| Affiliation: | 1. Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139 USA;2. Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139 USA
State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240 China;3. National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973 USA;4. Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai, 200240 China |
| Abstract: | Cycling LiCoO2 to above 4.5 V for higher capacity is enticing; however, hybrid O anion- and Co cation-redox (HACR) at high voltages facilitates intrinsic Oα? (α < 2) migration, causing oxygen loss, phase collapse, and electrolyte decomposition that severely degrade the battery cyclability. Hereby, commercial LiCoO2 particles are operando treated with selenium, a well-known anti-aging element to capture oxygen-radicals in the human body, showing an “anti-aging” effect in high-voltage battery cycling and successfully stopping the escape of oxygen from LiCoO2 even when the cathode is cycled to 4.62 V. Ab initio calculation and soft X-ray absorption spectroscopy analysis suggest that during deep charging, the precoated Se will initially substitute some mobile Oα? at the charged LiCoO2 surface, transplanting the pumped charges from Oα? and reducing it back to O2? to stabilize the oxygen lattice in prolonged cycling. As a result, the material retains 80% and 77% of its capacity after 450 and 550 cycles under 100 mA g?1 in 4.57 V pouch full-cells matched with a graphite anode and an ultralean electrolyte (2 g Ah?1). |
