Method for synthesizing spherical material particles

Abstract

The invention relates to a process for the synthesis of spherical particles of a material carried out in a continuous reactor. One introduction pipe is supplied with a solution A comprising at least one transition metal sulfate, and another introduction pipe is supplied with a solution B comprising a hydroxide or a carbonate. The process comprises feeding the solutions A and B into a reaction tube at flow rates d A and d B transporting the solutions A and B into the reaction tube, and recovering the precipitated precursor at the outlet of the reaction tube. The length of the reaction tube and the transport rates d A and d B are configured so that the residence time in the reaction tube is less than or equal to 10 seconds, wherein the pH in the reaction tube is between 7 and 12 and wherein the regime in the reaction tube is a laminar regime.

Description

[0001] This invention relates to a method for synthesizing spherical material particles, and more particularly to a method for synthesizing precursors for battery electrode materials.

[0002] Various methods, such as coprecipitation, sol-gel, or solid-solid techniques, are currently used to synthesize transition metal precursors (Ni, Mn, Co, etc.) with controlled morphology and / or composition. These different synthetic techniques can be used to obtain mixtures of transition metals in the form of carbonates or hydroxides. Coprecipitation is the most commonly used method because it produces aggregates with particularly homogeneous morphology and composition. It is mainly carried out in a temperature-controlled stirred reactor, into which a solution containing the transition metal and an alkaline solution (e.g., containing carbonates or hydroxides) to be precipitated together with the transition metal are introduced. Unfortunately, this technique requires several hours of aging time before obtaining the desired transition metal precursor. As described by Pimenta et al. (Chem. Mater. 2017, 29, 9923-9936), a aging time of 4 hours at 55°C is required to obtain homogeneous spherical aggregates with the desired composition in order to synthesize manganese-rich carbonates.

[0003] Therefore, these conventional synthesis methods need to be improved.

[0004] CN110875472 describes a synthesis apparatus having a T-shaped microfluidic reactor supplying two solutions: a first solution containing a mixture of metal salts and a second alkaline solution; leading to a ripening tank. Unfortunately, as in this case, ripening in the ripening tank for 2 to 10 hours is required to obtain the desired transition metal precursor.

[0005] The literature H. Liang et al., Chemical Engineering Journal 394(2020)124846 describes another device with a T-shaped microfluidic reactor. In this literature, the reactor is supplied with a first solution and a second sodium carbonate solution (Na2CO3) dissolved in N-hexadecyl-N,N,N-trimethylammonium bromide. The first solution contains a mixture of NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O, wherein the molar ratio of Ni / Co / Mn is equal to 0.6:0.2:0.2. The reaction is carried out at a temperature of 60 °C and the time in the reactor is only 12 seconds. The precipitated transition metal precursor is directly recovered at the reactor outlet. However, this synthetic method produces aggregates of several hundred nanometers instead of the micrometer-sized aggregates expected for use as high-performance electrochemical active materials in batteries.

[0006] The purpose of this invention is, in particular, to overcome these shortcomings in the prior art.

[0007] More specifically, the object of the present invention is to provide a method for rapidly synthesizing active material precursors for battery electrodes having uniform micron-sized shapes.

[0008] Therefore, the object of the present invention is a method for synthesizing spherical material particles, said method being carried out in a continuous reactor, said continuous reactor being formed of a reaction tube supplied by two inlet pipes, said reaction tube having a length L.

[0009] One of the two inlet tubes is supplied with solution A, which contains a sulfate of at least one transition metal selected from nickel (Ni), aluminum (Al), magnesium (Mg), titanium (Ti), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and cobalt (Co).

[0010] Another inlet tube supplies solution B, which contains a hydroxide or carbonate and optionally a chelating agent.

[0011] The method includes the following steps:

[0012] a) respectively with d A and d B The flow rate delivers solutions A and B to the reaction tube of the continuous reactor, thereby causing the precursor to precipitate in the reaction tube, and

[0013] b) The precursor of the precipitate is recovered at the outlet of the reaction tube, wherein the length of the reaction tube is L and the flow rate is d. A and d B It is configured such that the residence time in the reaction tube is less than or equal to 10 seconds, and wherein the pH in the reaction tube is 7 to 12.

[0014] The inventors unexpectedly discovered that short residence times in the reaction tube (less than or equal to 10 seconds) enabled the production of micron-sized spherical material particles with uniform morphology and composition. In fact, contrary to intuition, reaction times shorter than those of the same order of magnitude used in existing technologies allowed for the production of larger (micron-sized rather than nanometer-sized) and more uniformly shaped aggregates. Equally unexpectedly, drastically reduced reaction times (seconds instead of hours) produced aggregates of similar size. These different aspects enable a significantly faster production time for precursors used in micron-sized battery electrode materials.

