LITHIUM ION BATTERIES WITH SUPPLEMENTAL LITHIUM
Supplemental lithium can be used to stabilize lithium ion batteries with lithium rich metal oxides as the positive electrode active material. Dramatic improvements in the specific capacity at long cycling have been obtained. The supplemental lithium can be provided with the negative electrode, or alternatively as a sacrificial material that is subsequently driven into the negative electrode active material. The supplemental lithium can be provided to the negative electrode active material prior to assembly of the battery using electrochemical deposition. The positive electrode active materials can comprise a layered-layered structure comprising manganese as well as nickel and/or cobalt.
1 . A lithium ion battery comprising:
a negative electrode comprising an active composition that reversibly uptakes and releases lithium;
a positive electrode comprising an active material that reversibly uptakes and releases lithium;
a separator between the negative electrode and the positive electrode; and
an electrolyte comprising a lithium salt and a nonaqueous solvent,
wherein the capacity of the negative electrode exceeds the capacity of the positive electrode by at least about 10%, and
wherein after 20 charge-discharge cycles of the battery and discharge of the battery down to 98% of capacity, the negative electrode can be removed and electrochemically de-intercalated/de-alloyed with a capacity of at least about 2.5% of the negative electrode capacity with the corresponding removal of lithium from the negative electrode.
2 . The lithium ion battery of claim 1 wherein the active composition comprises supplemental lithium.
3 . The lithium ion battery of claim 1 wherein the anode comprises supplemental lithium, which comprises elemental lithium, a lithium alloy, or a lithium composition.
4 . The lithium ion battery of claim 1 wherein the active composition comprises silicon.
5 . The lithium ion battery of claim 1 wherein the positive electrode active material comprises a lithium metal oxide.
6 . The lithium ion battery of claim 5 wherein the lithium metal oxide comprises LiCoO 2 .
7 . The lithium ion battery of claim 5 wherein the lithium metal oxide has a formula Li 1+x M 1−y O 2 wherein M represents one or more non-lithium metals, x is from about 0.01 to about 0.33, and y is from about x−0.2 to about x+0.2 with the proviso that y≥0.
8 . The lithium ion battery of claim 1 wherein the lithium salt comprises lithium hexafluorophosphate, lithium bis(trifluoromethyl sulfonyl imide), lithium trifluoromethane sulfonate, lithium tetrafluoroborate, lithium difluoro oxalato borate, and a mixture thereof.
9 . The lithium ion battery of claim 1 wherein the negative electrode comprises silicon, a polymer binder and an electrically conductive powder distinct from the electroactive composition.
10 . The lithium ion battery of claim 1 wherein the negative electrode can be removed and electrochemically de-intercalated/de-alloyed with a capacity from about 5% to about 80% of the negative electrode capacity with the corresponding removal of lithium from the negative electrode
11 . A lithium ion battery comprising:
a negative electrode comprising an active composition that reversibly uptakes and releases lithium;
a positive electrode comprising an active material that reversibly uptakes and releases lithium;
a separator between the negative electrode and the positive electrode; and
an electrolyte comprising a lithium salt,
wherein the capacity of the negative electrode exceeds the capacity of the positive electrode by at least about 15%, and
wherein the negative electrode is preloaded with supplemental lithium in all forms corresponding with at least about 10% of the anode capacity.
12 . The lithium ion battery of claim 11 wherein the active composition comprises silicon.
13 . The lithium ion battery of claim 11 wherein the negative electrode is preloaded with supplemental lithium in all forms corresponding with at least about 20% of the anode capacity.
14 . The lithium ion battery of claim 13 wherein at a discharge rate of 1 C over 180 charge-discharge cycles, the lithium ion battery exhibits a reduced capacity fade as compared to a reference lithium ion battery equivalent to the lithium ion battery but without supplemental lithium.
15 . The lithium ion battery of claim 13 wherein after 20 charge-discharge cycles of the battery and discharge of the battery down to 98% of capacity, the negative electrode can be removed and electrochemically de-intercalated/de-alloyed with a capacity of at least about 2.5% of the negative electrode capacity with the corresponding removal of lithium from the negative electrode.
16 . The lithium ion battery of claim 11 wherein negative electrode comprises silicon, a polymer binder and an electrically conductive powder distinct from the electroactive composition.
17 . The lithium ion battery of claim 16 wherein the positive electrode active material comprises a lithium metal oxide.
18 . The lithium ion battery of claim 11 wherein the supplemental lithium comprises elemental lithium.
19 . The lithium ion battery of claim 18 wherein the elemental lithium is in the form of a foil.
20 . The lithium ion battery of claim 11 wherein the supplemental lithium is preloaded into the negative electrode active composition.