TWI437754B - High density and high voltage stable cathode materials for secondary batteries - Google Patents

Description

High density and high voltage stable cathode materials for secondary batteries

The present invention relates to a lithium metal oxide powder for use as a cathode material in a rechargeable battery.

Until recently, LiCoO ₂ was the main cathode material of choice. It combines a relatively high weight capacity, a high packing density, and good electrochemical performance along with relatively easy preparation. However, we have recently observed two major trends in rechargeable lithium batteries for portable applications. Lithium nickel manganese cobalt oxide (LMNCO) is replacing LiCoO ₂ in low-end applications (like a 2.2-2.6Ah cylindrical battery), while special LiCoO ₂ designed for high voltage stability and high density is used. In high-end applications (like 3.0Ah cylindrical batteries), they find their use in, for example, laptops.

A typical example of a substitute in a low-end application is a 2.2-2.4Ah cylindrical battery using the following cathode materials such as LiNi _0.5 Mn _0.3 Co _0.2 O ₂ or LiCoO ₂ and LiNi _0.5 Mn _0.3 Co A mixture of _0.2 O ₂ . When considering metal costs, LMNCO materials are much cheaper (Ni and Mn are much cheaper than Co), but are more difficult to prepare on a large scale. LiNi _0.5 Mn _0.3 Co _0.2 O ₂ has a similar volume energy density as LiCoO ₂ (expressed in mAh/cm ³ ) but it is difficult to obtain an electrode having a low porosity similar to LiCoO ₂ , so the actually obtained volume energy density (refers to the capacity achieved in a fixed volume of a fixed battery design) is still slightly lower.

Another trend is to introduce a specific "high end" LiCoO ₂ that has a high density and allows for a higher charging voltage (typically 4.5V or even 4.6V (for Li metal) when it is assembled in a coin cell, and When assembled in a full battery, it is 4.35V and 4.4V (for graphite) and can be used in end applications where more demand is required. This is due to two main reasons: (1) high packing density, which allows the manufacture of thick and low porosity electrodes, and (2) cathodes based on special "high end" LiCoO ₂ can be charged to higher voltages. And cycling at higher voltages, which increases the average battery voltage and also significantly increases the reversible (electrical) capacity as well as the rate (charge and discharge) capability. Therefore, there is clearly a need for cathodes based on high capacity LiCoO ₂ which have high rate capabilities and which can be circulated in a stable manner at higher voltages in real batteries.

Several approaches have been suggested in the prior art. To achieve high voltage stability, high end LiCoO ₂ materials are typically coated (eg, using Al ₂ O ₃ ) or otherwise chemically modified (eg, by providing a fluorinated surface). The problem is that the coated dense LiCoO ₂ often has a lower reversible capacity such that a portion of the gain by the energy density charged to a higher voltage is consumed by the lower inherent capacity. This effect can be observed in alumina protected and LiF protected coatings, and similar effects have been observed for other coating routes (ZrO ₂ , AlPO ₃ , ...).

In addition, research on the literature tells us that in order to achieve high voltage stability, coatings are not necessary at all. For example, Chen and Dahn (Electrochem. Solid-State Lett., Vol. 7, No. 1, pp. A11-A14 (2004)) teaches the newly prepared LiCoO ₂ if tested in a coin cell using a Li metal anode. It circulates in a stable manner at 4.5V. Such an approach may be appropriate for a coin cell but this effect cannot be replicated in a real commercial battery. These results are confirmed by the fact that, now, several years after publication, specially treated and not pure LiCoO ₂ is commercially sold for high voltage applications.

Other strategies for generating high voltage performance are not known at this time. It is an object of the present invention to provide new high density and high voltage performance but also high rate capability cathode materials for high end secondary battery applications.

From a first aspect, the present invention can provide a lithium metal oxide powder for use as a cathode material in a rechargeable battery, which has a conductivity of less than 10 when pressed at 6 ° C at 25 ° C. ^-5 S/cm, and when used as an active component in the cathode, the powder has a reversible electrode capacity of at least 180 mAh/g, and the cathode has a discharge rate of C/10 of 3.0 and 4.5 V at 25 °C. Loop through the interval of Li ⁺ /Li. In some embodiments, the conductivity is less than 10 ^-6 S/cm, or even less than 10 ^-7 S/cm. In other embodiments, the powder has a reversible electrode capacity at 25 ° C at a discharge rate of C/5 of at least 180 mAh/g, or even at 25 ° C at a discharge rate of 1 C of at least 180 mAh/g. In one embodiment, the lithium metal oxide powder comprises at least 50 mole % Co, or at least 70 mole % Co, or even at least 90 mole % Co.

In still another embodiment, the lithium metal oxide powder has a compact density of at least 3.5 g/cm ³ . In other embodiments, the compaction density is at least 3.7 g/cm ³ , or even at least 3.8 g/cm ³ . The pressed density was measured by applying 1.58 Ton/cm ² to the powder thus obtained.

The conductivity was measured at an applied pressure of 63.7 MPa. In the scope of the specification and the patent application, when an actual pressure of 63.7 MPa is applied, a value of 63 MPa is also mentioned as a rounding value.

From a second aspect, the present invention can provide a lithium metal oxide powder for use as a cathode material in a rechargeable battery, which has a conductivity of less than 10 when pressed at 25 ° C using 63.7 MPa. ^-5 S/cm, and when used as an active component in the cathode, the powder has a reversible electrode capacity of at least 200 mAh/g and an energy decay system of less than 60%, the cathode having a discharge of 0.5 C at 25 °C The rate is cycled between 3.0 and 4.6V (for Li ⁺ /Li). In some embodiments, the conductivity is less than 10 ^-6 S/cm, or even less than 10 ^-7 S/cm. In some embodiments, when used as an active component in a cathode, the powder has an energy decay of less than 40%, or even less than 30%, and the cathode has a discharge rate of 0.5 C at 25 ° C at 3.0 Cycle between 4.6V (compared to Li ⁺ /Li). In other embodiments, the powder has a reversible electrode capacity of at least 200 mAh/g at a discharge rate of 1 C at 25 ° C, and the same energy decay value. In one embodiment, the lithium metal oxide powder comprises at least 50 mole % Co, or at least 70 mole % Co, or even at least 90 mole % Co.

The lithium metal oxide powder of the above two specific examples may be composed of a core and a shell, wherein the shell has a conductivity of less than 1 * 10 ^-6 S/cm, and preferably less than 1 * 10 ^-7 S/cm. Or even less than 1 * 10 ^-8 S/cm, and wherein the electrical conductivity of the shell is less than the electrical conductivity of the core of the lithium metal oxide powder. In a specific example, at least 98 mol% of the metal in the lithium metal oxide powder is composed of the elements Li, Mn, Ni, and Co, or is composed of the elements Li, Mn, Fe, Ni, Co, and Ti. In another embodiment, at least 98 mole percent of the metal in both the shell and the core is comprised of the elements Li, Mn, Ni, and Co, or consists of the elements Li, Mn, Fe, Ni, Co, and Ti.

The lithium metal oxide powder of these two specific examples may have the general formula x LiCoO ₂ . (1-x)MO _y , where 0.1<x<1,0.5<y 2 and M consists of Li and M', where M' = Ni _a Mn _b Ti _c , where 0 c 0.1, a>b and a+b+c=1. In a specific example, 0.9 < x < 1 makes it easier to obtain a uniform sintered material, and also obtains a low conductivity final product.

