Trays for furnaces for the manufacture of cathode active materials

Abstract

The present disclosure relates to compositions for industrial furnace trays, and to methods for manufacturing the compositions thereof. The present disclosure also relates to a tray comprising a composition according to this disclosure. The tray has the characteristics of high thermal and chemical stability, and improved lifetime.

Description

[0001] TRAYS FOR FURNACES FOR THE MANUFACTURE OF CATHODE ACTIVE MATERIALS

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to chemical compositions for trays, and to methods for manufacturing the chemical compositions thereof. The disclosure also relates to a tray comprising a chemical composition according to this disclosure. The tray has the characteristics of high thermal and chemical stability, and improved lifetime.

[0004] BACKGROUND

[0005] The manufacture of cathode active materials for lithium batteries usually involves a firing step inside an industrial furnace which can reach temperatures above 800 °C. The raw materials for lithium batteries (metal oxides and lithium source) are usually placed in a tray and then subjected to a firing step. At high temperatures (for example >800 °C), the components of the tray can react with the raw materials for lithium batteries leading to the formation of side-products with low density. This generates a volume expansion and physical stress in the structure of the tray leading to micro- ruptures, cracking, and / or peeling. Such undesirable effects are known as corrosion and reduces the service life of the tray to usually less than 20 firing cycles. Moreover, due to the side reactions of the raw materials with the tray components, a certain amount of the Li source and / or the metal oxide is wasted, increasing the production cost of the cathode active material.

[0006] Conventional trays used in the lithium battery field are usually 20-50 cm wide, 20-50 cm long and 5-30 cm high, and their main components are aluminum oxide (AI2O3), silicon oxide (SiO?) and magnesium oxide (MgO). The amount of these major components plays an important role in the chemical and thermal stability of the tray. Therefore, it is desirable to balance their content in order to obtain a composition with high chemical stability, high thermal stability and low production cost. Additionally, trays can further comprise other components, such as ZrO? or TiO?, which bring benefits but increase the manufacturing cost of the tray. The trays may contain impurities, for example up to 2.0 wt%, such as Na?O, K2O, CaO and Fe2Os, present in the raw materials.

[0007] CN200910146662 describes a tray for manufacturing cathode active materials for lithium batteries. The tray comprises 46-68 wt% of aluminum oxide, 13-22 wt% of magnesium oxide, and 12-36 wt% of silicon dioxide.

[0008] CN200910096395 describes a tray comprising 45-70 wt% of aluminum oxide, 10-20 wt% of magnesium oxide, 15-35 wt% of silicon dioxide, 1-3 wt% of zirconium oxide, and 1- 5 wt% of metal aluminum powder.

[0009] CN102914165 describes a tray comprising 50-85 wt% of aluminum oxide, 1-15 wt% of magnesium oxide, 3-30 wt% of silicon dioxide, 1-10 wt% of zirconium oxide, 1-10 wt% of calcium oxide and 1-15 wt% of aluminum titanate. Some commercially available trays have shown relatively poor chemical and / or thermal stability when submitted to high temperatures (above 800 °C), see the Examples section for comparative data.

[0010] There is a need to provide trays with good chemical and thermal resistance, increasing the lifetime of the trays and reducing the manufacturing cost of the cathode active material.

[0011] SUMMARY

[0012] The present disclosure relates to novel compositions for trays for industrial furnaces. The present trays may, for example, be used in the manufacture of cathode active materials for lithium batteries.

[0013] The present disclosure provides a composition comprising SiO?, MgO, and AI2O3 in a SiChiMgOiA Os wt% ratio from 1.2: 12.3:84.4 to 12.3: 18.0:69.7.

[0014] The present disclosure provides a process for manufacturing the present compositions.

[0015] The present disclosure provides a tray for an industrial furnace, comprising the present compositions.

[0016] The present disclosure provides a process for manufacturing the present trays.

[0017] The present disclosure provides the use of the present trays in an industrial furnace. For example, for use in the manufacture of cathode active materials for lithium batteries.

