Cathode additives to provide an excess lithium source for lithium ion batteries
A lithium ion electrochemical cell is described in which the lithium comprising further comprises a lithiation agent. The lithiation agent, which comprises a lithium constituent, is designed to provide an excess source of lithium to minimize capacity loss of the lithium ion electrochemical cell. The anode of the lithium ion cell comprises a material matrix comprising carbon, graphene and an active element such as silicon or tin.
1. An electrochemical cell, comprising:
a negative electrode comprising a negative electrode active material;
a positive electrode comprising a positive electrode active material comprising lithium;
an ionically conductive electrolyte located between the positive electrode and the negative electrode; and
a lithiation agent located in at least one of the positive electrode and negative electrode, the lithiation agent comprising from about 0.01 weight percent to about 15 weight percent of the positive electrode or the negative electrode, and the lithiation agent comprising:
LiN 3 ;
Li 5 FeO 4 ;
Li x MF x , where 0.1≤X≤3 and M is selected from the group consisting of Fe, Mn, Co, Ni, Cu, Vn, Cr, and Bi;
Li (3−x) M x N, where 0≤X≤0.8 and M is selected from the group consisting of cobalt, nickel, copper, and combinations thereof; or
Li 2−x−y Z y Q x N, where 0.1≤x≤0.8, 0.1≤y≤1, Z is a Li vacancy and Q is selected from the group of elements consisting of Co, Ni, Cu, and combinations thereof.
2. The electrochemical cell of claim 1 , wherein:
the positive electrode active material has a first lithium extraction voltage;
the lithiation agent has a second lithium extraction voltage; and
the first lithium extraction voltage is greater than the second lithium extraction voltage.
3. The electrochemical cell of claim 1 , wherein:
the positive electrode active material has a first lithium extraction voltage;
the lithiation agent has a second lithium extraction voltage; and
the first lithium extraction voltage is less than the second lithium extraction voltage.
4. The electrochemical cell of claim 1 , wherein the negative electrode active material is selected from the group consisting of silicon, carbon, antimony, lead, tin, germanium, and combinations thereof.
5. The electrochemical cell of claim 1 , wherein the lithiation agent comprises from about 0.01 weight percent to about 15 weight percent of the positive electrode.
6. The electrochemical cell of claim 1 , wherein during operation of the electrochemical cell, lithium from the lithiation agent irreversibly reacts with the negative electrode active material to form a lithium compound in the negative electrode or in a solid electrolyte-interphase layer on an exterior surface of the negative electrode.
7. The electrochemical cell of claim 6 , wherein the lithium deintercalates from the lithiation agent, at a lithiation agent extraction voltage and irreversibly reacts with the negative electrode active material to form the lithium compound that does not substantially deintercalate lithium during a subsequent discharge step of the battery, the lithium compound comprising an organic or inorganic compound comprising lithium.
8. The electrochemical cell of claim 1 , wherein the positive electrode active material is selected from the group consisting of a lithium metal oxide, a lithium metal fluoride, a lithium sulfide, a lithium metal sulfide, a lithium metal phosphate, a lithium metal silicate, and combinations thereof, wherein the metal comprises a transition metal from the Periodic Table of Elements.
9. The electrochemical cell of claim 1 , wherein the positive electrode active material is selected from the group consisting of LiNi x Co y Al z O 2 , wherein x+y+z=1, LiCoO 2 , LiFePO 4 , LiMn 2 O 4 , Li 2 S, LiNi x Mn y Co z O 2 , wherein 0.3≤x≤1.0, 0.1≤y≤0.45, 0.1≤z≤0.4 and x+y+z=1, MF x wherein 0.1≤x≤3, LixMF x wherein 0.1≤x≤3, LiMPO 4 , Li 2 MSiO 4 , and LiMn 2 O 4 -LiMO, wherein M is a transition metal from the Periodic Table of Elements.
10. A positive electrode of an electrochemical cell comprising a mixture of:
a positive electrode active material; and
a lithiation agent comprising:
Li x MF x , where 0.1≤X≤3 and M is selected from the group consisting of Fe, Mn, Co, Ni, Cu, Vn, Cr, and Bi;
Li (3−x) M x N, where 0<X≤0.8 and M is selected from the group consisting of cobalt, nickel, copper, and combinations thereof; or
Li 2−x−y Z y Q x N, where 0.1≤x≤0.8, 0.1≤y≤1, Z is a Li vacancy and Q is selected from the group of elements consisting of Co, Ni, Cu, and combinations thereof.
11. The positive electrode of claim 10 , wherein the positive electrode active material is selected from the group consisting of a lithium metal oxide, a lithium metal fluoride, a lithium sulfide, a lithium metal sulfide, a lithium metal phosphate, a lithium metal silicate, and combinations thereof, wherein the metal comprises a transition metal from the Periodic Table of Elements.
12. The positive electrode of claim 11 , wherein positive electrode active material comprises silicon and graphene.
13. The positive electrode of claim 10 , wherein the lithiation agent comprises from about 0.01 weight percent to about 15 weight percent of the positive electrode.
14. The positive electrode of claim 10 , wherein the lithiation agent has a specific capacity of at least 400 mAh/g.