Viewed from a third aspect, the present invention can provide a lithium metal oxide powder for use as a cathode material for a rechargeable battery, which has a conductivity of less than 10 ^- when pressed at 6 ° C at 25 ° C. ⁵ S/cm, and preferably less than 10 ^-6 S/cm, or even less than 10 ^-7 S/cm, and the powder has at least 90%, preferably at least 95% when used as an active component in the cathode 10C rate performance (discharge capacity measured at 10C rate versus 0.1C rate, expressed in %), and energy attenuation of less than 10%, and preferably less than 7%, the cathode is at 3.0 and 4.4V (for Li ⁺ / Li) interval cycle. In a specific example, the lithium metal oxide powder may have a conductivity of less than 10 ^-5 S/cm, and preferably less than 10 ^-6 S/cm, or even when pressed at 63.7 MPa at 25 ° C. Less than 10 ^-7 S/cm, and when used as an active component in the cathode, the powder has a 20C rate performance of at least 85%, preferably at least 90% (discharge capacity measured at a 20C rate versus 01C rate, % expression), and an energy decay of less than 10%, and preferably less than 7%, the cathode is cycled between 3.0 and 4.4V (for Li ⁺ /Li). When circulating at intervals of 3.0C and 4.4V (for Li ⁺ /Li) at 20C-rate, the powder may have an average discharge voltage system greater than 3.7V, preferably 3.75V and optimally 3.77V. In one embodiment, the powder may have the general formula x LiCoO ₂ . (1-x)M _y O _z , where 0.1<x<1,0.5<z/y 2 and M consists of Li and M', where M' = Ni _a Mn _b Co _c Ti _d Mg _e , where a + b + c + d + e = 1, a + b > 0.5 and c 0,d 0,e 0. In one embodiment, 0.9 < x < 1 makes it easier to obtain a uniform sintered material and still obtain a low conductivity final product.

Viewed from a fourth aspect, the present invention can provide a process for the preparation of the lithium metal oxide powder described above, the process comprising the steps of: - providing a mixture of LiCoO ₂ powder and: - a Li-Ni- The Mn-Co-oxide is also - a powder containing Ni-Mn-Co, and a Li-containing compound, preferably lithium carbonate, the mixture comprising more than 90% by weight, and preferably at least 95% by weight of LiCoO ₂ powder, and - The mixture is sintered at a temperature T of at least 910 ° C, and preferably at least 950 ° C for a time t between 1 and 48 hours, wherein the amount of Li-containing compound in the mixture is selected to obtain 63.7 when used at 25 ° C. An insulating lithium metal oxide powder having a thickness of less than 10 ^-5 S/cm, preferably less than 10 ^-6 S/cm and most preferably less than 10 ^-7 S/cm is obtained upon MPa pressing.

In one embodiment, the LiCoO ₂ powder further comprises one or more of Al, Mg, and Ti and by sintering a doped Co precursor (eg, doped with one or more of Al, Mg, and Ti) It is prepared by a mixture of Co(OH) ₂ or Co ₃ O ₄ ) and a Li precursor (for example, Li ₂ CO ₃ ). The content of one or more of Al, Mg, and Ti may be between 0.1 mol% and 1 mol%, or between 0.25 mol% and 1 mol%.

In another embodiment, the mixture consists of such pure or doped LiCoO ₂ powder and Ni-Mn-Co hydroxide, Ni-Mn-Co oxyhydroxide, Ni-Mn-Co carbonate, and Ni. - One or more constituents of Mn-Co oxycarbonate.

In another embodiment of the method, the amount of the Li-containing compound (such as lithium carbonate) is selected such that the ratio of Li/M is less than 0.1 mol/mol, wherein the Mo/M molar ratio makes Li The addition (by the Li-containing compound) is related to the content of the transition metal in the entirety of LiCoO ₂ and MOOH (where M = Ni, Mn and Co), which corresponds to the transition metal in the finally obtained lithium metal oxide powder. content. It may also be less than 0.05 mol/mol, or even less than 0.02 mol/mol. In another embodiment, the Li/M ratio is zero.

In the scope of the patent application, d50 is defined as 50% of the volume of the powder consisting of particles having a size less than or equal to the value of d50, wherein d50 is by a suitable known method (for example, laser diffraction in dry or wet media) )measuring.

Detailed description

The present invention discloses a strategy to obtain a LiCoO ₂ -based cathode that is highly voltage stable and has a high rate capability. The obtained LiCoO ₂ -based cathode material has a high density and can be circulated in a stable manner at a high voltage in a real battery. A key point of this strategy is to achieve very low conductivity, on the order of magnitude lower than other cathode materials reported today.

It is widely accepted that sufficient conductivity is required when high performance cathode performance is targeted. A typical example is the use of carbon coated fine particles LiFePO ₄ . Capacity and rate performance are very poor without a carbon coating. In the case of LiFePO ₄ , a typical target for the electrical conductivity of the pressed cathode powder is 10 ^-3 to 10 ^-2 S/cm. Other cathode materials also have relatively high electrical conductivity.

The conductivity of the different reference materials was measured using pellets pressed at a pressure of 63.7 MPa at room temperature. With a typical electrolyte ionic conductivity of 10 mS/cm (10 ^-2 S/cm), we can define a cathode with similar or higher conductivity as "highly conductive"; if the conductivity is Above this value is about 1% (10 ^-4 S/cm), which we define as "low conductivity." If the conductivity is less than 0.1% (10 ^-5 S/cm), the cathode can be defined as "insulated". It is generally accepted that the cathode must have at least a low electrical conductivity and the insulated cathode does not work well.

The high Ni material like LiNi _0.8 Co _0.15 Al _0.05 O _{2 has,} for example, about 3.47 * 10 ^-2 S/cm, and LMNCO (LiNi _0.5 Mn _0.3 Co _0.2 O ₂ ) has about 2.21 * 10 ^-3 S/cm, the famous "111""(Li _1+x M _1-x O ₂ where M = Ni _1/3 Co _1/3 Mn _1/3 and x 0.05) has about 2.03 * 10 ^-4 S/cm. Commercial LiCoO ₂ has a relatively low conductivity in the range of 10 ^-2 to 10 ^-3 S/cm. Conductivity greater than 10 ^-5 S/cm was measured for all of these cathode materials. Therefore none of all of these cathodes are insulated.

The cathode material of the present invention is "insulated" using the definitions described above. They have electrical conductivity that is at least 2-3 orders of magnitude lower than those of currently known less conductive cathode materials. Low conductivity is believed to be a major cause of the high voltage stability of this new insulating cathode material. Such an insulated cathode can produce excellent electrochemical characteristics (i.e., large discharge capacity and rate performance) which is unexpected because it is generally accepted that Li cation diffusion is required within the solid cathode and across the interface between the electrolyte and the cathode. A certain conductivity.

When the cathode dominated by LiCoO ₂ is charged to a high voltage - meaning that the cathode system is strongly deintercalated - we obtain a Li _x CoO ₂ composition in which most of the Co systems are in the tetravalent state. The tetravalent Li _x CoO ₂ is a very strong oxidant and is highly reactive. The electrolyte is thermodynamically unstable when in contact with such an oxidized surface. The reaction with the electrolyte (reducing agent) is strong. Even at low temperatures (during normal cycling of the LiCoO ₂ cathode at high voltages) this reaction proceeds slowly but continuously. The reaction product covered the surface of the cathode and the electrolyte was decomposed, and both effects continuously caused degradation of the electrochemical performance of the battery; loss of capacity and a strong increase in electrical resistance were observed by polarization.

