Applications of lithium secondary electrochemical batteries containing a mixture of lithium nickel oxide and lithium manganese iron phosphate in automotive applications.

Abstract

A mixture of lithium nickel oxide and lithium manganese iron phosphate is used as an active material composition in the cathode of lithium secondary electrochemical batteries for automotive applications such as hybrid electric vehicles and electric vehicles. This mixture allows for a reduction in the porosity of the lithium manganese iron phosphate-based cathode. It also allows for improved detectability of gas release from the battery in the event of abnormal battery operation. It allows for a reduction in battery impedance at low states of charge (typically less than 30%) and a reduction in the increase in battery impedance during battery life.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium secondary electrochemical batteries for powering electric vehicles and hybrid electric vehicles. Background Technology

[0002] Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are rapidly entering the mainstream automotive market. EVs require long driving range and long lifespan, while HEVs emphasize good power and long lifespan. Currently, all automotive applications are served by two main technologies: 1) nickel oxide-based cathodes, such as nickel manganese cobalt oxide (NMC) or nickel cobalt aluminum oxide (NCA) or a combination of these two oxides; and 2) lithium iron phosphate-based cathodes (LFP). Both solutions have advantages, but also disadvantages.

[0003] NMC-based and NCA-based lithium-ion battery solutions offer the best energy for EVs, resulting in maximum driving range. A good NMC battery can provide energy exceeding 250Wh / kg and 500Wh / L, respectively. This allows automakers to design vehicles with a driving range of 480-640km (300-400 miles). However, nickel oxide-based solutions also present problems. Nickel oxide cathode materials are known to be highly reactive under abuse conditions. The demand for more energy and lower costs has prompted consumers to use NMC and NCA cathode materials with high nickel and low cobalt content. Typical examples are NMC formulations containing 60% and 80% nickel, respectively, in a 6:2:2 and 8:1:1 ratio. These materials with very high nickel content perform quite poorly under abuse conditions. In thermal runaway, the temperature of both NMC-based and NCA-based batteries exceeds 700°C, requiring caution when using such materials. Furthermore, nickel oxide cathodes exhibit impedance limitations in both the transient state of charge (SOC) region where the material undergoes a phase transition and in the low SOC (<30%) region where Li diffusion is hindered. This latter limitation effectively reduces the energy available at high power and low temperatures. Additionally, the impedance of both NMC and NCA cathodes increases with battery life, necessitating a pre-increased overall system size to compensate for power losses at the end of life. Moreover, high impedance generates heat and limits the power that an EV or HEV can provide.

[0004] LFP solutions address safety concerns for EV consumers to some extent. LFP cathodes do not thermally decompose and do not generate heat under abuse conditions. LFP cathodes are also better suited to provide stable impedance across the entire SOC range. The impedance of an LFP cathode is very stable throughout the battery and vehicle's lifespan. This impedance stability contributes to the stable power performance of EV or HEV vehicles. However, LFP also has some key drawbacks. Most importantly, because LFP lithium-ion battery cathodes operate at lower potentials, LFP-based lithium-ion batteries offer approximately 30% less energy and power compared to NMC and NCA solutions. The lack of excess Li in the LFP cathode forces the voltage of the LFP-based system to spike during overcharging, with little warning provided for this situation. The flat voltage of the system also makes managing the SOC and keeping the system within a manageable SOC range difficult and expensive.

[0005] Lithium manganese iron phosphate (LMFP) is another material derived from the olivine group. Similar to LFP, batteries using LMFP perform better under any abuse conditions. For Fe... 3+ / Fe 2+ and Mn 4+ / Mn 3+ The LMFP (Lithium Manganese Iron Phosphate) cathode is characterized by two consecutive voltage plateaus of 3.5V and 4.05V relative to lithium metal, while the LFP (Lithium Iron Phosphate) has an open-circuit voltage of 3.45V relative to lithium metal. LMFP-based cathodes should deliver higher energy than LFP-based cathodes. The challenge of using LMFPs alone in automotive applications stems from the fundamental properties of the material. Despite its higher operating potential, the specific capacity of LMFPs is still limited to 170 mAh / g. LMFP materials have low tap density and extremely high surface area (typically measured using BET technology). Due to its high surface area, electrodes containing only LMFP materials typically exhibit high porosity, usually 40% or higher. This high porosity value makes it impossible to produce electrodes for high-energy batteries, and LMFP materials alone are unlikely to deliver energy, thus unlikely to achieve the driving range required by electric vehicles. Lower porosity would allow for higher energy, higher power density, and higher driving range. Therefore, a lithium manganese iron phosphate (LMFP)-based cathode with lower porosity and thus higher tap density is needed. A porosity value as low as 35%, preferably as low as 25%, is required. To the applicant's knowledge, the porosity value has not yet reached below 30%.

