremely high rate capability will blur
  the distinction between supercapacitors and batteries. The power
  density based on the measured volume of the electrode film,
  including carbon and binder, is around 65 kWl^-1 in the 400C test.
  Assuming that the cathode film takes up about 40% of the volume of
  a complete cell, this will give a power density of ~25 kWl^-1 at the
  battery level, which is similar to or higher than the power density
  in a supercapacitor, yet with a specific energy and energy density
  one to two orders of magnitude higher. The fact that our material
  can obtain power densities similar to those of supercapacitors
  is consistent with there being an exceedingly fast bulk process.
  For LiFePO4, bulk lithium transport is so fast that the charging
  is ultimately limited by the surface adsorption and surface transfer,
  which is also the rate-limiting step in supercapacitors."
Bye,
   *GB*

 in 10-20 secondi!
Sapevatelo!
Svegliatemi quando ne posso comprare una.
FYI, MIT e' impelagato in una enorme disputa legale con Südchemie per 
l'uso di LiFePO4, e a quanto pare perderanno sonoramente. Quindi le 
possibilita' che questo materiale veda la luce commercialmente sono 
proprio pochine.
-- 
Best Regards, Jack
Linux User #264449
Powered by Debian GNU/Linux on AMD64

 sfruttamento del brevetto ?
Benvenuto nel magico mondo dell'industria, dove ogni brevetto, se non ti 
fa fare soldi, ti permette almeno di non farne fare ai tuoi concorrenti.
Tornando nel merito dell'articolo, che nel frattempo ho avuto modo di 
leggere, mostra dei numeri sicuramente interessanti, ma ovviamente i 
titoli "arriva la batteria che si carica in 10 secondi" sono un 
tantinello esagerati.
La performance da 10 secondi e' stata ottenuta su un elettrodo 
pesantemente ottimizzato per questo tipo di misure, e di nessun valore 
nel mondo reale. Inoltre, per quanto sia bello, per questo tipo di cose 
ci sono i supercapacitori. Le batterie lasciamole a fare altro.
La miglior performance "reale" e' cmq un rispettabilissimo 65% della 
carica massima ottenuta (reversibilmente) a 60C, ovvero in un minuto. Se 
non ricordo male, LiFePO4 "liscio" viaggia intorno al 40-50%.