The case of a high voltage charged cathode is not so different from a well studied carbon anode. The electrolyte is in a reducing condition during Li intercalation The lower system is unstable, and the potential is close to zero V (for Li/Li+) during the embedding process. Therefore, the electrolyte is decomposed and becomes less. However, in this case, the decomposition product of the electrolyte forms a so-called SEI (Solid Electrolyte Interface) with lithium. Generally accepted is an SEI-based ionic conductor but an electronic insulator. The SEI therefore still allows Li to transport across the surface between the solid and the electrolyte but it prevents further reduction of the electrolyte. The key point is that the reduction of electrolytes requires the simultaneous presence of Li cations and an electron at the local level. Li cations are present in the electrolyte and electrons are present in the carbon body. However, if the SEI as an electronic insulator physically separates electrons in the carbon from the Li cations in the electrolyte, then further electrolyte reduction is not possible.

This mechanism is well known and attempts have been made to apply a similar mechanism to the cathode. Much research has focused on electrolyte additives that will decompose on the surface of the cathode to form the cathode SEI. However, studies of electrode additives that form SEI at high voltages when in contact with highly oxidized (ie, delithiated) cathodes have not been successful or only partially successful.

Obviously, an electronically insulated cathode material will solve this problem. If an electrically insulating cathode material can be successfully circulated, we can expect a high voltage stability because the oxidation of the electrolyte requires electrons to be supplied to the cathode. However, it has heretofore been generally assumed that such an insulated cathode may not have good electrochemical properties.

The present invention is based on the following findings: 1) an insulated cathode can have high voltage stability, and 2) it is possible to obtain an insulated cathode that exhibits very good electrochemical performance.

Thus, an exemplary pressed powder of the cathode, as disclosed below, shows very low electrical conductivity and is actually a good insulator. Surprisingly, however, the cathode shows excellent electrochemical performance. In addition, the measurements show that the cathode particles are electrically conductive but surface-insulating.

In a specific example, in order to obtain good performance, the lithium metal oxide powder particles may have the following characteristics: 1) a core-shell structure in which the shell is electrically insulated and the core is electron-conducting, 2) an insulating shell. The insulating shell does not completely cover the core, typically much greater than 50% but less than 100%, and 3) a shell that is primarily composed of a transition metal.

A method for producing Mn island coated LiCoO ₂ is disclosed in WO 2008-092568. In an exemplary process embodiment of the invention, such Mn island coated LiCoO ₂ powder is prepared, however, a slight adjustment to the Li: metal ratio is required to achieve minimum conductivity. The LiCoO ₂ precursor is first mixed with a transition metal source such as a mixed hydroxide MOOH (M = Mn-Ni-Co) and a Li source (such as Li ₂ CO ₃ ). The ratio of the transition metal in LiCoO ₂ to the metal in MOOH may be, for example, between 0.95:0.05 and 0.8:0.2. Island coated LiCoO ₂ was obtained after a firing step. A typical firing temperature is 1000 °C. The obtained islands are rich in manganese, while manganese is missing in the LiCoO ₂ body. The amount of Li added to the blend is determined by the conductivity of the fired final sample: it can be achieved by a simple measurement of how much Li has to be added as Li ₂ CO ₃ to achieve the lowest possible conductivity. Established, this will be demonstrated in the examples below. In one embodiment, Li ₂ CO ₃ is not added at all.

Another important aspect of the invention is that the cores of the particles have a higher electrical conductivity than the outer regions. In a typical implementation of the invention, the outer side is more manganese rich than the inner side. Although the outer side of the LiCoO ₂ particles is covered by a non-conductive shell, we have observed a high electrochemical performance.

An exemplary morphology of the cathode of the present invention is as follows: a relatively electrically conductive core is mostly (but not to 100%) covered by an insulating shell. Furthermore, the insulating shell may consist essentially of a transition metal oxide, wherein the metal composition comprises at least 95% cobalt, manganese and nickel.

However, the presence of a core-shell structure is only one of these specific examples of the invention, which is especially observed in powders having a large average particle size (for example at least 10 μm, or even at least 20 μm). The proposed method allows the lowest possible conductivity to be obtained independent of the structure obtained. By changing the mixing ratio of Li:metal, cathodes having different electrical conductivities were obtained. The ratio of Li: metal according to a specific example produces a minimum ratio of electrical conductivity. High voltage stable cathodes are cathode materials that have a minimum conductivity as a function of Li:metal ratio.

The invention can be implemented, for example, by the different examples described below.

Example 1:

This example shows that the cycle stability improves as the conductivity decreases. This improved stability and reduction in conductivity is achieved by optimizing the Li: metal ratio.

LCO-1 prepared by: preparing a test line in 0.25 mole% and 0.5 mole% of titanium doped with Mg Co (OH) ₂ as a precursor LiCoO _2. Titanium and magnesium doped LiCoO ₂ (recorded as LCO-1) were obtained by a standard high temperature solid state synthesis by mixing the precursor with Li ₂ CO ₃ to achieve an average particle size of 25 μm.

Preparation of island coated LCO-1: transition metal oxyhydroxide by mixing 95 wt.% of titanium and magnesium-doped LiCoO ₂ (LCO-1) with 5 wt.% of MOOH (where M = Ni _0.55 Mn _0.30 Co _0.15 ) and no or a predetermined amount of Li ₂ CO ₃ were mixed to prepare a cathode powder material.

Examples 1a, 1b and 1c were prepared according to Table 1 and they were thoroughly mixed to prepare a homogeneous starting material mixture. The mixture was placed in an alumina crucible and heated at 1000 ° C for 8 h under constant air flow. After cooling, the resulting powder was sieved and characterized by 4-probe direct current conductivity and further assembled in a coin cell for electrochemical characterization.

Table 2 summarizes the electrical conductivity and electrochemical performance of Examples 1a, 1b and 1c and LCO-1 at an applied pressure of 63 MPa. SEM images of LCO-1 and Example 1a are shown in Figure 1. The morphology of the two products is very different: LCO-1 has non-agglomerated particles with a smooth surface, while Example 1a has a special island coating on the surface of LiCoO ₂ particles.

The relationship between conductivity and cycle stability at 4.5 V is shown in Figure 2. The coated samples (i.e., Examples 1a through 1c) have electrical conductivity that is 3 to 4 orders of magnitude smaller than uncoated LCO-1. The electrochemical properties of LCO-1, such as discharge capacity, rate performance, capacity decay, and energy decay, are very poor. Examples 1a to 1c show a significant improvement in these properties compared to LCO-1. For Examples 1a to 1c, the conductivity increased when lithium was added. At the same time, both capacity attenuation and energy attenuation are compromised. For coated and uncoated Both of the samples, the reduction in resistivity is related to the improvement in 4.5V stability. Examples 1a, 1b and 1c are insulated and are examples of a specific example of the invention.

In this and all of the following examples, electrochemical performance was tested in a coin type battery using Li foil as a counter electrode in a lithium hexafluorophosphate (LiPF ₆ ) type electrolyte at 25 °C. The loading weight of the active material is in the range of 10 to 12 mg/cm ² . The battery was charged to 4.3 V and discharged to 3.0 V to measure rate performance and capacity. The high voltage discharge capacity and capacity retention were measured at a charging voltage of 4.5 V or 4.6 V (in Examples 3-4 and 9) during the extended cycle.

