Electrode material

Abstract

A particulate mixed metal oxide material is described. The particulate mixed metal oxide material comprises an intra-particle porosity, as determined by mercury intrusion porosimetry, of from 2 to 35 %. The material is useful as an electrode material, in particular as a cathode material within an electrochemical cell or battery.

Description

[0001] ELECTRODE MATERIAL

[0002] BACKGROUND

[0003] Lithium-ion secondary batteries are the leading battery technology currently used in applications from small personal devices to electric vehicles. Lithium-ion batteries are favoured for their high energy density and long cycle life, among other benefits. They contain a plurality of lithium-ion secondary cells, which is one example of an alkali metal ion secondary cell.

[0004] One type of electrochemically active material commonly used in the cathodes of lithium- ion secondary cells is lithium nickel manganese cobalt oxide (NMC). These materials are mixed metal oxides having a layered structure.

[0005] SUMMARY

[0006] The present inventors have developed a particulate mixed metal oxide material which, due to the amount of intra-particle porosity within the material, can provide both high rate capability and high energy density, whilst also improving packing efficiency (i.e. highest tapped density).

[0007] Accordingly, in a first aspect, the present invention provides a particulate mixed metal oxide material comprising an intra-particle porosity, as determined by mercury intrusion porosimetry, of from 2 to 35 %.

[0008] Traditional methods of manufacturing particulate mixed metal oxide materials using the precipitation of a mixed metal hydroxide precursor followed by calcination result in dense particles with very low, or no, intra-particle porosity. The inventors adopt a manufacturing process, described in more detail below, which results in greater intra-particle porosity. Without wishing to be bound by theory, it is believed that this porosity facilitates the diffusion of electrolyte through the particle, thereby enabling faster lithium ion diffusion and improving the rate capability of the material, relative to a comparative material of similar particle size having lower porosity. A second aspect of the invention is a positive active material for a cathode, comprising the particulate lithium transition metal oxide material according to the first aspect.

[0009] A third aspect of the invention is a cathode comprising the positive active material according to the second aspect.

[0010] A fourth aspect of the invention is an electrochemical secondary cell or battery comprising the cathode according to the third aspect.

[0011] A fifth aspect of the invention is an electrical device or a vehicle comprising the cell or battery according to the fourth aspect.

[0012] A sixth aspect of the invention is a method of manufacturing the particulate lithium transition metal oxide material according to the first aspect.

[0013] A seventh aspect of the invention is a mixed metal carbonate precursor material used to prepare the material according to the first aspect.

[0014] FURTHER OPTIONS AND PREFERENCES

[0015] The material according to the first aspect comprises an intra-particle porosity, as determined by mercury intrusion porosimetry, of from 2 to 35 %.

[0016] The term “intra-particle porosity” refers to the porosity within the particle structure, and excludes porosity arising from the spaces between the particles of the material. As such, intra-particle porosity impacts the ability of electrolyte to penetrate any given particle, whereas inter-particle porosity instead impacts only the ability of the electrolyte to diffuse through the spaces between the particles, i.e. diffuse through the material itself.

[0017] The electrochemically active material is a particulate material, i.e. made up of a plurality of discrete particles. The particles may comprise primary particles and / or secondary particles formed from the agglomeration of a plurality of primary particles. The material may comprise a volumetric median particle diameter (Dv50) of at least 1 pm, for example at least 2 pm, at least 3 pm, at least 4 pm, at least 5 pm, at least 6 pm, or at least 7 pm.

[0018] The material may comprise a Dv50 of at least 7 pm, for example at least 10 pm, at least 12 pm, at least 15 pm, at least 20 pm, or at least 21 pm.

[0019] The material may comprise a Dv50 of up to 100 pm, for example up to 90 pm, up to 80 pm, up to 70 pm, up to 60 pm, up to 50 pm, up to 40 pm, up to 30 pm or up to 25 pm.

[0020] The material may comprise a Dv50 of from 1 to 100 pm, for example from 2 to 100 pm, from 2 to 90 pm, from 2 to 80 pm, from 2 to 70 pm, from 2 to 60 pm, from 2 to 50 pm, from 3 to 50 pm, from 4 to 50 pm, from 2 to 40 pm, from 3 to 40 pm, from 4 to 40 pm, from 4 to 30 pm, from 5 to 30 pm, from 5 to 25 pm or from 7 to 25 pm.

[0021] Such particle sizes may be sufficiently large to ensure a good density due to the greater packing achievable by larger particles. Without wishing to be bound by theory, it is believed that this is due to the reduced overall interparticle friction for larger particles, which allows larger particles to pack together more effectively than the equivalent mass of smaller particles. Combined with the high intra-particle porosity of the present material, the result is a material with high energy density (due to the larger particle size) and good rate capability (due to the high intra-particle porosity).

[0022] Dv50 is the volumetric median particle size. In other words, it represents the particle size in microns which splits the volume distribution of that population of particles in half, with 50 vol% of the particles having a particle size below that value and 50 vol% having a particle size above that value.

[0023] The skilled person will appreciate that the volume median particle size Dv50 can be measured using a Malvern Mastersizer 3000 using the light scattering method set out in ASTM B822-20, applying the Mie scattering theory. The skilled person will also understand that for particulate materials containing a multimodal particle size distribution (e.g. bimodal), the PSD may be deconvoluted to calculate the volumetric median particle size of each particle mode using straightforward techniques well-known to the skilled person.

[0024] The material may have a BET surface area of at least 4.0 m2 / g, for example at least 4.2 m2 / g, at least 4.4 m2 / g, at least 4.6 m2 / g, at least 4.8 m2 / g, at least 5.0 m2 / g, at least 5.2 m2 / g, at least 5.4 m2 / g, at least 5.6 m2 / g, at least 5.8 m2 / g or at least 6.0 m2 / g.

[0025] The material may have a BET surface area of up to 10.0 m2 / g, for example up to 9.5 m2 / g, up to 9.0 m2 / g, up to 8.5 m2 / g, up to 8.0 m2 / g, up to 7.5 m2 / g, up to 7.0 m2 / g, up to 6.5 m2 / g or up to 6.0 m2 / g.

[0026] The material may have a BET surface area of from 4.0 m2 / g to 10.0 m2 / g, for example from 4.0 m2 / g to 9.0 m2 / g, from 4.0 m2 / g to 8.0 m2 / g, from 4.0 m2 / g to 7.0 m2 / g, from 5.0 m2 / g to 7.0 m2 / g or from 5.5 m2 / g to 6.5 m2 / g.

[0027] BET surface area may be measured by nitrogen adsorption according to ASTM D3663-20.

[0028] The material according to the invention may comprise or consist of a mixed metal oxide material. The material may comprise or consist of a lithium nickel manganese oxide. The material may comprise or consist of a composition which is a mixed metal oxide comprising lithium, nickel and manganese, optionally further comprising cobalt. The material may comprise or consist of a lithium nickel manganese cobalt oxide. The material may comprise or consist of a lithium nickel manganese oxide and may not contain any cobalt. The material may comprise or consist of a lithium nickel manganese oxide or a lithium nickel manganese cobalt oxide, further comprising one or more dopant elements.

[0029] The material may comprise or consist of particles comprising or consisting of a composition according to formula I:

[0030] LiaNixCoyMnzAqO2+dFeFormula I wherein

[0031] A is one or more dopant elements selected from Na, Mg, Al, B, Ti, V, W, Sn, Zr, and Fe;

[0032] 0.1 <x<0.4;

[0033] 0<y<0.1;

[0034] 1.0<a< 1.3;

[0035] 0.33 <z< 0.66;

[0036] 0<q<0.10; d is within the range 0 to ±0.2; and e is within the range 0 to 0.1.

[0037] For example, a = 1.33 - (2x / 3) - (y / 3) ±5; and z = 0.66 - (x / 3) - (2y / 3) ± wherein 5 and are each independently selected from within the range 0 to 0.1.

[0038] For example, 5 and may each be zero.

[0039] For example, 0.1 < x < 0.4, for example 0.11 < x < 0.4, 0.12 < x < 0.4, 0.15 < x < 0.4, 0.2 < x < 0.4, 0.25 < x < 0.4, 0.3 < x < 0.4 or 0.35 < x < 0.4.

[0040] For example, x = 0.4.

[0041] For example, 0 < y < 0.1, for example 0 < y < 0.09, 0 < y < 0.08, 0 < y < 0.09, 0 < y < 0.07, 0 < y < 0.06, 0 < y < 0.05, 0 < y < 0.04, 0 < y < 0.03, 0 < y < 0.02 or 0 < y < 0.01.

[0042] For example, y = 0.

[0043] For example, 1.0 < a < 1.3, for example 1.0 < a < 1.25, 1.0 < a < 1.2, 1.06 < a < 1.14, 1.06

[0044] < a < 1.13, 1.0 < a < 1.15, 1.0 < a < 1.1, 1.0 < a < 1.07, 1.02 < a < 1.07, 1.04 < a < 1.07,

[0045] 1.05 <a< 1.07 or 1.06<a< 1.07. For example, a = 1.0667. For example, a = 1.13.

[0046] For example, 0.35 < z < 0.65, for example 0.40 < z < 0.65, 0.45 < z < 0.65, 0.45 < z < 0.60, 0.50 < z < 0.60, 0.50 < z < 0.55, 0.51 < z < 0.55, 0.51 < z < 0.54, 0.52 < z < 0.55, 0.53 < z < 0.55 or 0.53 < z < 0.54.

[0047] For example, z = 0.5333. For example, z = 0.5167. For example, z = 0.541.