[0006] Furthermore, it has been observed that LMFP-based cathodes release heat suddenly when approaching or even exceeding 100% SOC. By the time battery safety devices associated with the battery are thermally activated and stop current, the battery may have already reached high temperatures, such as 130-140°C. At such high temperatures, the battery separator may begin to melt, leading to contact between electrodes of opposite polarity. This results in an internal short circuit, potentially causing thermal runaway. Thermal runaway can ultimately lead to complete battery failure and expose the vehicle driver to a fire hazard. Under the real-world operating conditions of electric vehicles, the very rapid gas release caused by heat makes the use of LMFP as a cathode material in lithium-ion secondary electrochemical batteries dangerous. Therefore, there is a need for a lithium-ion secondary electrochemical battery incorporating an LMFP-based cathode where gas release occurs gradually as the battery approaches or exceeds 100% SOC. This would allow the battery management system to detect the end of charging in a more predictable manner. Summary of the Invention

[0007] Therefore, the present invention provides a mixture of at least one lithium nickel oxide and at least one lithium manganese iron phosphate as a cathode active material composition for a lithium secondary electrochemical battery. The lithium secondary electrochemical battery can be part of a battery that provides electrical energy to electric vehicles or hybrid electric vehicles. Unexpectedly, it has been found that adding lithium nickel oxide to lithium manganese iron phosphate can reduce the porosity of the lithium manganese iron phosphate-based cathode. Porosity values ​​below 40%, and typically below or equal to 35%, or even below or equal to 30%, can be obtained. The benefit of reducing cathode porosity is higher battery energy density, and therefore a longer driving range for EV or HEV vehicles. Therefore, one object of the present invention is the use of lithium nickel oxide in the lithium manganese iron phosphate-based cathode of a lithium secondary electrochemical battery for reducing the porosity of the lithium manganese iron phosphate-based cathode. Therefore, one object of the present invention is a method for preparing a lithium manganese iron phosphate-based cathode for a lithium secondary electrochemical battery, the method comprising the step of mixing lithium nickel oxide with lithium manganese iron phosphate, with the aim of reducing the porosity of the lithium manganese iron phosphate-based cathode.

[0008] Furthermore, it was unexpectedly found that adding lithium nickel oxide to lithium manganese iron phosphate can reduce the rate of energy release. As the battery approaches 100% SOC, the internal gas pressure can gradually increase. This allows for slower activation of battery safety devices. The benefit is improved driver safety. The battery management system can detect full charge at an early stage and take necessary measures to stop charging before thermal runaway begins. The benefit is easier detection of end-of-charge and easier battery management by the battery management system. Therefore, another object of the present invention is the use of lithium nickel oxide in the lithium manganese iron phosphate-based cathode of a lithium secondary electrochemical battery to improve the detection of gas flow released from the battery during overcharging. The gas flow can activate safety devices. Safety devices can be activated by overvoltage or overheating inside the battery. Safety devices can be conductive connection portions that electrically connect at least one anode or at least one cathode of the battery to terminals of the same polarity, wherein overvoltage in the battery causes current interruption in the connection portion. Therefore, one object of the present invention is a method for preparing a lithium manganese iron phosphate-based cathode for a lithium secondary electrochemical battery, the method comprising the step of mixing lithium nickel oxide with lithium manganese iron phosphate, the purpose of which is to reduce the gas flow rate inside the battery during overcharging.

[0009] Another technological benefit related to the use of mixtures of lithium nickel oxide and lithium manganese iron phosphate is the ability to obtain cathode active material compositions exhibiting both high gravimetric capacity and low impedance. Low impedance is observed even at low states of charge (typically less than 30% SOC). Due to the low impedance, high discharge currents, typically above C / 2 where C is the battery's rated capacity, are expected, even at low temperatures. The extended range of states of charge allows for the provision of higher energy. When combined with the possibility of discharging the battery at higher currents, it allows for greater driving range for electric vehicles or hybrid electric vehicles. The invention also reduces impedance increases during battery life, thus extending battery life. Therefore, another object of the invention is the use of lithium manganese iron phosphate in lithium nickel oxide-based cathodes of lithium secondary electrochemical batteries for reducing battery impedance at a state of charge less than or equal to 30%. Therefore, one object of the invention is a method for preparing a lithium nickel oxide-based cathode for a lithium secondary electrochemical battery, the method comprising the step of mixing lithium manganese iron phosphate with lithium nickel oxide for the purpose of reducing battery impedance at a state of charge less than or equal to 30%. Another object of the present invention is the use of lithium manganese iron phosphate in a lithium nickel oxide-based cathode of a lithium secondary electrochemical battery to reduce the increase in battery impedance during battery cycling. Therefore, one object of the present invention is a method for preparing a lithium nickel oxide-based cathode for a lithium secondary electrochemical battery, the method comprising the step of mixing lithium manganese iron phosphate with lithium nickel oxide, the purpose of which is to reduce the increase in battery impedance during battery cycling. Detailed Implementation