[0015] The residence time in the reaction tube is a crucial factor in carrying out the synthesis method according to the invention. According to one embodiment, the residence time in the reaction tube is from 1 millisecond to 10 seconds. Specifically, the residence time in the reaction tube is at least 10 milliseconds, particularly at least 50 milliseconds, and preferably at least 100 milliseconds. In this invention, "at least 10 milliseconds" is understood to be a time less than 10 seconds and at least 10 milliseconds, at least 20 milliseconds, at least 30 milliseconds, at least 40 milliseconds, at least 50 milliseconds, at least 60 milliseconds, at least 70 milliseconds, at least 80 milliseconds, at least 90 milliseconds, at least 100 milliseconds, at least 110 milliseconds, at least 120 milliseconds, at least 130 milliseconds, at least 140 milliseconds, at least 150 milliseconds, at least 160 milliseconds, at least 170 milliseconds, at least 180 milliseconds, at least 190 milliseconds, at least 200 milliseconds, at least 210 milliseconds, at least 220 milliseconds, at least 230 milliseconds, at least 240 milliseconds. Milliseconds, at least 250 milliseconds, at least 260 milliseconds, at least 270 milliseconds, at least 280 milliseconds, at least 290 milliseconds, at least 300 milliseconds, at least 310 milliseconds, at least 320 milliseconds, at least 330 milliseconds, at least 340 milliseconds, at least 350 milliseconds, at least 360 milliseconds, at least 370 milliseconds, at least 380 milliseconds, at least 390 milliseconds, at least 400 milliseconds, at least 410 milliseconds, at least 420 milliseconds, at least 430 milliseconds, at least 440 milliseconds, at least 450 milliseconds, at least 460 milliseconds, at least 470 milliseconds, at least 480 milliseconds, at least 490 milliseconds, or at least 500 milliseconds. The residence time in the reaction tube is less than 10 seconds, and in particular, it can be less than or equal to 5 seconds, for example, less than or equal to 1 second.In this invention, "less than 10 seconds" is understood to mean a time of at least 10 milliseconds and less than 10 seconds, less than or equal to 9 seconds, less than or equal to 8 seconds, less than or equal to 7 seconds, less than or equal to 6 seconds, less than or equal to 5 seconds, less than or equal to 4 seconds, less than or equal to 3 seconds, less than or equal to 2 seconds, less than or equal to 1 second, less than or equal to 900 milliseconds, less than or equal to 890 milliseconds, less than or equal to 880 milliseconds, less than or equal to 870 milliseconds, less than or equal to 860 milliseconds, less than or equal to 850 milliseconds, less than or equal to 840 milliseconds, less than or equal to 830 milliseconds, less than or equal to 820 milliseconds, less than or equal to 810 milliseconds, less than or equal to 800 milliseconds, less than or equal to 790 milliseconds, less than or equal to 780 milliseconds, less than or equal to 770 milliseconds, less than or equal to 760 milliseconds, less than or equal to 750 milliseconds, less than or equal to 740 milliseconds, less than or equal to 7... 30 milliseconds, less than or equal to 720 milliseconds, less than or equal to 710 milliseconds, less than or equal to 700 milliseconds, less than or equal to 690 milliseconds, less than or equal to 680 milliseconds, less than or equal to 670 milliseconds, less than or equal to 660 milliseconds, less than or equal to 650 milliseconds, less than or equal to 640 milliseconds, less than or equal to 630 milliseconds, less than or equal to 620 milliseconds, less than or equal to 610 milliseconds, less than or equal to 600 milliseconds, less than or equal to 590 milliseconds, less than or equal to 580 milliseconds, less than or equal to 570 milliseconds, less than or equal to 560 milliseconds, less than or equal to 550 milliseconds, less than or equal to 540 milliseconds, less than or equal to 530 milliseconds, less than or equal to 520 milliseconds, less than or equal to 510 milliseconds, less than or equal to 500 milliseconds, less than or equal to 470 milliseconds, less than or equal to 480 milliseconds, less than or equal to 490 milliseconds, or less than or equal to 500 milliseconds. For example, 1 millisecond to 10 seconds is understood in this invention as 1 millisecond, 10 milliseconds, 50 milliseconds, 100 milliseconds, 150 milliseconds, 200 milliseconds, 250 milliseconds, 300 milliseconds, 350 milliseconds, 400 milliseconds, 450 milliseconds, 500 milliseconds, 550 milliseconds, 600 milliseconds, 650 milliseconds, 700 milliseconds, 750 milliseconds, 800 milliseconds, 850 milliseconds, 900 milliseconds, 950 milliseconds, 1 second, 1.5 seconds, 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, 5 seconds, 5.5 seconds, 6 seconds, 6.5 seconds, 7 seconds, 7.5 seconds, 8 seconds, 8.5 seconds, 9 seconds, 9.5 seconds, and 10 seconds.

[0016] According to one embodiment of the invention, the state in the reaction tube is laminar. The inventors unexpectedly discovered that, surprisingly, laminar flow alone in the reaction tube produces greater reaction efficiency. In fact, conversely, the common practice in the prior art is to attempt to achieve a turbulent state to increase the likelihood of reactant encounters, particularly by using high flow rates in small-diameter tubes, or by adding elements such as spherical shapes or fixed mixing elements to the reaction tube. The conditions of the present invention allow for the production of precursors containing at least two transition metals, which is impossible in intermediate or turbulent states.

[0017] In this invention, "laminar flow" is understood to mean a fluid flow pattern in which all fluids flow more or less in the same direction without local differences that cancel each other out. Laminar flow is particularly characterized by Reynolds numbers less than 1500.

[0018] In this invention, "intermediate state" is understood to mean a fluid flow pattern in which all fluids flow more or less in the same direction with minimal mixing (small eddies). The intermediate state can be characterized, in particular, by a Reynolds number between 1500 and 3000.

[0019] In this invention, "turbulent state" is understood to mean a fluid flow pattern in which all fluids have eddies at every point, and the size, location, and direction of these eddies are constantly changing. Turbulent state can be particularly characterized by a Reynolds number greater than 3000.

[0020] According to one embodiment of the invention, the flow in the reaction tube is laminar and has a Reynolds number of less than 1500. Preferably, the flow in the reaction tube is laminar and has a Reynolds number of less than 1000; more preferably, the flow in the reaction tube is laminar and has a Reynolds number of less than 500.

[0021] The length L of the reaction tube in the continuous reactor used in the synthesis method of the present invention can be of any size, as long as the residence time in the tube is less than or equal to 10 seconds. The tube length L is suitable for the flow rates of solutions A and B, and particularly suitable for obtaining a laminar flow state in the reaction tube. In particular, the length L of the reaction tube is at least 1 mm.

[0022] According to the present invention, the inner diameter of each inlet pipe is adapted to achieve a laminar flow state.

[0023] Specifically, the inner diameter of each inlet tube and the inner diameter of the reaction tube are at least 0.5 mm.

[0024] The reaction tube and the inlet tube are preferably simple tubes, i.e., without any internal components. The reaction tube and the inlet tube preferably have a circular cross-section.

[0025] The inner diameter of each inlet tube and the inner diameter of the reaction tube are preferably greater than 1 mm, particularly greater than 1 cm, for example greater than 2 cm. More preferably, the inner diameter of each inlet tube and the inner diameter of the reaction tube are 1 mm to 1.5 mm.