[0048] For example, 0 < q < 0.09, for example 0 < q < 0.08, 0 < q < 0.07, 0 < q < 0.06, 0 < q < 0.05, 0 < q < 0.04, 0 < q < 0.03, 0 < q < 0.02 or 0 < q < 0.01.

[0049] For example, q = 0.

[0050] For example, d is within the range 0 to ±0.19, for example 0 to ±0.18, 0 to ±0.17, 0 to ±0.16, 0 to ±0.15, 0 to ±0.14, 0 to ±0.13, 0 to ±0.12, 0 to ±0.11 or 0 to ±0.10.

[0051] For example, d = 0.

[0052] For example, 0 < e < 0.09, for example 0 < e < 0.08, 0 < e < 0.07, 0 < e < 0.06, 0 < e < 0.05, 0 < e < 0.04, 0 < e < 0.03, 0 < e < 0.02 or 0 < e < 0.01.

[0053] For example, e = 0.

[0054] The material may comprise particles comprising or consisting of a composition according to formula I A:

[0055] LiaNixMnzAqO2+d Formula I A wherein a, x, z, q and d are as defined for Formula I. The material may comprise or consist of particles comprising or consisting of a composition according to any one of formula IIA to formula IIBB:

[0056] Lil.0667Nio.4Mno.533302 Formula IIA

[0057] Li 1.133Nio.25Coo.05Mno.5167 AI0.05O2 Formula I IB

[0058] Lil.133Nio.275Mno.541Alo.0502 Formula IIC

[0059] Lil.133Nio.2coo.15Mno.4667Alo.0502 Formula I ID

[0060] Lil.15Nio.25Mno.55Alo.0502 Formula HE

[0061] Lil.15Nio.2coo.lMno.5Alo.0502 Formula HF

[0062] Lil.15Nio.225coo.05Mno.525Alo.0502 Formula IIG

[0063] Lil.133Nio.275Mno.541Alo.0502 Formula IIH

[0064] Li 1.133Nio.25Coo.05Mno.5167 AI0.05O2 Formula III

[0065] Lil.133Nio.225coo.lMno.491Alo.0502 Formula IIJ

[0066] Lil.116Nio.3Mno.533Alo.0502 Formula I IK

[0067] Li 1.1 i6Ni0.275Co0.05Mn0.508 AI0.05O2 Formula HL

[0068] Lil.116Nio.25coo.lMno.483Alo.0502 Formula IIM

[0069] Lil.116Nio.225coo.15Mno.458Alo.0502 Formula UN

[0070] Lil.15Nio.25coo.05Mno.5502 Formula IIO

[0071] Lil.l5Nio.275Mno.57502 Formula HP

[0072] Lil.15Nio.2coo.15Mno.502 Formula IIQ

[0073] Lil.l67Nio.25Mno.58302 Formula HR

[0074] Lil.15Nio.25coo.05Mno.5502 Formula IIS

[0075] Lii.i67Nio.2Coo.iMno.53302 Formula IIT

[0076] Lil.l667Nio.225Coo.05Mno.558302 Formula HU

[0077] Lil.l5Nio.275Mno.57502 Formula IIV

[0078] Lil.15Nio.25coo.05Mno.5502 Formula II W

[0079] Lil.l5Nio.225Coo.lMno.52502 Formula IIX

[0080] Li 1.1 i3Nio.3Mno.56702 Formula II Y

[0081] Lil.U33Nio.275Coo.05Mno.541702 Formula HZ

[0082] Li 1.1 i33Nio.25Coo.iMno.5167O2 Formula II A A

[0083] Lil.U333Nio.225Coo.l5Mno.4916702 Formula IIBB The intra-particle porosity of the material, as determined by mercury intrusion porosimetry, may be from 3 to 35 %, for example from 4 to 35 %, from 5 to 35 %, from 6 to 35 %, from 7 to 35 %, from 8 to 35 %, from 9 to 35 %, from 10 to 35 %, from 15 to 35 %, from 20 to 35 %, from 25 to 35 %, from 30 to 35 %, from 31 to 35 %, from 32 to 35 %, from 33 to 35 % or from 34 to 35 %.

[0084] The intra-particle porosity of the material, as determined by mercury intrusion porosimetry, may be from 5 to 34 %, from 5 to 33 %, from 5 to 32 %, from 5 to 31 %, from 5 to 30 %, from 6 to 30 %, from 7 to 30 %, from 8 to 30 %, from 9 to 30 %, from 9 to 26 %, from 10 to 30 %, from 10 to 29 %, from 10 to 28 %, from 10 to 27 %, from 10 to 26 % or from 10 to 25 %.

[0085] The use of mercury intrusion porosimetry to determine the characteristics of material porosity is well-known. The method involves the gradual increase in the pressure applied to a column of mercury which is in contact with the material to be tested. As the pressure is increased, larger voids and pores will fill with mercury first, followed by smaller pores at higher pressures. For any material, inter-particle voids are larger than intra-particle pores. So, for a material with both inter-particle voids and intra-particle pores, it is possible to distinguish these during mercury intrusion porosimetry due to the higher pressure necessary to impregnate the intra-particle pores with mercury. The result is one or more low-pressure volume intrusion peaks for the filling of the larger inter-particle voids, along with one or more separate high-pressure volume intrusion peaks for the filling of the smaller intra-particle voids. For example, the presence of peaks at a pressure greater than 400 psia may be indicative of the presence of intra-particle porosity. A material lacking intra-particle porosity would only exhibit the low-pressure volume intrusion peak(s) for the filling of the larger inter-particle voids.

[0086] As used herein, “intra-particle porosity” refers to the volume of “open” pores within the particles as a percentage of the total volume occupied by the particles. Only the open pores are taken into account for intra-particle porosity, since mercury is unable to intrude into closed pores so such pores are “invisible” to mercury intrusion porosimetry. For the avoidance of doubt, the “total volume occupied by the particles” for the purposes of calculating intra-particle porosity does not include the voids between particles. In other words, the intra-particle porosity is an intrinsic property of the material and is independent of properties of the bulk material such as particle packing or bulk density.

[0087] At least 50% of the total pore volume of the intra-particle porosity may be open to the particle surface, for example at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% of the total pore volume. This can be determined by comparing the total intra-particle porosity determined by mercury intrusion porosity with the total porosity determined through image analysis of a cross section of the particle in an SEM image. The porosity calculated by such SEM image analysis will include all intra-particle porosity, including both open and closed pores. The porosity determined by mercury intrusion porosity will only factor in open pores which are able to be intruded by mercury. If the value for porosity determined by mercury intrusion porosity is significantly lower than the value determined through image analysis, then a significant proportion of the intra-particle porosity is closed porosity, which does not help to facilitate the delivery of lithium ions into the core of the particle. By ensuring that a high proportion of the intra-particle porosity is open porosity, the diffusion of lithium ions into the particle may be enhanced.

[0088] The materials of the invention may provide such high proportions of open porosity, as is evident from an analysis of SEM images of the particles.

[0089] The material may comprise intra-particle pores having a pore size distribution determined by mercury intrusion porosimetry, wherein the intra-particle pore size distribution is characterised by one or more of:

[0090] (a) a volume-based median pore diameter of from 0.01 to 0.30 pm;

[0091] (b) an area-based median pore diameter of from 0.01 to 0.20 pm;

[0092] (c) a 4V / A average pore diameter of from 0.01 to 0.25 pm;

[0093] (d) a total pore area of from 1 to 15 m2 / g;

[0094] (e) a tortuosity of from 2 to 12;

[0095] (f) a pore characteristic length of from 0.05 to 0.40 pm; and

[0096] (g) a permeability of from 0.001 to 0.010 mD. The intra-particle pore size distribution may be characterised by a volume-based median pore diameter of from 0.01 to 0.28 pm, for example from 0.01 to 0.25 pm, for example from 0.02 to 0.10 pm, from 0.03 to 0.10 pm, from 0.04 to 0.10 pm, from 0.04 to 0.09 pm, from 0.04 to 0.08 pm, from 0.05 to 0.08 pm or from 0.06 to 0.08 pm.

[0097] The intra-particle pore size distribution may be characterised by an area-based median pore diameter of from 0.01 to 0.20 pm, for example from 0.01 to 0.15 pm, from 0.01 to 0.10 pm, from 0.02 to 0.10 pm, from 0.03 to 0.10 pm, from 0.04 to 0.10 pm, from 0.04 to 0.09 pm, from 0.04 to 0.08 pm, from 0.05 to 0.08 pm or from 0.05 to 0.07 pm.

[0098] The intra-particle pore size distribution may be characterised by a 4V / A average pore diameter of from 0.01 to 0.25 pm, for example from 0.01 to 0.20 pm, from 0.01 to 0.15 pm, from 0.01 to 0.10 pm, from 0.02 to 0.10 pm, from 0.03 to 0.10 pm, from 0.04 to 0.10 pm, from 0.04 to 0.09 pm, from 0.04 to 0.08 pm, from 0.05 to 0.08 pm or from 0.05 to 0.07 pm.

[0099] The intra-particle pore size distribution may be characterised by a total pore area of from 1 to 15 m2 / g, for example from 2 to 15 m2 / g, from 5 to 15 m2 / g, from 5 to 12 m2 / g, from 5 to 10 m2 / g, from 6 to 10 m2 / g, from 7 to 10 m2 / g or from 8 to 10 m2 / g.

[0100] The intra-particle pore size distribution may be characterised by a tortuosity of from 2 to 12, for example from 5 to 12, from 5 to 11, from 5 to 10, from 6 to 10, from 7 to 10, from 7 to 9 or from 7 to 8.