[0018] BRIEF DESCRIPTION OF THE FIGURES

[0019] FIGURE 1 shows a SEM image of a cross-section sample of Example 1 after ten calcination cycles. The scale is defined in Figure 1.

[0020] FIGURE 2 shows a SEM image of a cross-section sample of Example 2 after ten calcination cycles. The scale is defined in Figure 2.

[0021] FIGURE 3 shows a SEM image of a cross-section sample of Example 3 after ten calcination cycles. The scale is defined in Figure 3.

[0022] FIGURE 4 shows a SEM image of a cross-section sample of Example 4 after ten calcination cycles. The scale is defined in Figure 4.

[0023] FIGURE 5 shows a SEM image of a cross-section sample of Example 5 after ten calcination cycles. The scale is defined in Figure 5.

[0024] FIGURE 6 shows a SEM image of a cross-section sample of Comparative Example 1 after ten calcination cycles. The scale is defined in Figure 6.

[0025] FIGURE 7 shows a SEM image of a cross-section sample of Comparative Example 2 after ten calcination cycles. The scale is defined in Figure 7.

[0026] FIGURE 8 shows a SEM image of a cross-section sample of Comparative Example 3 after ten calcination cycles. The scale is defined in Figure 8.

[0027] FIGURE 9 shows a SEM image of a cross-section sample of Comparative Example 4 after ten calcination cycles. The scale is defined in Figure 9. FIGURE 10 shows a SEM image of a cross-section sample of Comparative Example 5 after ten calcination cycles. The scale is defined in Figure 10.

[0028] DETAILED DESCRIPTION

[0029] In the following detailed description, preferred embodiments are described in detail to enable the practice of the present invention. Although the present invention is described with reference to these specific preferred embodiments, it will be understood that this invention is not limited to these preferred embodiments. On the contrary, this invention includes numerous alternatives, modifications and equivalents as will become apparent from the consideration of the description and accompanying drawings. The different parts of the description and drawings are not intended to be read as isolated disclosures. That is, unless the context dictates otherwise, each alternative, modification, and equivalent may be combined with any other alternative, modification, or equivalent.

[0030] The following terms are intended to have the meaning presented below and are useful in understanding the description and intended scope of this invention.

[0031] The term "comprising", as used herein and in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to compositions consisting only of components A and B. It means that with respect to the present disclosure, the only relevant components of the composition are A and B. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0032] The term "cathode active material" (also known as CAM or positive electrode active material) refers to a material which is electrochemically active in a positive electrode or cathode. By active material, it must be understood to be a material capable of capturing and releasing Li ions when subjected to a voltage change over a predetermined period of time.

[0033] The term "wt%" refers to the percentage by weight of a particular component relative to the total weight of the corresponding composition.

[0034] The term "tray" refers to a container or receptacle to allocate, carry, hold and / or transport a material. Trays are porous material composed from particles of different sizes. Usually, trays have a rectangular form with dimensions of about 20-50 cm wide, about 20-50 cm long and about 5-30 cm high. However, it is possible to manufacture trays with other shapes, forms, and measurements. In particular, the term refers to trays specifically designed for industrial furnaces reaching temperatures above about 800 °C. Trays can be obtained by mixing different powder oxides, such as MgO, SiO?, AI2O3, etc, to obtain a powder mixture.

[0035] The term "cracking" refers to damage caused to a material by physical or mechanical stress, which ultimately creates a physical separation between parts of the material.

[0036] The term "peeling" refers to the formation of uneven or rough irregularities in the surface of a material.

[0037] The following raw materials were used as reagents in order to obtain the exemplified compositions and / or the comparative examples:

[0038] Spinel with a particle size <400 pm, containing 74.8 wt% of AI2O3, 0.1 wt% of SiC>2, 24.6 wt% of MgO, and 0.2 wt% of Fe2Os.

[0039] Mullite-coarse with a particle size <400 pm, containing 76.4 wt% of AI2O3, and 23 wt% of SiO2.

[0040] Mullite-fine with a particle size <50 pm, containing 73.7 wt% of AI2O3, and 25.5 wt% of MgO, and 0.1 wt% of Fe2Os.