[0026] The synthesis method according to the invention advantageously eliminates the need for heating the reaction tube to obtain the precursor. This synthesis method can advantageously be carried out at room temperature as well as at higher temperatures. Accordingly, the temperature in the reaction tube is 20°C to 70°C, preferably 25°C to 50°C. In this invention, "20℃ to 70℃" is understood to mean 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, and 70℃.

[0027] The pH range in the reaction tube is obtained by adjusting the concentrations of the compounds in solutions A and B and / or the injection flow rates of solutions A and B. When carbonates are present in solution B, the pH value in the reaction tube is preferably 7 to 10, particularly 8. When hydroxides are present in solution B, the pH value in the reaction tube is 9 to 12, particularly 11.

[0028] The synthesis method according to the present invention can be used to obtain any type of precursor for active materials of battery electrodes, such as precursors for Li-ion or Na-ion batteries.

[0029] According to one embodiment of the invention, solution A comprises sulfates of at least two transition metals selected from nickel (Ni), aluminum (Al), magnesium (Mg), titanium (Ti), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and cobalt (Co). In particular, the solution comprises at least three transition metal sulfates, at least four transition metal sulfates, at least five transition metal sulfates, at least six transition metal sulfates, at least seven transition metal sulfates, or at least eight transition metal sulfates.

[0030] According to one embodiment of the invention, solution A contains a sulfate of at least one transition metal selected from nickel (Ni), aluminum (Al), manganese (Mn) and cobalt (Co), particularly at least two transition metal sulfates, particularly at least three transition metal sulfates, particularly four transition metal sulfates, and particularly the molar ratio of Ni:Co:Mn:Al is 0-1:0-1:0-1:0-1.

[0031] Specifically, solution A contains one of the following fourteen combinations of transition metal sulfates:

[0032] [Table 1]

[0033] combination Ni Al Mn Co 1 + 2 + 3 + 4 + + 5 + + 6 + + 7 + + 8 + + 9 + + 10 + + + 11 + + + 12 + + + 13 + + + 14 + + + +

[0034] For example, the molar ratio Ni:Co:Mn:Al is 0.8:0.05:0.1:0.05 or 0.2:0.15:0.6:0.05. Specifically, the precursor comprises transition metals Ni, Mn, and Co, wherein the molar ratio Ni:Mn:Co is 1 / 3:1 / 3:1 / 3 or 0.2:0.5:0.3. Specifically, the precursor comprises transition metals Ni and Mn, wherein the molar ratio Ni:Mn is 0.25:0.75. Such a composition of transition metals is particularly useful for obtaining precursors for Li-ion batteries. Specifically, solution A also contains sulfates of at least one transition metal selected from magnesium (Mg), titanium (Ti), copper (Cu), zinc (Zn), and iron (Fe), particularly at least two transition metal sulfates, particularly at least three transition metal sulfates, particularly at least four transition metal sulfates, particularly five transition metal sulfates. Such a composition of solution A is particularly useful for obtaining precursors for Na-ion batteries.

[0035] Specifically, solution A contains one of the following 433 combinations of transition metal sulfates:

[0036] [Table 2]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] Such a composition includes, for example, nickel sulfate, zinc sulfate, manganese sulfate and titanium sulfate, wherein the molar ratio Ni:Zn:Mn:Ti is equal to 0.48:0.02:0.4:0.1.

[0052] The concentration of the at least one transition metal sulfate in solution A is 0.1 mol / L until saturation, particularly 2 mol / L. Specifically, the concentration of the at least one transition metal sulfate in solution A is at least 0.1 mol / L. "At least 0.1 mol / L" is understood in this invention to mean at least 0.1 mol / L, at least 0.2 mol / L, at least 0.3 mol / L, at least 0.4 mol / L, at least 0.5 mol / L, at least 0.6 mol / L, at least 0.7 mol / L, at least 0.8 mol / L, at least 0.9 mol / L, at least 1 mol / L, at least 1.1 mol / L, at least 1.2 mol / L, at least 1.3 mol / L, at least 1.4 mol / L, at least 1.5 mol / L, at least 1.6 mol / L, at least 1.7 mol / L, at least 1.8 mol / L, and at least 1.9 mol / L.

[0053] Solution B is an aqueous solution containing hydroxides or carbonates and optionally chelating agents.

[0054] In this invention, "hydroxide" is understood to mean any compound that produces hydroxide ions (OH-) when dissolved in water. When these hydroxide ions come into contact with a transition metal in solution A in a reaction tube, the hydroxide ions precipitate together with the transition metal in solution A. According to one embodiment of the invention, the hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, 8-hydroxyquinoline, ammonia, lithium hydroxide, and mixtures thereof. Sodium hydroxide is preferred. The hydroxide concentration can range from 0.1 mol / L to saturation. For example, in the case of sodium hydroxide, the saturation concentration is 27 mol / L. A hydroxide concentration of 4 mol / L is preferred.

[0055] In this invention, "carbonate" is understood to mean the carbonate ion (CO3) produced when dissolved in water. 2-Any compound of ( ). When the carbonate ion comes into contact with the transition metal of solution A in the reaction tube, the carbonate ion precipitates together with the transition metal of solution A. According to one embodiment, the carbonate is selected from the group consisting of ammonium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, and mixtures thereof. In particular, the carbonate is selected from the group consisting of sodium carbonate, potassium carbonate, lithium carbonate, and mixtures thereof. The carbonate is preferably sodium carbonate. The carbonate concentration can range from 0.1 mol / L to saturation. In the case of sodium carbonate, saturation corresponds to a concentration of 2 mol / L at room temperature. The carbonate concentration is preferably a saturation concentration.

[0056] In this invention, "chelating agent" is understood to mean any compound having the property of chelating / combining with transition metals present in solution A. The presence of such a compound is advantageous because it allows for control of the composition during precipitation. According to one embodiment of the invention, the chelating agent can be any type of ammonium, such as primary, secondary, tertiary, or quaternary ammonium. In particular, the chelating agent is selected from the group consisting of ammonia and N-hexadecyl-N,N,N-trimethylammonium bromide. Ammonia is preferred as the chelating agent. The concentration of the chelating agent can range from 0.1 mol / L to 5 mol / L. In particular, in the case of ammonia, the concentration is preferably 0.4 mol / L.