[0101] The intra-particle pore size distribution may be characterised by a pore characteristic length of from 0.05 to 0.40 pm, for example from 0.05 to 0.40 pm, from 0.05 to 0.37 pm, from 0.05 to 0.30 pm, from 0.05 to 0.20 pm, from 0.05 to 0.10 pm, from 0.05 to 0.095 pm, from 0.055 to 0.095 pm, from 0.06 to 0.10 pm, from 0.065 to 0.10 pm, from 0.07 to 0.10 pm, from 0.075 to 0.10 pm, from 0.08 to 0.10 pm, from 0.08 to 0.095 pm or from 0.08 to 0.09 pm. The intra-particle pore size distribution may be characterised by a permeability of from 0.001 to 0.010 mD, for example from 0.002 to 0.010 mD, from 0.003 to 0.010 mD, from 0.003 to 0.009 mD, from 0.004 to 0.008 mD, from 0.004 to 0.0075 mD or from 0.0045 to 0.0075 mD.

[0102] Without wishing to be bound by theory, it is believed that the intra-particle pore structure of the present material results at least in part from the use of a mixed metal carbonate precursor material during synthesis. When such a carbonate precursor is subsequently calcined to form the oxide material of the invention, carbon dioxide is evolved during the calcination, creating a network of pores through the entire body of the particle, the pores being open to the particle surface and extend radially from the surface towards the particle centre, as observed by a qualitative assessment of the pores in an SEM image. Such pores have low tortuosity and form an essentially continuous network of intra-particle porosity. Since all or substantially all of this porosity is open to the particle surface, electrolyte can more easily diffuse deep into the body of the particle, allowing lithium ions to diffuse quickly through the entire material of a particle.

[0103] By contrast, materials made by an analogous synthesis route which uses a mixed metal hydroxide precursor material instead of a mixed metal carbonate precursor material produces dense particles with little or no intra-particle porosity, and any small amount of porosity present includes primarily closed porosity which cannot facilitate electrolyte diffusion into the particle.

[0104] The material may comprise a density determined by the application of trans-axial pressure (TAP) of from 1.0 to 4.0 g / cm3, for example from 1.0 to 2.5 g / cm3, from 1.0 to 2.0 g / cm3, from 1.0 to 1.8 g / cm3, from 1.0 to 1.6 g / cm3, from 1.1 to 1.6 g / cm3or from 1.2 to 1.6 g / cm3. The material may comprise a density determined by the application of trans-axial pressure (TAP) of from 1.4 to 2.2 g / cm3.

[0105] Such TAP density may be measured using methods and apparatus known to the skilled person, for example using an Envelope and Density Analyzer 1365 GeoPyc. Such values measured by TAP in this way tend to be comparable with the tapped density of the material, i.e. the final density of the material after repeatedly mechanically tapping the material.

[0106] The material may comprise particles having a shape which is near- spherical, or potato-like. The material may comprise particles having a sphericity of at least 60 %, for example at least 70 %, at least 75 %, at least 80 %, at least 85 %, at least 90 % or at least 95 %.

[0107] The material may exhibit a bimodal pore size distribution when determined by mercury intrusion porosimetry. The bimodal pore size distribution may arise from a first peak resulting from the intrusion of mercury at lower pressure into inter-particle voids, and a second peak resulting from the intrusion of mercury at higher pressure into intra-particle pores.

[0108] The total porosity of the material, made up of inter-particle and intra-particle porosity, as determined by mercury intrusion porosimetry, may be from 55 to 80 %, for example from 60 to 80 %, from 60 to 75 %, from 60 to 70 % or from 65 to 70 %.

[0109] The skilled person understands that inter-particle porosity values provided herein (and total porosity values towards which inter-particle porosity contributes) are as determined by mercury intrusion porosimetry on a sample of the material in powdered form. As such, the values may be different when the material is processed into other forms, where that processing has an impact on the inter-particle porosity. For example, when the material is incorporated into an electrode composition (e.g. a solid, solvent-cast electrode) and subjected to calendaring under pressure, the material may be densified and the interparticle porosity (and therefore total porosity) may reduce relative to that determined by mercury intrusion porosimetry.

[0110] The material may comprise a multimodal particle size distribution comprising a first particle mode and a second particle mode, the material having a D1so / D25o in the range 2 to 15; wherein D^o is the volumetric median particle diameter of the first particle mode and D25O is the volumetric median particle diameter of the second particle mode. The intra-particle porosity (pl) of the first particle mode, may be higher than the intraparticle porosity (p2) of the second particle mode, wherein pl and p2 are determined by mercury intrusion porosimetry.

[0111] For example, pl may be from 10 to 30 %, and p2 may be less than 5 %. For example, pl may be from 10 to 25 %, and p2 may be less than 5 %. For example, pl may be from 10 to 20 %, and p2 may be less than 5 %.

[0112] For example, pl and p2 may be the same, or the difference between pl and p2 may be within the range 0 to ±5%.

[0113] The second particle mode may make up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode.

[0114] DX5O may be within the range 2 to 60 pm. D2so may be within the range 1 to 5 pm.

[0115] For example, D^o may be within the range 18 to 25 pm, D2so may be within the range 2 to 5 pm, and the second particle mode may make up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode.

[0116] The material may be manufactured by a method which includes the precipitation of a mixed metal carbonate precursor material, followed by reaction with a lithium source and calcination to form the particulate lithium transition metal oxide material. Such methods are described in more detail below.

[0117] A second aspect of the invention is a positive active material for a cathode, comprising the particulate lithium transition metal oxide material according to the first aspect.

[0118] The positive active material may comprise the particulate lithium transition metal oxide material according to the first aspect alongside a second particulate lithium transition metal oxide material. The second particulate lithium transition metal oxide material may have an intra-particle porosity, as determined by mercury intrusion porosimetry, of less than 2 %, for example less than 1.9 %, less than 1.8 %, less than 1.7 %, less than 1.6 %, less than 1.5 %, less than 1 % or less than 1.5 %. The second particulate lithium transition metal oxide material may comprise or consist of single crystal particles.

[0119] For example, the positive active material may comprise a multimodal particle size distribution comprising the particulate lithium transition metal oxide material according to the first aspect as a first particle mode, and the second particulate lithium transition metal oxide material as a second particle mode, the positive active material having a D35o / D4so in the range 2 to 15; wherein D3so is the volumetric median particle diameter of the first particle mode and D45O is the volumetric median particle diameter of the second particle mode.

[0120] For example, the positive active material may comprise a multimodal particle size distribution comprising the particulate lithium transition metal oxide material according to the first aspect, having an intra-particle porosity of from 2 to 35 %, as a first particle mode, and the second particulate lithium transition metal oxide material, having an intra-particle porosity of less than 2 %, for example less than 1 %, as a second particle mode, the material having a D3so / D4so in the range 2 to 15; wherein D3so is the volumetric median particle diameter of the first particle mode and D45O is the volumetric median particle diameter of the second particle mode.

[0121] In this way, the positive active material contains a first mode of larger particles having higher intra-particle porosity, alongside a second mode of smaller particles having low, negligible, or zero intra-particle porosity. The mixture of large and small particles may provide good packing efficiency of the overall material, since the small particles fill the voids between the large particles. In addition, ensuring relatively high intra-particle porosity in the first (larger) mode can improve the rate capability, as lithium ions can more easily penetrate the particles. Providing dense particles in the second mode, with low or zero porosity, can increase the energy density of the material with minimal impact on rate capability, since the particles are sufficiently small to ensure lithium ion diffusion without the need for porosity to facilitate this. The second particle mode may make up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode in the positive active material of the second aspect.

[0122] D35O may be within the range 2 to 60 pm. D4so may be within the range 1 to 5 pm.

[0123] For example, D3so may be within the range 18 to 25 pm, D4so may be within the range 2 to 5 pm, the second particle mode may make up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode in the positive active material of the second aspect.

[0124] A third aspect of the invention is a cathode comprising the positive active material according to the second aspect, and a binder.

[0125] The binder may comprise a polymer.

[0126] The positive active material may make up at least 50 vol% of the cathode, based on the total volume of cathode, for example at least 55 vol%, at least 60 vol%, at least 62 vol%, at least 64 vol%, or at least 65 vol%. For example, the positive active material may make up from 50 to 90 vol% of the cathode, based on the total volume of cathode, for example from 55 to 90 vol%, or from 60 to 90 vol%. Suitably, the positive active material may make up about 64 vol% of the cathode.

[0127] The cathode may be a solid, solvent-cast cathode. Alternatively, the cathode may be a polymer gel cathode, comprising a gelled polymer matrix made up of a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the dispersed phase comprises the positive active material.

[0128] The polymer-electrolyte gel matrix phase may be formed from one or more electrolyte components and at least one gelling polymer. The one or more electrolyte components may include a solvent suitable for use as an electrolyte solvent in a gel electrode, for example an organic solvent. The one or more electrolyte components may include a salt. The one or more electrolyte components may constitute an electrolyte salt solution or liquid electrolyte.

[0129] The one or more electrolyte components may comprise a solvent comprising one or more cyclic or linear carbonate compounds. The solvent may comprise one or more cyclic carbonate compounds. The solvent may comprise one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate and y-butyrolactone.

[0130] The solvent may comprise a blend of at least two different compounds, for example at least three or at least four different compounds. The solvent may comprise a blend of at least two different organic carbonate compounds, for example at least three or at least four different organic carbonate compounds.

[0131] The electrolyte component(s) may comprise a solvent with low vapor pressure and high flash point to enable safe processing. An example of a solvent fulfilling these criteria is propylene carbonate. Accordingly, the one or more electrolyte components may comprise or consist of propylene carbonate, or a blend of propylene carbonate with one or more of the above listed solvents.

