HK1174891A - Phase-pure lithium-aluminium-titanium phosphate and method for the production and use thereof - Google Patents

Description

Phase-pure lithium-aluminium-titanium phosphate, method for the production thereof and use thereof

The invention relates to phase-pure lithium aluminum titanium phosphate, a method for the production thereof, the use thereof, and a secondary lithium ion battery containing the phase-pure lithium aluminum titanium phosphate.

Recently, battery powered motor vehicles have become increasingly the focus of research and development because of the increasing scarcity of fossil feedstocks.

In particular lithium ion batteries (also called secondary lithium ion batteries) have proven to be the most promising battery model for this application.

These so-called "lithium ion batteries" are also widely used in fields such as electric tools, computers, mobile phones, and the like. In particular the cathode and electrolyte and the anode are composed of lithium containing materials.

Such as LiMn₂O₄And LiCoO₂Have been used for some time as cathode materials. Recently, particularly since the work of Goodenough et al (U.S. Pat. No. 5,910,382), there have also been doped or undoped mixed lithium transition metal phosphates, particularly LiFePO₄。

Conventionally, graphite, for example, or also the lithium compounds already mentioned above such as lithium titanate, are used as anode materials, in particular for large-capacity batteries.

Lithium titanate refers herein to Li having the space group Fd3m 0 ≦ x ≦ 1/3_1+xTi_2-xO₄Doped or undoped lithium titanium spinels of the type and all having the general formula Li_xTi_yO (x is more than or equal to 0 and y is less than or equal to 1).

Generally, lithium salts or their solutions are used for the solid electrolyte in such secondary lithium ion batteries.

Also, ceramic separators such as are commercially available from, for example, Evonik Degussa(DE 19653484A 1) has also been proposed. However, instead of a solid electrolyte, the separination contains a ceramic filler such as nanoscale Al₂O₃And SiO₂。

Lithium titanium phosphate has been proposed as a solid electrolyte for some time (JP A19902-225310). Lithium titanium phosphates, depending on structure and doping, have increased lithium ion conductivity and low electrical conductivity, which, in addition to their excellent hardness, also make them very suitable as solid electrolytes in secondary lithium ion batteries.

Aono et al have examined the ionic (lithium) conductivity of doped and undoped lithium titanium phosphates (j.electrochem. soc., vol.137, No.4,1990, pp.1023-1027, j.electrochem. soc., vol.136, No.2,1989, pp.590-591).

Systems doped with aluminum, scandium, yttrium and lanthanum were examined in particular. It was found that doping with aluminium in particular provides good results, since aluminium has the highest lithium ion conductivity compared to other doping metals, depending on the degree of doping, and it acquires the space occupied by titanium very well due to its cationic radius in the crystal (less than Ti4 +).

Kosova et al, Chemistry for Sustainable development 13 (2005) 253-260 propose appropriately doped lithium titanium phosphate as cathode, anode and electrolyte for lithium ion rechargeable batteries.

In EP 1570113B 1 Li is proposed_1.3Al_0.3Ti_1.7(PO₄) As a ceramic filler for an "active" separator, such a separator has additional ionic conductivity to the electrochemical components.

Also, other doped lithium titanium phosphates, in particular doped with iron, aluminum, and rare earths, are described in US 4,985,317.

However, all of the above-mentioned lithium titanium phosphates have in common the utilization of a secondary solidSolid state synthesis production starting from bulk phosphates is very expensive, wherein the corresponding lithium titanium phosphate thus obtained is usually additionally contaminated with foreign phases such as AlPO₄Or TiP₂O₇And (4) pollution. So far, phase pure lithium titanium phosphate or doped lithium titanium phosphate is not known.

It is therefore an object of the present invention to provide phase pure lithium aluminum titanium phosphate, since it combines the features of high lithium ion conductivity and low electrical conductivity. Because of the absence of a foreign phase, even better ion conductivity should also be achieved compared to the state of the art non-phase pure lithium aluminum titanium phosphates.

This object is achieved by providing a polymer having the formula Li_1+xTi_2-xAl_x(PO₄)₃Wherein x is 0.4 or less and the level of magnetic metals and metal compounds of the elements Fe, Cr and Ni is 1ppm or less.