[0057] Solutions A and B are transported by any means, particularly by any type of pump. For example, solutions A and B are transported by a pump that ensures a constant flow rate. Based on this, the pump used can be a pneumatic diaphragm pump, a peristaltic pump, or a positive displacement pump. According to one embodiment of the invention, solutions A and B are each transported by a peristaltic pump.

[0058] Adjust the flow rates of solutions A and B such that the residence time in the reaction tube is less than or equal to 10 seconds, and specifically, the flow state in the reaction tube is laminar. Solutions A and B can be delivered at the same or different flow rates. Specifically, the flow rate d of solution A... A The flow rate d is greater than that of solution B B The ratio d of the flow rates of solution A and solution B. A :d B The preferred ratio is 0.5:1 to 5:1. According to one embodiment of the invention, the conveying flow rate d... A and d B Each of them is at least 0.01 ml / min.

[0059] The inlet pipe has an outlet that opens in the initial portion of the reaction tube. The initial portion of the reaction tube is understood to be in the direction of flow through the reaction tube. This initial portion (also called the mixer) is the mixing space for solution A and solution B. According to one embodiment of the invention, the outlet of the inlet pipe is configured such that the mixing of solution A and solution B in the mixer is carried out by co-current or counter-current flow.

[0060] To achieve countercurrent mixing, the flows of solutions A and B must be substantially parallel to each other but in opposite directions. In this way, the flow of solution A projects onto the flow of solution B. Countercurrent mixing can be achieved, in particular, by orienting the outlets of the inlet pipes to be substantially parallel to each other and facing each other. The term "substantially" is understood here to encompass a parallel orientation deviation of no more than 10 degrees between the two outlets of the inlet pipes. The outlets can be arranged in various ways. For example, the intersection between the inlet pipe and the reaction pipe will have a "T" shape. The remaining portions of the reaction pipe and the inlet pipe can take any orientation. Alternatively, one outlet of the inlet pipe may have a larger diameter than the other outlet. The mixer of the reaction pipe can then correspond to the continuity of the inlet pipe with the largest diameter opening, and at the end which includes the smallest inlet pipe. Again, the remaining portions of the reaction pipe and the inlet pipe can take any orientation. In any case, the flow rate of the solution is suitable and high enough that there is no backflow in the inlet pipes. In particular, one or more check valves can be arranged at the end of the smallest inlet pipe to prevent such backflow.

[0061] To achieve co-current mixing, solutions A and B have flows that are substantially parallel to each other and in the same direction, and the flow of one solution must be contained within the flow of the other. In this way, the two solutions are mixed in a virtual tube corresponding to the contact zone between the two solution flows. The term "substantially" is understood here to mean that the parallel orientation deviation of the two outlets of the inlet tube does not exceed 10 degrees. Co-current mixing can be achieved, in particular, by arranging the outlet of one inlet tube within the outlet of the other tube. In this way, one outlet has a larger diameter than the other. Similarly, the mixer of the reaction tube corresponds to an extension of the inlet tube with the outlet having the largest diameter. Also, the remaining portions of the reaction tube and the inlet tube can take any orientation.

[0062] According to one embodiment of the invention, during step b), the precipitated precursor is recovered at the reactor outlet only after a duration of at least 5 seconds, particularly at least 10 seconds, particularly at least 20 seconds, for example at least 30 seconds. In practice, the precipitate obtained within the first 5 seconds may exhibit a certain degree of inhomogeneity that is no longer present after that time. Therefore, it is preferable not to recover the precipitate leaving the reactor within the first 5 seconds.

[0063] The present invention also relates to the use of a continuous reactor for synthesizing spherical material particles, said continuous reactor being formed of a reaction tube supplied by two inlet pipes, the reaction tube having a length L.

[0064] One of the two inlet tubes is supplied with solution A, which contains a sulfate of at least one transition metal selected from nickel (Ni), aluminum (Al), magnesium (Mg), titanium (Ti), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and cobalt (Co).

[0065] Another inlet tube supplies solution B, which contains a hydroxide or carbonate and optionally a chelating agent.

[0066] Solution A and solution B are respectively expressed as d A and d B The flow rate is fed into the reaction tube of the continuous reactor, causing the precursor to precipitate in the reaction tube, and the precipitated precursor is recovered at the outlet of the reaction tube.

[0067] Furthermore, the length L of the reaction tube and the flow rate d are specified. A and d B It is configured such that the residence time in the reaction tube is less than or equal to 10 seconds, and wherein the pH in the reaction tube is 7 to 12.

[0068] Finally, the present invention relates to spherical particles obtained using the above method or that can be obtained using the above method. Attached Figure Description

[0069] [ Figure 1 [Illustration] is a diagram of the T-shaped continuous reactor used in the synthesis method according to the present invention.

[0070] [ Figure 2 Two figures (A and B) are combined, relating to the chemical classification and purity of the precursor precipitated using the synthetic method according to the invention. Figure a) shows the results of X-ray diffraction of the precursor. The x-axis represents 2θ in degrees and the y-axis represents intensity in arbitrary units. Figure b) shows the results of thermogravimetric analysis of a 30 mg sample of the precursor. The x-axis shows temperature in °C and the y-axis shows the mass of the sample as a percentage. The double arrows indicate the mass loss (-35.5%) obtained at 640 °C.

[0071] [ Figure 3 [A and B] are a series of images (A and B) obtained by scanning electron microscopy of aggregates of precursors precipitated according to the synthesis method of the present invention. The white bars indicate the scale of each image.

[0072] [ Figure 4 The diagram shows the volumetric distribution of aggregate sizes of precursor samples precipitated using the synthesis method according to the invention. Figure 4 A) and distribution in terms of quantity ( Figure 4 (B). In Figure 4In A, the x-axis shows the size of the aggregates in micrometers and the y-axis shows the volume occupied by the aggregates as a percentage. Figure 4 In B, the x-axis shows the size of the aggregates in micrometers and the y-axis shows the number of aggregates as a percentage.