[0132] The one or more electrolyte components may comprise an alkali metal salt. The alkali metal of the alkali metal salt may be any suitable alkali metal (Group I of the periodic table). The alkali metal salt may be a lithium, sodium, or potassium salt.

[0133] The anion of the alkali metal salt may be any suitable anion. Typical anions are known to the skilled person and may be chosen based on the kind of alkali metal. When the alkali metal is lithium, the anion of the salt may comprise a halogen such as fluorine. Examples include BF4‘, PF6’, TFST, FST, OTf, DFOB" and TDT. The one or more electrolyte components may comprise a lithium salt. The electrolyte may comprise a mixture of at least two different lithium salts. Examples of suitable lithium salts include LiPFe, LiBF4, LiTFSI, LiFSI, LiOTf, LiDFOB and LiTDI. The salt may be a thermally stable salt. It has been found that LiPFe has relatively low thermal stability relative to other available lithium salts, and accordingly use of LiPFe may be avoided - that is, suitably, the electrolyte component s) may not include LiPFe.

[0134] One or more kinds of alkali metal salt may be used in accordance with the present invention. Typically, but not exclusively, when more than one kind of alkali metal salt is used, they share a common alkali metal.

[0135] The polymer-electrolyte gel matrix phase may comprise a gel matrix formed by the gelling of one or more gelling polymers when the polymer(s) absorb a liquid electrolyte. The polymer-electrolyte gel matrix phase therefore comprises a gel comprising the polymer(s) and absorbed liquid electrolyte.

[0136] The gelling polymer may comprise one or more gelling polymers independently selected from carboxymethyl cellulose (CMC), poly(ethyleneglycol dimethacrylate), poly(ethyleneglycol diacrylate), poly(propyleneglycol dimethacrylate), poly(propyleneglycol diacrylate), poly(methyl methacrylate) (PMMA), poly(acrylonitrile) (PAN), polyurethane (PU), poly(vinylidene difluoride) (PVDF), poly(vinylidene fluoride- co-hexafluoropropylene) (PVDF-HFP), polyethylene oxide) (PEO), poly-L-lactic acid (PLA), polystyrene (PS), poly(ethyleneglycol dimethylether), poly(ethyleneglycol diethylether), poly [bi s(m ethoxy ethoxyethoxide)-phosphazene], poly(dimethylsiloxane) (PDMS), polyacene, polydisulfide, polystyrene, polystyrene sulfonate, polypyrrole, polyaniline, polythiophene, polythione, polyvinyl pyridine (PVP), polyvinyl chloride (PVC), polyaniline, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene), poly(triphenylene), polyazulene, polyfluorene, polynaphthalene, polyanthracene, polyfuran, polycarbazole, tetrathiafulvalene- substituted polystyrene, ferrocene- substituted polyethylene, carbazole-substituted polyethylene, polyoxyphenazine, poly(heteroacene), poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide-co-methoxy- polyethyleneglycolacrylate] (Li[PSTFSI-co-MPEGA]), sulfonated poly(phenylene oxide) (PPO), N,N-dimethylacryl amide (DMAAm), lithium 2-acrylamido-2-methyl-l -propane sulfonate (LiAMPS), Poly(lithium 2-Acryl ami do-2 -Methylpropanesulfonic Acid-Co- Vinyl Triethoxysilane), polyethyleneoxide(PEO) / poly(lithium sorbate), PEO / poly(lithium muconate), PEO / [poly(lithium sorbate)+BF3], PEO copolymer, PEO terpolymer, and NIPPON SHOKUB Al® polymer, or mixtures or co-polymers thereof.

[0137] In some examples, the gelling polymer may comprise one or more gelling polymers independently selected from carboxymethyl cellulose (CMC), poly(vinylidene difluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO), poly-L-lactic acid (PLA) and polystyrene (PS)

[0138] The polymer-electrolyte gel matrix phase may make up from 20 vol% to 50 vol% of the cathode, for example from 25 vol% to 45 vol%, from 28 vol% to 42 vol%, from 30 vol% to 40 vol%, from 31 vol% to 39 vol% or from 32 vol% to 38 vol%. Suitably, the polymer- electrolyte gel matrix phase may make up about 33.52 vol%, about 34.11 vol%, or about 34.72 vol% of the cathode.

[0139] The gel cathode may be produced by processing a cathode precursor composition to form a film or coating.

[0140] The processing may comprise thermal processing and / or extrusion. The gel cathode may be an extruded cathode. The gel cathode may be a hot-rolled cathode. The gel cathode may be prepared by extruding a cathode precursor composition through a die to form a film.

[0141] The gel cathode may be both extruded and hot-rolled, for example by a process which comprises first extruding the cathode through a die followed by hot-rolling the cathode down to a desired thickness.

[0142] The cathode may be a solid, solvent-cast cathode. Such solid, solvent-cast cathodes may be prepared by mixing the positive active material, binder and optional further additive(s) with a solvent, before casting onto a foil layer and drying to remove solvent. Calendaring may then be performed after drying.

[0143] The cathode may comprise the positive active material, a conductive additive and a binder. The conductive additive may comprise or consist of carbon, for example carbon black. The polymer may comprise or consist of one or more of the polymers set out in the list of gelling polymers above. For example, the polymer may comprise or consist of PvDF, or PvDF-HFP.

[0144] The cathode may be for a lithium-ion secondary electrochemical cell.

[0145] A fourth aspect of the invention is an electrochemical secondary cell or battery comprising the cathode according to the third aspect.

[0146] The cell may be an alkali metal ion secondary cell, for example a sodium-ion secondary cell or a lithium-ion secondary cell. The cell may be a lithium-ion secondary cell. The electrochemical secondary cell may comprise a cathode according to the third aspect, and an anode, and an electrolyte between the cathode and the anode. The electrochemical secondary cell may comprise a cathode according to the third aspect laminated with a current collector, for example a metallic foil.

[0147] A fifth aspect of the invention is an electrical device or a vehicle comprising the cell or battery according to the fourth aspect.

[0148] A sixth aspect of the invention is a method of manufacturing the particulate lithium transition metal oxide material according to the first aspect, the method comprising: performing a precipitation reaction between a Ni source, a Mn source and optionally a Co source to form a mixed metal carbonate precursor compound; adding a Li source to the mixed metal carbonate precursor compound; and calcining the mixture of the Li source and the mixed metal carbonate precursor compound to form the particulate lithium transition metal oxide material. The method may comprise performing a precipitation reaction between a Ni source, a Mn source and a Co source to form the mixed metal carbonate precursor compound. In some examples, no source of Co is used.

[0149] The Ni source may comprise or consist of a Ni salt. The Ni source may comprise or consist of one or more of Ni acetate, Ni bromide, Ni chloride, Ni iodide, Ni nitrate, Ni sulfate and hydrated forms thereof. For example, the Ni source may comprise or consist of Ni sulfate or a hydrated form thereof.

[0150] The Mn source may comprise or consist of a Mn salt. The Mn source may comprise or consist of one or more of Mn acetate, Mn bromide, Mn chloride, Mn iodide, Mn nitrate, Mn permanganate, Mn sulfate and hydrated forms thereof. For example, the Mn source may comprise or consist of Mn sulfate or a hydrated form thereof.

[0151] Both the Ni source and the Mn source may be salts of the same anion. For example, the Ni source may consist of Ni sulfate, or a hydrated form thereof, and the Mn source may consist of Mn sulfate, or a hydrated form thereof.

[0152] The Co source may comprise or consist of a Co salt. The Co source may comprise or consist of one or more of Co acetate, Co bromide, Co chloride, Co iodide, Co nitrate, Co sulfate and hydrated forms thereof. For example, the Co source may comprise or consist of Co sulfate or a hydrated form thereof.

[0153] The Ni source, the Mn source and the Co source may be salts of the same anion. For example, the Ni source may consist of Ni sulfate, or a hydrated form thereof, the Mn source may consist of Mn sulfate, or a hydrated form thereof, and the Co source may consist of Co sulfate or a hydrated form thereof.

[0154] The precipitation reaction may comprise reacting the Ni source, Mn source and optional Co source with a carbonate or bicarbonate compound in the presence of a base, to precipitate the mixed metal carbonate precursor compound. The precipitation reaction may comprise reacting the Ni source, Mn source and optional Co source with a carbonate compound in the presence of a base, to precipitate the mixed metal carbonate precursor compound. The carbonate or bicarbonate compound may comprise an alkali metal or alkaline earth metal carbonate or bicarbonate. The carbonate or bicarbonate compound may comprise a lithium, sodium or potassium carbonate or bicarbonate. The carbonate compound may comprise or consist of one or more of K2CO3, Li2CCh and Na2CO3. The carbonate compound may comprise or consist of Na2CO3. The base may comprise or consist of a hydroxide compound. The base may comprise or consist of ammonium hydroxide.

[0155] The precipitation reaction may comprise dissolving the Ni source, Mn source and optional Co source in water to form a first solution; dissolving the carbonate or bicarbonate compound in water to form a second solution; dissolving the base in water to form a third solution; and mixing the first, second and third solutions together.

[0156] The precipitation may be performed in any suitable vessel or reactor. For example, the precipitation may be performed in a stirred tank reactor.

[0157] The precipitation reaction may be performed in a reactor which comprises a heater, for example an external heating jacket. The temperature in the reactor may be in the range 40 to 80 °C during the precipitation reaction.

[0158] The precipitation reaction may be performed in batch or continuous mode.

[0159] The precipitation reaction may be performed in continuous mode and the first, second and third solutions may be continuously fed into the reactor until the precipitated mixed metal carbonate precursor compound has formed with a desired particle size.

