WO2023233144A1

WO2023233144A1 - Process for the production of a cathode material for rechargeable lithium and/or sodium-ion batteries

Info

Publication number: WO2023233144A1
Application number: PCT/GB2023/051425
Authority: WO
Inventors: Dr. Shutao WANG; Dr Thomas Edward ASHTON; Professor Jawwad Arshad DARR
Original assignee: Ucl Business Ltd
Priority date: 2022-05-30
Filing date: 2023-05-30
Publication date: 2023-12-07
Also published as: GB202207971D0

Abstract

A process for the production of a cathode material for a rechargeable lithium (Li) and/or sodium (Na)-ion battery is described. The process comprises the steps of :- a. preparing an uncalcined precursor blend of one or more metal compounds suitable to form a Li-ion and/or Na-ion intercalatable structure upon solid state thermal treatment; b. further blending the uncalcined precursor blend produced in step a. with a Li and/or Na-ion source; c. drying the Li and/or Na-ion containing mixture produced in step b.; and d. flash heating the uncalcined Li and/or Na-ion containing mixture produced in step c. to produce a metal compound intercalatable structure with intercalated Li and/or Na- ions, wherein the intercalatable structure is defective. The process continues by quenching the intercalatable structure produced in step d. The flash heating and quenching rate whether heating or cooling is from 2400 to 100°C per minute.

Description

PROCESS FOR THE PRODUCTION OF A CATHODE MATERIAL FOR RECHARGEABLE LITHIUM AND/OR SODIUM-ION BATTERIES

FIELD

[01] The present invention relates to a cathode material for a rechargeable lithium (Li) and/or sodium (Na)-ion battery and to a process of production of such a cathode material.

BACKGROUND

[02] Research in relation to improved materials for rechargeable Li-ion batteries has recently focussed on identifying more environmentally friendly and sustainable ways to manufacture battery materials. Research has focussed on both the anode and the cathode. The cathode materials can include metal oxide mixtures in specific structures such as layered structures. Amongst the current leading cathode materials for rechargeable Li-ion batteries, metal oxides containing mixtures of nickel, manganese and cobalt have been widely employed. These mixtures may also contain additional dopants or other elements which confer specific favourable properties. The amounts of the three main elements can vary from 0 to nearly 100%. While the nickel content is maximised to achieve greater energy density, the amount of cobalt is being reduced due to political and/or sustainability issues and cost. However, high amounts of nickel and low amounts of cobalt also confer instability issues during battery operation unless mitigating precautions are taken. These materials are known as the NMC (Ni, Mn, Co) family and/or NCA (Ni, Co, Al) and/or similar high nickel cathode materials.

[03] Much of the known research focusses on the manufacture of battery materials which use idealised structures which are highly crystalline and generally well ordered on the atomic scale. These highly crystalline structures are usually synthesised under energy intensive conditions with heat treatments in excess of eight hours at temperatures of 850°C or greater. These conditions present a substantial energy cost, and commonly take place in a batch process inviting potential batch-to-batch variation in the products.

[04] Continuous Hydrothermal Flow Synthesis (CHFS) reactors, utilising a Confined Jet Mixer (CJM) have been described in the art (US 9192901). The CHFS process has been described at lab and pilot plant scales in the literature (for example, Ind. Eng. Chem. Res. 2013, 52, 5270, Ind. Eng. Chem. Res. 2013, 52, 5522).

[05] It is one object of the present invention to produce a cathode material under more efficient conditions.

[06] It is another object of the present invention to produce a cathode material with a high energy density or capacity at high power. [07] Advantageously, it has been found that the cathode materials are particularly effective when the battery is charged or discharged rapidly such as at >1 C.

SUMMARY

[08] According to the present invention, there is provided a process for the production of a cathode material for a rechargeable Li and/or Na-ion battery comprising the steps of a. preparing an uncalcined precursor blend of one or more metal compounds suitable to form a Li and/or Na-ion intercalatable structure upon solid state thermal treatment; b. further blending the uncalcined precursor blend produced in step a. with a Li and/or Na-ion source; c. drying the Li and/or Na-ion containing mixture produced in step b.; d. flash heating the uncalcined Li and/or Na-ion containing mixture produced in step c. to produce a metal compound intercalatable structure with intercalated Li and/or Na-ions, wherein the intercalatable structure is defective; e. quenching the intercalatable structure produced in step d; wherein the flash heating and quenching rate whether heating or cooling is from 2400 to 100°C per minute.