[0041] Cordierite with a particle size <50 pm, containing 39.6 wt% of AI2O3, 48.4 wt% of SiO2, 8.1 wt% of MgO, 0.8 wt% of Fe2Os, and 1.1 wt% of TiO2.

[0042] Alumina with a particle size < 100 pm, containing >99 wt% of AI2O3.

[0043] Silica with a particle size < 10 pm, containing >99 wt% of SiO2.

[0044] Aluminum titanate with a particle size < 100 pm, containing >99 wt% of A TiOs.

[0045] Zirconia with a particle size < 10 pm, containing 92 wt% of ZrO2 and 8 wt% of Y2O3.

[0046] Forsterite with a particle size < 100 pm, containing <99 wt% of Mg2SiO4.

[0047] Lithium carbonate with a particle size < 100 pm.

[0048] Tungsten trioxide with a particle size < 100 pm.

[0049] Chemical compositions

[0050] The present disclosure provides a composition comprising SiC>2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio from 1.2: 12.3 :84.4 to 12.3 : 18.0 :69.7.

[0051] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio from 1.2: 15.5 :83.3 to 10.5 : 19.3:70.2.

[0052] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio from 1.7 : 16.8:81.5 to 6.4:20.2 :73.4.

[0053] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio from 1.7: 16.8:81.5 to 4.7:20.6:74.7.

[0054] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 4.7: 18.3 :77.0. The present composition may comprise SiO?, MgO, and AI2O3 in a SiChi MgCHA Os wt% ratio of 11.7 : 18.3 :70.0.

[0055] The present composition may comprise SiO?, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 4.7:22.0 :73.3.

[0056] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 4.7 : 15.3:80.0.

[0057] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 1.7: 18.3 :80.0.

[0058] The present composition may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 2.0: 13.0 :85.0.

[0059] The present composition may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein

[0060] 1.0 < x < 15.0 wt%,

[0061] 10.0 < y < 22.0 wt%, and

[0062] 70.0 < z < 85.0 wt%.

[0063] The present composition may comprise 1.0 < x < 12.0 wt%; 1.5 < x < 7.0 wt%; 1.5 < x < 5.0 wt%; 1.7 < x < 4.7 wt%. For example, x may be 1.7 or 4.7 wt%.

[0064] The present composition may comprise 13.0 < y < 22.0 wt%; 15.0 < y < 22.0 wt%. For example, y may be 15.3, 18.3, or 22.0 wt%.

[0065] The present composition may comprise 70.0 < z < 80.0 wt%; 73.0 < z < 80.0 wt%. For example, z may be 73.3 or 80.0 wt%.

[0066] The present composition may consist essentially of SiC>2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein

[0067] 4.5 < x < 15.0 wt%,

[0068] 10.0 < y < 22.0 wt%, and

[0069] 72.0 < z < 85.0 wt%.

[0070] The present composition may comprise 6.0 < x < 15.0 wt%; 8.0 < x < 14.0 wt%; 10.0 < x < 14.0 wt%; For example, x may be 10.0, 11.0, 12.0, 13.0, or 14.0 wt%.

[0071] The present composition may comprise 13.0 < y < 22.0 wt%; 15.0 < y < 22.0 wt%. For example, y may be 15.3, 18.3, or 22.0 wt%.

[0072] The present composition may comprise 72.0 < z < 83.0 wt%; 75.0 < z < 83.0 wt%. For example, z may be 75.0, 76.0, 77.0, 78.0, 79.0, 80.0, 81.0, 82.0 or 83.0 wt%.

[0073] The present composition may consist essentially of SiC>2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein

[0074] 10.0 < x < 15.0 wt%, 10.0 < y < 22.0 wt%, and

[0075] 75.0 < z < 85.0 wt%.

[0076] The present composition may consist essentially of SiC>2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0077] 1.0 < x < 12.0 wt%,

[0078] 13.0 < y < 22.0 wt%, and

[0079] 70.0 < z < 80.0 wt%.