Herein, the term "phase pure" means that the reflections of the foreign phase cannot be identified in the X-ray powder diffraction pattern (XRD). The absence of foreign phase reflections in the lithium aluminum titanium phosphate of the present invention, as shown by way of example in FIG. 2 below, corresponds to a foreign phase such as AlPO₄And TiP₂O₇The maximum proportion of (C) is 1%.

As already explained above, the foreign phase reduces the intrinsic ionic conductivity, so that the phase-pure lithium aluminum titanium phosphate according to the invention has a higher intrinsic conductivity than all those of the state of the art which contain the foreign phase than the state of the art.

Unexpectedly, it has also been found that the total level of magnetic metals and metal compounds of Fe, Cr, and Ni (Σ Fe + Cr + Ni) in the lithium aluminum titanium phosphate of the present invention is 1ppm or less. When any destructive zinc is also taken into account, the total content E Fe + Cr + Ni + Zn is 1.1ppm, compared to 2.3-3.3ppm for the state of the art lithium aluminum titanium phosphate described above.

Specifically, the lithium aluminum titanium phosphate of the present invention exhibits only metallic or magnetic iron exposureAnd magnetic iron compounds (e.g. Fe)₃O₄) Is/are as follows<Very little contamination of 0.5 ppm. The determination of the concentration of the magnetic metal or metal compound is described in detail in the experimental section below. In the previously known lithium aluminum titanium phosphates of the state of the art, the customary values for magnetic iron or magnetic iron compounds are about 1 to 1000 ppm. As a result of contamination with metallic iron or magnetic iron compounds, in addition to the formation of dendrites associated with the reduction of current, the risk of short circuits increases significantly in electrochemical cells in which lithium aluminum titanium phosphate is used as a solid electrolyte and therefore represents a risk for producing such cells on an industrial scale. This disadvantage can be avoided with the phase pure lithium aluminum titanium phosphate herein.

Also unexpectedly, the phase pure lithium aluminum titanium phosphate of the present invention also has<3.5m²Relatively high BET surface area in g. Typical values are for example 2.7 to 3.1m²In terms of/g, depending on the duration of the synthesis. On the other hand, the lithium aluminum titanium phosphates known in the literature have a size of less than 2m²A/g, in particular less than 1.5m²BET surface area in g.

The lithium aluminum titanium phosphate of the invention preferably has d₉₀<6μm、d₅₀<2.1 μm, and d₁₀<A particle size distribution of 1 μm, which results in a large proportion of the particles being particularly small and thus achieving particularly high ion conductivity. This confirms similar results from the above-mentioned japanese unexamined patent application, in which attempts are also made to obtain smaller particle sizes by various grinding methods. However, since lithium aluminum titanium phosphate is extremely hard (Mohs hardness)>7, i.e., close to diamond), which is difficult to achieve with conventional grinding methods.

In a further preferred embodiment of the invention, the lithium aluminum titanium phosphate has the following empirical formula: li_1.2Ti_1.8Al_0.2(PO₄)₃It has about 5x 10at 298K^-4Very good total ionic conductivity of S/cm; and Li_1.3Ti_1.7Al_0.3(PO₄)₃In particular in phase pure form, at 293KWith 7x10^-4Particularly high total ion conductivity of S/cm.

Furthermore, it is an object of the present invention to provide a process for producing the phase pure lithium aluminium titanium phosphate of the present invention. This object is achieved by a method comprising the steps of:

a) providing phosphoric acid

b) Addition of titanium dioxide

c) Converting the mixture at a temperature of greater than 100 ℃

d) Adding oxygen-containing aluminium compounds and lithium compounds

e) Calcining the suspended reaction product obtained in step d).

It has surprisingly been found that liquid phosphoric acid, i.e. typically aqueous phosphoric acid, can also be used instead of solid phosphate, unlike all previously known syntheses of the state of the art. The process of the invention can also be referred to as the "hot water process". The use of phosphoric acid makes it possible to carry out the process more simply and therefore also to choose to remove impurities already in solution or suspended matter in solution and therefore also to obtain a product with better phase purity. In particular, dilute phosphoric acid in aqueous solution is used according to the invention.

The first reaction step c) of the process according to the invention consists in rendering the TiO originally inert₂Dissolve and, by not having to isolate the intermediate product Ti within the framework of the process of the invention₂O(PO₄)₂A faster and better reaction in the subsequent step d) and a better separation of the end product are made possible.