[09] The metal compounds are not restricted and may be any compound that forms a suitable intercalatable structure for the Li and/or Na-ions at the cathode. However, typically, the metals are selected from manganese, nickel, iron, cobalt, copper and aluminium.

[10] Typically, the metal compounds in step a. are in the form of oxides, hydroxides, oxyhydroxides or a combination thereof. Typically, the metal compounds in step d. are in the form of oxides or hydroxides, or a combination thereof.

[11] Suitable metal compounds are transition metal oxides and/or hydroxides such as nickel, manganese and cobalt oxides and/or hydroxides; mixed metal oxides and/or hydroxides of nickel and manganese; nickel, manganese and cobalt; and/or nickel, cobalt and aluminium. Accordingly, the defective metal compound intercalatable structures produced in step e. may suitably include: i. Na_xFe_qCurMnsO2 where q + r + s = 1 , and where x is from 0.6 to 1.1 , typically x is from 0.7 to 0.9; ii. Li_xNiaC0bAlcC>2 where a + b + c = 1 ± 0.1 , and where x is from 0.9 to 1.1 , typically x is about 1 ;

Hi. Li_xNiaMnbCocC>2 where a + b + c = 1 ± 0.1 , and where x is from 0.9 to 1 .1 , typically x is about 1 ; iv. LixMriaC where x is from 0.9 to 1.1 , typically x is about 1 , and where a is from 1 .8 to 2.2; and/or v. LixNiaMnbC where x is from 0.9 to 1 .1 , typically x is about 1 , and where a + b is from 1 .8 to 2.2, typically is about 2;

[12] It will be appreciated, that the intercalatable structures may not only be based on intercalatable metal compounds and can also include suitable dopants and surface treatments known to the skilled person.

[13] Advantageously, by flash heating the mixture produced in step c. defects are produced in the transition metal compound structure. Surprisingly such defects, especially in optimal quantities, have been found to improve the performance of the cathode material.

[14] The blend produced in step a. may have any suitable average particle size. The average particle size may be <25 pm, such as, <15 pm, such as, <5 pm. Typically, the blend produced in step a. may have an average particle size range of 1-25 pm, more typically, 1-15 pm, most typically, 1 to 5 pm.

[15] The process of the present invention may be a batch or continuous process. The flash heating may be carried out in a continuous heating process (for example using a mobile conveyor that allows rapid heating and cooling). Alternatively, the flash heating may be carried out in a batch/semi batch heating process in which the material is rapidly heated and cooled for set time periods.

[16] It has been found that for a given mixture of the metal ions with Li and/or Na-ions, there is an optimum heat treatment time and temperature for which the most favourable defective structure may be obtained and accordingly for which the best capacity and power performance may be obtained.

[17] Without being bound by theory, it is believed that, because the materials are heat-treated for different times and temperatures, there is a change in the phases present and/or the ratio of any disordered sites, and the specific ratio of these disordered sites or phases, seems to give an optimum performance for that specific composition.

[18] A suitable method for producing the precursor blend in step a. may be a wet chemical process such as precipitation. A suitable wet precipitation process is one in which a precursor blend is produced that contains an intimate mixture of the elements, such as oxides and/or hydroxides and/or oxyhydroxides. A suitable process may be the continuous hydrothermal flow synthesis process, which produces very small particles of precursor blend.

[19] In the continuous hydrothermal flow process, the metal compounds may be mixed in aqueous solution and then precipitated through the process to form the precursor blend. This precursor blend may be washed and cleaned to remove residual chemicals from the manufacture. The resulting wet solid precursor may be dried.

[20] The dry precursor blend produced in step a. is typically in the form of a powder.

[21] The dry precursor blend may then be mixed thoroughly with a Li and/or Na-ion source such as lithium hydroxide and/or sodium hydroxide in the presence of a suitable liquid or solvent, such as water, and then dried. Suitably, the Li and/or Na-ion source should remain well mixed after drying. Typically, the dry mixture produced in step c., flash heated in step d. and quenched in step e. is in the form of a powder.

[22] Preferably the powder produced has a homogenous distribution of elements, preferably at the micro or nanoparticle level.

[23] Although a continuous hydrothermal flow process is described above, alternative techniques such as wet chemical precipitation processes suitable for this step will be known to those skilled in the art.

