Cathode materials for secondary (rechargeable) lithium batteries

Abstract

The invention relates to materials for use as electrodes in an alkali-ion secondary (rechargeable) battery, particularly a lithium-ion battery. The invention provides transition-metal compounds having the ordered-olivine, a modified olivine, or the rhombohedral NASICON structure and the polyanion (PO 4 ) 3− as at least one constituent for use as electrode material for alkali-ion rechargeable batteries.

1 - 22 . (canceled)  
     
     
         23 . A cathode material for a rechargeable electrochemical cell, said cell also comprising an anode and an electrolyte, the cathode material comprising a compound having the formula:  
         Li x+y M 1-(y+d+t+q+r) D d T t Q q R r [PO 4]   1-(p+s+v) [SO 4 ] p [SiO 4 ] s [VO 4 ] v    where 
 M may be Fe 2+  or Mn 2+  or mixtures thereof;  
 D is a metal in the +2 oxidation state selected from the group consisting of:  
   Mg 2+ , Ni 2+ , Co 2+ , Zn 2+ , Cu 2+ , and Ti 2+ ;  
 T is a metal in the +3 oxidation state selected from the group consisting of:  
   Al 3+ , Ti 3+ , Cr 3+ , Fe 3+ , Mn 3+ , Ga 3+ , Zn 2+ , and V 3+ ;  
 Q is a metal in the +4 oxidation state selected from the group consisting of:  
   Ti 4+ , Ge 4+ , Sn 4+ , and V 4+ ;  
 R is a metal in the +5 oxidation state selected from the group consisting of:  
   V 5+ , Nb 5+ , and Ta 5+ ;  0≦x≦1;  
 0≦y, d, t, q, r, p, s, v≦1 where at least one of y, d, t, q, r, p, s, and v differ from 0 and  
     y+d+t+q+r≦ 1;    p+s+v≦ 1; and  3 +s−p=x−y+t+ 2 q+ 3 r;    
   where x is the degree of intercalation during operation of the electrode material, y represents the fraction of lithium ions on the initial Fe 2+  sites; d represents the fraction of divalent ions (noted as D) on the initial Fe 2+  sites; t represents the fraction of trivalent ions (noted as T) on the initial Fe 2+  sites; q represents the fraction of tetravalent ions (noted as Q) on the initial Fe 2+  sites; r represents the fraction of pentavalent ions (noted as R) on the initial Fe 2+  sites; p represents the fraction of hexavalent sulfur (as discrete SO 4   2−  tetrahedra) on the initial P 5+  sites; s represents the fraction of tetravalent silicon (as discrete SiO 4   2−  tetrahedra) on the initial P 5+  sites; and v represents the fraction of pentavalent vanadium ions on the initial P 5+  sites, and M, D, T, Q and R reside in octahedral sites.    
     
     
         24 - 60 . (canceled)  
     
     
         61 . A variable optical transmission device comprising transparent semi-conductor coated glass or plastic, and including at least one positive electrode and at least one negative electrode separated by a solid or gel electrolyte, wherein at least one electrode comprises a modified olivine compound as set forth in  claim 23.