Intermediate product Ti₂O(PO₄)₂No separation is necessary, as the process of the invention is preferably carried out as a "one-pot process". However, in a further development of the invention which is not so preferred, it is also possible to isolate and optionally purify Ti by methods known per se to the person skilled in the art, for example precipitation, spray drying, etc₂O(PO₄)₂Then execute a process ofMethod steps d) and e) of step (a). The method thus performed may be particularly recommended when phosphoric acid other than orthophosphoric acid is used. However, in the separation of Ti₂O(PO₄)₂Thereafter, in order to have the correct stoichiometry of the final product, phosphoric acid or a phosphate salt must be added.

As already stated, diluted orthophosphoric acid, for example in the form of a 30% to 50% solution, is preferably used as phosphoric acid, but in further embodiments of the invention which are less preferred, other phosphoric acids, for example metaphosphoric acid and the like, can also be used. According to the invention, it is also possible to use all condensation products of orthophosphoric acid such as: pendant polyphosphoric acids (diphosphoric acid, triphosphoric acid, oligophosphoric acid, etc.), cyclic metaphosphoric acids (tri-, tetra-metaphosphoric acid), up to phosphoric anhydride P₂O₅. According to the invention, it is important that all of the phosphoric acid mentioned above is used only in diluted form in solution, preferably in aqueous solution.

According to the invention, any suitable lithium compound can be used as lithium compound, such as Li₂CO₃、LiOH、Li₂O、LiNO₃Among them, lithium carbonate is particularly preferable because it is most cost-advantageous, particularly when used on an industrial scale. Typically, according to the invention, the aluminum compound is not added until step d) and the lithium compound is not added after 30 minutes to 1 hour. In the present case, this reaction process is also referred to as "cascaded phosphating".

In fact, any oxide or hydroxide or mixed oxide/hydroxide of aluminum can be used as the oxygen-containing aluminum compound. In the state of the art, preference is given to using aluminum oxide Al₂O₃Because it is readily available. However, in the present case, the best results were found with Al (OH)₃And (4) realizing. With Al₂O₃In contrast, Al (OH)₃Is even more cost-effective and also better than Al₂O₃More reactive, particularly in the calcination step. Of course, although less preferred, Al₂O₃Can also be used in the method of the invention; however, with the use of Al (OH)₃CompareIn particular, calcination is continued for a long time.

The step of heating the mixture of phosphoric acid and titanium dioxide ("phosphating") is carried out at a temperature greater than 100 ℃, in particular in the range from 140 to 200 ℃, preferably from 140 to 180 ℃. Thus ensuring a gentle, furthermore controlled conversion to a homogeneous product.

The reaction product obtained according to the invention from step d) is then isolated by conventional methods, for example evaporation or spray drying. Spray drying is particularly preferred.

The calcination preferably takes place at temperatures of 850-950 ℃ and very particularly preferably at temperatures of 880-900 ℃ since the risk of appearance of foreign phases is particularly great below 850 ℃.

Typically, in>At a temperature of 950 ℃ of compound Li_1+xTi_2-xAl_x(PO₄)₃The lithium vapor pressure in (1) also increases, i.e., in>At a temperature of 950 ℃, the compound Li formed_1+xTi_2-xAl_x(PO₄)₃Losing more and more lithium as Li in air atmosphere₂O and Li₂CO₃Settling on the furnace wall. This can be compensated for by an excess of lithium, for example as described below, but it becomes more difficult to set the stoichiometry accurately. Thus, lower temperatures are preferred by the previously performed method compared to the state of the art, and are also unexpectedly possible. This result can be attributed to the use of dilute phosphoric acid, as compared to the state of the art solid phosphates.

In addition, temperatures greater than 1000 ℃ place higher demands on the furnace and crucible materials.

The calcination is carried out for a period of time of from 5 to 24 hours, preferably from 10 to 18 hours, very particularly preferably from 12 to 15 hours. It was unexpectedly found that, unlike the processes of the state of the art, a single calcination step is sufficient to obtain a phase-pure product.

Since the process according to the invention is carried out hydrothermally, the stoichiometric excess of lithium starting compounds which is customary in the state of the art is not necessary for step d). At the reaction temperatures used in the present invention, the lithium compounds are not volatile. Furthermore, because the implementation method is hydrothermal, monitoring stoichiometry becomes particularly easy compared to the solid-state method.