[0160] The precipitation reaction may be carried out in the presence of a source of dopant A, wherein A is one or more dopant elements selected from Na, Mg, Al, B, F, Ti, V, W, Sn, Zr, and Fe. The source of dopant A may be an oxide, hydroxide, carbonate, acetate, bromide, chloride, iodide, nitrate or sulfate of element A, or a hydrated form thereof. The source of dopant A may be a sulfate of element A.

[0161] The source of dopant A may not present during the precipitation reaction, but may be added later. For example, a source of dopant A may be combined with the mixed metal carbonate precursor compound prior to calcination, optionally along with a Li source.

[0162] The pH during the precipitation reaction may be maintained within the range pH 5 to pH 11, for example pH 6.5 to pH 7.8. pH may be controlled by controlling the rate of addition of the third solution to the reactor.

[0163] The precipitation reaction may be performed in the presence of seed particles which may act as nuclei onto which a precipitate may be deposited. Alternatively, the precipitation reaction may be performed in the absence of such seed particles.

[0164] After the precipitation reaction is complete or has progressed to a desired extent of reaction, the reactor may be emptied to isolate the mixed metal carbonate precursor compound. The mixed metal carbonate precursor compound may be washed with a solvent, for example water. The mixed metal carbonate precursor compound may be filtered. After washing and optionally filtering, the mixed metal carbonate precursor compound may be dried. The mixed metal carbonate precursor compound may be dried at a temperature of from 30 to 100 °C for a time of from 2 to 20 hours.

[0165] After forming the mixed metal carbonate precursor compound, the Li source may be mixed with the mixed metal carbonate precursor compound.

[0166] The Li source may comprise or consist of a Li compound. The Li source may comprise or consist of a Li salt. For example, the Li source may comprise or consist of Li carbonate. In this way, after mixing the Li source with the mixed metal carbonate precursor compound, only carbonate compounds may be present in the mixture, which may facilitate the formation of a porous structure of the particles during calcination. Mixing of the Li source and the mixed metal carbonate precursor compound may be achieved by any suitable mixing method and apparatus. Mixing of the Li source and the mixed metal carbonate precursor compound may comprise acoustic mixing, for example using a Resodyn acoustic mixer.

[0167] After mixing, the mixture of the Li source and the mixed metal carbonate precursor compound may be calcined. Calcination may be performed in any suitable calciner or furnace, for example a muffle furnace, rotary furnace or a roller hearth kiln (RHK).

[0168] Calcining the mixture may comprise holding the mixture at a temperature of at least 200 °C, for example at least 240 °C, at least 300 °C, at least 350 °C, at least 400 °C, at least 500 °C, at least 600 °C, at least 700 °C, at least 800 °C or at least 900 °C for a predetermined period of time. Calcining the mixture may comprise holding the mixture at a temperature of at least 200 °C, for example at least 240 °C, at least 300 °C, at least 350 °C, at least 400 °C, at least 500 °C, at least 600 °C, at least 700 °C, at least 800 °C or at least 900 °C for at least 5 hours.

[0169] Calcining the mixture may comprise a first calcination step at a temperature Ti, wherein Ti may be a temperature within the range 200 to 600 °C. Calcining the mixture may additionally comprise a second calcination step at a temperature T2, wherein T2 may be a temperature within the range 600 to 1000 °. Heating to Ti, and heating from Ti to T2, may each be performed at a ramping rate of from 1 to 5 °C / min.

[0170] The material may be held at Ti for a period of from 2 to 10 hours. The material may be held at T2 for a period of from 2 to 10 hours.

[0171] A seventh aspect of the invention is a mixed metal carbonate precursor material used to prepare the material according to the first aspect. The mixed metal carbonate precursor material may comprise or consist of particles comprising of consisting of a composition according to formula III:

[0172] NixCoyMnzAq(CO3)r Formula III wherein

[0173] A is one or more dopant elements selected from Na, Mg, Al, B, Ti, V, W, Sn, Zr, and Fe;

[0174] 0.1 < x < 0.4;

[0175] 0 < y < 0.1;

[0176] 0.33 < z < 0.66;

[0177] 0 < q < 0.10; r is within the range 0.8 to 1.2.

[0178] The values of x, y, z, and q may be chosen from any of the values or ranges for those indices set out above under the first aspect.

[0179] For example, r = 1.

[0180] The mixed metal carbonate precursor material of the seventh aspect may be converted into the material of the first aspect by the calcination method described in detail above under the method of the sixth aspect.

[0181] The mixed metal carbonate precursor material of the seventh aspect may be prepared by a method comprising: performing a precipitation reaction between a Ni source, a Mn source and optionally a Co source to form the mixed metal carbonate precursor material.

[0182] After the precipitation, the mixed metal carbonate precursor material may be isolated from a reaction vessel. The mixed metal carbonate precursor material may then be washed, filtered and dried before further processing, e.g. into a material according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0183] Figure 1 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the carbonate precursor intermediate made during the synthesis of Example 1, as a function of pore diameter.

[0184] Figure 2 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 1, as a function of applied pressure.

[0185] Figure 3 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 1, as a function of pore diameter.

[0186] Figure 4 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 1, as a function of pore diameter.

[0187] Figure 5 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 1, as a function of pore diameter.

[0188] Figure 6 shows cumulative pore area as a function of pore diameter for Example 1, obtained from mercury intrusion porosimetry.

[0189] Figure 7 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 1, as a function of applied pressure.

[0190] Figure 8 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 2, as a function of applied pressure.

[0191] Figure 9 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 2, as a function of pore diameter.

[0192] Figure 10 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 2, as a function of pore diameter. Figure 11 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 2, as a function of pore diameter.

[0193] Figure 12 shows cumulative pore area as a function of pore diameter for Example 2, obtained from mercury intrusion porosimetry.

[0194] Figure 13 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 2, as a function of applied pressure.

[0195] Figure 14 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 3, as a function of applied pressure.

[0196] Figure 15 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 3, as a function of pore diameter.

[0197] Figure 16 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 3, as a function of pore diameter.

[0198] Figure 17 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 3, as a function of pore diameter.

[0199] Figure 18 shows cumulative pore area as a function of pore diameter for Example 3, obtained from mercury intrusion porosimetry.

[0200] Figure 19 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Example 3, as a function of applied pressure.

[0201] Figure 20 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 1, as a function of applied pressure. Figure 21 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 1, as a function of pore diameter.

[0202] Figure 22 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 1, as a function of pore diameter.

[0203] Figure 23 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 1, as a function of pore diameter.

[0204] Figure 24 shows cumulative pore area as a function of pore diameter for Comparative Example 1, obtained from mercury intrusion porosimetry.

[0205] Figure 25 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 1, as a function of applied pressure.

[0206] Figure 26 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 2, as a function of applied pressure.

[0207] Figure 27 shows total volume intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 2, as a function of pore diameter.

[0208] Figure 28 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 2, as a function of pore diameter.

[0209] Figure 29 shows a pore size distribution in terms of a differential intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 2, as a function of pore diameter.

[0210] Figure 30 shows cumulative pore area as a function of pore diameter for Comparative Example 2, obtained from mercury intrusion porosimetry. Figure 31 shows percentage intrusion / extrusion curves obtained from mercury intrusion porosimetry on the material of Comparative Example 2, as a function of applied pressure.

[0211] Figure 32 shows overlay intrusion / extrusion plots from mercury intrusion porosimetry on Examples 2 and 3 and Comparative Examples 1 and 2, in terms of percentage volume intrusion as a function of pore diameter.

[0212] Figure 33 shows overlay intrusion / extrusion plots of pore size distributions from mercury intrusion porosimetry on Examples 2 and 3 and Comparative Examples 1 and 2, in terms of differential intrusion as a function of pore size diameter.

[0213] Figure 34 shows SEM images of four different materials according to the invention, having different Dv50 volumetric median particle sizes.

[0214] Figure 35 shows SEM images of (a) a cross section of a particle according to the invention, and (b) a cross section of a comparative particle made by the precipitation of a hydroxide precursor material.

[0215] Figure 36(a) shows the results of electrochemical testing on materials of Example 6 having a variety of Dv50 particle sizes.

[0216] Figure 36(b) shows charge / discharge curves for the material of Example 3 and the material of Comparative Example 2.

[0217] EXAMPLES & DETAILED DESCRIPTION

[0218] Example 1 - Li1.133Ni0.25Co005Mn0.55O2 by carbonate precipitation of 8,7 urn precursor 1417.9 g NiSO4.6H2O, 1891.0 g MnSO4.H2O and 301.3 g CoSO4.6H2O were dissolved in deionised water up to a final volume of 5000 mL (3665.3 g of water needed), to form Solution A.

[0219] 814.8 g Na2CCh was dissolved in 2046.2 g of deionised water to form Solution B. 74.99 g of a 28 wt% ammonia solution (NH4OH) was dissolved in 300.5 g of deionised water to form Solution C. A 5000 mL stirred tank reactor was filled with 500 mL deionised water, which was heated up to 55 °C and stirred at 500 rpm with a 90 mm PBT impeller. Once the temperature of the water had stabilised, coprecipitation was starting by adding Solution A at a rate of roughly 2.22 g / min addition. The pH was controlled to pH 7.5 by the addition of Solution B.

[0220] Solution C was fed to the reactor at a constant rate to allow precipitation to occur.

[0221] The particle size distribution of the formed precipitate was measured regularly throughout the precipitation at the results were as follows: Without wishing to be bound by theory, it is believed that for around the first 1-2 hours of the reaction many carbonate seeds are formed in the form of chelates that are agglomerated, hence the relatively large D50 early in the reaction. For around the first 1-2 hours these agglomerates then de-agglomerate and begin to grow as precipitated carbonate compounds, hence the gradual increase in size from 2 hours onwards.