[24] The Li and/or Na-ion containing mixture produced in step c. is subjected to heat treatment using flash heating in step d. Flash heating comprises the steps of exposing the precursor mixture to an elevated temperature for a short period of time, typically less than two hours, more typically less than 1 hour, such as less than 40 minutes. The flash heating step may be carried out for any suitable time period. The time period for carrying out the flash heating step may be <90 minutes, such as <60 minutes, such as <45 minutes, such as <30 minutes, for example <25, <15, <10 or <5 minutes. Typically, the flash heating is for >1 second, such >5 seconds, such as >20 seconds, such as >30 seconds, for example >50, >100, >200 or >400 seconds. The flash heating step may be carried out for 1 second to 90 minutes, typically, 5 seconds to 60 minutes, more typically 20 seconds to 45 minutes, most typically, 30 seconds to 30 minutes, such as 50 seconds to 30 minutes, such as 100 seconds to 30 minutes, such as 200 seconds to 30 minutes, such as 400 seconds to 30 minutes.

[25] The flash heating step d. may be carried out at any suitable temperature. The flash heating temperature to which the Li and/or Na-ion containing mixture produced in step c. is exposed may be <1600°C, such as <1400°C, such as <1200°C. Typical temperature ranges for the flash heating step d. are from above the sintering temperature of the mixture, for example >700°C, such as >750°C, such as >800°C. Typical ranges for the flash heating step may be 700 to 1600°C, more typically, 750 to 1250°C, most typically, 800 to 1200°C.

[26] The flash heating step d. may be carried out at a rate and temperature that minimises Li and/or Na evaporation, and allows an efficient solid state reaction.

[27] It will be appreciated that priorto flash heating, the sample is generally at room temperature or at least in the range 0 to 45°C. [28] The intercalatable structure produced in step d. is then quenched in step e. so as to “freeze” the state of the material through rapid and controlled cooling.

[29] Rapid and controlled cooling of the sample in step e. is operable to lock in the desired defect structure resulting from the flash heating. Accordingly, the quenching time is determined by the time necessary to effectively lock in structure, typically the desired structure containing the desired amount and type of defects for optimal performance. The quenching step e. may be carried out for any suitable time period to effect the desired material properties, in particular the freezing of the defective structure produced in step d. The quenching time may be carried out for between 1 second to 1 hour, more typically, between 20 seconds to 30 minutes, most typically, 1 to 10 minutes. The quenching time may be carried out for <55 minutes, more typically, <45 minutes, most typically, <25 minutes, such as <15 minutes or <5 minutes. Rapid quenching may be achieved using suitable refrigerants.

[30] The quenching time may be taken as the time taken to reduce the temperature of the heated sample from its temperature at the end of the flash heating step in step d. to <100°C.

[31] Flash heating and quenching rates are from 2400 to 100°C per minute. Suitably, the flash heating and quenching rate whether heating or cooling is from 1200 to 150°C per minute, such as from 600 to 200 °C.

[32] The flash heating and quenching steps may be part of a batch process where the samples are introduced one-by-one into a static furnace or may be part of a continuous process where the samples pass into or through a furnace to heat up and subsequently cool down again, or via a process where a heater is moved over a bed of sample.

[33] Advantageously, the invention provides high-performance cathode materials using considerably less energy than current industrial processes which typically involve heating the materials to >800°C for 12 hours or more. Further ramping and cooling of the temperature each add several additional hours to the process. The invention provides the possibility for materials to be heated and cooled in as little as 20 minutes or less.

[34] According to a further aspect of the present invention there is provided a cathode material for a Li ion and/or Na-ion battery comprising a metal compound intercalatable structure and a Li ion and/or Na-ion source intercalated into said structure wherein the said metal compound intercalatable structure is defective.

[35] Typically, the intercalatable structure is at least 1 % defective, such as at least 2% defective, such as at least 3% defective, such as at least 4% defective, or even at least 5 or 6% defective. The intercalatable structure may be up to 10% defective, such as up to 9% defective, such as up to 8% defective, such as up to 7% defective. The intercalatable structure may have defects present in the range of from 1 to 10%, more typically from 2 to 9%, most typically from 3 to 8%, especially from 4 to 7%. [36] The nature of such defects are typically anti-site defects, i.e. Li⁺/M^x+ or Na⁺/M^x+ cation mixing. The amount of defects(%) are measurable with structural techniques, such as XRD (X- ray Powder Diffraction) or NPD (Neutron powder diffraction). Unless indicated otherwise, the % defects refers to the degree of this anti-site mixing as determined by XRD or NPD, more typically, XRD.

