Precursors for Lithium Transition Metal Oxide Cathode Materials for Rechargeable Batteries

Abstract

A particulate precursor compound for manufacturing a lithium transition metal (M)-oxide powder usable as an active positive electrode material in lithium-ion batteries, wherein (M) is Ni.sub.xMn.sub.yCo.sub.zA.sub.v, A being a dopant, wherein 0.33x0.60, 0.20y0.33, and 0.20z0.33, v0.05, and x+y+z+v=1, the precursor having a specific surface area PBET in m.sup.2/g, a tapped density PTD in g/cm.sup.3, a median particle size PD50 in m, and wherein (I).

Claims

1-5. (canceled)

6. A particulate precursor compound for manufacturing a lithium transition metal (M)-oxide powder usable as an active positive electrode material in lithium-ion batteries, wherein (M) is Ni.sub.xMn.sub.yCo.sub.zA.sub.v, A being a dopant, wherein 0.33x0.60, 0.20y0.33, and 0.20z0.33, v0.05, and x+y+z+v=1, the precursor having a specific surface area PBET in m.sup.2/g, a tapped density PTD in g/cm.sup.3, a median particle size PD50 in m, and wherein $\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}\frac{0.021}{\left(0.1566*x\right)-0.0466},$ wherein: for 0.33x0.35, the median particle size PD50, the tapped density PTD, and the median particle size are: 2.5PD503.5, 0.90PTD<1.30 and 20<PBET<40; or for 0.35<x0.45, PD50, PDT, and PBET are: 2.5PD503.5, 1.30<PTD<1.45 and 12<PBET<20; or for 0.45<x0.55, PD50, PDT, and PBET are: 5.0PD509.0, 1.25<PTD<1.45 and 15<PBET<25.

7. The precursor compound of claim 6, wherein $\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

8. The precursor compound of claim 6, wherein v=0, the compound having a PTD<2 g/cm.sup.3.

9. The precursor compound of claim 6, wherein the precursor is a hydroxide M-OH or an oxyhydroxide M-OOH compound.

Description

DETAILED DESCRIPTION

[0024] In this invention, an upper limit for the irreversible capacity of less than 10% or even less than 8% is realized for the cathode materials made with the precursor compounds according to the invention, when cycling in a 4.33.0V/Li metal window range in a standard 2325-type coin cell.

[0025] Since the Ni content of the precursor is equal to the Ni content of the final lithium metal oxide cathode powder, both Ni contents may be exchanged in equations (1) and (2) above.

General Description of Experimental Data

a) PBET Precursor Specific Surface Area

[0026] The specific surface area is measured with the Brunauer-Emmett-Teller (BET) method using a Micromeritics Tristar 3000. 2 g of precursor powder sample is first dried in an oven at 120 C. for 2 h, followed by N2 purging. Then the precursor is degassed in vacuum at 120 C. for 1 hour prior to the measurement, in order to remove adsorbed species. A higher drying temperature is not recommended in precursor BET measurements, since a precursor may oxidize at relatively high temperature, which could result in cracks or nano-sized holes, leading to an unrealistically high BET.

b) PTD Precursor Tapped Density

[0027] The tapped density (PTD) measurement of the precursor in this invention is carried out by mechanically tapping a graduated measuring cylinder (100 ml) containing the precursor sample (having a mass W, around 60-120 g). After observing the initial powder volume, the measuring cylinder is mechanically tapped for 5000 times according to ASTM B527 standard test method, so that no further volume (V in cm.sup.3) or mass (W) change is observed. The PTD is calculated as PTD=W/V. The PTD measurement is carried out on an ERWEKA instrument.

c) PD50 Precursor Particle Size

[0028] The median particle size (PD50) of the precursor compound is preferably obtained by a laser particle size distribution measurement method. In this description, the laser particle size distribution is measured using a Malvern Mastersizer 2000 with Hydro 2000MU wet dispersion accessory, after dispersing the powder in an aqueous medium. In order to improve the dispersion of the powder in the aqueous medium, sufficient ultrasonic irradiation, typically 1 minute for an ultrasonic displacement of 12, and stirring, are applied and an appropriate surfactant is introduced.

d) Cathode Material Preparation

[0029] In this invention, in order to evaluate the electrochemical behaviour in a coin cell, cathode materials have been prepared from the precursor compounds according to the invention, by using conventional high temperature sintering. Li.sub.2CO.sub.3 (Chemetall) or LiOH (SQM) is dry mixed with the precursor compound in a certain Li:M molar ratio using a Henschel Mixer for 30 mins. The mixture is reacted at a certain temperature for 10 hours under air, using pilot-scale equipment. The Li:M molar blending ratio and sintering temperature are standard, but different for precursors with different Ni content, which will be specified in each individual example. After firing, the sintered cake is crushed, classified and sieved so as to obtain a non-agglomerated powder with a mean particle size D50 similar to that of the corresponding precursor.