[0080] The present composition may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0081] 1.5 < x < 7.0 wt%,

[0082] 15.0 < y < 22.0 wt%, and

[0083] 73.0 < z < 80.0 wt%.

[0084] The present composition may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0085] 1.5 < x < 5.0 wt%,

[0086] 15.0 < y < 22.0 wt%, and

[0087] 73.0 < z < 80.0 wt%.

[0088] The present composition may consist essentially of 4.7 wt% of SiC>2, 18.3 wt% of MgO, and 77.0 wt% of AI2O3.

[0089] The present composition may consist essentially of 11.7 wt% of SiC>2, 18.3 wt% of MgO, and 70.0 wt% of AI2O3.

[0090] The present composition may consist essentially of 4.7 wt% of SiO2, 22.0 wt% of MgO, and 73.3 wt% of AI2O3.

[0091] The present composition may consist essentially of 4.7 wt% of SiO2, 15.3 wt% of MgO, and 80.0 wt% of AI2O3.

[0092] The present composition may consist essentially of 1.7 wt% of SiO2, 18.3 wt% of MgO, and 80.0 wt% of AI2O3.

[0093] The present composition may consist essentially of 2.0 wt% of SiO2, 13.0 wt% of MgO, and 85.0 wt% of AI2O3.

[0094] While the content of each component (SiO2, MgO, AI2O3) has been listed above separately for certain embodiments, the present disclosure is intended to include all the possible combinations of such embodiments.

[0095] A process for manufacturing a chemical composition

[0096] The present disclosure provides a process for manufacturing the present compositions, said process comprising the following steps: Step a) providing and mixing the raw materials with the corresponding stoichiometric ratios to provide a mixture;

[0097] Step b) pressing the mixture to form a material with a thickness between 2 and 6 mm;

[0098] Step c) heating the material at a temperature of at least 800 °C.

[0099] The present Step a) may further comprise the addition of 3 wt% of paraffin.

[0100] The raw materials and the paraffin may be mixed for at least 4 hours during Step a), for example, for 4 hours.

[0101] In Step b), the mixture may be cold pressed at least at 100 MPa, for example, at 100 MPa.

[0102] The material obtained in Step b) may be, for example, in the form of a disc. The disc may have a diameter of 15 mm and a thickness between 3 and 4 mm.

[0103] During Step c), the material may be heated from room temperature to 1350 °C, for example, at a heating rate of 2 °C / min, and then heated at 1350 °C for 4 hours.

[0104] During Step c), the material may be heated from room temperature to 400 °C at a heating rate of 2 °C / min, then the temperature is hold for 1 hour at 400 °C. Then, the temperature is increased from 400 °C to 1350 °C at a heating rate of 10 °C / min, and finally the material is heated at 1350 °C for 4 hours.

[0105] In an embodiment of the present process, the corresponding reagents are mixed and stirred with 3 wt% of paraffin wax for 4 hours. Then, the mixture is cold pressed at 100 MPa into discs with a diameter of 15 mm, and a thickness of 3-4 mm. The discs are placed on AI2O3 plates and then heated at 1350 °C, at a heating rate of 2 °C / min from room temperature to 400 °C. The temperature is hold at 400 °C for 1 hour, followed by heating at 10 °C / min up to the 1350 °C. Then, the material is heated at 1350 °C for 4 hours. Finally, the resulting material is cooled down to room temperature with a heating rate of 5°C / min.

[0106] Trays comprising a chemical composition

[0107] The present disclosure provides a tray comprising the present composition.

[0108] The present tray may comprise SiC>2, MgO, and AI2O3 in a SiO2:MgO:Al2O3 wt% ratio from 1.2: 12.3:84.4 to 12.3: 18.0:69.7.

[0109] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2:MgO:Al2O3 wt% ratio from 1.2: 15.5:83.3 to 10.5: 19.3:70.2.

[0110] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2:MgO:Al2O3 wt% ratio from 1.7: 16.8:81.5 to 6.4:20.2:73.4.