[37] Typically, the average particle size of the particles produced by the process of the invention or the cathode material product of the invention may be any suitable average particle size. The average particle size may be <20 pm, such as <10 pm, such as <5 pm. Typically, the average particle size may be 1 to 20 pm, more typically, 1 to 10 pm, most typically, 1 to 5 pm.

[38] Definitions

[39] By “intercalatable” is meant the structure may accommodate intercalated Li and/or Na-ions therein, and may be effective to allow migration thereof to the anode of Li and/or Na-ions during charging, and may be effective to accommodate the return of the Li and/or Na-ions during use of a battery incorporating the structure at the cathode.

[40] BRIEF DESCRIPTION OF DRAWINGS

[41] The invention will now be described by way of example only and with reference to the accompanying figures in which: -

[42] Figure 1 shows a configuration diagram of the Continuous Hydrothermal Flow Synthesis (CHFS) used to produce Example 1 (NMC532) and Example 2 (NCA) precursor powders.

[43] Figure 2 shows the tabulated values for Example 1 (NMC532) and Example 2 (NCA) cycled at C/10 (‘low’ rate, charge or discharge in 10 hours);

[44] Figure 3 shows the tabulated values for Example 1 (NMC532) and Example 2 (NCA) cycled at 10C (‘high’ rate, charge or discharge in 6 min); and

[45] Figure 4 shows a comparison of gravimetric capacity of Example 1 (NMC532) and Example 2 (NCA) to Comparative Example 1 (commercial NCA-powder) and Comparative Example 2 (commercial NCA-sheet).

DESCRIPTION OF EMBODIMENTS

Examples

[46] The precursor powder was synthesised according to the following method using a Continuous Hydrothermal Flow Synthesis (CHFS) reactor, utilising a Confined Jet Mixer (CJM).

[47] In CHFS, two identical high-pressure pumps (Primeroyal K, Milton Roy, France) were used to deliver pressurised feeds (240 bar) of: (i) an aqueous solution containing a mixture of metals (metal precursor), typically nitrates, at <0.6M (Figure 1 , pump P2) and (ii) an aqueous KOH (1 .5- 2M) base feed (Figure 1 , pump P3). Solutions (i) and (ii) were pre-mixed in flow in a %” stainless steel dead volume tee mixer (Swagelok) to produce (Hi), which is then delivered to the CJM at an ambient temperature, at 200 mL min^-1.

[48] A third pump (Figure 1 , pump P1) was used to pump ambient temperature deionised water under pressure (240 bar) at a rate of 400 mL min^-1 into a heat exchanger at 450°C which produced a supercritical water flow. The combined P2 and P3 flow (iii), was mixed in the CJM with the supercritical water flow at a mixing temperature of about 335°C, whereupon precipitation and crystallisation occurred to produce a slurry. The slurry was cooled to 40°C using a pipe-in-pipe heat exchanger. The cooled slurry product was then collected at the exit of the CHFS process at about 50°C.

[49] The collected slurry was then centrifuged at 4000 rpm (using model Sigma 6-16S, Sigma Aldrich, Dorset, UK) until the solid content settled and the liquid was removed by pouring. The remaining wet solids were cleaned by dialysis in Visking Dialysis Membrane (Medicell Membranes Ltd) using deionised water until a conductivity value below 100 pS was achieved. The cleaned slurry was then centrifuged at 4000 rpm for 30 minutes (using model Sigma 6-16S, Sigma Aldrich, Dorset, UK) into a thick paste and any remaining bulk water poured off.

[50] The material was then freeze-dried at -40°C, 3x1 O’⁷ MPa for 20 hours (using Virtis Genesis 35XL, Biopharma process systems, Winchester, UK) to obtain a free-flowing freeze dried precursor powder.

[51] The freeze dried precursor powder was then mixed with a lithium source. 167.85 g of LiOH’F was dissolved in 800 mL deionised water for 30 minutes to produce a 5M LiOH aqueous solution. The LiOH aqueous solution (LiOH«H2O) was then added (80 mL min^-1) to 200 g of the precursor powder under continuous stirring using a high shear mixer (IKA, T18 digital package S2, Ultra-turrax) for 20 minutes (10 minutes at 12000 rpm followed by 10 minutes at 16000 rpm) to obtain a composite material.

[52] This resulting composite material was dried for 24 hours to obtain a solid dry mixture.