e) Evaluation of Electrochemical Properties in Coin Cells

[0030] Electrodes are prepared as follows: about 27.27 wt. % of active cathode material, 1.52 wt. % polyvinylidene fluoride polymer (KF polymer L #9305, Kureha America Inc.), 1.52 wt. % conductive carbon black (Super P, Erachem Comilog Inc.) and 69.70 wt. % N-methyl-2-pyrrolidone (NMP) (from Sigma-Aldrich) are intimately mixed by means of high speed homogenizers. The slurry is then spread in a thin layer (typically 100 micrometer thick) on an aluminum foil by a tape-casting method. After evaporating the NMP solvent at 120 C. for 3 hours, the cast film is processed through two constantly spinning rolls with a 40 micrometer gap. Electrodes are punched from the film using a circular die cutter measuring 14 mm in diameter. The electrodes are then dried overnight at 90 C. The electrodes are subsequently weighed to determine the active material loading. Typically, the electrodes contain 90 wt. % active materials with an active materials loading weight of about 17 mg (11 mg/cm.sup.2). The electrodes are then put in an argon-filled glove box and assembled within a 2325-type coin cell body. The anode is a lithium foil having a thickness of 500 micrometers (origin: Hosen); the separator is a Tonen 20MMS microporous polyethylene film. The coin cell is filled with a 1M solution of LiPF.sub.6 dissolved in a mixture of ethylene carbonate and dimethyl carbonate in a 1:2 volume ratio (origin: Techno Semichem Co.).

[0031] Each cell is cycled at 25 C. using Toscat-3100 computer-controlled galvanostatic cycling stations (from Toyo) at different rate in the 4.33.0V/Li metal window range. The initial charge capacity CQ1 and discharge capacity DQ1 are measured in constant current mode (CC). The irreversible capacity Q.sub.irr. is expressed in % as:

[00003]$Q_{\mathrm{Irr}.}=\frac{\left(\mathrm{CQ}.Math..Math.1-\mathrm{DQ}.Math..Math.1\right)}{\mathrm{CQ}.Math..Math.1}100.Math..Math.\left(\%\right)$

[0032] The invention is further illustrated in the following examples:

Example 16

[0033] These examples contain NMC111 precursor compounds with different particle size, different BET and different tap density as shown in Table 2. Each precursor compound is blended with Li.sub.2CO.sub.3 in a Li:M molar ratio of 1.10 and fired at 930 C. for 10 hours using pilot-scale equipment. The sintered cake is then crushed and classified so as to obtain a non-agglomerated powder with a mean particle size D50 similar with that of the corresponding precursor. The precursor compounds in Examples 13 have a

[00004]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

larger than

[00005]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math.\left(x=0.35\right)$

and the cathode materials made from these precursor compounds show a Qirr lower than 8%, which is very good. On the contrary, precursor compounds in Examples 5 and 6 have a

[00006]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

smaller than

[00007]$\frac{0.041}{\left(0.1566*x\right)-0.0466},$

even smaller than

[00008]$\frac{0.021}{\left(0.1566*x\right)-0.0466},$

and the cathode materials made from these two precursors have a Qirr higher than 10%, which is not good. The precursor compound in Example 4 has a

[00009]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

smaller than

[00010]$\frac{0.041}{\left(0.1566*x\right)-0.0466}$

but larger than

[00011]$\frac{0.021}{\left(0.1566*x\right)-0.0466}.$

The Qirr of the cathode material is between 8% and 10%. Conclusion: NMC111 precursor compounds with

[00012]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

are desired, more preferably

[00013]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

Example 713

[0034] These examples contain NMC433 precursor compounds with different particle size, different BET and different tap density as shown in Table 3. Each precursor compound is blended with Li.sub.2CO.sub.3 in a Li:M molar ratio of 1.08 and fired at 910 C. for 10 hours using pilot-scale equipment. The sintered cake is then crushed and classified so as to obtain a non-agglomerated powder with a mean particle size D50 similar with that of the corresponding precursor. The precursor compounds in Examples 7 and 8 have a

[00014]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

larger than

[00015]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math.\left(x=0.38\right)$

and the cathode materials made from these precursors show a Qirr lower than 8%. Precursor compounds in Examples 12 and 13 have a

[00016]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

smaller than

[00017]$\frac{0.021}{\left(0.1566*x\right)-0.0466},$

and their corresponding cathode materials have a Qirr>10%. The precursor compounds in Examples 911 have a