Subject of the invention is also compounds of formula Li_1+xTi_2-xAl_x(PO₄)₃And wherein x is 0.4, which can be obtained by the process according to the invention and which can be carried out hydrothermally, in particular, to obtain a phase purity within the meaning defined above. All previously known products obtainable by solid-state synthesis, as already mentioned above, have a foreign phase which can be avoided by carrying out the process of the invention hydrothermally. Furthermore, previously known products obtainable by solid state synthesis have a higher amount of destructive magnetic impurities.

The invention also relates to the use of the phase-pure lithium aluminum titanium phosphates according to the invention as solid electrolytes in secondary lithium ion batteries.

The objects of the invention are further achieved by providing an improved secondary lithium ion battery containing the phase pure lithium aluminum titanium phosphate of the invention, particularly as a solid electrolyte. The solid electrolyte is particularly suitable due to its high lithium ion conductivity and is particularly stable and also short-circuit resistant due to its phase purity and low iron content.

In a preferred development of the invention, the cathode of the secondary lithium ion battery of the invention contains a doped or undoped lithium transition metal phosphate as cathode, wherein the transition metal of the lithium transition metal phosphate is selected from the group consisting of Fe, Co, Ni, Mn, Cr and Cu. Doped or undoped lithium iron phosphate LiFePO₄Is particularly preferred.

In a further preferred development of the invention, the cathode material also contains a different doping or undoped lithium transition metal phosphate from that usedMixed lithium transition metal oxy compounds. Suitable lithium transition metal oxy compounds according to the invention are, for example, LiMn₂O₄、LiNiO₂、LiCoO₂、NCA（LiNi_1-x-yCo_xAl_yO₂E.g. LiNi_0.8Co_0.15Al_0.05O₂) Or NCM (LiNi)_1/3Co_1/3Mn_1/3O₂). The proportion of lithium transition metal phosphate in this combination is in the range of 1 to 60 wt%. The preferred ratio is in LiCoO₂/LiFePO₄In mixtures of, for example, 6 to 25% by weight, preferably 8 to 12% by weight, and in LiNiO₂/LiFePO₄25-60wt% of the mixture.

In a further preferred development of the invention, the anode material of the secondary lithium ion battery of the invention contains a doped or undoped lithium titanate. In a less preferred development, the anode material contains only carbon, such as graphite or the like. The lithium titanate in the preferred developments mentioned above is typically doped or undoped Li₄Ti₅O₁₂Thus, for example, for the preferred lithium transition metal phosphate cathodes, voltages of, for example, 2 volts can be achieved.

As already explained above, the lithium transition metal phosphate of the cathode material and the lithium titanate of the anode material, which are preferably developed, are both doped or undoped. The doping is carried out with at least one other metal or also with several other metals, which leads in particular to an increased stability and cycling stability of the doped material when used as cathode or anode. Metal ions which can be incorporated into the lattice structure of the cathode or anode material, such as, for example, Al, B, Mg, Ga, Fe, Co, Sc, Y, Mn, Ni, Cr, V, Sb, Bi, Nb or several of these ions, are preferred as doping materials. Mg, Nb, and Al are very particularly preferred. The lithium titanate is generally preferably rutile-free and thus equates to phase pure.

The doping metal cation is present in the lithium transition metal phosphate or lithium titanate in an amount of 0.05 to 3wt%, preferably 1 to 3wt%, relative to the total mixed lithium transition metal phosphate or lithium titanate. The amount of doping metal cations is up to 20at%, preferably 5-10at%, relative to the transition metal (values expressed in at%), or, in the case of lithium titanate, relative to lithium and/or titanium.

The dopant metal cations occupy lattice sites of the metal or lithium. The exception to this is mixed Fe, Co, Mn, Ni, Cr, Cu, lithium transition metal phosphates containing at least two of the above elements, wherein also larger amounts of doping metal cations, in extreme cases up to 50wt%, may be present.

Typical additional components of the secondary lithium ion battery electrode of the present invention include carbon black and a binder in addition to the active material, i.e., lithium transition metal phosphate or lithium titanate.

Binders known per se to the person skilled in the art can be used here as binders, for example Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride hexafluoropropylene copolymer (PVDF-HFP), ethylene-propylene-diene terpolymer (EPDM), tetrafluoroethylene hexafluoropropylene copolymer, polyethylene oxide (PEO), Polyacrylonitrile (PAN), polyacryl methacrylate (PMMA), carboxymethyl cellulose (CMC), and derivatives and mixtures thereof.

