Engineering topics

He, Rong

Publications and source records attributed to He, Rong.

4 records

DOE OSTI2025

Unveiling the Mechanism of Mn Dissolution Through a Dynamic Cathode‐Electrolyte Interphase on LiMn2O4

Abstract Understanding the formation and evolution of the cathode‐electrolyte interphase (CEI), which forms at the interface between the cathode and electrolyte, is crucial for revealing degradation mechanisms in cathode materials, especially for developing strategies to stabilize the interphase in the strongly oxidizing conditions that evolve at high operating voltages in next‐generation Li‐ion batteries. However, The present understanding of the CEI is challenged by its complex and dynamic nature. In this work, near‐edge X‐ray absorption fine structure spectroscopy, electrochemical characterization, and reactive molecular dynamics simulations are combined to reveal a mechanism for CEI formation and evolution above model LiMn 2 O 4 (LMO) thin‐film electrodes in contact with conventional carbonate‐based electrolytes. It is found that Mn dissolution from LMO can be understood in terms of repetitive Mn 3 O 4 formation and dissolution behavior during cycling, which is closely connected to electrolyte decomposition and a key aspect of the CEI formation and growth. The behavior of the CEI in this model system offers detailed insight into the dynamic chemistry of the interphase, underscoring the important role of electrolyte composition and cathode surface structure in interphase degradation.

Ou, Wenhan↗

DOE OSTI2023

Basics of the scanning electrochemical microscope and its application in the characterization of lithium-ion batteries: a brief review

A scanning electrochemical microscope (SECM) can directly monitor electrochemical processes at interfaces of electrodes and electrolytes and has been used as an analytical tool for lithium-ion battery (LIB) studies. Through SECM, we can visualize the electrochemical reactivities of active species in LIBs in-situ during cycling. This review begins with introducing SECM-based LIB research and then summarizes the working mechanism and operating modes of the technique as well as combinations of SECM with other techniques for LIB studies. We review the results with a focus on the interfacial properties, surface reactions and electrochemical activity of different electrode materials for LIBs. The investigations of battery degradation, kinetic parameters and electrolyte swelling by SECM are also discussed. Finally, the current limitations and perspectives are also described regarding future developments.

25 ENERGY STORAGE↗

DOE OSTI2022

Environmental evaluation of radioactivity levels and associated radiation hazards in groundwater around the WIPP site

Groundwater may contain radioactive substances which can be dangerous to human health. Concentrations of natural radionuclides polonium (Po), thorium (Th), uranium (U), and radium (Ra) isotopes were measured in groundwater samples collected from different locations in the vicinity of the Waste Isolation Pilot Plant (WIPP) site in Carlsbad, New Mexico. The average values of gross activity concentrations of 210 Po, 228 Th, 238 U, 234 U, 226 Ra and 228 Ra isotopes were determined to be 1.62 Bq L -1 in shallow groundwater and 5.88 Bq L -1 in deep groundwater, respectively. The total radioactivity in deep groundwater was higher than that in shallow groundwater, and most of the radioactivity in the water is from 226 Ra. Furthermore, the effective doses for ingestion of natural radionuclides were about 0.333 mSv y–1 for shallow groundwater and about 1.338 mSv y –1 for deep groundwater samples, which are higher than the World Health Organization (WHO, 2017) guideline level (0.1 mSv y –1 ) for drinking water. Ra dominated the total ingestion dose, contributing 93.06 % and 75.40 % of the total effective doses to the deep and shallow groundwater, respectively. The ingrowth and decay of natural radionuclides suggested that 228 Ra/ 226 Ra ratio can be a useful indicator of the source of radioactive contamination. The radioactivity data obtained from the investigated groundwater samples can be used to establish a baseline for radioactivity levels in groundwater around the WIPP site.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗

DOE OSTI2020

Cathode Electrolyte Diagnostics Based on Scanning Probe Microscopy

Various processes lead to degradation of cathodes in lithium-ion batteries. Questions remain regarding mechanisms of many of these processes. Probe microscopy methods including scanning electrochemical microscopy (SECM) are capable of directly probing processes at the cathode/electrolyte interface. SECM uses a small electrode to perform rapid electrochemical analysis of transient species generated at an active cathode/electrolyte interface. This paper discusses the background of the SECM instrument and its application to lithium-ion battery research. We also describe the application of SECM methods to the study of cathode degradation processes observed in lithium-ion batteries. Specifically, we focus on characterizing the dissolution of manganese from LiMn2O4 (LMO) based on recent debate in the literature. We describe experiments to observe and characterize the electrochemical properties of manganese complexes emerging from degrading LMO electrode materials.

cathode/electrolyte interface↗