[53] The resulting solid dry mixture was then placed into an alumina crucible before being slowly fed into a pre-heated tube furnace, at the desired temperature (typically, “slowly” means over about 1 or 2 minutes to avoid thermal shock). The crucible was maintained in the furnace at the temperature for the desired time and subsequently removed and allowed to cool to room temperature. The heating process referred to is a flash heat treatment.

[54] Example 1 (NMC532 - nickel manganese cobalt) was synthesised and processed according to the above methodology. The aqueous solution containing a mixture of metals in (i) was as follows: - 0.556M total metal concentration solution comprised of 0.266M Ni(NO₃)2'6H2O; 0.15M Mn(NO₃)2'4H₂O and 0.14M Co(N0₃)₂'6H₂0. A 2M KOH was used as the base feed (ii). [55] The formed solid dry mixture of NMC532 was heated in a furnace at 1090, 1100, 1110 and 1120°C for 0.5, 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 minutes to prepare a library of Example 1 samples (i.e. 40 different materials).

[56] Example 2 (NCA - nickel cobalt aluminium) was synthesised and processed according to the above methodology. The aqueous solution containing a mixture of metals in (i) was as follows: - 0.5M total metal concentration solution comprised of 0.4M Ni(NO3)2'6H2O, 0.025M AI(NC>3)3'9H2O and 0.075M Co(NC>3)2'6H20. A 1 ,5M KOH was used as the base feed (ii).

[57] The formed solid dry mixture of NCA was heated in a furnace at 850, 875 and 900°C for 1 , 2, 4, 6, 8, 10, 12, 16, 20, 25 minutes to prepare a library of Example 2 samples (i.e. 24 different materials).

[58] The powder materials prepared by the continuous hydrothermal flow synthesis and flash heat treatment process were characterised using XRD to understand the structural and other changes.

[59] The powder materials prepared by the continuous hydrothermal flow synthesis and flash heat treatment process described above were made into electrodes and electrochemically tested as coin cells. The electrochemical testing was carried out to assess the performance of the powder materials as battery materials.

[60] The results of electrochemical testing for the library of samples of Example 1 and Example 2 are shown in Figures 2-4.

[61] Figure 2 shows the tabulated values for Example 1 (NMC532) and Example 2 (NCA) cycled at C/10 (‘low’ rate, charge or discharge in 10 hours). It can be seen from the results that the performance is dependent on the time and temperature conditions. The optimum time was lower, and temperature higher for Example 1 (NMC532) with a best performance at a time range of 4.0 to 4.5 minutes at 1090°C, compared to Example 2 (NCA) with a best performance at a time range 8 to 10 minutes at 850°C.

[62] A maximum capacity was achieved of 161.64 mAh g^-1 for Example 1 (NMC532 - 4.5 minutes at 1090°C) and 195.82 mAh g^-1 for Example 2 (NCA - 8 minutes at 850°C), which is competitive with values for commercial cathodes of similar composition.

[63] Figure 3 shows the tabulated values for NMC532 and NCA cycled at 10C (‘high’ rate, charge or discharge in 6 minutes) where a similar relationship to the low-rate data between time, temperature and gravimetric capacity is observed.

[64] A maximum capacity was achieved of 108 mAh g^-1 for Example 1 (NMC532 - 4 minutes at 1090°C) and 128 mAh g^-1 for Example 2 (NCA - 10 minutes at 850°C), exceeding values for current commercial materials. [65] The shading in Figures 2 and 3 provides a key where the darkest shading is high values and the lightest shading is lowest capacity at that specific current rate (or c rate)

[66] Figure 4 shows the capacities achieved for Example 1 (NMC52) and Example 2 (NCA) compared to the capacity of commercial cathodes Comparative Example 1 (NCA powder - Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAI02)) and Comparative Example 2 (NCA sheet - Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAI02)). Comparative Example 1 (NCA powder) and Comparative Example 2 (NCA sheet) are cathodes that are commercially available from Targray, Canada.

[67] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[68] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[69] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[70] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 . A process for the production of a cathode material for a rechargeable lithium (Li) and/or sodium (Na)-ion battery comprising the steps of a. preparing an uncalcined precursor blend of one or more metal compounds suitable to form a Li-ion and/or Na-ion intercalatable structure upon solid state thermal treatment; b. further blending the uncalcined precursor blend produced in step a. with a Li and/or Na-ion source; c. drying the Li and/or Na-ion containing mixture produced in step b.; d. flash heating the uncalcined Li and/or Na-ion containing mixture produced in step c. to produce a metal compound intercalatable structure with intercalated Li and/or Na-ions, wherein the intercalatable structure is defective. e. quenching the intercalatable structure produced in step d; wherein the flash heating and quenching rate whether heating or cooling is from 2400 to 100°C per minute.