A specific capacity of 160 mAh/g was chosen to determine the discharge rate. For example, for a discharge at 2 C, a specific current of 320 mA/g is used.

This is an overview of the tests for all coins or full batteries used in this specification:

The following definitions are used for data analysis: (Q: capacity, D: discharge, C: charge). The discharge capacity QD1 was measured during the first cycle at a range of 4.3-3.0 V at 0.1 C. Irreversible capacity Qirr system (QC1-QD1) / QC1 (in %).

Rate performance: QD at 0.2, 0.5, 1, 2, 3C, respectively, vs. QD at 0.1C.

For capacity, the decay rate per 100 cycles (0.1 C): (1-QD31/QD7)* 100/23.

For capacity, the decay rate per 100 cycles (1.0 C): (1-QD32/QD8)* 100/23.

Energy attenuation: Instead of using the discharge capacity QD, discharge energy (capacity × average discharge voltage) is used.

Example 2:

This example will demonstrate that the cycle stability of island coated LiCoO ₂ will be much higher than uncoated LiCoO ₂ while its conductivity is about five orders of magnitude lower. This example also provides clear evidence that the cycle stability of island coated LiCoO ₂ increases with decreasing intrinsic conductivity.

Preparation of LCO-2: 1 mol% magnesium coated Co(OH) _{2 was prepared} as a precursor to LiCoO ₂ on a test line. Magnesium-doped LiCoO ₂ (recorded as LCO-2) was obtained by a standard high temperature solid state synthesis by mixing the precursor with Li ₂ CO ₃ to achieve an average particle size of 25 μm.

Preparation of LCO-3: 1 mol% of magnesium doped cobalt tetraoxide (Co ₃ O ₄ ) powder was used as a precursor of LiCoO ₂ (a product commercially available from Umicore, Korea). Magnesium-doped LiCoO ₂ (recorded as LCO-3) was obtained by a standard high temperature solid state synthesis by mixing the precursor with Li ₂ CO ₃ to achieve an average particle size of 25 μm.

Preparation of island coated LCO-2 and LCO-3: a cathode powder material by mixing 95 wt.% of LCO-2 or LCO-3 with 5 wt.% of MOOH (where M = Ni _0.55 Mn _0.30 Co _0.15 ) and a predetermined amount of Li ₂ CO ₃ were mixed and prepared. Examples 2a, 2b and 2c obtained from LCO-2 and Examples 2d, 2e and 2f obtained from LCO-3 were prepared according to the precursor contents listed in Table 1 and thoroughly mixed to prepare a homogeneous raw material mixture. .

The mixtures were placed in an alumina crucible and heated at 1000 ° C for 8 h at a constant gas flow rate. After cooling, the resulting powders were sieved and characterized by 4-probe direct current conductivity and further assembled in a coin cell for electrochemical characterization. Table 4 summarizes the electrical conductivity and electrochemical performance of Examples 2a through 2f and LCO-2 and LCO-3 at an applied pressure of 63 MPa (as in the experimental scheme of Example 1). SEM images of LCO-3 and Example 2d are shown in Figure 3 (note that similar results were obtained for the LCO-2 series). The morphology of the two products is very different: LCO-3 has non-agglomerated particles with smooth surfaces and Example 2d shows a special island coating at the surface of the LiCoO ₂ particles.

The relationship between conductivity and cycle stability at 4.5 V is shown in Figure 4. The island coated samples (i.e., Examples 2a through 2f) have a conductivity that is 5 to 6 orders of magnitude smaller than uncoated LCO-2 and LCO-3. The electrochemical properties of LCO-2 and LCO-3, such as discharge capacity, rate performance, capacity decay, and energy decay are very poor. Examples 2a through 2f show a significant improvement in these properties compared to LCO-2 and LCO-3. For Examples 2a to 2c and 2d to 2f, the conductivity increased when lithium was added. At the same time, both capacity attenuation and energy attenuation are compromised. For both coated and uncoated samples, the reduction in resistivity is related to the improvement in 4.5V stability. Example 2 a-2 f is insulated and is an example of a specific example of the present invention.

Example 3:

This example demonstrates that island coated LiCoO ₂ with electronic insulating behavior has excellent cycle stability in a full cell.

Preparation of Example 3 (Ex3): Example 3 was carried out on a test line by a mixture of 95:5 molar ratios of LCO-3 and MOOH (M=Ni _0.55 Mn _0.30 Co _0.15 ) and a suitable lithium carbonate addition. Sintering is prepared to achieve a conductivity of less than 5 * 10 ^-8 S/cm. The average particle diameter of Example 3 was 25 μm. In this case, the electrical conductivity at a pressure of 63 MPa applied was measured to be 3.94 * 10 ^-8 S/cm. The performance of the coin cell of Example 3 at 4.5 V and 4.6 V is listed in Table 5a and shows excellent electrochemical performance.

The pressed density was measured by applying 1.58 Ton/cm ² to the powder thus obtained. The compact density of Example 3 was 3.82 g/cm ³ .

Example 3 A 10 μm polyethylene separator was used in a lithium ion polymer battery (LiPB) and a graphite type anode was used as a counter electrode in a lithium hexafluoride (LiPF ₆ ) type electrolyte at 25 ° C. After formation, the LiPB cells were cycled 500 times between 4.35 V (or 4.40 V) and 3.0 V to measure capacity retention during the extended cycle. It is assumed that the 800 mAh specific capacity C is used to determine the charging and discharging rates. Charging was performed in CC/CV mode at a 1 C rate using a termination current of 40 mA and discharging was completed in CC mode at 1 C to 3 V.

The attenuation of the discharge capacity of Example 3 at high voltage (4.35 V) and very high voltage (4.4 V) is shown in Figures 5a and 5b, respectively. The lifetime performance of Example 3 is compared to standard LiCoO ₂ (commercially produced by Umicore having an average particle size of 17 μm), the data of which is shown in FIG. The conductivity of this standard LiCoO ₂ is 9.0 * 10 ^-2 S/cm.

Full cell experiments confirmed that Example 3 (always having lower conductivity) has superior cycle stability compared to standard LiCoO ₂ . At the end of 500 cycles, Example 3 shows a reversible capacity that is better than 85% of the initial capacity at both 4.35V and 4.40V, where the standard LiCoO _{2 is} reached very quickly after 200 cycles at 4.35V. 85% reduction.

Example 4: Al ₂ O ₃ coated LiCoO ₂

This example again demonstrates that cycle stability improves with decreasing conductivity. This improved stability can be achieved by coating. However, a sufficiently low conductivity value is not obtained, and as it approaches a lower value, the reversible capacity is also degraded.

LiCoO ₂ precursor (LCO-4) is a 1 mol% Mg doped LiCoO ₂ (a commercially produced product of Umicore mass production). It has potato-shaped particles having a d50 of a particle size distribution of about 17 μm. Three samples were prepared by a large-scale production coating process using LiCoO ₂ precursors, which is disclosed in co-pending application EP 10008563. By this coating method, fine Al ₂ O ₃ powder adheres to the surface, followed by a gentle heat treatment of higher than 500 ° C to react the Al ₂ O ₃ powder with the surface of LiCoO ₂ (LCO-4).