[0073] [ Figure 5 The diagram illustrates the thermal cycling used to synthesize a positive electrode active material from a precursor obtained using the synthesis method according to the invention. In this figure, A represents the initial conditions corresponding to room temperature (25°C). The temperature is then increased at a rate of 3.5°C / min until it reaches 400°C. B corresponds to decarburization, where the temperature is held at 400°C for 2 hours. The temperature is then increased at a rate of 3.5°C / min until it reaches 900°C. C corresponds to crystallization, where the temperature is held at 900°C for 12 hours. The temperature is then decreased at a rate of 2°C / min, returning to room temperature at point D.

[0074] [ Figure 6 The diagram shows an X-ray diffraction pattern of a positive electrode active material obtained from a precursor synthesized using the method according to the invention. The x-axis represents 2θ in degrees, and the y-axis represents intensity in arbitrary units. The inset shows a revised view of the diffraction pattern with 2θ values ​​ranging from 30° to 80°. Hollow circles represent observed intensity values. Black lines within the hollow circles represent expected theoretical values. The black lines at the bottom represent the difference between the observed and expected values ​​(no peak corresponds to no observed difference). The vertical black lines above the black lines indicate the location of Bragg reflections.

[0075] [ Figure 7 [A and B] are a series of images (A and B) obtained by scanning electron microscopy of aggregates of positive electrode active materials obtained by precipitating precursors using the synthesis method according to the invention. The white bars indicate the scale on each image.

[0076] [ Figure 8 The figure shows the discharge capacity (mAh.g) of the 2032 button cell as a function of cycle number. -1 The button cell contains a positive electrode active material obtained from a precursor precipitated using the synthesis method according to the invention.

[0077] [ Figure 9 The diagram shows X-ray diffraction patterns of two precursors obtained by comparative synthesis methods, where solutions A and B are delivered at flow rates of 4 ml / min, and the reaction tubes of the microfluidic reactors are 1 m (curve 1) or 2 m (curve 2). The x-axis represents 2θ in degrees, and the y-axis represents intensity in arbitrary units. The origin of the y-axis in curve 2 has been shifted for easier reading of the diagram.

[0078] [ Figure 10 Two images of aggregates of precursors precipitated using a comparative synthesis method, obtained by scanning electron microscopy, are shown, with flow rates of 4 ml / min for solutions A and B, and with reaction tubes of microfluidic reactors 1 meter in length. Figure 10 A) or 2 meters ( Figure 10 (B). The white bars indicate the proportions on each image.

[0079] [ Figure 11 The image shows the precursor Ni obtained according to the method of the present invention. 0.25 Mn 0.75 The result of the X-ray diffraction pattern of CO3. The x-axis represents 2θ in degrees and the y-axis represents the intensity in arbitrary units.

[0080] [ Figure 12 [ ] is the precursor Ni obtained according to the method of the present invention. 0.25 Mn 0.75 A series of images (A and B) of CO3 aggregates obtained by scanning electron microscopy. The white bars indicate the scale of each image.

[0081] [ Figure 13 The image shows the precursor Ni obtained according to the method of the present invention. 1 / 3 Mn 1 / 3 Co 1 / 3 The result of the X-ray diffraction pattern of CO3. The x-axis represents 2θ in degrees and the y-axis represents the intensity in arbitrary units.

[0082] [ Figure 14 [ ] is the precursor Ni obtained according to the method of the present invention. 1 / 3 Mn 1 / 3 Co 1 / 3 A series of images (A and B) of CO3 aggregates obtained by scanning electron microscopy. The white bars indicate the scale of each image.

[0083] [ Figure 15 The image shows the precursor Ni obtained according to a method in which the state in the reaction tube is turbulent. 1 / 3 Mn 1 / 3Co 1 / 3 The result of the X-ray diffraction pattern of CO3. The x-axis represents 2θ in degrees and the y-axis represents the intensity in arbitrary units.

[0084] [ Figure 16 The precursor Ni was obtained using a method based on turbulent flow in the reaction tube. 1 / 3 Mn 1 / 3 Co 1 / 3A series of images (A, B, and C) of CO3 aggregates obtained by scanning electron microscopy. The white bars indicate the scale of each image. Example

[0085] 1. T-shaped continuous reactor

[0086] The continuous reactor 1 used in this invention is shown in Figure 1 The diagram illustrates a T-shaped continuous reactor consisting of two mutually facing inlet pipes 3, each supplied with a solution (A or B). These solutions converge at an intersection and flow into a reaction pipe 5, which is perpendicular to the direction of the inlet pipes 3 at the intersection. Thus, countercurrent flow is achieved at the intersection of the two inlet pipes 3. Solution A contains a transition metal sulfate, and solution B contains a hydroxide or carbonate and a complexing agent. Solutions A and B are transported to reactor 1 by means of a peristaltic pump 7. Precursors precipitate in the reaction pipe, which leads to a tank 9 for recovering the precipitated precursors.

[0087] 2. Carbonate precursor Ni 0.2 Mn 0.5 Co 0.3 CO3

[0088] The inventors first synthesized a manganese-rich carbonate precursor with the composition Ni. 0.2 Mn 0.5 Co 0.3 CO3.

[0089] a. Preparation of the starting solution

[0090] To this end, a 250 mL solution A of transition metal sulfates was prepared by weighing 26.29 g NiSO4·6H2O, 42.26 g MnSO4·H2O, and 42.17 g CoSO4·7H2O. These sulfates were dissolved in distilled water and then placed in a 250 mL volumetric flask and filled to the mark. The Ni / Mn / Co molar ratio was 2 / 5 / 3. The concentration of this solution was 2 mol / L. A 250 mL solution B containing sodium carbonate and a complexing agent (NH4OH) was prepared by dissolving 47.69 g Na2CO3 and 11.26 g NH4OH in distilled water and then placing the solution in a 250 mL volumetric flask and filling to the mark. The concentration of Na2CO3 was 1.8 mol / L, and the concentration of NH4OH was 0.36 mol / L.

