SUBSTITUTED LITHIUM-MANGANESE METAL PHOSPHATE
A substituted lithium-manganese metal phosphate of formula LiFe x Mn 1-x-y M y PO 4 in which M is a bivalent metal from the group Sn, Pb, Zn, Mg, Ca, Sr, Ba, Co, Ti and Cd and wherein: x<1, y<0.3 and x+y<1, a process for producing it as well as its use as cathode material in a secondary lithium-ion battery.
1 . A substituted lithium-manganese metal phosphate of formula
LiFe x Mn 1-x-y M y PO 4
in which M is a bivalent metal selected from the group consisting of Sn, Pb, Zn, Mg, Ca, Sr, Ba, Co, Ti and Cd and wherein: x<1, y<0.3 and x+y<1.
2 . Lithium-manganese metal phosphate according to claim 1 , in which M is Zn or Ca.
3 . Lithium-manganese metal phosphate according to claim 1 , in which 0<y<0.15.
4 . Lithium-manganese metal phosphate according to claim 1 , in which 0<x<0.35.
5 . Lithium-manganese metal phosphate according to claim 1 , in which M is Mg.
6 . Lithium-manganese metal phosphate according to claim 5 , wherein 0.01≦x≦0.11, 0.07<y≦0.20 and x+y<0.2.
7 . Lithium-manganese metal phosphate according to claim 1 , further comprising carbon.
8 . Lithium-manganese metal phosphate according to claim 7 , wherein the carbon is evenly distributed throughout the substituted lithium-manganese metal phosphate.
9 . Lithium-manganese metal phosphate according to claim 7 , wherein the carbon covers the individual particles of the substituted lithium-manganese metal phosphate.
10 . Lithium-manganese metal phosphate according to claim 7 , wherein the proportion of carbon relative to the substituted lithium-manganese metal phosphate is ≦4 wt.-%.
11 . Cathode for a secondary lithium-ion battery containing a lithium-manganese metal phosphate according to claim 1 .
12 . Cathode according to claim 11 , containing a further lithium-metal-oxygen compound.
13 . Cathode according to claim 12 , wherein the further lithium-metal-oxygen compound is selected from the group LiCoO 2 , and LiNiO 2 , LiFePO 4 , LiMnPO 4 and LiMnFePO 4 as well as mixtures thereof.
14 . Cathode according to claim 11 , which is free of added conductive agents.
15 . Process for producing a lithium-manganese metal phosphate according to claim 1 , comprising the following steps:
a. producing a mixture containing at least a Li starting compound, a Mn starting compound, an Fe starting compound, a M 2+ starting compound and a PO 4 3− starting compound,
b. heating the mixture at a temperature of 450-850° C.,
c. isolating the lithium-manganese metal phosphate LiFe x Mn 1-x-y M y PO 4 .
16 . Process according to claim 15 , wherein in step a) a further, carbon-containing, component is added.
17 . Process according to claim 15 , wherein the LiFe x Mn 1-x-y M y PO 4 obtained in step c) is mixed with a carbon-containing component.
18 . Process according to claim 15 , wherein LiOH, Li 2 O, lithium oxalate, lithium acetate or Li 2 CO 3 is used as lithium source.
19 . Process according to claim 16 , wherein an Fe 2+ salt, selected from FeSO 4 , FeCl 2 , Fe 3 (PO 4 ) 2 , FeO, FeHPO 4 or an iron-organyl salt or an Fe 3+ salt, selected from FePO 4 , Fe 2 O 3 , FeCl 3 or a mixed Fe salt such as Fe 3 O 4 is used as Fe source.
20 . Process according to claim 17 , wherein a Mn 2+ salt, selected from MnSO 4 , MnCl 2 , MnO, MnHPO 4 , manganese oxalate, manganese acetate or a Mn 3+ salt, selected from MnPO 4 , Mn 2 O 3 , MnCl 3 or a mixed manganese salt such as Mn 3 O 4 is used as Mn source.
21 . Process according to claim 18 , wherein phosphoric acid, a phosphate, hydrogen phosphate, dihydrogen phosphate or P 2 O 5 is used as PO 4 3− source.