[0010] According to the present invention, the cathode of a lithium secondary electrochemical battery comprises an active material composition comprising a mixture of at least one lithium nickel oxide and at least one lithium manganese iron phosphate. The lithium nickel oxide has a layered crystal structure. The lithium manganese iron phosphate has the same crystal structure as olivine.

[0011] Lithium nickel oxide can be selected from:

[0012] Li w (Ni x Mn y Co z M t O2(NMC), where 0.9≤w≤1.1, x>0, y>0, z>0, t≥0,

[0013] M is selected from Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof, and

[0014] Li w (Ni x Co y Al z M t O2(NCA), where 0.9≤w≤1.1, x>0, y>0, z>0, t≥0,

[0015] M is selected from B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof.

[0016] In one implementation, the lithium nickel oxide is Li w (Ni x Mn y Co z M t The lithium nickel oxide (NMC) is selected from Al, B, Mg, and mixtures thereof. Preferably, M is Al and t ≤ 0.05. Most transition elements are preferably nickel, i.e., x ≥ 0.5, or even more preferably x ≥ 0.6. A high nickel content in the lithium nickel oxide is preferred because it provides high energy to the lithium nickel oxide.

[0017] Lithium nickel oxide can be Li w (Ni x Mn y Co z M tO2, where 0.9≤w≤1.1, x≥0.6, y≥0.1, z≥0.1, t≥0, and M is selected from Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and their mixtures.

[0018] For example, lithium nickel oxide can be selected from LiNi 0.6 Mn 0.2 Co 0.2 O2 and LiNi 0.8 Mn 0.1 Co 0.1 O2.

[0019] In another embodiment, the lithium nickel oxide is Li w (Ni x Co y Al z M t The oxide is O2, wherein 0.9 ≤ w ≤ 1.1, x > 0, y > 0, z > 0, t ≥ 0, and M is selected from B, Mg, and mixtures thereof. Preferably, 0.70 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.25, z ≤ 0.10, t = 0 and x + y + z + t = 1. More preferably, 0.75 ≤ x ≤ 0.85, 0.10 ≤ y ≤ 0.20. The lithium nickel oxide may have the chemical formula LiNi. 0.8 Co 0.15 Al 0.05 .

[0020] Lithium manganese iron phosphate has the following chemical formula:

[0021] Li x Mn 1-y-z Fe y M z PO4, where 0.8 ≤ x ≤ 1.2, 1 > 1 - yz ≥ 0.5, 0 <y≤0.5,0≤z≤0.2,

[0022] And M is selected from B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo. In one embodiment, 0.9 ≥ 1 - yz ≥ 0.7 or 0.9 ≥ 1 - yz ≥ 0.75. In one embodiment, 0.15 ≥ y ≥ 0.25.

[0023] The typical chemical formula for lithium manganese iron phosphate is LiMn. 0.8 Fe 0.2 PO4, LiMn 0.7 Fe 0.3 PO4, LiMn 2 / 3 Fe 1 / 3 PO4 and LiMn 0.5 Fe0.5 PO4. Lithium manganese iron phosphate can be coated with a conductive material, such as carbon.

[0024] The composition of the cathode active material may contain active materials other than at least one lithium nickel oxide and at least one lithium manganese iron phosphate. Preferably, the composition of the cathode active material does not contain any active materials other than at least one lithium nickel oxide and at least one lithium manganese iron phosphate.

[0025] The lithium iron phosphate (LFP) based cathode comprises a mixture of active materials, which may contain or be composed of the following substances:

[0026] - Lithium manganese iron phosphate, relative to the total mass of all active materials, is 90 wt.% to 50 wt.%, 80 wt.% to 60 wt.%, or 70 wt.% to 60 wt.% of lithium manganese iron phosphate.