[0091] b. Synthesis conditions

[0092] The sampling flow rate for solutions containing transition metals was 20 mL / min, while that for solutions containing carbonates was 12 mL / min. The pH of the solution containing the precipitate was 7.8. The discharge tube from the reactor was 10 cm long and had an inner diameter of 1.39 mm. Under these conditions, the residence time in the discharge tube was 0.3 seconds, and the fluid state in the reactor was laminar. No precipitate was sampled for the first 30 seconds of the reaction, followed by sampling for 60 seconds. The precipitate was then washed with distilled water by centrifugation (until the wash water was neutralized) and dried overnight in an oven at 70°C.

[0093] The recovered transition metal carbonate after drying weighed 2.56 g, consistent with the expected theoretical yield (2.53 g). This indicates that the reaction yield was close to 100%.

[0094] c. Analysis of precipitates

[0095] X-ray diffraction (XRD) was performed and the results are shown in... Figure 2 In A. The diffraction pattern shows that all lines are indexable in space group R-3c, with lattice parameters as follows: Therefore, the diffraction pattern confirmed the acquisition of a carbonate without any crystalline impurities. Furthermore, thermogravimetric analysis was performed on approximately 30 mg of the powder in air at a rising rate of 10 °C / min at temperatures ranging from 25 °C to 700 °C. The results are shown in... Figure 2 In B, it was also confirmed that carbonates without any crystallization impurities were obtained, as the experimental mass loss (-35.5%) was comparable to the expected theoretical mass loss (-37.6%).

[0096] Chemical analysis was performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the chemical composition of the precipitate:

[0097] [Table 3]

[0098] Ni Mn Co experiment 0.17±0.01 0.53±0.02 0.30±0.01 theory 0.2 0.5 0.3

[0099] The experimental setup was consistent with the expected theoretical setup.

[0100] The morphology of the aggregates was verified by scanning electron microscopy (SEM), and the results are shown in... Figure 3 The observed aggregate diameter was approximately 6 micrometers. This value and uniformity were verified by laser particle size analysis, the results of which are shown in [Figure / Reference]. Figure 4 The volume distribution 50 (D50) of the precipitate was 6.3 μm, consistent with observations made using SEM.

[0101] d. Preparation of active materials and electrochemical properties

[0102] Then, the inventors used the precursor Ni 0.2 Mn 0.5 Co 0.3 CO3 is mixed with Li2CO3 to synthesize Li(Li) 0.15 Ni 0.17 Mn 0.425 Co 0.255 O2 is used as the positive electrode active material in batteries.

[0103] Therefore, 2g of Ni was placed in an agate mortar. 0.2 Mn 0.5 Co 0.3 CO3 was mixed with 0.8980 g Li2CO3 (5% excess by mass to prevent any lithium loss during calcination of the material at high temperature) for at least 5 minutes until a homogeneous colored mixture was obtained. The mixture was then placed in a gold crucible and placed in a tube furnace for heat treatment in air at high temperature, the thermal cycle of which is shown in [illustration]. Figure 5 middle.

[0104] XRD was performed on the active material. The results are shown in... Figure 6 In the study, a layered oxide was obtained, whose X-ray diffraction pattern can be indexed in space group R-3m, where the lattice parameters are... as well as The synthesized material was pure, and no crystalline second phase was observed. The lattice parameters obtained after refining using the Le Bail method were consistent with those obtained for the same compound from a precursor synthesized via coprecipitation. as well as The Le Bail method is described in particular in the literature Petricek, V., Dusek, M. & Palatinus, L. (2014). Z. Kristallogr. 229(5), 345-352.

[0105] The chemical composition was verified by ICP-OES, and the results are shown in the table below.

[0106] [Table 4]

[0107] Li Ni Mn Co carbonates 1.18±0.03 0.137±0.004 0.435±0.013 0.247±0.007 oxides 1.15 0.144 0.450 0.255 Theoretical 1.15 0.17 0.425 0.255

[0108] Given a Ni / Mn / Co ratio of 2 / 5 / 3, the last row of Table 2 corresponds to the expected composition of lithium oxide. Considering the Ni / Mn / Co ratio of 2 / 5 / 3, the obtained carbonates (first row of the table) and oxides (second row of the table) deviate very slightly from the expected composition of lithium oxide (last row of the table). Therefore, the obtained material is ideal for use as an active material in a battery cathode.

[0109] Figure 7 The SEM images shown illustrate the morphology of the aggregates of the obtained material. Similar to the precursor, spherical aggregates of approximately 6 μm were obtained.

[0110] An electrode was prepared consisting of 92% active material, 4% carbon black, and 4% polyvinylidene fluoride (PVDF) (92 / 4 / 4 by mass). For this purpose, a PVDF solution dissolved in N-methyl-2-pyrrolidone (5% by mass) was first prepared. The active material and carbon black were then suspended in this solution, and the desired amount of N-methyl-2-pyrrolidone was added to obtain a dry matter content of approximately 30% to 40%. The mixture was allowed to stand for 1 hour with magnetic stirring. The electrode was then coated using a method known as "DoctorBlade". The 4340 coater applies the resulting ink to an aluminum strip (coating thickness of 150 μm).

[0111] Finally, the electrodes were placed in an 80°C oven to evaporate the solvent. Electrodes with a diameter of 16 mm were die-cut and then calendered under 5 tons of unidirectional pressure. Finally, these electrodes were dried in a vacuum at 80°C for 12 hours and then stored in a glove box under a controlled argon atmosphere. The basis weight was 4 mg of active material / cm³. 2 Then, in the presence of Li, two [unclear] were used in the CR2032 button cell. Electrochemical tests were performed on a 2400-separator. The electrolyte used was a mixture of fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) (30 / 70 by mass%) in which 1M lithium hexafluorophosphate (LiPF6) was dissolved. Continuous charge and discharge cycles (i.e., 10 hours to fully charge or discharge the battery) were performed at C / 10. The change in discharge capacity as a function of the number of cycles is shown below. Figure 8 The figure shows that the capacity remained stable at approximately 200 mAh / g during the first 30 cycles of the tested battery.

[0112] e. The effect of residence time in the reactor

[0113] The inventors tested the effects of longer residence times (greater than 10 seconds) in the discharge tube from the reactor on the morphology and uniformity of the obtained precursors.

