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 - 61 . (canceled)  
     
     
         62 . A cathode material comprising a compound containing oxide polyanions including PO 4   −3 , the compound having the general formula MPO 4  in the charged state, wherein the compound has an heterosite-type structure that is lithium reversible and wherein M is at least a first row transition metal cation, at least one of which is selected from the group consisting of Fe and Mn.  
     
     
         63 . The cathode material of  claim 62 , obtained by synthesizing a lithiated compound having an ordered or modified olivine structure of the general formula LiMPO 4  and by subsequent chemical or electrochemical de-insertion of lithium ions, the cathode material being characterized by at least a charge/discharge plateau at 3.4-3.5 Volts vs a lithium anode corresponding to a FePO 4 /LiFePO 4  two phase interface when M is Fe or at least a charge/discharge plateau at about 4.1 Volts vs a lithium anode corresponding to a MnPO 4 /LiMnPO 4  two phase interface when M is Mn.  
     
     
         64 . The cathode material of  claim 62 , obtained by synthesizing a lithiated compound having a modified olivine structure of the general formula LiMXO 4  in which the M cation, the XO 4  polyanion or both can be partially replaced by chemically and structurally related agents, and subsequently by chemical or electrochemical de-insertion of lithium ions, the cathode material corresponding to a MXO 4 /LiMXO 4  two phase interface in which the two phases can be non-stoichiometric or mutually miscible.  
     
     
         65 . The cathode material of  claim 64  in which the lithiated compound having the modified olivine structure has the formula  
         Li x+y M 1−(y+d+t+q+r) D d T t Q q R r [XO4] 
       where: 
 M may be Fe+2 or Mn+2 metal or mixtures thereof;  
 D is a divalent cation of a metal other than cobalt and d represents a fraction of D cations at octahedral sites for M within the olivine crystal structure;  
 T is a trivalent cation of a metal other than cobalt and t represents a fraction of T cations at octahedral sites for M within the olivine crystal structure;  
 Q is a tetravalent cation of a metal other than cobalt and q represents a fraction of Q cations at octahedral sites for M within the olivine crystal structure;  
 R is a pentavalent cation of a metal other than cobalt and r represents a fraction of R cations at octahedral sites for M within the olivine crystal structure;  
 XO 4  represents PO 4   −3  or PO 4   −3  partially substituted by other polyanions;  
 0≦x≦1; and  
 0<y+d+t+q+r<1.  
 
     
     
         66 . The cathode of  claim 65 , wherein 
 3+s−p=x−y+2+t+2q+3r.    
     
     
         67 . The cathode of  claim 65 , wherein each of y, d, t, q and r may vary between 0 and 1, with at least one of y, d, t, q and r being greater than 0.  
     
     
         68 . A cathode material according to  claim 65 , in which D is selected from the group consisting of Mg +2 , Ni +2 , Zn +2 , Cu +2  or Ti +2 , T is selected from the group consisting of Al +3 , Ti +3 , Cr +3 , Fe +3 , Mn +3 , Ga +3 , Zn +3  or V +3 , Q is selected from the group consisting of Ti +4 , Ge +4 , Sn +4  or V+ 4  and R is selected from the group consisting of V +5 , Nb +5  or Ta +5 .  
     
     
         69 . A cathode material according to  claim 65  in which each of y, d, t, q and r of vary between 0 and 0.2.  
     
     
         70 . A cathode material according to  claim 65  wherein the polyanions partially substituting for PO 4   −3  in XO 4  are selected in the group consisting of SiO 4   −4 , VO 4   −3 , SO 4   −2 , AsO 4   −3 , MoO 4   −2 , WO 4   −2 , and combinations of at least two thereof.  
     
     
         71 . The cathode material according to  claim 65  in which the particle size is at the nanometer scale.  
     
     
         72 . A rechargeable electrochemical cell, comprising the cathode comprising the cathode material according to  claim 62 , the electrochemical cell further comprising: 
 an anode material comprising a reductant host structure and    an electrolyte.    
     
     
         73 . A rechargeable electrochemical cell of  claim 72 , wherein both the anode and the cathode are hosts for reversible insertion or removal of the working lithium-ion into and from the electrolyte, which is of the rocking-chair type.  
     
     
         74 . A rechargeable electrochemical cell according to  claim 72 , wherein the cathode material comprises particles at the nanometer scale and is of a high current density type.