[0222] After 23 hours of reaction the Dv50 particle size had reached approximately 8.7 pm and the reaction was stopped by halting the feeds to the reactor and cooling the reactor.

[0223] The reactor was emptied and the transition metal carbonate precursor was washed with hot water at 60 °C and filtered with a Buchner filter until the conductivity of the washings had reached 200 pS / cm, before being dried at 80 °C overnight.

[0224] After drying, the purity of the carbonate precursor was measured by X-Ray fluorescence (XRF).

[0225] The resulting density determined using an Envelope and Density Analyzer 1365 GeoPyc (trans-axial pressure) was 1.5482 g / cc before calcination. The moisture content was 1.06 wt%.

[0226] 61.5 g of Li2CO3 was then added to 155 g of the transition metal carbonate precursor.

[0227] The mixture was mixed using a Resodyn mixer and then calcined in a muffle furnace under a flow of 4 L / min N2 and 1 L / min O2, using the following calcination protocol:

[0228] • heat to 240 °C at 0.5 °C / min;

[0229] • hold at 240 °C for 5 h;

[0230] • heat to 850 °C at 1 °C / min;

[0231] • hold at 850 °C for 15 h; cool from 850 °C to 100 °C at 2 °C / min.

[0232] The composition of the material was Li1.133Ni0.25Co0.05Mn0.55O2. The BET surface area was determined by nitrogen adsorption according to ASTM D3663- 20 and found to be 5.4030 m2 / g for the precursor sample (sample mass: 1.0353 g; cold free space: 20.8722 cm3; analysis bath temperature: 77.3 K; warm free space: 8.0305 cm3measured; equilibration interval: 10s) and 100.87 m2 / g for the final oxide material.

[0233] Example 2 - Lii.o667Nio.4Mno.5333Q2 by carbonate precipitation of 7 mn precursor

[0234] 197.14 g N1SO4.6H2O and 169.01 g MnSCh.EEO was dissolved in deionised water up to a final volume of 500 mL, to form Solution A.

[0235] 222.58 g Na2CO3 was dissolved in deionised water up to a final volume of 600 mL, to form Solution B.

[0236] 14.3 g of a 28 wt% ammonia solution (NH4OH) was dissolved in deionised water up to a final volume of 200 mL to form Solution C.

[0237] A 1000 mL stirred tank reactor was filled with 150 mL deionised water, which was heated up to 55 °C and stirred at 1000 rpm. Once the temperature of the water had stabilised, coprecipitation was starting by adding Solution A at a rate of 3 rpm (size of the tubings: ID = 1.6 mm) equivalent to roughly 1.23 g / min addition.

[0238] The pH was controlled to pH 7.5 by the addition of Solution B.

[0239] Solution C was added at a rate of 6 rpm (size of the tubings: ID = 0.5 mm) equivalent to roughly 0.21 g / min addition.

[0240] The particle size distribution of the formed precipitate was measured regularly throughout the precipitation at the results were as follows:

[0241] Without wishing to be bound by theory, it is believed that for around the first hour of the reaction many carbonate seeds are formed in the form of chelates that are agglomerated, hence the relatively large Dso early in the reaction. For around the first hour these agglomerates then de-agglomerate and begin to grow as precipitated carbonate compounds, hence the gradual increase in size from 1 hour onwards.

[0242] After 8 hours of reaction the Dv50 particle size had reached approximately 7 pm and the reaction was stopped by halting the feeds to the reactor and cooling the reactor.

[0243] The reactor was emptied and the transition metal carbonate precursor was washed with hot water at 60 °C and filtered with a Buchner filter until the conductivity of the washings had reached 200 pS / cm, before being dried at 80 °C overnight.

[0244] After drying, the purity of the carbonate precursor was measured by X-Ray fluorescence (XRF).

[0245] 1.4491g g of Li2CO3 was then added to 4.0921 g of the transition metal carbonate precursor.

[0246] The mixture was mixed using a Resodyn mixer and then calcined in a muffle furnace using the following calcination protocol:

[0247] • heat to 500 °C at l°C / min;

[0248] • hold at 500 °C for 5 h;

[0249] • heat to 900 °C at l°C / min; hold at 900 °C for 6 h.

[0250] The resulting density determined using an Envelope and Density Analyzer 1365 GeoPyc (trans-axial pressure) was 1.2 g / cc before calcination, and 1.39 g / cc after calcination.

[0251] The composition of the material was determined by ICP to be the target composition Lil.0667Ni0.4Mn0.5333O2.

[0252] Example 3 - Lii.o667Nio.4Mno.5333Q2 by carbonate precipitation of 11 urn precursor

[0253] 812 g NiSO4.6H2O and 675.8 g MnSCU.EEO was dissolved in deionised water up to a final volume of 2000 mL, to form Solution A (1452.7 g water was required).

[0254] 740.7 g Na2CO3 was dissolved in deionised water up to a final volume of 2000 mL, to form Solution B (1860 g water was required).

[0255] 75 g of a 28 wt% ammonia solution (NH4OH) was dissolved in deionised water up to a final volume of 300 mL to form Solution C.

[0256] A 3000 mL stirred tank reactor was filled with 300 mL deionised water, which was heated up to 55 °C and stirred at 421 rpm. Once the temperature of the water had stabilised, coprecipitation was starting by adding Solution A at a rate of 3 rpm (size of the tubings: ID = 1.6 mm) equivalent to roughly 1.23 g / min addition.

[0257] The pH was controlled to pH 7.5 by the addition of Solution B.

[0258] Solution C was added at a rate of 6 rpm (size of the tubings: ID = 0.5 mm) equivalent to roughly 0.21 g / min addition.

[0259] The particle size distribution of the formed precipitate was measured regularly throughout the precipitation at the results were as follows:

[0260] After 23 hours of reaction the Dv50 particle size had reached approximately 11 pm and the reaction was stopped by halting the feeds to the reactor and cooling the reactor. The reactor was emptied and the transition metal carbonate precursor was washed with hot water at 60 °C and filtered with a Buchner filter until the conductivity of the washings had reached 100 pS / cm, before being dried at 80 °C overnight.

[0261] After drying, the purity of the carbonate precursor was measured by X-Ray fluorescence (XRF).

[0262] 1.71 g of Li2CO3was then added to 4.9577 g of the transition metal carbonate precursor.

[0263] The mixture was mixed using a Resodyn mixer and then calcined in a muffle furnace using the following calcination protocol:

[0264] • heat to 500 °C at l°C / min;

[0265] • hold at 500 °C for 5 h; heat to 900 °C at l°C / min; hold at 900 °C for 6 h.

[0266] The resulting density determined using an Envelope and Density Analyzer 1365 GeoPyc (trans-axial pressure) was 1.52 g / cc before calcination, and 1.55 g / cc after calcination.

[0267] The composition of the material was determined by ICP to be the target composition Lil.0667Ni0.4Mn0.5333O2.

[0268] Comparative Example 1 - hydroxide precipitation of 7 urn precursor

[0269] 225.31 g N1SO4.6H2O and 193.16 g MnSCh.EEO was dissolved in deionised water up to a final volume of 1000 mL, to form Solution A.

[0270] 160 g NaOH and 81.85 g NH4OH was dissolved in deionised water up to a final volume of 1000 mL, to form Solution B.

[0271] 8.758 g of a 0.7 M (28 wt%) NH4OH solution was dissolved in 200 mL deionised water to form Solution C.

[0272] A 1000 mL stirred tank reactor was filled with 200 mL Solution C, which was heated up to 50 °C and stirred at 1200 rpm. Once the temperature of the water had stabilised, coprecipitation was starting by adding Solution A at a rate of 3 rpm (size of the tubings: ID = 1.6 mm) equivalent to roughly 1.1 g / min addition.

[0273] The precipitation was performed under a nitrogen atmosphere.

[0274] The pH was controlled to pH 10.8 for the first 30 minutes and then pH 10.2 for the remainder of the reaction, by the addition of Solution B.

[0275] The particle size distribution of the formed precipitate was measured regularly throughout the precipitation at the results were as follows:

[0276] After 11 hours of reaction the Dv50 particle size had reached approximately 7 pm and the reaction was stopped by halting the feeds to the reactor and cooling the reactor.

[0277] The reactor was emptied and the transition metal hydroxide precursor was washed with cold water (room temperature) and filtered with a Buchner filter until the conductivity of the washings had reached 200 pS / cm, before being dried at 80 °C overnight.

[0278] After drying, the purity of the carbonate precursor was measured by X-Ray fluorescence (XRF).

[0279] 2.6988 g of Li2CO3was then added to 5 g of the transition metal hydroxide precursor.

[0280] The mixture was mixed using a Resodyn mixer and then calcined in a muffle furnace using the following calcination protocol:

[0281] • heat to 500 °C at l°C / min;

[0282] • hold at 500 °C for 5 h;

[0283] • heat to 900 °C at l°C / min;

[0284] • hold at 900 °C for 15 h. The resulting density determined using an Envelope and Density Analyzer 1365 GeoPyc (trans-axial pressure) was 1.59 g / cc before calcination, and 2.00 g / cc after calcination.

[0285] The composition of the material was determined by ICP to be the target composition Lil.0667Nio.4Mno.533302.

[0286] Comparative Example 2 - hydroxide precipitation of 11 urn precursor

[0287] The same process of Comparative Example 1 was followed, except that the pH throughout the precipitation was controlled by the addition of Solution B to be pH 10.2.