[00018]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

value between

[00019]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math..Math.\mathrm{and}.Math..Math.\frac{0.021}{\left(0.1566*x\right)-0.0466}.$

Their Q.sub.irr's are all between 8% and 10%. Therefore, NMC433 precursor with

[00020]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

are desired, and more preferably

[00021]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

Example 1417

[0035] These examples contain NMC532 precursor compounds with different particle size, different BET and different tap density as shown in Table 4. Each precursor compound is blended with Li.sub.2CO.sub.3 in a Li:M molar ratio of 1.02 and fired at 920 C. for 10 hours using pilot-scale equipment. The sintered cake is then crushed and classified so as to obtain a non-agglomerated powder with a mean particle size D50 similar with that of the corresponding precursor. As shown in Table 4, the

[00022]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

value of precursor Example 14 is larger than

[00023]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math.\left(x=0.51\right),$

which corresponds to a Qirr of its cathode materials smaller than 8%. The

[00024]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

values of precursor Examples 16 and 17 are smaller than

[00025]$\frac{0.021}{\left(0.1566*x\right)-0.0466},$

corresponding to a Qirr of their cathode materials larger than 10%. Example 15 has a

[00026]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

value between

[00027]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math..Math.\mathrm{and}.Math..Math.\frac{0.021}{\left(0.1566*x\right)-0.0466}$

and a Qirr between 8% and 10%. Therefore, NMC532 precursors with

[00028]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

are desired, more preferably

[00029]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

Example 18, 19

[0036] These two examples demonstrate that the present invention also applies to NMC622. The precursor compounds are well mixed with LiOH at a blend Li:M ratio of 1.021.04 (see Table 4). The mixture is reacted at a temperature of 880 C. for 10 hours using pilot-scale equipment. The sintered cake is then crushed and classified so as to obtain a non-agglomerated powder with a mean particle size D50 similar with that of the corresponding precursor. Example 18 shows

[00030]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

value between

[00031]$\frac{0.041}{\left(0.1566*x\right)-0.0466}.Math..Math.\mathrm{and}.Math..Math.\frac{0.021}{\left(0.1566*x\right)-0.0466}$

and Q.sub.irr between 8% and 10%. Example 19 shows

[00032]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}$

value smaller than

[00033]$\frac{0.021}{\left(0.1566*x\right)-0.0466}$

and Qirr larger than 10%. Both fit our formula very well.

[0037] All precursor compounds used in the current invention Umicore mass-produced metal hydroxide or oxy-hydroxide. As seen in the above examples, low Ni % NMC111 and NMC433 precursors have a broad range of PBET, PTD at fixed PD50 while high Ni % NMC532, especially NMC622 precursors have a rather narrow range of PBET and PTD. It seems more difficult to have high PBET or low PTD precursor in high Ni NMC than in low Ni NMC. It is also normal that the higher the Ni content, the more difficult to achieve a low Q.sub.irr. Therefore, NMC622 precursor compounds satisfying

[00034]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

are desired, more preferably

[00035]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

Example 20, 21

[0038] Generally, dopants do not necessarily have a strong impact on the Qirr of the cathode material, especially when the doping amount is small. These two examples demonstrate that the present invention also applies to 1 mol % zirconium doped NMC111 and NMC433. The precursor compounds are well mixed with nano-size ZrO.sub.2 (Evonik, Germany) for 10 minutes and then mixed with Li.sub.2CO.sub.3 at a blend Li:M ratio of 1.08 or 1.10 (see Table 5). The ZrO.sub.2 particles are in tetragonal and monoclinic phases, and have an average primary particle size of 12 nm and a BET of 6015 m.sup.2/g. The mixture is reacted at a temperature of 910 or 930 C. for 10 hours using pilot-scale equipment. The sintered cake is then crushed and classified so as to obtain a non-agglomerated powder with a mean particle size D50 similar with that of the corresponding precursor. Both NMC precursors satisfy with

[00036]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

and the Qirr's of the cathodes are smaller than 8%. Therefore, for cathode materials with dopants, precursors with

[00037]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.021}{\left(0.1566*x\right)-0.0466}$

are desired, more preferably

[00038]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math..Math.50}>\frac{0.041}{\left(0.1566*x\right)-0.0466}.$