These 3 samples (Comparative Example 4a, Comparative Example 4b, Comparative Example 4c) had different levels of Al coating. Comparative Example 4a contained 0.05 wt% of Al, Comparative Example 4b contained 0.1 wt%, and Comparative Example 4c contained 0.2 wt%. Conductivity results are listed in Table 5b. Aluminum coated samples have lower electrical conductivity than uncoated LCO-4 and, for coated samples, conductivity As the thickness of the Al coating continues to decrease.

Electrochemical performance (capacity, rate, cycle stability at 4.5 V) was tested in coin cells. Uncoated samples have very poor stability. The coated samples showed good stability and Table 6 shows these results. The discharge capacity was from 4.5 to 3.0 V and was obtained from Cycle 7 of the cycle schedule given above. A significant improvement in cycle stability was observed with increasing coating levels, which did not depend on how the cycle stability was measured. However, at the same time, the electrochemical properties (capacity, rate) deteriorate as the thickness of the Al ₂ O ₃ coating increases.

Figure 7 summarizes the capacity and cycle stability at 4.5V as a function of conductivity: in the top graph, the capacity (triangle) and energy (solid black circle) attenuation are plotted against conductivity; at the bottom In the figure, the discharge capacity is plotted against the conductivity. It can be clearly observed that for lower conductivity, better high voltage stability at 4.5V is obtained. At the same time, however, the reversible capacity is degraded. Therefore, in the case of alumina-coated LiCoO ₂ , it is difficult to further improve cycle stability by reducing electrical conductivity without losing electrochemical performance. Furthermore, the electrochemical properties at 4.6 V, which are independent of the level of the aluminum coating, are very low compared to Example 3.

Example 5:

This example demonstrates that island coated LiCoO ₂ has an electronically insulating shell (thus providing excellent cycle stability) as well as an electron conducting core.

Example 5a sample LiCoO ₂ (label: LCO-5) and MOOH (M=) having an average particle size of 23 μm doped with a mass-produced 1 mol% magnesium at 95:5 molar ratio on a test line. Ni _0.55 Mn _0.30 Co _0.15 ) and a suitable lithium carbonate additive were prepared by sintering to achieve an electrical conductivity of less than 1 * 10 ^-7 S/cm. The compacted density of Example 5a was 3.87 g/cm ³ . Preparation of Comparative Example 5b: 30 g of Example 5a and 400 g of 1 cm diameter zirconia balls were placed in a 1 L jar and shaken for 12 h by a Turbula mixer. The powder thus prepared was then collected for further experimentation.

SEM images of LCO-5 and Example 5a and Comparative Example 5b are shown in Figure 8 (two different magnifications at a time). The morphology of these products is very different. LCO-5 has non-agglomerated particles with a smooth surface, while Example 5a shows a special island coating at the surface of the LiCoO ₂ particles. The SEM image of Comparative Example 5b clearly demonstrates that the ball rolling treatment breaks up the island coated particles. The particle size distributions of Examples 5a and 5b as measured by laser diffraction in a dry medium are shown in FIG. The particle size distribution of this ball-milled sample showed a sharp decrease in the average particle diameter from 23 μm to 10 μm, and clearly confirmed the increase in the fine particle fraction. This ball milling method indiscriminately breaks up the particles, resulting in a large exposure of the core material. This core material has a conductivity comparable to that of untreated LCO-5. Thus, it is shown that the core of Example 5a has an electrical conductivity > 1 * 10 ^-3 S/cm while the shell has a conductivity of less than 1 * 10 ^-7 S/cm. PSD also shows small amounts of large particles derived from loose agglomeration of relatively viscous powders.

The conductivity of Example 5a was measured at 25 ° C under the applied pressure of 63 MPa to be 7.13 * 10 ^-8 S/cm, which is 6 orders of magnitude smaller than uncoated LCO-5. The feature of Comparative Example 5b of ball milling was an increase of 5 orders of magnitude of conductivity compared to 5a. This result brings evidence to support a higher conductivity of the core compared to the shell.

The coin cell test performance and conductivity of Example 5a and Comparative Example 5b and LCO-5 are listed in Table 7. As previously shown in Examples 1 and 2, the capacity of Example 5a and the energy decay (between 3.0 and 4.5 V) were significantly improved compared to uncoated LCO-5, where the conductivity was simultaneously Reduced. The electrochemical performance of the sample of Comparative Example 5b was substantially impaired, which we believe was caused by the disappearance of the electronically insulating shell structure.

Control example 6:

This example demonstrates that conventional transition metal oxide based cathode materials do not achieve low electrical conductivity and at the same time good high voltage stability. The conductivity and electrochemical performance of several commercially available products (from Umicore, Korea) are summarized in Table 8. These materials have a general composition of Li _1+x M _1-x O ₂ , where x 0.05, for Comparative Example 6a, where M = Ni _0.5 Mn _0.3 Co _0.2 , for Comparative Example 6b, M = Ni _1/3 Mn _1/3 Co _1/3 , and for Comparative Example 6c, M = Ni _0.8 Co _0.15 Al _0.05 . It is generally accepted that the conductivity of LiCoO ₂ is highly sensitive to its stoichiometric system of lithium and increases with excess lithium. In Levasseur, Thesis #2457, Bordeaux 1 University, 2001, there are reported two orders of magnitude difference in electrical conductivity between overstoichiometric and stoichiometric LiCoO ₂ at room temperature. A method for the preparation of highly stoichiometric LiCoO ₂ is reported by M. Ménétrier, D. Carlier, M. Blangero, and C. Delmas, in Electrochemical and Solid-State Letters, 11 (11) A179-A182 (2008). The preparation of this highly stoichiometric LiCoO ₂ sample was repeated and used to prepare Comparative Example 6d.

In addition, the compact density was measured because a high compact density is important for cathode applications in high end batteries. The compression densities of Comparative Examples 6a-6d were at least 0.4 g/cm ³ lower than the exemplary embodiment of the present invention, making the materials unsuitable for use in high-end batteries. The volume energy density actually available (referred to as the capacity obtained in a fixed volume of a fixed battery design) is still slightly lower. Furthermore, the characteristics of the cathode materials are greater than the conductivity of 10 ^-5 S/cm. This is at least 2-3 orders of magnitude greater than the electrical conductivity of an exemplary cathode material of some embodiments of the present invention.

Reference example 7:

This example demonstrates that known transition metal-based oxides can have electrical conductivity below 10 ^-5 S/cm and support the presence of electrically insulating transition metal-based shells.

The conductivity of the following materials was measured: commercially available MnOOH (Chuo Denki Kogyo Co., labeled: REX 7a), commercially available TiO ₂ (Cosmo Chemicals KA300, labeled REX 7b), commercially available Fe ₂ O ₃ (Yakuri Pure Chemicals Co., labeled REX 7c) and commercially available Co ₃ O ₄ (Umicore, labeled REX 7d). The results are shown in Table 9.

All of these materials are characterized by a conductivity of less than 10 ^-5 S/cm. These electrical conductivities are in the same range as the electrical conductivity of the electronically insulated cathode material of the present invention and provide an example of a transition metal based shell having electrically insulating behavior.

