Engineering topics

Lee, Sang‐Jun

Publications and source records attributed to Lee, Sang‐Jun.

4 records

DOE OSTI2022

Structural, Dynamic, and Chemical Complexities in Zinc Anode of an Operating Aqueous Zn-Ion Battery

Aqueous Zn-ion battery is a promising technology for electrochemical energy storage. The formation of Zn dendrites, however, can jeopardize the cell cycle life and thus, hinders the industrial adoption of this technology. A fundamental understanding of the kinetic mechanisms is crucial for improving the Zn-ion battery. Here, in situ and operando X-ray microscopy methods are utilized to visualize the Zn plating and stripping behaviors under different electrochemical conditions. It is demonstrated that the substrate curvature, local morphology, electrochemical protocols, and the surface chemistry can collectively affect the Zn plating behavior. Furthermore, these results provide new insights for developing the next-generation dendrite-free and long-span aqueous Zn-ion battery.

25 ENERGY STORAGE↗

DOE OSTI2021

Multiphase, Multiscale Chemomechanics at Extreme Low Temperatures: Battery Electrodes for Operation in a Wide Temperature Range

Understanding the behavior of lithium-ion batteries (LIBs) under extreme conditions, for example, low temperature, is key to broad adoption of LIBs in various application scenarios. LIBs, poor performance at low temperatures is often attributed to the inferior lithium-ion transport in the electrolyte, which has motivated new electrolyte development as well as the battery preheating approach that is popular in electric vehicles. A significant irrevocable capacity loss, however, is not resolved by these measures nor well understood. Herein, multiphase, multiscale chemomechanical behaviors in composite LiNi x Mn y Co z O 2 (NMC, x + y + z = 1) cathodes at extremely low temperatures are systematically elucidated. The low-temperature storage of LIBs can result in irreversible structural damage in active electrodes, which can negatively impact the subsequent battery cycling performance at ambient temperature. Furthermore, beside developing electrolytes that have stable performance, designing batteries for use in a wide temperature range also calls for the development of electrode components that are structurally and morphologically robust when the cell is switched between different temperatures.

25 ENERGY STORAGE↗

DOE OSTI2020

Operando Tailoring of Defects and Strains in Corrugated β-Ni(OH) 2 Nanosheets for Stable and High-Rate Energy Storage

Nickel hydroxide represents a technologically important material for energy storage, such as hybrid supercapacitors. It has two different crystallographic polymorphs, α- and β-Ni(OH) 2 , showing advantages in either theoretical capacity or cycling/rate performance, manifesting a trade-off trend that needs to be optimized for practical applications. In this work, the synergistic superiorities in both activity and stability of corrugated β-Ni(OH) 2 nanosheets are demonstrated through an electrochemical abuse approach. With ≈91% capacity retention after 10 000 cycles, the corrugated β-Ni(OH) 2 nanosheets can deliver a gravimetric capacity of 457 C g -1 at a high current density of 30 A g -1 , which is nearly two and four times that of the regular α- and β-Ni(OH) 2 , respectively. Operando spectroscopy and finite element analysis reveal that greatly enhanced chemical activity and structural robustness can be attributed to the in situ tailored lattice defects and the strain-induced highly curved micromorphology. This work demonstrates a multi-scale defect-and-strain co-design strategy, which is helpful for rational design and tuned fabrication of next-generation electrode materials for stable and high-rate energy storage.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Enabling Stable Cycling of 4.2 V High-Voltage All-Solid-State Batteries with PEO-Based Solid Electrolyte

Poly(ethylene oxide) (PEO)-based solid electrolytes are expected to be exploited in solid-state batteries with high safety. Its narrow electrochemical window, however, limits the potential for high voltage and high energy density applications. In this paper, the electrochemical oxidation behavior of PEO and the failure mechanisms of LiCoO 2 -PEO solid-state batteries are studied. It is found that although for pure PEO it starts to oxidize at a voltage of above 3.9 V versus Li/Li + , the decomposition products have appropriate Li + conductivity that unexpectedly form a relatively stable cathode electrolyte interphase (CEI) layer at the PEO and electrode interface. The performance degradation of the LiCoO 2 -PEO battery originates from the strong oxidizing ability of LiCoO 2 after delithiation at high voltages, which accelerates the decomposition of PEO and drives the self-oxygen-release of LiCoO 2 , leading to the unceasing growth of CEI and the destruction of the LiCoO 2 surface. When LiCoO 2 is well coated or a stable cathode LiMn 0.7 Fe 0.3 PO 4 is used, a substantially improved electrochemical performance can be achieved, with 88.6% capacity retention after 50 cycles for Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 coated LiCoO 2 and 90.3% capacity retention after 100 cycles for LiMn 0.7 Fe 0.3 PO 4 . The results suggest that, when paired with stable cathodes, the PEO-based solid polymer electrolytes could be compatible with high voltage operation.

25 ENERGY STORAGE↗