[0111] The present tray may comprise SiO?, MgO, and AI2O3 in a SiChiMgChAhOs wt% ratio from 1.7: 16.8:81.5 to 4.7:20.6:74.7. The present tray may comprise SiO?, MgO, and AI2O3 in a SiChi MgCHA Os wt% ratio of 4.7: 18.3 :77.0.

[0112] The present tray may comprise SiO?, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 11.7: 18.3:70.0.

[0113] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 4.7 :22.0 :73.3.

[0114] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 4.7: 15.3 :80.0.

[0115] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 1.7: 18.3 :80.0.

[0116] The present tray may comprise SiO2, MgO, and AI2O3 in a SiO2: MgO:Al2O3 wt% ratio of 2.0: 13.0:85.0.

[0117] The present tray may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein

[0118] 1.0 < x < 15.0 wt%,

[0119] 10.0 < y < 22.0 wt%, and

[0120] 70.0 < z < 85.0 wt%,

[0121] The present tray may comprise 1.0 < x < 12.0 wt%; 1.5 < x < 7.0 wt%; 1.5 < x < 5.0 wt%; 1.7 < x < 4.7 wt%. For example, x may be 1.7 or 4.7 wt%.

[0122] The present tray may comprise 13.0 < y < 22.0 wt%, 15.0 < y < 22.0 wt%. For example, y may be 15.3, 18.3 or 22 wt%.

[0123] The present tray may comprise 70.0 < z < 80.0 wt%; 73.0 < z < 80.0 wt%. For example, z may be 73.3 or 80.0 wt%.

[0124] The present tray may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein

[0125] 4.5 < x < 15.0 wt%,

[0126] 10.0 < y < 22.0 wt%, and

[0127] 72.0 < z < 85.0 wt%.

[0128] The present tray may comprise 6.0 < x < 15.0 wt%; 8.0 < x < 14.0 wt%; 10.0 < x < 14.0 wt%; For example, x may be 10.0, 11.0, 12.0, 13.0, or 14.0 wt%.

[0129] The present tray may comprise 13.0 < y < 22.0 wt%; 15.0 < y < 22.0 wt%. For example, y may be 15.3, 18.3, or 22.0 wt%.

[0130] The present tray may comprise 72.0 < z < 83.0 wt%; 75.0 < z < 83.0 wt%. For example, z may be 75.0, 76.0, 77.0, 78.0, 79.0, 80.0, 81.0, 82.0 or 83.0 wt%. The present tray may consist essentially of SiO? in a content x, MgO in a content y and AI2O3 in a content z, wherein

[0131] 10.0 < x < 15.0 wt%,

[0132] 10.0 < y < 22.0 wt%, and

[0133] 75.0 < z < 85.0 wt%.

[0134] The present tray may consist essentially of SiO? in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0135] 1.0 < x < 12.0 wt%,

[0136] 13.0 < y < 22.0 wt%, and

[0137] 70.0 < z < 80.0 wt%,

[0138] The present tray may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0139] 1.5 < x < 7.0 wt%,

[0140] 15.0 < y < 22.0 wt%, and

[0141] 73.0 < z < 80.0 wt%.

[0142] The present tray may consist essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein:

[0143] 1.5 < x < 5.0 wt%,

[0144] 15.0 < y < 22.0 wt%, and

[0145] 73.0 < z < 80.0 wt%.

[0146] The present tray may consist essentially of 4.7 wt% of SiO2, 18.3 wt% of MgO, and 77.0 wt% of AI2O3.

[0147] The present tray may consist essentially of 11.7 wt% of SiO2, 18.3 wt% of MgO, and 70.0 wt% of AI2O3.

[0148] The present tray may consist essentially of 4.7 wt% of SiO2, 22.0 wt% of MgO, and 73.3 wt% of AI2O3.

[0149] The present tray may consist essentially of 4.7 wt% of SiO2, 15.3 wt% of MgO, and 80.0 wt% of AI2O3.

[0150] The present tray may consist essentially of 1.7 wt% of SiO2, 18.3 wt% of MgO, and 80.0 wt% of AI2O3.

