| abstract |
A positive electrode material having a nominal stoichiometry Li 1+y/2 Co 1−x−y−z−d Si z Fe x M y M′ d (PO 4 ) 1+y/2 where M is a trivalent cation selected from at least one of Cr, Ti, Al, Mn, Ni, V, Sc, La and/or Ga, M′ is a divalent cation selected from at least one of Mn, Ni, Zn, Sr, Cu, Ca and/or Mg, y is within a range of 0<y≦0.10 and x is within a range of 0≦x≦0.2. The use of double compositional modification to LiCoPO 4 increases the discharge capacity from ˜100 mAh/g to about 130 mAh/g while retaining the discharge capacity retention of the singly Fe-substituted LiCoPO 4 . Additional compositional modification to include Si increases the cycle life and greatly improved the coulombic efficiency to between 97-100% at a C/3 cycle rate. |