skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Decomposition of Trace Li2CO3 During Charging Leads to Cathode Interface Degradation with the Solid Electrolyte LLZO
A major challenge for lithium-containing electrochemical systems is the formation of lithium carbonates. Solid-state electrolytes circumvent the use of organic liquids that can generate these species, but they are still susceptible to Li2CO3 formation from exposure to water vapor and carbon dioxide. It is reported here that trace quantities of Li2CO3, which are re-formed following standard mitigation and handling procedures, can decompose at high charging potentials and degrade the electrolyte–cathode interface. Operando electrochemical mass spectrometry (EC–MS) is employed to monitor the outgassing of solid-state batteries containing the garnet electrolyte Li7La3Zr2O12 (LLZO) and using appropriate controls CO2 and O2 are identified to emanate from the electrolyte–cathode interface at charging potentials > 3.8 V (vs Li/Li+). The gas evolution is correlated with a large increase in cathode interfacial resistance observed by potential-resolved impedance spectroscopy. This is the first evidence of electrochemical decomposition of interfacial Li2CO3 in garnet cells and suggests a need to report “time-to-assembly” for cell preparation methods  more » « less
Award ID(s):
1806059
PAR ID:
10311560
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Advanced functional materials
Volume:
31
ISSN:
1616-301X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; (, Small Methods)
    Abstract A thin solid electrolyte with a high Li+conductivity is used to separate the metallic lithium anode and the cathode in an all‐solid‐state Li‐metal battery. However, most solid Li‐ion electrolytes have a small electrochemical stability window, large interfacial resistance, and cannot block lithium‐dendrite growth when lithium is plated on charging of the cell. Mg2+stabilizes a rhombohedral NASICON‐structured solid electrolyte of the formula Li1.2Mg0.1Zr1.9(PO4)3(LMZP). This solid electrolyte has Li‐ion conductivity two orders of magnitude higher at 25 °C than that of the triclinic LiZr2(PO4)3.7Li and6Li NMR confirm the Li‐ions in two different crystallographic sites of the NASICON framework with 85% of the Li‐ions having a relatively higher mobility than the other 15%. The anode–electrolyte interface is further investigated with symmetric Li/LMZP/Li cell testing, while the cathode–electrolyte interface is explored with an all‐solid‐state Li/LMZP/LiFePO4cell. The enhanced performance of these cells enabled by the Li1.2Mg0.1Zr1.9(PO4)3solid electrolyte is stable upon repeated charge/discharge cycling. 
    more » « less
  2. ; ; ; ; ; (, Small)
    Abstract Solid‐state lithium metal batteries with garnet‐type electrolyte provide several advantages over conventional lithium‐ion batteries, especially for safety and energy density. However, a few grand challenges such as the propagation of Li dendrites, poor interfacial contact between the solid electrolyte and the electrodes, and formation of lithium carbonate during ambient exposure over the solid‐state electrolyte prevent the viability of such batteries. Herein, an ultrathin sub‐nanometer porous carbon nanomembrane (CNM) is employed on the surface of solid‐state electrolyte (SSE) that increases the adhesion of SSE with electrodes, prevents lithium carbonate formation over the surface, regulates the flow of Li‐ions, and blocks any electronic leakage. The sub‐nanometer scale pores in CNM allow rapid permeation of Li‐ions across the electrode–electrolyte interface without the presence of any liquid medium. Additionally, CNM suppresses the propagation of Li dendrites by over sevenfold up to a current density of 0.7 mA cm−2and enables the cycling of all‐solid‐state batteries at low stack pressure of 2 MPa using LiFePO4cathode and Li metal anode. The CNM provides chemical stability to the solid electrolyte for over 4 weeks of ambient exposure with less than a 4% increase in surface impurities. 
    more » « less
  3. ; ; ; ; ; (, Materials Advances)
    The all-solid-state battery is a promising alternative to conventional lithium-ion batteries that have reached the limit of their technological capabilities. The next-generation lithium-ion batteries are expected to be eco-friendly, long-lasting, and safe while demonstrating high energy density and providing ultrafast charging. These much-needed properties require significant efforts to uncover and utilize the chemical, morphological, and electrochemical properties of solid-state electrolytes and cathode nanocomposites. Here we report solid-state electrochemical cells based on lithium oxyhalide electrolyte that is produced by melt-casting. This method results in enhanced cathode/electrolyte interfaces that allow exceptionally high charging rates (>4000C) while maintaining the electrochemical stability of solid-state electrolyte in the presence of lithium metal anode and lithium iron phosphate-based cathode. The cells exhibit long cycle life (>1800 cycles at 100 °C) and offer a promising route to the next-generation all-solid-state battery technology. 