[0288] The particle size distribution of the formed precipitate was measured regularly throughout the precipitation at the results were as follows: After 19 hours of reaction the Dv50 particle size had reached approximately 11 pm and the reaction was stopped.

[0289] The reactor was emptied and the transition metal hydroxide precursor was washed with cold water (room temperature) and filtered with a Buchner filter until the conductivity had reached 100 pS / cm, before being dried at 80 °C overnight.

[0290] After drying, the purity of the carbonate precursor was measured by X-Ray fluorescence (XRF).

[0291] 2.6332 g of Li2CO3was then added to 5 g of the transition metal hydroxide precursor.

[0292] The mixture was mixed using a Resodyn mixer and then calcined in a muffle furnace using the following calcination protocol:

[0293] • heat to 500 °C at l°C / min;

[0294] • hold at 500 °C for 5 h;

[0295] • heat to 900 °C at l°C / min;

[0296] • hold at 900 °C for 15 h.

[0297] The resulting density determined using an Envelope and Density Analyzer 1365 GeoPyc (trans-axial pressure) was 2.04 g / cc before calcination, and 2.25 g / cc after calcination.

[0298] The composition of the material was determined by ICP to be the target composition Lil.0667Ni0.4Mn0.5333O2.

[0299] Example 4 - Carbonate precursor porosity measurements

[0300] The porosity of the carbonate precursor material prepared by the precipitation reaction in Example 1 (i.e. the precipitated carbonate prior to calcination) was characterised using mercury intrusion porosimetry.

[0301] The tests were performed using a MicroActive AutoPore V 9600, version 2.03.00. The parameters used for the porosimetry measurements were as follows: Figure 1 shows the results of the mercury intrusion porosimetry measurements on the carbonate precursor made during Example 1. No intra-particle porosity is evident, with the pore size distribution showing a single peak for inter-particle pores of a diameter approximately 3.5 pm.

[0302] Example 5 - Oxide porosity measurements

[0303] The porosity of the oxide materials prepared in Examples 1, 2, 3 and Comparative Examples 1 and 2 was characterised using mercury intrusion porosimetry. The tests were performed using a MicroActive AutoPore V 9600, version 2.03.00.

[0304] The parameters used for the porosimetry measurements were as follows:

[0305] Figures 2-7 show the results of the mercury intrusion porosimetry measurements on the oxide material of Example 1.

[0306] Figure 5 in particular clearly shows the presence of a bimodal pore size distribution in the material. A first peak at a pore diameter of 3.2 pm relates to the inter-particle pores, i.e. the spaces between individual particles within the material. A second distinctive peak is observed at a pore size of 0.12 pm, which relates to intra-particle open porosity within the particles themselves.

[0307] Figures 8-13 show the results of the mercury intrusion porosimetry measurements on the material of Example 2.

[0308] Figure 11 in particular clearly shows the presence of a bimodal pore size distribution in the material. A first peak at a pore diameter of 3.0 pm relates to the inter-particle pores, i.e. the spaces between individual particles within the material. A second distinctive peak is observed at a pore size of 0.07 pm, which relates to intra-particle open porosity within the particles themselves.

[0309] Figures 14-19 show the results of the mercury intrusion porosimetry measurements on the material of Example 3.

[0310] Figure 17 in particular clearly shows the presence of a bimodal pore size distribution in the material. A first peak at a pore diameter of 4.1 pm relates to the inter-particle pores, i.e. the spaces between individual particles within the material. A second distinctive peak is observed at a pore size of 0.05 pm, which relates to intra-particle open porosity within the particles themselves.

[0311] Figures 20-25 show the results of the mercury intrusion porosimetry measurements on the material of Comparative Example 1.

[0312] Figure 23 shows the pore size distribution for Comparative Example 1 and a single peak is evident at a pore size of 3.0 pm, representing the inter-particle pores. There is no evidence of any intra-particle pores within the pore size distribution.

[0313] Figures 26-31 show the results of the mercury intrusion porosimetry measurements on the material of Comparative Example 2.

[0314] Figure 29 shows the pore size distribution for Comparative Example 2 and a single prominent peak is evident at a pore size of 4.6 pm, representing the inter-particle pores. There is a second very small peak at a pore size of 0.17 pm, showing essentially negligible level of intra-particle porosity.

[0315] Figures 32 and 33 show overlay plots for the results of the mercury intrusion porosimetry measurements on the materials of Examples and Comparative Examples, for ease of comparison. The secondary peaks ay high pressure (low pore size) are clearly evident for Examples 2 and 3, but corresponding peaks are absent for Comparative Examples 2 and 3.

[0316] Characteristics of the inter-particle porosity of each of the materials prepared were calculated from the mercury intrusion porosimetry results. Percentage porosity was calculated using the following standard method:

[0317] The equation for the calculation of percentage porosity of a sample is: where Ppc = percentage porosity;

[0318] Vtot = total intrusion volume; and

[0319] Vb = bulk volume of sample (i.e. including all pores, open and closed).

[0320] Vtot is obtained from the maximum intrusion pressure and represents the volume of pores within the pressure range applied during analysis (typically up to 60,000 psia). Open pores smaller than 0.003 pm diameter are thus excluded.

[0321] Furthermore: where

[0322] VP= calibrated penetrometer volume; and Vm = volume of mercury in penetrometer.

[0323] Mercury volume is calculated from where

[0324] Wpsm = weight of penetrometer + mercury + sample (end of LP analysis);

[0325] Ws= sample weight;

[0326] WP= penetrometer weight; and

[0327] Ym = density of mercury.

[0328] The porosity results are given in the Table below. These were based on an analysis of the intrusion into pores in the order of 5 pm diameter, representing the voids between the particles within the material.

[0329] The intra-particle porosity for Examples 1-3 was analysed separately in more detail by focussing only on the higher-pressure peaks in the pore size distribution (smaller pore size) and the following results were obtained.

[0330] The results show that the material of the invention includes significant levels of intraparticle porosity. This was investigated further using SEM to qualitatively analyse the particle porosity.

[0331] Figure 34(a) shows SEM images of the oxide material of Example 1.

[0332] Figure 34(b), (c) and (d) show SEM images of materials made by processes analogous to that of Example 2, except that the Dv50 particle sizes are 14 pm, 17 pm and 21 pm respectively.

[0333] Figure 35(a) shows an SEM image of a cross section of a particle from the material of Example 3. A clear continuous network of open porosity through the entire cross section of the particle is evident. Figure 35(b) shows an SEM image of a cross section of a particle from the material of Comparative Example 2. There is very little porosity discernible, and the small amount of porosity present seems to be closed pores within the internal structure of the particle.

[0334] Example 6 - Lii.o667Nio.4Mno.5333Q2 by carbonate precipitation of 14 um, 17 um and 21 um precursors onto seed particles

[0335] Processes similar to that of Example 1 were used to prepare three different carbonate precursors with Dv50 of 14 pm, 17 pm and 21 pm respectively, which were each calcined to provide mixed metal oxide active materials.

[0336] Seed particles were used on which to precipitate the carbonate precursor during the precipitation reactions. The three reactions were carried out in the same way, except that different masses of seed particles were added for each.

[0337] 172.18 g of seed particles were used in the reaction to form the 14 pm precursor; 86.09 g of seed particles were used in the reaction to form the 17 pm precursor; and 43.04 g of seed particles were used in the reaction to form the 21 pm precursor.

[0338] Other than the quantity of seed particles, the reaction conditions used were the same and a summary of the conditions used is provided in the Table below:

[0339] In each case the reactor was emptied and the transition metal carbonate precursor was washed with cold water (room temperature) and filtered with a Buchner filter until the conductivity of the washings had reached 200 pS / cm, before being dried at 80 °C overnight. Each precursor was then calcined in the same way as Example 1. Some properties of the precursor and the final calcined oxides are provided below:

[0340] NM = not measured

[0341] Example 7 - Electrode preparation

[0342] The materials of Examples 2, 3 and 6, and Comparative Examples 1 and 2, were used to prepare electrodes for testing.

[0343] A TE1INKY ARE-250 mixer was used to prepare electrode slurries for casting.

[0344] Predetermined amounts of PVdF binder and carbon black were mixed in the TE1INKY mixer at 1500 rpm for 30 minutes. A predetermined amount of cathode material was then added along with NMP solvent, before mixing again at 1500 rpm for another 30 minutes. A further aliquot of NMP was added before mixing for a final time at 1500 rpm for 10 minutes to form an electrode slurry.

[0345] Working in a fume cupboard, a piece of industrial grade aluminium foil large enough to completely cover the vacuum table of an MTI Vacuum Table was cut. The vacuum was turned on to hold the foil securely in place. The surface of the aluminium foil was wiped with acetone, to remove any dust / impurities which may affect the adhesion and conductivity of the electrode.

[0346] The draw down bar was set to 350 pm on both sides by checking the aligned dials on top. Using a clean spatula, the electrode slurry was dripped directly in front of the drawdown bar.

[0347] When all the slurry had been deposited, the foil was coated with the slurry using the drawdown bar.

[0348] The cast was left to dry for approximately 45 minutes at 90 °C.

[0349] Once the cast was fully dried, the heating plate was turned off and the sample was allowed to cool, before removing from the fume cupboard.

[0350] The cast was calendared using a Durston Mill to achieve the desired electrode loading and thickness. An electrode punch was then used to cut out as many electrodes as possible from the sample. The cut out electrodes were then each placed in a small pouch made of aluminium foil to prevent the edges of the electrodes curling during the drying step.

[0351] The pouched electrodes were then transferred into a Buchi glass vacuum oven where they were heated at 120 °C for 15 hours under vacuum (30 mbar). The electrodes were then ready for coin cell preparation and testing.