TABLE-US-00002 TABLE 2 NMC111 precursor compounds property, firing conditions and coin cell irreversible capacity Coin Examples Precursor Ni/Mn/Co PD50 (m) PBET (m.sup.2/g) PTD (g/cm.sup.3) Lithium source Blend ratio Firing T/ C. [00039]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math.50}$ [00040]$\frac{0.041}{0.1566*x-0.0466}$ [00041]$\frac{0.021}{0.1566*x-0.0466}$ cell Qirr Ex1 35/32/33 3.06 26.25 1.01 Li.sub.2CO.sub.3 1.10 930 8.49 4.99 2.56 6.5% Ex2 35/32/33 3.01 19.85 1.27 Li.sub.2CO.sub.3 1.10 930 5.19 4.99 2.56 7.7% EX3 35/32/33 2.50 17.22 0.90 Li.sub.2CO.sub.3 1.10 930 7.65 4.99 2.56 7.9% EX4 35/32/33 3.30 20.19 1.32 Li.sub.2CO.sub.3 1.10 930 4.63 4.99 2.56 9.0% EX5 35/32/33 6.62 6.95 1.80 Li.sub.2CO.sub.3 1.10 930 0.58 4.99 2.56 11.7% EX6 35/32/33 10.43 5.42 2.19 Li.sub.2CO.sub.3 1.10 930 0.24 4.99 2.56 12.2%

TABLE-US-00003 TABLE 3 NMC433 precursor compounds property, firing conditions and coin cell irreversible capacity Coin Examples Precursor Ni/Mn/Co PD50 (m) PBET (m.sup.2/g) PTD (g/cm.sup.3) Lithium source Blend ratio Firing T/ C. [00042]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math.50}$ [00043]$\frac{0.041}{0.1566*x-0.0466}$ [00044]$\frac{0.021}{0.1566*x-0.0466}$ cell Qirr Ex7 38/29/33 3.29 19.34 1.37 Li.sub.2CO.sub.3 1.08 910 4.29 3.18 1.63 5.9% EX8 38/29/33 3.36 17.42 1.31 Li.sub.2CO.sub.3 1.08 910 3.96 3.18 1.63 6.2% EX9 38/29/33 4.92 12.25 1.32 Li.sub.2CO.sub.3 1.08 910 1.89 3.18 1.63 8.5% EX10 38/29/33 4.68 11.03 1.20 Li.sub.2CO.sub.3 1.08 910 1.96 3.18 1.63 9.0% EX11 38/29/33 4.75 10.55 0.89 Li.sub.2CO.sub.3 1.08 910 2.50 3.18 1.63 8.8% EX12 38/29/33 7.64 8.34 1.82 Li.sub.2CO.sub.3 1.08 910 0.60 3.18 1.63 11.0% EX13 38/29/33 12.53 4.22 2.31 Li.sub.2CO.sub.3 1.08 910 0.15 3.18 1.63 12.1%

TABLE-US-00004 TABLE 4 NMC532 and NMC622 precursor compounds property, firing conditions and coin cell irreversible capacity Coin Examples Precursor Ni/Mn/Co PD50 (m) PBET (m.sup.2/g) PTD (g/cm.sup.3) Lithium source Blend ratio Firing T/ C. [00045]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math.50}$ [00046]$\frac{0.041}{0.1566*x-0.0466}$ [00047]$\frac{0.021}{0.1566*x-0.0466}$ cell Qirr Ex14 51/29/20 7.46 15.97 1.31 Li.sub.2CO.sub.3 1.02 920 1.63 1.23 0.63 6.7% EX15 51/29/20 6.56 10.45 1.73 Li.sub.2CO.sub.3 1.02 920 0.92 1.23 0.63 9.4% EX16 51/29/20 12.97 4.47 2.39 Li.sub.2CO.sub.3 1.02 920 0.14 1.23 0.63 12.1% EX17 51/29/20 10.63 4.70 2.29 Li.sub.2CO.sub.3 1.02 920 0.19 1.23 0.63 11.0% EX18 60/20/20 4.55 5.66 1.99 LiOH 1.04 880 0.63 0.87 0.44 9.7% EX19 60/20/20 12.77 4.54 2.42 LiOH 1.02 880 0.15 0.87 0.44 10.7%

TABLE-US-00005 TABLE 5 precursor compounds property, firing conditions and coin cell irreversible capacity for Zr doped NMC111 and NMC433 Coin Examples Precursor Ni/Mn/Co PD50 (m) PBET (m.sup.2/g) PTD (g/cm.sup.3) Lithium source Blend ratio Firing T/ C. [00048]$\frac{\mathrm{PBET}}{\mathrm{PTD}*\mathrm{PD}.Math.50}$ [00049]$\frac{0.041}{0.1566*x-0.0466}$ [00050]$\frac{0.021}{0.1566*x-0.0466}$ cell Qirr Ex20 35/32/33 3.20 21.10 1.23 Li.sub.2CO.sub.3 1.10 920 5.36 4.99 2.56 7.3% EX21 38/29/33 3.33 14.01 1.28 Li.sub.2CO.sub.3 1.08 920 3.29 3.18 1.63 7.9%