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Title: Self-healing SEI enables full-cell cycling of a silicon-majority anode with a coulombic efficiency exceeding 99.9%

Despite active developments, full-cell cycling of Li-battery anodes with >50 wt% Si (a Si-majority anode, SiMA) is rare. The main challenge lies in the solid electrolyte interphase (SEI), which when formed naturally (nSEI), is fragile and cannot tolerate the large volume changes of Si during lithiation/delithiation. An artificial SEI (aSEI) with a specific set of mechanical characteristics is henceforth designed; we enclose Si within a TiO 2 shell thinner than 15 nm, which may or may not be completely hermetic at the beginning. In situ TEM experiments show that the TiO 2 shell exhibits 5× greater strength than an amorphous carbon shell. Void-padded compartmentalization of Si can survive the huge volume changes and electrolyte ingression, with a self-healing aSEI + nSEI. The half-cell capacity exceeds 990 mA h g -1 after 1500 cycles. To improve the volumetric capacity, we further compress SiMA 3-fold from its tap density (0.4 g cm -3) to 1.4 g cm -3, and then run the full-cell battery tests against a 3 mA h cm -2 LiCoO 2 cathode. Despite some TiO 2 enclosures being inevitably broken, 2× the volumetric capacity (1100 mA h cm -3) and 2× the gravimetric capacity (762 mA h g -1)more » of commercial graphite anode is achieved in stable full-cell battery cycling, with a stabilized areal capacity of 1.6 mA h cm -2 at the 100th cycle. The initial lithium loss, characterized by the coulombic inefficiency (CI), is carefully tallied on a logarithmic scale and compared with the actual full-cell capacity loss. In conclusion, it is shown that a strong, non-adherent aSEI, even if partially cracked, facilitates an adaptive self-repair mechanism that enables full-cell cycling of a SiMA, leading to a stabilized coulombic efficiency exceeding 99.9%.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [5] ;  [3] ;  [5] ;  [4] ;  [5] ;  [5] ;  [3] ;  [3] ;  [6] ; ORCiD logo [7]
  1. Xi'an Jiaotong Univ., Xi'an (China). State Key Lab. of Electrical Insulation and Power Equipment, School of Electrical Engineering; Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering and Dept. of Materials Science and Engineering; Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
  2. Tongji Univ., Shanghai (China). School of Materials Science and Engineering
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering and Dept. of Materials Science and Engineering
  4. Xi'an Jiaotong Univ., Xi'an (China). State Key Lab. of Electrical Insulation and Power Equipment, School of Electrical Engineering
  5. Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
  6. Stanford Univ., CA (United States). Dept. of Materials Science and Engineering; SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES)
  7. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering and Dept. of Materials Science and Engineering; Tongji Univ., Shanghai (China). School of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Energy & Environmental Science
Additional Journal Information:
Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 1754-5692
Publisher:
Royal Society of Chemistry
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); National Science Foundation (NSF); National Natural Science Foundation of China (NNSFC)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE
OSTI Identifier:
1353104