[0352] Example 8 - Electrochemical testing

[0353] Cathodes were electrochemically tested in half-cell configuration. Typical diameters of the cathodes were 12.7 mm.

[0354] 2032 stainless steel coincells (Hohsen Corp) were assembled. Glass fibre (Whatman) was used as a separator and a 1 mm stainless steel disk as spacer. A Li chip (PI-KEM) was used as a counter electrode. LP40 (Tomiyama) was used as liquid electrolyte.

[0355] During coincell assembly, the various components were stacked inside the coincell base which was pre-equipped with a plastic gasket meant to guarantee complete air tightness after the coincell was sealed. The different components were stacked in the following order: cathode with the current collector side facing the coincell base, glass fibre separator, Li chip, spacer, and spring. A 1.4 mm stainless steel spring was required to guarantee sufficient stack pressure. 90 pL of electrolyte was pipetted onto the glass fibre separator during stack assembly, before loading the Li chip. The coincell was then sealed by crimping a lid onto it (Hohsen Corp).

[0356] All these steps were performed inside an Ar-filled glovebox with <0.5 ppm of O2 and <0.5 ppm of H2O.

[0357] Once assembled, the coincell was connected to a battery cycler (MPG2, Biologic) which was operated with EC -Lab software (vl l.43, Biologic). All coincells were connected using a coincell holder which was kept inside an incubator throughout the duration of the experiment. This was done to avoid fluctuation of the temperature which may alter the electrochemical results. All experiments were performed at 30 °C.

[0358] The typical experiment comprised a 10 h resting step before testing, which allowed for proper wetting by the electrolyte of the various components built inside the coincell.

[0359] The cell then underwent 5 formation cycles within the voltage window of 2.0 to 4.8 V vs Li+ / Li. In a typical cycle, during charge, a positive constant current density of 30 mA / g is applied to the cell up to an upper cutoff voltage of 4.8 V vs Li+ / Li. Once the cell voltage reached this value, it was held at 4.8 V until the current density reached a value of 6 mA / g. A constant negative current density of 30 mA / g was then applied until a lower voltage cutoff of 2.0 V was reached. This whole process which corresponds to a full cycle was then repeated four times.

[0360] Once the formation step was concluded, the rate test was carried out. The cell was cycled within the same voltage window of 2.0 to 4.8V vs Li+ / Li. Differently from the formation stage, during rate tests the charge current density was kept constant at 30 mA / g, whereas the discharge current density was increased after every cycle to 60, 90, 150, 300, 600, 900, 1500, 2100, and 3000 mA / g.

[0361] The results are shown in Figure 36. Figure 36(a) shows the specific capacity for the three different oxide materials prepared in Example 6, having different particle sizes (14 pm, 17 pm and 21 pm respectively), across a range of discharge rates from C / 5 to 10C. It is evident that, for the materials of the invention, rate capability is unaffected by a change in particle size. This is surprising because it would usually be expected for rate capability to decrease as the particle size increases, since for larger particles it becomes more difficult for lithium ions to diffuse into the particle core.

[0362] The open and continuous nature of the porosity for the inventive materials appears to prevent any drop in rate capability as the particle sizes increase, thus making rate capability essentially independent of particle size for the present materials.

[0363] Figure 36(b) shows first cycle charge / discharge curves for the materials of Example 3 and Comparative Example 2, which each have a particle size of 11 pm. The material of Example 3 achieves a discharge capacity of around 255 mAh g'1, compared with only 205 mAh g'1for the Comparative Example 2 material. Figures 36(a) and (b) taken together show that, as particle size increases, the materials of the invention will have a higher discharge capacity than comparative materials of a similar particle size, without any decrease in rate capability.

Claims

CLAIMS1. A particulate mixed metal oxide material comprising an intra-particle porosity, as determined by mercury intrusion porosimetry, of from 2 to 35 %.

2. The material according to claim 1, comprising a volumetric median particle diameter (Dv50) of from 1 to 100 pm.

3. The material according to claim 1 or 2, comprising a BET surface area of at least 4.0 m2 / g.

4. The material according to any one of the preceding claims, wherein the particulate mixed metal oxide material comprises particles comprising a composition according to formula I:LiaNixCoyMnzAqCh+dFe Formula I whereinA is one or more dopant elements selected from Na, Mg, Al, B, Ti, V, W, Sn, Zr, and Fe;0.1 < x < 0.4;0 < y < 0.1;1.0 < a < 1.3;0.33 < z < 0.66;0 < q < 0.10; d is within the range 0 to ±0.2; and e is within the range 0 to 0.1.

5. The material according to claim 4, wherein a = 1.33 - (2x / 3) - (y / 3) ±5; and z = 0.66 - (x / 3) - (2y / 3) ±wherein 5 and are each independently selected from within the range 0 to 0.1.

6. The material according to any one of the preceding claims, wherein the intraparticle porosity of the material, as determined by mercury intrusion porosimetry, is from 10 to 35 %.

7. The material according to any one of the preceding claims, wherein the particles comprise intra-particle pores having a pore size distribution determined by mercury intrusion porosimetry, wherein the intra-particle pore size distribution is characterised by one or more of:(a) a volume-based median pore diameter of from 0.01 to 0.30 pm;(b) an area-based median pore diameter of from 0.01 to 0.20 pm;(c) a 4V / A average pore diameter of from 0.01 to 0.25 pm;(d) a total pore area of from 1 to 15 m2 / g;(e) a tortuosity of from 2 to 12;(f) a pore characteristic length of from 0.05 to 0.40 pm; and(g) a permeability of from 0.001 to 0.010 mD.

8. The material according to any one of the preceding claims, having a density determined by the application of trans-axial pressure (TAP) of from 1.0 to 4.0 g / cm3.

9. The material according to any one of the preceding claims, comprising particles having a shape which is near-spherical, or potato-like.

10. The material according to any one of the preceding claims, wherein the material exhibits a bimodal pore size distribution when determined by mercury intrusion porosimetry.

11. The material according to any one of the preceding claims, wherein the total porosity of the material, made up of inter-particle and intra-particle porosity, as determined by mercury intrusion porosimetry, is from 55 to 80 %.

12. The material according to any one of the preceding claims, wherein the particulate mixed metal oxide material has a multimodal particle size distribution comprising a first particle mode and a second particle mode, the material having a D1so / D25o in the range 2 to 15; wherein Dho is the volumetric median particle diameter of the first particle mode and D25O is the volumetric median particle diameter of the second particle mode.

13. The material according to claim 12, wherein the intra-particle porosity (pl) of the first particle mode, is higher than the intra-particle porosity (p2) of the second particle mode, wherein pl and p2 are determined by mercury intrusion porosimetry.

14. The material according to claim 13, wherein pl is from 10 to 30 %, and p2 is less than 5 %.

15. The material according to any one of claims 12 to 14, wherein the second particle mode makes up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode.

16. The material according to any one of claims 12 to 15, wherein D^o is within the range 2 to 60 pm, and D2so is within the range 1 to 5 pm.

17. The material according to any one of claims 12 to 16, wherein D^o is within the range 18 to 25 pm, D2so is within the range 2 to 5 pm, the second particle mode makes up from 5 to 35 wt% of the total mass of the first particle mode and the second particle mode18. The material according to any one of the preceding claims, wherein the particulate lithium transition metal oxide material is manufactured by a method which includes the precipitation of a mixed metal carbonate precursor material, followed by reaction with a lithium source and calcination to form the particulate lithium transition metal oxide material.

19. A positive active material for a cathode, comprising the particulate lithium transition metal oxide material according to any one of claims 1 to 18.

20. A cathode comprising the positive active material according to claim 19, and a binder.

21. An electrochemical secondary cell or battery comprising the cathode according to claim 20.

22. An electrical device or a vehicle comprising the cell or battery according to claim 21.

23. A method of manufacturing the particulate lithium transition metal oxide material according to any one of claims 1 to 18, the method comprising: performing a precipitation reaction between a Ni source, a Mn source and optionally a Co source to form a mixed metal carbonate precursor compound; adding a Li source to the mixed metal carbonate precursor compound; and calcining the mixture of the Li source and the mixed metal carbonate precursor compound to form the particulate lithium transition metal oxide material.

24. The method according to claim 23, wherein the precipitation reaction is carried out in the presence of a source of dopant A, wherein A is one or more dopant elements selected from Na, Mg, Al, B, F, Ti, V, W, Sn, Zr, and Fe.

25. The method according to claim 23 or 24, wherein the pH during the precipitation reaction is maintained within the range pH 5 to pH 11.

26. The method according to any one of claims 23 to 25, wherein calcining the mixture comprises a first calcination step at a temperature Ti, wherein Ti is a temperature within the range 200 to 600 °C, and a second calcination step at a temperature T2, wherein T2 is a temperature within the range 600 to 1000 °C, wherein heating to Ti, and heating from Ti to T2, are each performed at a ramping rate of from 1 to 5 °C / min.

27. The method according to claim 26, wherein the material is held at Ti for a period of from 2 to 10 hours, and the material is held at T2 for a period of from 2 to 10 hours.

28. A mixed metal carbonate precursor material used to prepare the material according to any one of claims 1-18.

29. The mixed metal carbonate precursor material according to claim 28, wherein the mixed metal carbonate precursor material comprises particles comprising a composition according to formula III:NixCoyMnzAq(CO3)r Formula III whereinA is one or more dopant elements selected from Na, Mg, Al, B, Ti, V, W, Sn, Zr, and Fe;0.1 <x <0.4;0 < y <0.1;0.33 < z < 0.66;0 < q < 0.10; r is within the range 0.8 to 1.2.

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