[0027] - Lithium nickel oxide, 10 wt.% to 50 wt.% or 20 wt.% to 40 wt.% or 30 wt.% to 40 wt.% relative to the total mass of all active materials.

[0028] Lithium manganese iron phosphate and lithium nickel oxide can have the above chemical formula.

[0029] Mixtures can consist of the following substances:

[0030] - Approximately 90 wt.% of lithium manganese iron phosphate is present relative to the total mass of all active materials.

[0031] - Approximately 10 wt.% lithium nickel oxide relative to the total mass of all active materials. This mixture exhibits a porosity of less than or equal to 35%, and for prismatic batteries, the capacity per surface unit of the layer deposited on the current collector is 42 mg / cm². 2 (3mAh / cm 2 For pouch cells, the capacity per surface unit of the layer deposited on the current collector is 46.4 mg / cm². 2 (3.3mAh / cm 2 ).

[0032] Mixtures can also consist of the following substances:

[0033] - Relative to the total mass of active materials, approximately 70 wt.% of lithium iron manganese phosphate,

[0034] - Approximately 30 wt.% lithium nickel oxide relative to the total mass of the active materials.

[0035] Mixtures can also consist of the following substances:

[0036] - Relative to the total mass of active materials, approximately 50 wt.% of lithium iron manganese phosphate,

[0037] - Approximately 50 wt.% lithium nickel oxide relative to the total mass of the active material. This mixture exhibits a porosity of less than or equal to 25%, and a capacity per surface unit of 42.6 mg / cm² for the layer deposited on the current collector. 2 (3.36mAh / cm 2 ).

[0038] According to the present invention, both the lithium nickel oxide and lithium manganese iron phosphate used are in powder form. The size distribution of the lithium nickel oxide particles is determined by a first median volume diameter Dv. 50 1 Characterization. The size distribution of lithium manganese iron phosphate particles is determined by the second median volume diameter Dv. 50 2 Characterization. The term "equivalent diameter" for a particle refers to the diameter of a sphere with the same volume as that particle. The term "median" refers to the diameter of 50% of the volume of lithium nickel oxide (or lithium manganese iron phosphate) particles with an equivalent diameter less than Dv. 50 The particle composition is 50% lithium nickel oxide (or lithium manganese iron phosphate) particles by volume, consisting of particles with an equivalent diameter greater than Dv. 50 The particle size distribution is determined by the particle size distribution. Particle size can be measured using laser particle size analysis technology.

[0039] In a preferred embodiment, the porosity of the mixture is less than 30%, or less than or equal to 28%, or less than or equal to 26%, or less than or equal to 25%. This particularly low porosity can be achieved by using a mixture consisting of 45-55 wt.% lithium nickel oxide and 55 wt.% to 45 wt.% lithium manganese iron phosphate, and by selecting a Dv of less than or equal to 0.70. 50 2 / Dv 50 1 The ratio and Dv of at least 500 nm or even at least 1.5 μm 50 2 Value. In a preferred embodiment, Dv 50 2 / Dv 50 1 The ratio is 0.15-0.60. In a more preferred embodiment, Dv 50 2 / Dv 50 1 The ratio is 0.30-0.50, or 0.30-0.40. This is achieved through the use of Dv... 50 2 Lithium manganese iron phosphate particles ranging from 1.7 μm to 3.2 μm and Dv 50 1Lithium nickel oxide particles with a diameter of 6.0 μm to 12.0 μm can achieve a Dv of 0.14–0.53. 50 2 / Dv 50 1 Ratio. Preferably, the lithium nickel oxide is of the NMC type.

[0040] Examples of preferred compositions for producing mixtures with a porosity of less than 30% are as follows:

[0041] -45 wt.% to 55 wt.% of lithium nickel oxide, selected from:

[0042] Li w (Ni x Mn y Co z M t O2(NMC), where 0.9≤w≤1.1, 0.6≤x, 0.1≤y, 0.1≤z,

[0043] 0≤t, M is selected from Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof;

[0044] -55wt.% to 45wt.% of lithium manganese iron phosphate having the following formula:

[0045] Li x Mn 1-y-z Fe y M z PO4, where 0.8 ≤ x ≤ 1.2, 0.6 ≤ 1 - yz < 0.9, 0 <y≤0.5,0≤z≤0.2,

[0046] Furthermore, M is selected from B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo. Preferably, 0.7 ≤ 1-yz ≤ 0.9 or 0.75 ≤ 1-yz ≤ 0.9.