[0114] For this purpose, initial solutions A and B from Example 2.a. were used. Two different reactors (1 and 2) were then used, with reactor 1 having a 1-meter discharge pipe length and reactor 2 having a 2-meter discharge pipe length. The inner diameter of each reactor 1 and 2 was 1.39 mm. In each case, the sampling flow rate for solutions A and B was 4 mL / min. The residence time in the discharge pipe of reactor 1 was 11.4 seconds, and the residence time in the discharge pipe of reactor 2 was 22.8 seconds. The fluid state in the reactors was laminar flow. The pH of each solution containing the precipitate was 8.

[0115] The obtained precipitate was subjected to X-ray diffraction (XRD) and the results are shown in... Figure 9 The diffraction pattern shows that all lines are indexable in the R-3c space group, with the following lattice parameters: The diffraction pattern confirmed the presence of carbonates without any crystalline impurities.

[0116] The chemical composition was verified by ICP-OES, and the results are shown in the table below.

[0117] [Table 5]

[0118] Ni Mn Co Reactor 1 0.18±0.01 0.51±0.02 0.31±0.01 Reactor 2 0.18±0.01 0.51±0.02 0.31±0.01 Theoretical 0.2 0.5 0.3

[0119] The experimental composition obtained from each reactor was consistent with the expected theoretical composition.

[0120] The morphology of the aggregates was verified using scanning electron microscopy, and the results are shown in... Figure 10 In each case, the observed aggregates are partially spherical, exhibiting a high degree of inhomogeneity in both shape and size. Furthermore, the aggregate size is at most about 1 μm. Therefore, a residence time exceeding 10 seconds in the discharge tube degrades the properties of the obtained precursor, which no longer possesses the diameter and uniformity of the precursor obtained using the synthesis method according to the invention.

[0121] 3. Carbonate precursor Ni 0.25 Mn 0.75 CO3

[0122] The inventors then synthesized a manganese-rich carbonate precursor with the composition Ni. 0.25 Mn 0.75 CO3.

[0123] a. Preparation of the starting solution

[0124] To this end, a 50 mL solution of transition metal sulfates was prepared by weighing 6.57 g of NiSO4·6H2O and 12.68 g of MnSO4·H2O. These sulfates were dissolved in distilled water and then placed in a 50 mL volumetric flask, filled to the mark. The Ni / Mn / Co molar ratio was 1 / 3:1 / 3:1 / 3. The concentration of this solution was 2 mol / L. A 50 mL solution containing sodium carbonate and a complexing agent (NH4OH) was prepared by weighing 10.60 g of Na2CO3 and 2.25 g of NH4OH. Na2CO3 was dissolved in distilled water in the presence of NH4OH and then placed in a 50 mL volumetric flask, filled to the mark. The concentration of Na2CO3 was 2 mol / L, and the concentration of NH4OH was 0.36 mol / L.

[0125] b. Synthesis conditions

[0126] The solution was injected into the mixer / reactor system using a peristaltic pump. The sampling flow rate for the solution containing the transition metal was set to 5 mL / min (Qa), and the sampling flow rate for the solution containing the carbonate was set to 5 mL / min (Qb) (therefore Qa = Qb). The reactor was 10 cm long and had an inner diameter of 1.39 mm. Under these conditions, the residence time in the reactor was 0.91 seconds, and the fluid state in the reactor was laminar. To ensure the homogeneity of the recovered precipitate, the precipitate was not recovered for the first 30 seconds of the reaction, and then sampled under the aforementioned conditions for 60 seconds. The pH of the solution containing the precipitate was 8.7. The precipitate was then washed with distilled water by centrifugation (until the wash water was neutralized) and dried overnight in an oven at 70°C.

[0127] The recovered transition metal carbonate after drying was 2.33 g, consistent with the expected theoretical yield (2.37 g). This indicates that the reaction yield was close to 100%. Therefore, 2.33 g of Ni carbonate was produced within 60 seconds. 0.25 Mn 0.75 CO3. This represents a yield of 140 g / hour for a 0.15 mL reactor, compared to 16 g in a 500 mL batch reactor over 6 hours as used in the prior art.

[0128] c. Analysis of precipitates

[0129] X-ray diffraction (XRD) was performed and the results are shown in... Figure 11 The diffraction pattern confirms the presence of a carbonate without any crystalline impurities.

[0130] Chemical analysis was performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the chemical composition of the precipitate:

[0131] [Table 6]

[0132] Ni Mn experiment 0.24 0.76 theory 0.25 0.75

[0133] The experimental setup was consistent with the expected theoretical setup.

[0134] The morphology of the aggregates was verified by scanning electron microscopy (SEM), and the results are shown in... Figure 12 The observed aggregates have a diameter of approximately 4 micrometers.

[0135] All these characteristics (XRD, ICP-OES, SEM) demonstrate that transition metal carbonates with controlled composition and morphology have been obtained.

[0136] 4. Carbonate precursor Ni 1 / 3 Mn 1 / 3 Co 1 / 3 CO3

[0137] The inventors then synthesized a carbonate precursor with the composition Ni. 1 / 3 Mn 1 / 3 Co 1 / 3 CO3.

[0138] a. Preparation of the starting solution

[0139] To this end, a 50 mL solution of transition metal sulfates was prepared by weighing 8.67 g NiSO4·6H2O, 5.58 g MnSO4·H2O, and 9.28 g CoSO4·7H2O. These sulfates were dissolved in distilled water and then placed in a 50 mL volumetric flask, filled to the mark. The Ni / Mn / Co molar ratio was 1 / 3:1 / 3:1 / 3. The concentration of this solution was 2 mol / L. A 50 mL solution containing sodium carbonate and a complexing agent (NH4OH) was prepared by weighing 10.60 g Na2CO3 and 2.25 g NH4OH. Na2CO3 was dissolved in distilled water in the presence of NH4OH and then placed in a 50 mL volumetric flask, filled to the mark. The concentration of Na2CO3 was 2 mol / L, and the concentration of NH4OH was 0.36 mol / L.