Control example 8:

This example demonstrates that it is very difficult or impossible to obtain an insulating cathode material with good properties by an inorganic coating (not based on transition metals). A suitable example of a LiF inorganic non-transition metal coating. A dense and fully coated LiF surface can be obtained by a PVDF based preparation route. Details of the mechanism are described in the co-pending application PCT/EP2010/006352. A coating that is too thin to significantly reduce the conductivity has blocked the diffusion of Li. This electrically insulating shell needs to have enough Ionic conductivity. If the shell is not based on a transition metal (for example in the case of a LiF coating) the ionic conductivity is too low and the cathode does not work well.

LiF coated LiCoO _{2 was} prepared in the following manner: A sample mass produced using a lithium cobalt oxide was used as a cathode precursor. Its composition is 1 mol% Mg-doped LiCoO ₂ having an average particle diameter of 17 μm. 1000 g of this precursor powder and 10 g of PVDF powder (1 wt%) were carefully mixed using a Henschel type mixer. Another sample was prepared in a similar manner by using 3 times less PVDF (0.3 wt%). The final sample (having a 150 g size) was prepared in air by heat treatment. During the heat treatment at 300 ° C and 350 ° C for 9 h, the PCDF was first melted and the surface was perfectly wetted. Then, gradually, PCDF is decomposed and fluorine reacts with lithium to form a dense LiF layer. 1 wt% PVDF corresponds to about 3 mole % LiF.

The LiF layer was fully developed at 300 ° C (Comparative Example 8b). The coin cell test shows very low performance. These capacities are very small and large polarization effects are observed. These results are not the result of poor coin cell preparation (2 cells give the same result) and have been reproduced several times using other samples. If much less PVDF (0.3 wt%) was used, full capacity was obtained, but the sample still showed large polarization (Comparative Example 8d). However, the coating is too thin or too weak to obtain low electrical conductivity. The isocratic cycle data can be compared to a sample prepared at 150 ° C (with 1 wt% PVDF: Control Example 8a), wherein the PVDF melts but no LiF-forming reaction occurs and results in a much higher capacity and rate performance. Table 10 summarizes the information and Figure 10 compares the A charge-discharge (C/10 rate). Similar results can be obtained with other inorganic, transition metal free coatings. Obviously, the inorganic layer of LiF completely encloses the surface such that Li does not penetrate over the electrolyte solid interface. The situation is quite different in the specific examples of the invention, in which the insulating shell has a high ionic conductivity, as evidenced by the large rate performance.

Example 9:

This example demonstrates that island coated magnesium and aluminum doped LiCoO ₂ (having electronic insulating behavior) have excellent cycle stability in coin cells.

Preparation of Example 9 (Ex9):

1 mol% of magnesium and 1 mol% of aluminum doped cobalt tetraoxide (Co ₃ O ₄ ) powder were used as precursors of LiCoO ₂ (commercially available from Umicore, Korea). Magnesium and aluminum doped LiCoO ₂ (recorded as LCO-6) were obtained by a standard high temperature solid state synthesis by mixing the precursor with Li ₂ CO ₃ to achieve an average particle size of 20 μm. Example 9 was achieved on a pilot line by sintering 95:5 molar ratios of LCO-6 and MOOH (M=Ni _0.55 Mn _0.30 Co _0.15 ) and a suitable lithium carbonate addition to achieve less than 5 * 10 ^-8 S/ Prepared by the conductivity of cm. The average particle diameter of Example 9 was 20 μm. In this case, the electrical conductivity at a pressure of 63 MPa applied was measured to be 4.40 * 10 ^-8 S/cm. The coin cell performance of Example 9 is listed in Table 11 and shows excellent electrochemical performance.

The pressed density was measured by applying 1.58 Ton/cm ² to the powder thus obtained. The compacted density is high, 3.82 g/cm ³ , and this high value, along with good electrochemical properties, makes these cathodes good candidates for high-end battery applications.

Example 10: Materials with high rate capability

It has been recognized that materials with high rate capabilities should combine both high electrons and ionic conductivity. The latter is often achieved by reducing the particle size and increasing the specific surface area (BET) of the particles to allow lithium diffusion to be easier in the particles. However, increasing the specific surface area is not desirable because it will result in accelerated electrolyte oxidation and safety issues, further limiting its practical application.

This example will demonstrate that as the conductivity decreases, the rate performance of the co-sintered LiCoO ₂ and the high voltage stability (characterized to be smaller than the particle size of the previous examples) increase, while the BET value may be less than 1 m ² /g. And in this case even below 0.4 m ² /g. The enhanced performance of co-sintered LiCoO ₂ is achieved by controlling the stoichiometry of lithium.

Preparation of LCO-10: LiCoO ₂ (recorded as LCO-10) was obtained by a standard high temperature solid state synthesis by mixing Co ₃ O ₄ with Li ₂ CO ₃ to achieve an average particle diameter of 6.1 μm.

Preparation of Example 10: A final cathode powder material by mixing 95.3 wt.% of LiCoO ₂ (LCO-10) with 4.70 wt.% of MOOH (where M = Ni _0.55 Mn _0.30 Co) _0.15 ) and a predetermined amount of Li ₂ CO ₃ were mixed and prepared. Examples 10a, 10b, 10c and 10d were prepared according to Table 12 and thoroughly mixed to prepare a homogeneous starting material mixture. The mixture was placed in an alumina crucible and heated at 1000 ° C for 8 h at a constant gas flow rate. After cooling, the resulting powder was sorted to achieve a final average particle size of 6.6 μm. The properties of the powders were measured and are listed in Table 13.

The anode materials were further assembled in a coin cell for electrochemical characterization. The active material loading of the cathode is about 4 mg/cm ² . In this example and after, the rate performance of 10C and 20C was measured at 4.4V using a specific capacity of 160 mAh/g to determine the discharge rate current. The experimental parameters are listed below:

The following definitions were used for data analysis: Q: capacity, D: discharge, C: charge, followed by a number to indicate the number of cycles.

- The initial discharge capacity QD1 is measured in the range of 4.4V-3.0V at 0.1C during the first cycle, - rate performance is DQi/DQ1 × 100, where 1C for i = 2 rate; 5C for i = 3 series For i=4 series 10C, for i=5 series 15C and for i=6 series 20C.

- Irreversible capacity Qirr (in %) system (CQ1-DQ1) / CQ1 × 100, - Capacity decay rate per 100 cycles at 1C, Q attenuation system (1-DQ56/DQ7) × 2, and - energy attenuation : Instead of using the discharge capacity QD, the discharge energy (capacity × average discharge voltage) is used.

Table 14 summarizes the rate performance of Examples 10a through 10d and LCO-10 at 4.4V. The development of 20C rate performance for Examples 10a through 10d and LCO-10 is shown in Figure 11 as a function of conductivity.

It is clearly observed that for lower conductivity, better 10C and 20C rate performance is obtained. The average discharge voltage of Examples 10a to 10d at 20C was also strongly increased by at least 0.1 V compared to LCO-10. Materials characterized by increased 10C and 20C rate capacity and an average discharge voltage of 20C are highly desirable because they produce higher weight energy (Wh/g) and produce higher volumes when combined with higher compaction density. Energy (Wh/L). Such materials, as exemplified by Examples 10a through 10d, are good candidates for applications requiring high energy, such as electric vehicles and power tools.

The high voltage performance of Examples 10a, 10c and 10d and LCO-10 is shown in Table 15.