Within the framework of the invention, typical proportions of the individual components of the electrode material are preferably 80 to 98 parts by weight of active substance electrode material, 10 to 1 part by weight of conductive carbon and 10 to 1 part by weight of binder.

Within the framework of the invention, a preferred cathode/solid electrolyte/anode combination is for example LiFePO₄/Li_1.3Ti_1.7Al_0.3(PO₄)₃/Li_xTi_yO, cell voltage of about 2 volts, which is very suitable as a replacement for lead acid batteries, or LiCo_zMn_yFe_xPO₄/Li_1.3Ti_1.7Al_0.3(PO₄)₃/Li_xTi_yO, where x, y and z are as further specified above, and the cell voltage is increased and the energy density is improved. .

The invention is explained in more detail below with the aid of figures and examples, which are not to be understood as limiting the scope of the invention. The figure shows that:

FIG. 1 Structure of phase pure lithium aluminum titanium phosphate according to the invention,

FIG. 2 XRD spectrum of lithium aluminum titanium phosphate according to the present invention,

FIG. 3 is an X-ray powder diffraction pattern (XRD) of a conventionally produced lithium aluminum titanium phosphate,

FIG. 4 is a graph showing the particle size distribution of the lithium aluminum titanium phosphate according to the present invention.

1. Measuring method

The BET surface area is determined in accordance with DIN 66131 (DIN-ISO 9277).

The particle size distribution was determined by laser granulometry using a Malvern Mastersizer2000 according to DIN 66131.

X' Pert PRO diffractometer using PANalytical: an X-ray powder diffraction pattern (XRD) is measured by a goniometer theta/theta, a copper anode PW3376 (the maximum output is 2.2 kW), a detector X 'Celerator and X' Pert software.

The level of the magnetic component in the lithium aluminum titanium phosphate of the present invention was determined by separation using a magnet, followed by acid decomposition, followed by ICP analysis of the resulting solution.

The lithium aluminium titanium phosphate powder to be tested was suspended in ethanol with magnets of a specific size (diameter 1.7cm, length 5.5cm <6000 gauss). The ethanol suspension was exposed to the magnet for 30 minutes in an ultrasonic bath at a frequency of 135 kHz. The magnet attracts magnetic particles from the suspension or powder. The magnet with the magnetic particles is then removed from the suspension. The magnetic impurities were dissolved with the aid of acid decomposition and examined by ICP (ion chromatography) analysis to determine the exact amount and composition of the magnetic impurities. The instrument used for ICP analysis was ICP-EOS, Varian Vista Pro 720-ES.

Example 1

Production of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃

29.65kg of orthophosphoric acid (80%) were introduced into a reaction vessel (Thale vessel having a volume of 200L) and diluted with deionized water to a volume of 110L of liquid, corresponding to 2.2M of orthophosphoric acid. Then, 10.97kg of TiO was slowly added with vigorous stirring by an anchor stirrer with a Teflon coating₂(anatase form) and stirring was continued at 160 ℃ for 16 h. The reaction mixture was then cooled to 80 ℃ and 1.89kg of Al (OH) was added₃) (gibbsite) and stirring was continued for half an hour. 4.65kg LiOH dissolved in 23L of deionized water was then added. Towards the end of the addition, the colorless suspension became more viscous. The suspension is then spray-dried and the crude non-hygroscopic product thus obtained is finely ground for a period of 6 hours to obtain<Particle size of 50 μm.

The finely ground premix was heated from 200 ℃ to 900 ℃ in 6 hours at a heating rate of 2 ℃/min, since otherwise amorphous foreign phases could be detected in the X-ray diffraction pattern (XRD spectrum). The product was then sintered at 900 ℃ for 6 hours, followed by fine grinding with ceramic spheres in a ball mill.

No evidence of a foreign phase was found in the product (fig. 2). The total amount of magnetic Fe, Cr, and Ni and/or their compounds was 0.73 ppm. In this example, the amount of Fe and/or its magnetic compound was 0.22 ppm. On the other hand, the comparative examples produced according to JP A19902-225310 contain 2.79ppm and 1.52ppm of magnetic iron or iron compounds.

Obtained according to the inventionProduct Li_1.3Al_0.3Ti_1.7(PO₄)₃Is shown in FIG. 1 and corresponds to the so-called NASICON (Na)⁺Superionic conductor) structure (see Nuspl et al, j.appl.phys.vol.06, No.10, p.5484, 1999)).