[0047] Electrode porosity is defined as the percentage of pore volume to the electrode's geometric volume. Pore volume includes the volume of voids between compound particles in the layer deposited on the electrode current collector and the pore volume within the compound particles themselves. Pores within the particles include accessible and inaccessible pores. Electrode porosity can be obtained through two methods:

[0048] - In the first method, mercury techniques are used to determine the pore volume. The geometric volume of the electrode is obtained by multiplying the thickness of the layer deposited on the current collector by the area covered by that layer. The porosity is obtained by calculating the ratio between the pore volume and the geometric volume of the electrode.

[0049] - In the second method, the theoretical density d is calculated from the density of each compound in the layer deposited in the current collector. 真实 Given the mass and volume of the layer deposited on the current collector, the bulk density d can be calculated. 堆积 .

[0050] The relationship between porosity and true density and bulk density is as follows:

[0051] Porosity = 1 - (d) 堆积 / d 真实 )

[0052] The porosity of cathodes containing lithium manganese iron phosphate (LMFP) as the sole active material is typically at least 40%. Adding only 10 wt.% lithium nickel oxide to LMFP is sufficient to reduce the cathode porosity to approximately 35%. Adding 50 wt.% lithium nickel oxide reduces the porosity to approximately 25%. The cathode porosity of the mixture is typically 25-35%. Due to the reduced porosity, this invention allows for the fabrication of cathodes with a higher content of LMFP per unit surface area. Mixtures of LMFP with NMC or NCA overcome the low-density problem by achieving a low-porosity electrode, thus enabling high-energy LMFP systems.

[0053] A mixture of at least one lithium nickel oxide and at least one lithium manganese iron phosphate also allows for a more slow release of gases from the battery container during overcharging. Therefore, the internal pressure of the battery increases gradually. The rate of heat release is lower compared to using lithium manganese iron phosphate as the sole active material. This gradual increase in pressure allows for the activation of safety devices before the temperature reaches a threshold beyond which the risk of thermal runaway is significant. This result is unexpected, as olivine phosphates are known in the art to be more thermally stable than lithium nickel oxides. While it is recognized that LMFP-based cathodes exhibit better thermal stability than nickel oxide-based cathodes and release less heat when exposed to excessive external heat (overheating), this does not hold true when LMFP-based cathodes are exposed to overcharging. During overcharging of an LMFP-based cathode, current continuously flows through the battery, whereas this is not the case when the battery is only exposed to excessive external heat. Almost all of the overcharge current is used to oxidize the electrolyte. This oxidation reaction leads to a sudden gas release, which is the object of this invention to mitigate. The applicant discovered that although lithium nickel oxide generates higher energy upon overcharging, this energy is released in a more gradual manner, thereby improving the detectability of the overcharge state. The gas is released at a rate capable of activating safety devices before thermal runaway begins. Typically, when the cathode contains a mixture of lithium nickel oxide and lithium manganese iron phosphate, the safety devices activate at below 130-140°C, while when the cathode contains only lithium manganese iron phosphate, the safety devices activate at a temperature of at least 130°C. The gas release signal provided by the mixture allows for earlier detection of the battery's state of charge approaching 100%. The gas release signal provided by the nickel oxide cathode offers an additional warning and mitigation tool for management system abuse.

[0054] Another benefit of this invention is that the addition of LMFP offsets the increased impedance of the nickel oxide cathode under low charge conditions, thereby maximizing the use of NMC or NCA cathode materials at any rate or temperature. Using a hybrid LMFP / NMC (or NCA) cathode, 3% to 5% of the energy density of a nickel oxide cathode alone can be achieved. The mixture according to the invention can be used in the cathode of lithium-ion secondary electrochemical batteries powering hybrid electric vehicles or electric vehicles. The increased energy density provides extended driving range for electric vehicles.

[0055] Furthermore, the LMFP and nickel oxide cathode exhibit good voltage matching, resulting in a SOC curve with both slope and plateau. The LMFP displays two voltage plateaus at 3.5V / Li° and 4.05V / Li°, while the NMC shows a slope from 3.5V to the end of charging. This SOC curve facilitates SOC management. The excess Li in the nickel-based cathode causes a gradual voltage increase during overcharging, which can be detected and prevented by electronic devices. The benefits include easier detection of the end of charging and easier battery management system management.

[0056] Lithium manganese iron phosphate and lithium nickel oxide can be mixed by any method known in the art, such as ball milling.