[0151] The present tray may consist essentially of 2.0 wt% of SiO2, 13.0 wt% of MgO, and

[0152] 85.0 wt% of AI2O3.

[0153] The present tray may be any suitable width, length, and height. For example, the tray may be 20 to 50 cm wide, 20 to 50 cm long, and / or 5 to 30 cm high. Process for manufacturing a tray

[0154] The present disclosure provides a process for manufacture the tray as described herein. The process comprising the following steps:

[0155] Step a) providing and mixing the raw materials with the corresponding stoichiometric ratios to provide a mixture;

[0156] Step b) pressing the mixture to generate a material with the dimensions of 20 to 50 cm wide, 20 to 50 cm long, and 5 to 30 cm high.

[0157] Step c) heating the material obtained in Step c) at a temperature of at least 800 °C.

[0158] Use of a tray in an industrial furnace

[0159] The present trays may be used in an industrial furnace. For example, in the manufacture of a cathode active material for lithium batteries.

[0160] The present trays may be used in industrial furnaces reaching temperatures higher than 800 °C.

[0161] The present tray may be used in industrial furnace reaching temperatures higher than 1000 °C.

[0162] EXAMPLES - CHEMICAL PROCEDURES

[0163] The chemical compositions of this disclosure can be prepared from readily available materials using the following general methods and procedures. It will be appreciated that although typical or preferred process conditions (i.e. reaction temperatures, times, pressures, etc.) are given, other process conditions can also be used unless otherwise stated.

[0164] The following methods are presented with details as to the preparation of the present compositions as defined hereinabove and the comparative examples. A composition of this disclosure may be prepared from known or commercially available starting materials.

[0165] All the raw materials are of commercial grade and are used as received without further purification, unless otherwise stated.

[0166] General protocol for the preparation of the chemical compositions

[0167] The reagents are mixed and stirred with 3 wt% of paraffin wax for 4 hours. Then, the mixture is cold pressed at 100 MPa into discs with a diameter of 15 mm, and a thickness of 3-4 mm. The discs are placed on AI2O3 plates and then heated at 1350 °C, at a heating rate of 2 °C / min from room temperature to 400 °C, dwelling for 1 hour at 400 °C, followed by heating at 10 °C / min up to the 1350 °C, and heated at 1350 °C for 4 hours. Then, the resulting product is cooled down to room temperature with a heating rate of 5°C / min. Illustrative example of the general protocol: preparation of Example 1

[0168] 51.0 grams of AI2O3, 14.0 grams of SiO? and 35.0 grams of MgO were mixed and stirred with 3 wt% paraffin wax for 4 hours. The mixture was cold pressed at 100 MPa into a disc (15 mm diameter and 3 mm thickness). The disc was placed on AI2O3 plate and then heated at 1350 °C, at a heating rate of 2 °C / min from room temperature to 400 °C, dwelling for 1 hour at 400 °C, followed by heating at 10 °C / min up to 1350 °C, and heated at 1350 °C for 4 hours. Then, Example 1 was cooled down to room temperature with a heating rate of 5°C / min.

[0169] Examples 2, 3, 4, 5 and 6 were obtained following the conditions described in the general protocol.

[0170] Comparative examples 1, 2 and 3 are commercially available. However, they can also be prepared following the conditions described in the general protocol using the corresponding raw materials.

[0171] Comparative example 4 has been prepared following the conditions described in the general protocol using 31.3 gr of spinel, 30.2 grams of cordierite and 38.6 gr of AI2O3.

[0172] Comparative example 5 has been prepared following the conditions described in the general protocol using 22.0 gr of mullite-coarse, 25.0 gr of mullite-fine, 40.0 gr of cordierite and 12.0 gr of AI2O3.

[0173] Table I. Examples of the present disclosure and Comparative examples.