Three-dimensional Li of crystal structure⁺The channels and at the same time the very low activation energy of 0.30eV for Li transport in these channels bring about a high intrinsic Li ion conductivity. Al doping hardly affects the intrinsic Li⁺Conductivity, but reduces the conductivity of Li ions at the particle boundaries.

Except for Li_3xLa_2/3-xTiO₃Other than the compound, Li_1.3Al_0.3Ti_1.7(PO₄)₃Are known in the literature to have the highest Li⁺An ion-conducting solid electrolyte.

It can be seen from the X-ray powder diffraction pattern (XRD) of the product in fig. 2 that the reaction process of the present invention produces a particularly phase pure product.

In contrast, FIG. 3 shows that the X-ray powder diffraction pattern of the state-of-the-art lithium aluminum titanium phosphate produced according to JP A19902-225310 has a foreign-body phase such as TiP₂O₇And AlPO₄. The same foreign phase is also found in the material described by Kosova et al (see above).

FIG. 4 shows the particle size distribution of the product from example 1, which has a completely monomodal particle size distribution and d₉₀Value of<6μm，d₅₀Value of<2.1 μm, and d₁₀Value of<1μm。

Claims (20)

1. Formula Li_1+xTi_2-xAl_x(PO₄)₃Wherein x is 0.4 or less and the level of magnetic metals and magnetic metal compounds of the elements Fe, Co and Ni therein is 1ppm or less.

2. The lithium aluminum titanium phosphate of claim 1 having a particle size distribution d90<6 μm.

3. The lithium aluminium titanium phosphate according to claim 1 or 2, having a content of metallic iron and magnetic iron compounds <0.5 ppm.

4. The lithium aluminum titanium phosphate of claim 3, wherein x has a value of 0.2 or 0.3.

5. Li for the production of one of the preceding claims_1+xTi_2-xAl_x(PO₄)₃Wherein x is less than or equal to 0.4, comprising the steps of:

a) providing phosphoric acid

b) Addition of titanium dioxide

c) Converting the mixture at a temperature above 100 ℃

d) Adding an oxygen-containing aluminum compound, and a lithium compound

e) Calcining the suspended reaction product obtained in step d).

6. The process of claim 5, wherein phosphoric acid selected from the group consisting of liquid phosphoric acid, aqueous phosphoric acid and/or phosphoric acid in phosphoric acid solution is used as phosphoric acid;

and/or wherein dilute orthophosphoric acid is used as phosphoric acid.

7. The process of claim 5 or 6, wherein lithium carbonate is used as the lithium compound.

8. The process of claims 5 to 7, wherein Al (OH)₃Is used as the oxygen-containing aluminum compound.

9. The process according to any one of claims 5 to 8, wherein step c) is carried out at a temperature of from 140 ℃ to 200 ℃.

10. The process of claim 9 wherein the suspended reaction product is spray dried after step d).

11. The method of claim 10, wherein the calcining is conducted at a temperature of 850 ℃ to 950 ℃.

12. The method of claim 11, wherein the calcining is carried out for a period of time of 5 to 24 hours.

13. Formula Li_1+xTi_2-xAl_x(PO₄)₃Phase-pure lithium aluminium titanium phosphate according to (1), wherein x is 0.4 or less, obtainable by the process according to any one of the preceding claims 6 to 12.

14. Use of the phase pure lithium aluminum titanium phosphate of claims 1 to 4 or 13 as a solid electrolyte in a secondary lithium ion battery.

15. A secondary lithium ion battery comprising the phase pure lithium titanium phosphate of one of claims 1 to 4 or 13.

16. The secondary lithium ion battery of claim 15 further comprising doped or undoped lithium transition metal phosphate as a cathode material.

17. The secondary lithium ion battery of claim 16 wherein the transition metal of the lithium transition metal phosphate is selected from the group consisting of Fe, Co, Ni, Mn, Cu, Cr.

18. The secondary lithium ion battery of claim 17 wherein the transition metal is Fe.

19. The secondary lithium ion battery of claim 18 wherein the cathode material contains an additional doped or undoped lithium transition metal oxy compound.

20. The secondary lithium ion battery of any of claims 15 to 19 wherein the anode material comprises doped or undoped lithium titanate.