[0057] The cathode is prepared in a conventional manner. It consists of a conductive carrier used as a current collector, coated with a layer containing an active material composition, and also contains an adhesive and a conductive material. The mixture of active materials is typically mixed with one or more adhesives, which function to bind the active material particles together and adhere them to the current collector on which they are deposited. The current collector is preferably a two-dimensional conductive carrier, such as a solid or perforated tape, typically made of aluminum or an aluminum alloy. Commonly used adhesives are selected from polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyamide-imide (PAI), polyimide (PI), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyvinyl alcohol, polyacrylic acid, and mixtures thereof. The conductive material is typically carbon. A solvent is added to the resulting mixture. A paste is obtained deposited on one or both sides of the current collector. The current collector coated with the paste is laminated to adjust its thickness.

[0058] The composition of the paste deposited on the current collector can be as follows:

[0059] -75-96% active material composition, preferably 80-90%.

[0060] -2-15% adhesive, preferably 4%;

[0061] -2-10% carbon, preferably 4%.

[0062] The battery is manufactured in a conventional manner. The cathode, separator, and anode are stacked together. This assembly is rolled up (stacked separately) to form an electrochemical gel roll (respectively, an electrochemical stack). Connecting portions are attached to the edge of the cathode and connected to the current output terminal. The anode can be electrically connected to the battery casing. Conversely, the cathode can be connected to the casing, and the anode to the output terminal. After being inserted into the casing, the electrochemical stack is impregnated with an organic electrolyte. The battery is then sealed in a hermetically sealed manner. The casing can also be conventionally equipped with a safety valve that opens the battery if the internal gas pressure exceeds a predetermined value. The shape of the casing is not limited; in the case of planar electrodes, it can be cylindrical or prismatic.

[0063] Several electrochemical cells can be connected in series, parallel, parallel-series, or series-parallel to form a module. These cells are assembled within a container forming the module's housing. Each cell is equipped with the necessary devices for electrical connection to the other cells in the module (e.g., devices in the form of metal bars (busbars)), devices for measuring battery operating parameters (temperature, voltage, current), and optional safety devices (valve, membrane seal). These modules are connected together to form a battery that can be used to power pure electric vehicles, hybrid electric vehicles, or plug-in hybrid electric vehicles.

Claims

1. Use of lithium nickel oxide in a lithium manganese iron phosphate-based cathode of a lithium secondary electrochemical battery for reducing the porosity of the lithium manganese iron phosphate-based cathode, wherein the lithium manganese iron phosphate-based cathode comprises a mixture of active materials consisting of: -45 wt.% to 55 wt.% of lithium nickel oxide; -55wt.% to 45wt.% of lithium manganese iron phosphate; The lithium nickel oxide and the lithium manganese iron phosphate are in particulate form; The particle size distribution of the lithium nickel oxide is determined by the first median volume diameter Dv of the particles. 50 1 Characterization; The particle size distribution of the lithium manganese iron phosphate is determined by the second median volume diameter Dv of the particles. 50 2 Characterization; Dv 50 2 / Dv 50 1 The value ranges from 0.14 to 0.53, Dv 50 2 The thickness ranges from 1.7 μm to 3.2 μm and Dv 50 1 The micrometer size ranges from 6.0 μm to 12.0 μm, resulting in a porosity of less than 30%.

2. The use according to claim 1, wherein the lithium manganese iron phosphate-based cathode comprises a mixture of active materials consisting of 50 wt.% lithium nickel oxide and 50 wt.% lithium manganese iron phosphate, and the cathode porosity is less than or equal to 25%.

3. The use according to claim 1, wherein the lithium manganese iron phosphate-based cathode comprises a mixture of active materials consisting of: -45 wt.% to 55 wt.% of the chemical formula Li w (Ni x Mn y Co z M t Lithium nickel oxide of O2 (NMC), wherein 0.9≤w≤1.1, 0.6≤x, 0.1≤y, 0.1≤z, 0≤t, and M is selected from Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo and mixtures thereof; -55 wt.% to 45 wt.% of lithium iron manganese phosphate with the chemical formula Li x Mn 1-y-z Fe y M z PO4, where 0.8 ≤ x ≤ 1.2, 0.6 ≤ 1 - y - z < 0.9, 0 < y ≤ 0.5, 0 ≤ z ≤ 0.2, and M is selected from B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo.

4. The use according to any one of claims 1-3, wherein the lithium secondary electrochemical battery is part of a battery that provides electrical energy to an electric vehicle or a hybrid electric vehicle.