The relationship between conductivity and energy decay at 1 C, 4.5 V is shown in Figure 12. The conductivity of Examples 10a through 10d was 3 to 4 orders of magnitude smaller than the original LCO-10. The high voltage 1C rate performance, capacity attenuation, and energy attenuation of Examples 10a through 10d were significantly improved compared to LCO-10. For Examples 10a through 10d, the conductivity increased when lithium was added. At the same time, both capacity attenuation and energy attenuation are compromised. The decrease in resistivity is related to the stability improvement of 4.5V and the rate performance. Examples 10a, b, c, and d are examples of insulating materials and are examples of one embodiment of the present invention.

Example 11: Materials with high rate capability

This example will demonstrate an increase in the rate performance and high voltage stability of co-sintered LiCoO ₂ as the conductivity decreases, where the BET value may be less than 1 m ² /g, and in this case even less than 0.4 m ² /g. The enhanced performance of Example 11 was achieved by controlling the stoichiometry of lithium.

Preparation of Example 11: A cathode powder material was mixed by mixing 95.3 wt% of LiCoO ₂ (LCO-10) with 4.70 wt% of MOOH mixed transition metal oxyhydroxide (where M = Ni _0.55 Mn _0.30 Co _0.15 ) And prepared. The addition of lithium carbonate is determined to achieve a conductivity of less than 10 ^-7 S/cm. 50 Kg of the mixture was thoroughly mixed to form a homogeneous blend which was placed in an alumina crucible and then heated at 1000 ° C for 8 h under constant air flow. After cooling, the resulting powder was classified to achieve a final average particle diameter of 6.6 μm. The compact density of Example 11 was 3.4 g/cm ³ . These properties of the powder were measured and are listed in Table 16.

The cathode materials were further assembled in a coin cell for electrochemical characterization. Table 17 summarizes the rate performance of Example 11 and LCO-10 at 4.4V.

It is clearly observed that for lower conductivity, better 10C and 20C rate performance is obtained. The average discharge voltage at 20 C of Example 11 was also strongly increased by at least 0.16 V compared to LCO-10.

The high voltage performance of 4.6 and 4.5 V of Example 11 is shown in Table 18. The conductivity of Example 11 was 3 to 4 orders of magnitude smaller than the original LCO-10. The high voltage 1C rate performance, capacity decay, and energy attenuation of Example 11 were significantly improved compared to LCO-10.

The resistivity reduction of Example 11 was associated with improved stability of 4.6V and 4.5V and increased performance of 10C and 20C. Example 11 is an insulated cathode material An example of a specific example of the present invention is also provided.

Although specific specific examples and/or details of the present invention have been shown and described above in order to illustrate the application of the principles of the present invention, it should be understood that the invention should be It is to be understood that the invention is more fully described in the scope of the invention, and is understood by those skilled in the art.

Figure 1: SEM images of a) LCO-1 and b) Example 1a at 2000x magnification.

Figure 2: A graph of energy attenuation (open circles) and capacity attenuation (filled circles) as a function of conductivity on a logarithmic scale at 4.5V.

Figure 3: SEM images of a) LCO-3 at 2000x magnification and b) Example 2d at 2000x and 5000x magnification (bottom).

Figure 4: Conductivity for a) LCO-2, Examples 2a, 2b and 2c and b) Examples 2d, 2e and 2f at 4.5V energy attenuation (open circles) and capacity attenuation (filled circles) as a logarithmic scale The graph of the function.

Figure 5: Example 3 full cell test at a) 4.35 V, and b) 4.40 V. The discharge capacity (mAh/g) is plotted against the number of cycles (#).

Figure 6: Full cell test of standard LiCoO ₂ at 4.35V. The discharge capacity is plotted against the number of cycles.

Figure 7: Relationship between stability and conductivity of alumina coated LiCoO ₂ at high voltages.

Figure 8: SEM images of a) LCO-5 at 2000x magnification, b) Example 5a at 2000x and 5000x magnification, and c) Control Example 5b at 2000x and 5000x magnification.

Figure 9: Graph of Example 5a (open circles) and 5b (filled circles) volume fraction as a function of particle size.

Figure 10: Coin cell test: LiC coated LiCoO ₂ heated at different temperatures at 25 ° C at a C/10 rate (1 C = 160 mAh / g) in the first cycle charge-discharge obtained in the range of 4.3 and 3.0V Voltage curve.

Figure 11: Development of 20C rate performance for Examples 10a-10d and LCO-10 as a function of conductivity.

Figure 12: The relationship between the conductivity and energy decay of LCO-10 at 4.5 V at 1 C for Examples 10a, 10c and 10d.

Claims (43)