[0174] Some examples and comparative examples might contain up to 2.0 wt% of impurities present in the raw materials (i.e. CaO, Na2O, K2O, or Fe2C>3). Characterization methods:

[0175] Inductively coupled plasma optical emission spectroscopy (ICP-OES)

[0176] The ICP-OES is used to quantify the components present in the samples. Inductively ICP-OES measurements are performed on an Agilent 5110 ICP-OES spectrometer. Accordingly, 1 g of powder of the sample is dissolved in 50 mL hydrochloric acid in an Erlenmeyer flask. The flask is covered by glass and heated on a hot plate for complete dissolution of the material. After being cooled to room temperature, the solution is moved to a 500 mL volumetric flask that has been thoroughly cleaned and rinsed with distilled (DI) water. After filling the flask with the solution, the volumetric flask is filled with DI water up to the 500 mL mark, followed by complete homogenization. 5 mL solution is taken out with a 5 mL pipette and transferred into a 50 mL volumetric flask along with an internal standard for a second dilution, where the volumetric flask is filled with 10% hydrochloric acid up to the 50 mL mark and then homogenized. Finally, this 50 mL solution is used in the spectrometer.

[0177] X-Ray Fluorescence Spectrometry (XRF)

[0178] The X-Ray fluorescence spectrometry method is used to quantify the components present in the samples. WD-XRF spectrometer Bruker S8 TIGER 4K is used to perform XRF measurements. A sample of the corresponding Example or Comparative example is ground into powder using disc mill at 1100 rpm for 1 min. Then, about 1 gram of the ground powder is loaded into XRF sample holder to perform the measurement.

[0179] EXAMPLES - TESTING PROCEDURES

[0180] Calcination protocol:

[0181] This experiment is performed using a tube furnace to heat the tray samples. A tray sample comprising the corresponding exemplified composition or comparative exemplified composition and having the dimensions of 1 cm x 1 cm x 1 cm is placed inside an alumina crucible. The crucible is filled with 10 grams of Li1.0Ni0.8Mn0.1Co0.1O2. Then, the crucible is subjected to 10 calcination cycles.

[0182] For each calcination cycle, the temperature increases from room temperature to 900 °C at a heating rate of 5 °C per min, then the temperature is hold at 900 °C for 12 hours and cool down to room temperature at 5 °C / min. A gas flow rate of 10 L per min of O2 is used during each calcination cycle.

[0183] The general calcination protocol is used in the following tests to evaluate the chemical and thermal stability of the Examples and Comparative examples.

[0184] Weight gain test: o Aim of the experiment:

[0185] This experiment is designed to determine the weight gain by a tray sample after a calcination cycle. Due to the interactions between Li and the tray sample at high temperatures, a certain amount of Li remains in the tray after a calcination cycle. A higher weight gain correlates to a lower chemical stability, higher level of corrosion and higher amount of Li wasted. o Protocol:

[0186] Samples are submitted to the general calcination protocol described above. After each calcination cycle, the sample is weight using a precision balance to measure the weight gain. o Results:

[0187] Table II shows the % weight gain for each example and comparative example at each calcination cycle. The % weight gain has been calculated using the following formula: n / . . . .

[0188] % weight gam wherein "weight cycle n" is the weight of the sample after the calcination cycle number "n", wherein "n" is a number between 1 and 10; and "weight cycle o" is the initial weight of sample before the first calcination cycle. The results are summarized in Table II.

[0189] Table II. Results of the weight gain test for each Example and Comparative examples.

[0190] Morphology test: o Aim of the experiment:

[0191] Li can diffuse into the tray sample in an uniform manner creating a corrosion layer and eventually cracking the sample. Alternatively, Li can diffuse in a local manner generating lower stress over the whole surface of the tray and thus reducing the cracking.

[0192] Accordingly, a tray wherein the Li diffuses in local manner has an improved corrosion resistance and therefore, an improved lifetime. Scanning Electron Microscopy (SEM) technique is used to investigate the morphology of the corrosion layer (uniform or local). Jeol JSM-F100 microscope is used in this test.

[0193] As mentioned above, the interaction of Li with the components of the tray generates byproducts with a low density which can be easily identified in the SEM images using a backscatter mode. Low density compounds are shown with a darker color in the SEM images, see FIGURES 1 to 10.