2. A process according to any preceding claim, wherein the flash heating in step d. is carried out for <90 minutes, such as <60 minutes, <45 minutes or <30 minutes.

3. A process according to any preceding claim, wherein the flash heating in step d. is carried out for >1 second, such as >5 seconds, >20 seconds, >30 seconds, >50 seconds, >100 seconds, >200 seconds or >400 seconds.

4. A process according to any preceding claim, wherein immediately prior to flash heating, the mixture is in the range 0 to 45°C.

5. A process according to any preceding claim, wherein the flash heating temperature is <1600°C, such as <1400°C or <1300°C.

6. A process according to any preceding claim, wherein the flash heating temperature is above the sintering temperature of the mixture, for example >700°C, such as >750°C or >800°C.

7. A process according to any preceding claim, wherein the quenching in step e. is carried out for between 1 second and 1 hour, more typically, between 20 seconds and 30 minutes, most typically, between 1 and 10 minutes.

8. A process according to any preceding claim, wherein the quenching in step e. is carried out for <55 minutes, more typically, <45 minutes, most typically, <25 minutes, such as <15 or <5 minutes.

9. A process according to claim, wherein step e. is operable to lock in the desired defect structure resulting from step d.

10. A process according to any preceding claim, wherein the intercalatable structure is at least 2% defective, such as at least 3% defective, such as at least 4% defective, such as at least 5 or 6% defective.

11. A process according to any preceding claim, wherein the intercalatable structure comprises defects, typically anti-site defects, in the range of 1-10%, such as 2-9%, such as 3-8%, such as 4-7%.

12. A process according to any preceding claim, wherein the quenched intercalatable structure has an average particle size of <20 pm, such as <10 pm or <5 pm.

13. A process according to any preceding claim, wherein the metal in the metal compounds suitable to form a Li-ion and/or Na-ion intercalatable structure are selected from manganese, nickel, iron, cobalt, aluminium, or a combination thereof.

14. A process according to any preceding claim, wherein the metal compounds suitable to form a Li-ion and/or Na-ion intercalatable structure are in the form of oxides, phosphates, silicates, hydroxides, oxyhydroxides, or a combination thereof.

15. A process according to any preceding claim, wherein the metal compounds suitable to form a Li-ion and/or Na-ion intercalatable structure are selected from iron phosphate, transition metal oxides such as nickel, manganese and cobalt oxides and hydroxides; and mixed metal oxides and hydroxides of nickel/manganese, nickel/manganese/cobalt and/or nickel/cobalt/aluminium.

16. A process according to any preceding claim, wherein the defective intercalatable structures produced in step e. include: - i. Na_xFe_qCurMnsO2 where q + r + s = 1 , and where x is from 0.6 to 1.1 , typically x is from 0.7 to 0.9; ii. LixNiaC0bAlcC>2 where a + b + c = 1 ± 0.1 , and where x is from 0.9 to 1.1 , typically x is about 1 ;

Hi. LixNiaMnbCo_c02 where a + b + c = 1 ± 0.1 , and where x is from 0.9 to 1 .1 , typically x is about 1 ; iv. Li_xMn_aO4 where x is from 0.9 to 1.1 , typically x is about 1 , and where a is from 1 .8 to 2.2; and/or v. LixNiaMnbC where x is from 0.9 to 1 .1 , typically x is about 1 , and where a + b is from 1 .8 to 2.2, typically is about 2.

17. A process according to any preceding claim, wherein the intercalatable structure further comprises suitable dopants and/or surface treatments.

18. A process according to any preceding claim, wherein the blend produced in step a. has an average particle size of <25 pm, such as <15 pm or <5 pm.

19. A process according to any preceding claim, wherein the product of steps a., c., d., and/or e. is in the form of a powder.

20. A process according to any preceding claim, wherein the process is a batch, semi-batch or continuous process.

21. A cathode material for a Li ion and/or Na-ion battery comprising a metal compound intercalatable structure and a Li ion and/or Na-ion source intercalated into said structure wherein the said metal compound intercalatable structure is defective.

22. A cathode material according to claim 21 , wherein the intercalatable structure is at least 1% defective, such as at least 2% defective, such as at least 3% defective, such as at least 4% defective, or even at least 5 or 6% defective.

23. A cathode material according to claim 21 or 22, wherein the defects are anti-site defects.