A lithium metal oxide powder used as a cathode material in a rechargeable battery, which has a conductivity of less than 10 ^-5 S/cm when pressed at 63.7 MPa at 25 ° C, and when used as a cathode In the case of an active component, the powder has a reversible electrode capacity of at least 180 mAh/g, and the cathode system circulates at intervals of 3.0 and 4.5 V to Li ⁺ /Li at a discharge rate of C/10 at 25 °C. The lithium metal oxide powder of claim 1, wherein when pressed at 25 ° C using 63.7 MPa, the powder has a conductivity of less than 10 ^-7 S/cm and is used as an activity in the cathode. In the case of a component, the powder has a reversible electrode capacity of at least 180 mAh/g, and the cathode system circulates at intervals of 3.0 and 4.5 V to Li ⁺ /Li at a discharge rate of C/10 at 25 °C. The lithium metal oxide powder of claim 1, wherein when pressed at 25 ° C using 63.7 MPa, the powder has a conductivity of less than 10 ^-5 S/cm and is used as an activity in the cathode. In the case of a component, the powder has a reversible electrode capacity of at least 180 mAh/g, and the cathode system circulates at intervals of 3.0 and 4.5 V to Li ⁺ /Li at a discharge rate of 1 C at 25 °C. A lithium metal oxide powder used as a cathode material in a rechargeable battery, when pressed at 63.7 MPa at 25 ° C, the powder has a conductivity of less than 10 ^-5 S/cm, and when used as a cathode An active component having a reversible electrode capacity of at least 200 mAh/g and an energy decay system of less than 60%, the cathode system at a rate of 0.5 C at 25 ° C at 3.0 and 4.6 V versus Li ⁺ / The interval of Li is looped. A lithium metal oxide powder according to claim 4, which when pressed at 25 ° C using 63.7 MPa, has a conductivity of less than 10 ^-7 S/cm and is used as an activity in the cathode. In the case of a component, the powder has a reversible electrode capacity of at least 200 mAh/g and an energy decay system of less than 60%. The cathode system has a discharge rate of 0.5 C at a temperature of 0.5 C and a range of 3.0 and 4.6 V to Li ⁺ /Li at 25 ° C. Loop. A lithium metal oxide powder according to claim 4, which when pressed at 25 ° C using 63.7 MPa, has a conductivity of less than 10 ^-5 S/cm and is used as an activity in the cathode. In the composition, the powder has a reversible electrode capacity of at least 200 mAh/g and an energy attenuation system of less than 60%. The cathode system is subjected to a discharge rate of 1 C at a temperature of 1 C at a rate of 1 C and a range of 3.0 and 4.6 V to Li ⁺ /Li. cycle. The lithium metal oxide powder according to any one of claims 1 to 6, comprising at least 50 mol% of Co. The lithium metal oxide powder according to any one of claims 1 to 6, wherein the lithium oxide powder is composed of a core and a shell, and wherein at least 98 mol% of the shell and the core are The metal is composed of the elements Li, Mn, Ni, and Co, or consists of the elements Li, Mn, Fe, Ni, Co, and Ti. The lithium metal oxide powder of any one of claims 1 to 6, wherein the shell comprises more Mn than the core, and wherein the shell comprises less Co than the core. The lithium metal oxide powder according to any one of claims 1 to 6, wherein the core has a conductivity greater than a conductivity of the shell. The lithium metal oxide powder according to any one of claims 1 to 6, wherein the lithium metal oxide powder is composed of a core and a shell, and wherein the shell has a conductivity of less than 1*10 ^-6 S /cm, and wherein the electrical conductivity of the shell is less than the electrical conductivity of the core of the lithium metal oxide powder. The lithium metal oxide powder according to any one of claims 1 to 6, wherein the lithium metal oxide powder is composed of a core and a shell, and wherein the shell has a conductivity of less than 1*10 ^-8 S /cm, and wherein the electrical conductivity of the shell is less than the electrical conductivity of the core of the lithium metal oxide powder. The lithium metal oxide powder according to any one of claims 1 to 6, wherein the lithium metal oxide powder is composed of a cation and an anion, wherein at least 93 mol% of the cation is composed of Li and Co. The lithium metal oxide powder according to any one of claims 1 to 6, which has the general formula x LiCoO ₂ . (1-x)MO _y , where 0.1<x<1,0.5<y 2, and M consists of Li and M', where M' = Ni _a Mn _b Ti _c , where 0 c 0.1, a>b and a+b+c=1. A lithium metal oxide powder according to any one of claims 1 to 3, comprising LiCoO ₂ particles with Mn and Ni, the particles having islands rich in Mn and Ni on the surface thereof, the islands having The concentrations of Mn and Ni are higher than the concentrations in the bulk of the particles, and the islands include at least 5 mole % Mn. The lithium metal oxide powder of claim 15, wherein the Mn and Ni-rich islands have a thickness of at least 100 nm and cover less than 70% of the surface of the LiCoO ₂ particles with Mn and Ni. A lithium metal oxide powder according to claim 15 wherein the Mn concentration in the islands is at least 4 mol% higher than the Mn concentration in the bulk of the LiCoO ₂ particles having Mn and Ni. A lithium metal oxide powder according to claim 15 wherein the concentration of Ni in the Mn-rich and Ni-rich islands is at least 2 moles higher than the concentration of Ni in the bulk of the LiCoO ₂ particles having Mn and Ni. %. A lithium metal oxide powder according to claim 15 wherein the concentration of Ni in the Mn-rich and Ni-rich islands is at least 6 moles higher than the concentration of Ni in the bulk of the LiCoO ₂ particles having Mn and Ni. %. A lithium metal oxide powder according to claim 15 wherein the LiCoO ₂ particles bearing Mn and Ni comprise at least 3 mol% of both Ni and Mn. A lithium metal oxide powder according to claim 15 wherein the LiCoO ₂ particles bearing Mn and Ni comprise at least 10 mol% of both Ni and Mn. A lithium metal oxide powder according to claim 15 wherein the size distribution of the LiCoO ₂ particles having Mn and Ni has a d50 of more than 10 μm. The lithium metal oxide powder according to any one of claims 1 to 6, comprising less than 3 mol% of one or more dopants selected from the group consisting of Al and Mg, and less than 1 mol% One or more dopants in the group consisting of Be, B, Ca, Zr, S, F, and P are selected. The lithium metal oxide powder according to any one of claims 1 to 6, which has a compact density of at least 3.5 g/cm ³ . The lithium metal oxide powder according to any one of claims 1 to 6, which has a compact density of at least 3.7 g/cm ³ . A lithium metal oxide powder used as a cathode material in a rechargeable battery, when pressed at 63.7 MPa at 25 ° C, the powder has a conductivity of less than 10 ^-5 S/cm, and when used as a cathode For an active component, the powder has a 10C rate performance of at least 90% and an energy decay of less than 10%, and the cathode circulates between 3.0 and 4.4V versus Li ⁺ /Li. A lithium metal oxide powder used as a cathode material in a rechargeable battery, when pressed at 63.7 MPa at 25 ° C, the powder has a conductivity of less than 10 ^-5 S/cm and is used as a cathode The powder has an ATC rate performance of at least 85% and an energy decay of less than 10% with an active component that circulates between 3.0 and 4.4 V versus Li ⁺ /Li. A lithium metal oxide powder according to claim 26, wherein the 20C rate property is at least 92%. The lithium metal oxide powder having a conductivity of less than 10 ^-7 S/cm, as claimed in any one of claims 26 to 28. The lithium metal oxide powder according to any one of claims 26 to 28, which has an average particle diameter of a particle size distribution of less than 12 μm. The lithium metal oxide powder according to any one of claims 26 to 28, which has a BET surface area of less than 1 m ² /g. The lithium metal oxide powder according to any one of claims 26 to 28, which has the general formula x LiCoO ₂ . (1-x)MO _y , where 0.1<x<1,0.5<y 2, and M consists of Li and M', where M' = Ni _a Mn _b Co _c Ti _d Mg _e , where a + b + c + d + e = 1, a + b > 0.5, and c 0,d 0,e 0. The lithium metal oxide powder according to any one of claims 26 to 28, which has a compact density of at least 3.2 g/cm ³ . The lithium metal oxide powder according to any one of claims 26 to 28, which has a lithium metal oxide powder having a ratio of more than 3.60 V when it is cycled at a CC rate of 3.0 and 4.4 V vs. Li ⁺ /Li. Average discharge voltage. An electrochemical cell comprising a cathode comprising, as an active material, a lithium metal oxide powder according to any one of claims 1 to 34. A method for producing a lithium metal oxide powder according to any one of claims 1 to 34, which comprises the steps of providing a mixture of a LiCoO ₂ powder and a Li-Ni-Mn- a Co-oxide or a powder containing Ni-Mn-Co, and a Li-containing compound comprising more than 90% by weight of LiCoO ₂ powder, and sintering the mixture at a temperature T of at least 910 ° C for 1 and 48 hours Between the times t, wherein the amount of the Li-containing compound in the mixture is selected to obtain an insulating lithium metal oxide having an electrical conductivity of less than 10 ^-5 S/cm when pressed at 25 ° C using 63.7 MPa. Powder. The method of claim 36, wherein the mixture comprises LiCoO ₂ powder and Ni-Mn-Co hydroxide, Ni-Mn-Co oxyhydroxide, Ni Mn Co oxide, Ni-Mn-Co carbonate And one or more of Ni-Mn-Co oxycarbonate. The method of claim 36, wherein the LiCoO ₂ powder further comprises one or more of Al, Mg, and Ti, and is sintered by mixing a doped Co precursor and a Li precursor. And prepared. The method of any one of claims 36 to 37, wherein the Ni-Mn-Co precursor powder further comprises Ti, or the LiCoO ₂ particles are doped with Ti. The method of any one of claims 36 to 37, wherein the Ni-Mn-Co precursor powder further comprises Ti in the form of TiO ₂ particles having a d50 of less than 100 nm, or the LiCoO ₂ particles doped There is Ti. A use of a lithium metal oxide powder according to any one of claims 1 to 34 in a mixture as a cathode material in a rechargeable battery, the mixture further comprising a conductive additive. The use of claim 41, wherein the mixture comprises at least 1% by weight of the conductive additive. The use of claim 41 or 42 wherein the conductive additive is carbon.