[0140] b. Synthesis conditions

[0141] The solution was injected into the mixer / reactor system using a peristaltic pump. The sampling flow rate for the solution containing the transition metal was set to 15 mL / min (Qa), and the sampling flow rate for the solution containing the carbonate was set to 15 mL / min (Qb) (therefore Qa = Qb). The reactor was 10 cm long and had an inner diameter of 1.39 mm. Under these conditions, the residence time in the reactor was 0.3 seconds, and the fluid state in the reactor was laminar. To ensure the homogeneity of the recovered precipitate, the precipitate was not recovered for the first 30 seconds of the reaction, and then sampled under the aforementioned conditions for 60 seconds. The pH of the solution containing the precipitate was 7.3. The precipitate was then washed with distilled water by centrifugation (until the wash water was neutralized) and dried overnight in an oven at 70°C.

[0142] The recovered transition metal carbonate after drying was 2.24 g, consistent with the expected theoretical yield (2.27 g). This indicates that the reaction yield was close to 100%. Therefore, 2.24 g of Ni carbonate was produced within 60 seconds. 1 / 3 Mn 1 / 3 Co 1 / 3 CO3. This represents a yield of 136 g / hour for a 0.15 mL reactor, compared to 16 g in a 500 mL batch reactor over 6 hours as used in the prior art.

[0143] c. Analysis of precipitates

[0144] X-ray diffraction (XRD) was performed and the results are shown in... Figure 13 The diffraction pattern indicates that a carbonate with a small amount of hydroxyl oxides has been obtained.

[0145] Chemical analysis was performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the chemical composition of the precipitate:

[0146] [Table 7]

[0147] Ni Mn Co experiment 0.33 0.33 0.33 theory 0.33 0.33 0.33

[0148] The experimental setup was consistent with the expected theoretical setup.

[0149] The morphology of the aggregates was verified by scanning electron microscopy (SEM), and the results are shown in... Figure 14 The observed aggregates were approximately 5 micrometers in diameter.

[0150] All these characteristics (XRD, ICP-OES, SEM) demonstrate that transition metal carbonates with controlled composition and morphology have been obtained.

[0151] d. The influence of the state in the reaction tube

[0152] The inventors tested the state in the reaction tube for obtaining the precursor Ni. 1 / 3 Mn 1 / 3 Co 1 / 3 The effects of CO3.

[0153] To this end, a 50 mL solution of metal sulfate with a Ni / Mn / Co molar ratio of 1 / 3:1 / 3:1 / 3 and a concentration of 0.1 mol / L was prepared. A 50 mL solution containing 0.2 mol / L ammonium bicarbonate was also prepared.

[0154] The solution was injected into the mixer / reactor system using a peristaltic pump. The sampling flow rate for the solution containing the transition metal was set to 50 mL / min (Qa), and the sampling flow rate for the solution containing the carbonate was set to 50 mL / min (Qb) (therefore Qa = Qb). The reactor was 10 cm long and had an inner diameter of 1.39 mm. Under these conditions, the fluid in the reactor was in an intermediate state. To ensure the homogeneity of the recovered precipitate, the precipitate was not recovered for the first 30 seconds of the reaction, and then sampled for 60 seconds under the aforementioned conditions. The pH of the solution containing the precipitate was 7.5. The precipitate was then washed with distilled water by centrifugation (until the wash water was neutralized) and dried overnight in an oven at 70°C.

[0155] X-ray diffraction (XRD) was performed and the results are shown in... Figure 15 The diffraction pattern indicates the absence of a crystalline phase precipitate, therefore it is impossible to obtain Ni using this method. 1 / 3 Mn 1 / 3 Co 1 / 3 Carbonates composed of CO3.

[0156] The morphology of the aggregates was verified by scanning electron microscopy (SEM), and the results are shown in... Figure 16 The figure clearly shows that a spherical shape was not obtained and proves that intermediate states do not produce Ni. 1 / 3 Mn 1 / 3 Co 1 / 3 Carbonates composed of CO3.

Claims

1. A method for synthesizing spherical material particles, said method being carried out in a continuous reactor, said continuous reactor being formed of a reaction tube supplied by two inlet pipes, said reaction tube having a length L, One of the two inlet tubes is supplied with solution A, which contains sulfates of at least two transition metals selected from nickel (Ni), aluminum (Al), magnesium (Mg), titanium (Ti), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and cobalt (Co). Another inlet tube supplies solution B, which contains a hydroxide or carbonate and optionally a chelating agent. The method includes the following steps: a) respectively with d A and d B The flow rate delivers solutions A and B to the reaction tube of the continuous reactor, thereby causing precipitation of the precursor in the reaction tube, and b) Recover the precursor of the precipitate at the outlet of the reaction tube. The length L of the reaction tube and the flow rate d are described. A and d B It is configured such that the residence time in the reaction tube is less than or equal to 10 seconds, wherein the pH in the reaction tube is 7 to 12 and wherein the state in the reaction tube is a laminar flow state with a Reynolds number of less than 1500.

2. The synthesis method according to claim 1, wherein the residence time in the reaction tube is from 1 millisecond to 10 seconds.

3. The synthesis method according to claim 1 or 2, wherein the length L of the reaction tube is at least 1 mm.

4. The synthesis method according to any one of claims 1 to 2, wherein the inner diameter of each inlet tube and the reaction tube is at least 0.5 mm.

5. The synthesis method according to any one of claims 1 to 2, wherein the temperature in the reaction tube is 20°C to 70°C.

6. The synthesis method according to any one of claims 1 to 2, wherein the solution A comprises a sulfate of at least three transition metals selected from nickel (Ni), aluminum (Al), manganese (Mn) and cobalt (Co).

7. The synthesis method according to any one of claims 1 to 2, wherein the hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, 8-hydroxyquinoline, ammonia, lithium hydroxide, and mixtures thereof.

8. The synthesis method according to any one of claims 1 to 2, wherein the carbonate is selected from the group consisting of ammonium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, and mixtures thereof.

9. The synthesis method according to any one of claims 1 to 2, wherein solution A and solution B are each delivered by a peristaltic pump.

10. The synthesis method according to any one of claims 1 to 2, wherein the conveying flow rate d A and d B Each is at least 0.01 ml / min.

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