[0194] Therefore, by analyzing the SEM images, it is possible to identify the morphology of the corrosion layer, to measure the thickness of the corrosion layer, and to identify the presence or absence of cracks. o Protocol:

[0195] The samples are submitted to the general calcination protocol described above. Then, samples are embedded in an epoxy resin and cut in half using a water-free cutting fluid (Struers) to obtain a cross-section sample.

[0196] To remove the cutting fluid from the pores of the sample, each sample is dried in vacuum for 8 hours at room temperature. The cross-sections samples are grounded (water- free) to 800 grid on SiC using iso-propanol as lubricant and polished in three steps (9 pm - 3 pm - 1 pm) using Struers DP-suspension A combined with DP-lubricant brown. Then, the sample is placed inside the Jeol JSM-F100 microscope using the EDS module. Micrographs are taken in backscatter electron mode (BSE) using an accelerating voltage of 20 kV. o Results:

[0197] Table III shows the morphology of the corrosion layer, the presence or absence of cracks, and the thickness of the corrosion layer for each Example and Comparative example, after 10 calcination cycles.

[0198] Table III. Results of the morphology test for each Example and Comparative examples. Surprisingly, it was found that Li diffuses in a local manner for Examples 1 to 5. Moreover, they also did not show any signs of cracking, see FIGURES 1 to 5. On contrary, comparative examples 1 to 5, show significant signs of cracking, see FIGURES 6 to 10.

[0199] As it can be observed in FIGURES 6 to 10, particularly at the top part of FIGURE 10 in grey color, a layer has been formed on the surface of tray due to formation of low-density side-products. This layer created a volume expansion resulting in the formation of cracks extending almost vertically from the top to the bottom (black lines) of the figures.

Claims

CLAIMS1. A composition for an industrial tray, consisting essentially of SiO? in a content x, MgO in a content y, and AI2O3 in a content z, wherein1.0 < x < 15.0 wt%,10.0 < y < 22.0 wt%, and70.0 < z < 85.0 wt%.

2. A composition according to claim 1, wherein 1.5 < x < 7.0 wt%.

3. A composition according to claim 1 or 2, wherein 13.0 < y < 22.0 wt%.

4. A composition according to any of the claims 1 to 3, wherein 70.0 < z < 80.0 wt%.

5. A composition according to any of the claims 1 to 4, wherein1.5 < x < 5.0 wt%,15.0 < y < 22.0 wt%, and73.0 < z < 80.0 wt%.

6. An industrial furnace tray consisting essentially of SiO? in a content x, MgO in a content y, and AI2O3 in a content z, wherein1.0 < x < 15.0 wt,10.0 < y < 22.0 wt%, and70.0 < z < 85.0 wt%.

7. An industrial furnace tray according to claim 6, consisting essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein1.5 < x < 7.0 wt%,15.0 < y < 22.0 wt%, and73.0 < z < 80.0 wt%.

8. An industrial furnace tray according to claim 6 or 7, consisting essentially of SiO2 in a content x, MgO in a content y, and AI2O3 in a content z, wherein1.5 < x < 5.0 wt%,15.0 < y < 22.0 wt%, and73.0 < z < 80.0 wt.

9. A process for the manufacture of a composition according to any of the claim 1 to 5, comprising the following steps:Step a) providing and mixing the raw materials with the corresponding stoichiometric ratios to provide a mixture;Step b) pressing the mixture to form a material with a thickness between 2 and 6 mm; Step c) heating the material at a temperature of at least 800 °C.

10. A process according to claim 9, wherein 3 wt% of paraffin is also added during Step a.

11. A process according to claim 9 or 10, wherein in Step b), the mixture is cold pressed at least at 100 MPa.

12. The use of an industrial furnace tray according to any of the claims 6 to 8, in the manufacturing process of a cathode active material for lithium batteries.

13. The use of an industrial furnace tray according to claim 12, wherein the industrial furnace reaches temperatures above 800 °C.

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