ELECTROCHEMICAL CELLS
An electrochemical cell includes a negative electrode that includes an active material including silicon. The electrochemical cell further includes a positive electrode that includes a first lithium metal oxide and a second lithium metal oxide. The first lithium metal oxide includes a material having (i) a nickel content of less than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of greater than 2 micrometers. The second lithium metal oxide includes a material having (i) a nickel content of greater than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of less than 2 micrometers. The second lithium metal oxide is provided in the positive electrode composition in an amount of less than 20 wt. %, based on the total weight of the first lithium metal oxide and second lithium metal oxide in the positive electrode composition.
1 . An electrochemical cell comprising:
a negative electrode comprising an active material comprising silicon; and
a positive electrode comprising a first lithium metal oxide and a second lithium metal oxide;
wherein the first lithium metal oxide comprises a material having (i) a nickel content of less than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of greater than 2 micrometers;
wherein the second lithium metal oxide comprises a material having (i) a nickel content of greater than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of less than 2 micrometers; and
wherein the second lithium metal oxide is provided in the positive electrode composition in an amount of less than 20 wt. %, based on the total weight of the first lithium metal oxide and second lithium metal oxide in the positive electrode composition.
2 . The electrochemical cell of claim 1 , wherein the first lithium metal oxide comprises lithium cobalt oxide.
3 . The electrochemical cell of claim 1 , wherein the second lithium metal oxide comprises a material having a formula: Li(Ni x Mn y Co z )O 2 , where x, y, and z are greater than zero, x+y+z=1, and x is greater than 0.33.
4 . The electrochemical cell of claim 3 , wherein x is 0.58-0.62, y is 0.18-0.22, and z is 0.18-0.22.
5 . The electrochemical cell of claim 3 , wherein x is 0.78-0.82, y is 0.08-0.12, and z is 0.08-0.12.
6 . The electrochemical cell of claim 3 , wherein x is equal to or greater than 0.6.
7 . The electrochemical cell of claim 1 , wherein the second lithium metal oxide comprises a material having a formula: Li 1+x′ (Ni a Mn b Co c ) 1-x′ O 2 , wherein 0.05≤x′≤0.10, a+b+c=1, c/(a+b)<0.25, a>0.30, and a, b and c are each greater than zero.
8 . The electrochemical cell of claim 1 , wherein the second lithium metal oxide comprises a material having a formula: Li 1+x′ (Ni a Co b Al c ) 1-x″ O 2 , where x″≥0, and a, b, and c are each greater than zero, a+b+c=1 and a>0.7.
9 . The electrochemical cell of claim 1 , wherein the first lithium metal oxide comprises a material having a D50 greater than 5 micrometers and the second lithium metal oxide comprises a material having a D50 less than 1 micrometer.
10 . The electrochemical cell of claim 1 , wherein the second lithium metal oxide is provided in an amount such that the second lithium metal oxide accounts for less than 10% of the reversible capacity of the positive electrode composition.
11 . The electrochemical cell of claim 1 , wherein the active material comprising silicon comprises a silicon alloy comprising a transition metal, a silicon carbide, or a silicon oxide.
12 . The electrochemical cell of claim 1 , wherein a production surface of the second lithium metal oxide is greater than 0.003 m2/mAh and less than 0.015 m2/mAh.
13 . An electrochemical cell comprising:
a negative electrode comprising an active material comprising silicon; and
a positive electrode comprising a first lithium metal oxide and a second lithium metal oxide;
wherein the first lithium metal oxide comprises a material having (i) a nickel content of less than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of greater than 2 micrometers;
wherein the second lithium metal oxide comprises a material having (i) a nickel content of greater than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of less than 2 micrometers; and
wherein a production surface of the second lithium metal oxide is greater than 0.003 m2/mAh and less than 0.015 m2/mAh.
14 . The electrochemical cell of claim 1 , further comprising an electrolyte comprising an acetate.
15 . The electrochemical cell of claim 13 , further comprising an electrolyte comprising an acetate.
16 . The electrochemical cell of claim 1 , further comprising a carbon dioxide producing additive.
17 . The electrochemical cell of claim 1 , further comprising an electrolyte comprising a linear pyrocarbonate.
18 . A method of forming an electrochemical cell comprising:
providing a negative electrode comprising an active material comprising silicon; and
providing a positive electrode comprising a first lithium metal oxide and a second lithium metal oxide;
wherein the first lithium metal oxide comprises a material having (i) a nickel content of less than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of greater than 2 micrometers;
wherein the second lithium metal oxide comprises a material having (i) a nickel content of greater than 30 mole %, based on the total moles of non-lithium metals in the first lithium metal oxide; and (ii) a D50 of less than 2 micrometers; and
wherein the second lithium metal oxide is provided in the positive electrode composition in an amount of less than 20 wt. %, based on the total weight of the first lithium metal oxide and second lithium metal oxide in the positive electrode composition.