    more » « less
  4. ; ; ; ; ; ; ; (, Chem)
    The cathode material in a lithium (Li) battery determines the system cost, energy density, and thermal stability. In anode-free batteries, the cathode also serves as the source of Li for electrodeposition, thus impacting the reversibility of plating and stripping. Here, we show that the reason LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes deliver lower Coulombic efficiencies than LiFePO4 (LFP) is the formation of tortuous Li deposits, acidic species in the electrolyte, and accumulation of “dead” Li0. Batteries containing an LFP cathode generate dense Li deposits that can be reversibly stripped, but Li is lost to the solid electrolyte interphase (SEI) and corrosion according to operando 7Li NMR, which seemingly “revives” dead Li0. X-ray photoelectron spectroscopy (XPS) and in situ 19F/1H NMR indicate that these differences arise because upper cutoff voltage alters electrolyte decomposition, where low-voltage LFP cells prevent anodic decomposition, ultimately mitigating the formation of protic species that proliferate upon charging NMC811. 
    more » « less
  5. ; ; (, Materials Research Society)
    Metal-ion batteries (e.g., lithium and sodium ion batteries) are the promising power sources for portable electronics, electric vehicles, and smart grids. Recent metal-ion batteries with organic liquid electrolytes still suffer from safety issues regarding inflammability and insufficient lifetime.1 As the next generation energy storage devices, all-solid-state batteries (ASSBs) have promising potentials for the improved safety, higher energy density, and longer cycle life than conventional Li-ion batteries.2 The nonflammable solid electrolytes (SEs), where only Li ions are mobile, could prevent battery combustion and explosion since the side reactions that cause safety issues as well as degradation of the battery performance are largely suppressed. However, their practical application is hampered by the high resistance arising at the solid–solid electrode–electrolyte interface (including cathode-electrolyte interface and anode-electrolyte interface).3 Several methods have been introduced to optimize the contact capability as well as the electrochemical/chemical stability between the metal anodes (i.e.: Li and Na) and the SEs, which exhibited decent results in decreasing the charge transfer resistance and broadening the range of the stable energy window (i.e., lowing the chemical potential of metal anode below the highest occupied molecular orbital of the SEs).4 Nevertheless, mitigation for the cathode in ASSB is tardily developed because: (1) the porous structure of the cathode is hard to be infiltrated by SEs;5 (2) SEs would be oxidized and decomposed by the high valence state elements at the surface of the cathode at high state of charge.5 Herein, we demonstrate a universal cathode design strategy to achieve superior contact capability and high electrochemical/chemical stability with SEs. Stereolithography is adopted as a manufacturing technique to realize a hierarchical three-dimensional (HTD) electrode architecture with micro-size channels, which is expected to provide larger contact areas with SEs. Then, the manufactured cathode is sintered at 700 °C in a reducing atmosphere (e.g.: H2) to accomplish the carbonization of the resin, delivering sufficiently high electronic conductivity for the cathode. To avoid the direct exposure of the cathode active materials to the SEs, oxidative chemical vapor deposition technique (oCVD) is leveraged to build conformal and highly conducting poly(3,4-ethylenedioxythiophene) (PEDOT) on the surface of the HTD cathode.6 To demonstrate our design strategy, both NCM811 and Na3V2(PO4)3 is selected as active materials in the HTD cathode, then each cathode is paired with organic (polyacrylonitrile-based) and inorganic (sulfur-based) SEs assembled into two batteries (total four batteries). SEM and TEM reveal the micro-size HTD structure with built-in channels. Featured by the HTD architecture, the intrinsic kinetic and thermodynamic conditions will be enhanced by larger surface contact areas, more active sites, improved infusion and electrolyte ion accessibility, and larger volume expansion capability. Disclosed by X-ray computed tomography, the interface between cathode and SEs in the four modified samples demonstrates higher homogeneity at the interface between the cathode and SEs than that of all other pristine samples. Atomic force microscopy is employed to measure the potential image of the cross-sectional interface by the peak force tapping mode. The average potential of modified samples is lower than that of pristine samples, which confirms a weakened space charge layer by the enhanced contact capability. In addition, through Electron Energy Loss Spectroscopy coupled with Scanning Transmission Electron Microscopy, the preserved interface between HTD cathode and SE is identified; however, the decomposing of the pristine cathode is clearly observed. In addition, Finite element method simulations validate that the diffusion dynamics of lithium ions is favored by HTD structure. Such a demonstrated universal strategy provides a new guideline to engineer cathode electrolyte interface by reconstructing electrode structures that can be applicable to all solid-state batteries in a wide range of chemical conditions. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email