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DOE OSTI2021

Defect–Concentration–Mediated T–Nb 2 O 5 Anodes for Durable and Fast–Charging Li–Ion Batteries

Metastable orthorhombic niobium pentoxide (T-Nb 2 O 5 ) is a promising anode to fulfill the requirements for high-rate Li-ion batteries (LIBs). Stoichiometric T-Nb 2 O 5 is plagued by low electric conductivity and particle pulverization after repeated charge/discharge processes. In this work, oxygen vacancies are implanted into T-Nb 2 O 5 particles via acid immersion of Nb 2 O 5 ·nH 2 O with the formation of Lewis acid sites. The multiple characterizations and simulations reveal the lengthening of Nb–O bonds, and the transformation from NbO 7 pentagonal bipyramids and NbO 6 tetragonal bipyramids in T-Nb 2 O 5–x . The enrichment of oxygen vacancies endows T-Nb 2 O 5–x with higher electric conductivity, better electrochemical kinetics, larger pseudocapacitive contribution. O-doped graphitic C 3 N 4 is creatively proposed as a trace oxygen pump to repair excessive oxygen vacancies, and it also serves as a sacrifice template for Nb 2 O 5–x growth to construct a porous and monolithic electrode network. Defect-modulated Nb 2 O 5–x displays extraordinary cycling stability (164 mAh g –1 at 5 C after 1100 cycles), high capacity retention (104 mAh g –1 ) at an ultrahigh rate (25 C), and large areal capacity (0.74 mAh cm –2 ) under high mass loading (4 mg cm –2 ). The practical prospect is proved by Nb 2 O 5–x /LiNi 0.8 Co 0.1 Mn 0.1 O 2 full cells with high average platform (2.12 V) and high specific capacity (229 mAh g –1 ). Finally, the oxygen-defect modulation strategy on oxide anodes provides an alternative solution to fast-charging and durable LIBs.

25 ENERGY STORAGE↗

DOE OSTI2020

A Lithium Metal Anode Surviving Battery Cycling Above 200 °C

Lithium (Li) metal electrode cannot endure elevated temperature (e.g., >200 °C) with the regular battery configuration due to its low melting point (180.5 °C) and high reactivity, which restricts its application in high-temperature Li metal batteries for energy storage and causes safety concerns for regular ambient-temperature Li metal batteries. Herein, this work reports a Li 5 B 4 /Li composite featuring a 3D Li 5 B 4 fibrillar framework filled with metallic Li, which maintains its initial structure at 325 °C in Ar atmosphere without leakage of the liquid Li. The capillary force caused by the porous structure of the Li 4 B 5 fibrillar framework, together with its lithiophilic surface, restricts the leakage of liquid metallic Li and enables good thermal tolerance of the Li 5 B 4 /Li composite. Thus, it can be facilely operated for rechargeable high-temperature Li metal batteries. Li 5 B 4 /Li electrodes are coupled with a garnet-type ceramic electrolyte (Li 6.5 La 3 Zr 0.5 Ta 1.5 O 12 ) to fabricate symmetric cells, which exhibit stable Li stripping/plating behaviors with low overpotential of approximate to 6 mV at 200 °C using a regular sandwich-type cell configuration. This study affords new insights into realizing a stable Li metal anode for high-temperature Li metal batteries with a simple battery configuration and high safety, which is different from traditional molten-salt Li metal batteries using a pristine metallic Li anode.

25 ENERGY STORAGE↗

DOE OSTI2022

Early Failure of Lithium–Sulfur Batteries at Practical Conditions: Crosstalk between Sulfur Cathode and Lithium Anode

Lithium–sulfur (Li–S) batteries are one of the most promising next-generation energy storage technologies due to their high theoretical energy and low cost. However, Li–S cells with practically high energy still suffer from a very limited cycle life with reasons which remain unclear. Here, through cell study under practical conditions, it is proved that an internal short circuit (ISC) is a root cause of early cell failure and is ascribed to the crosstalk between the S cathode and Li anode. The cathode topography affects S reactions through influencing the local resistance and electrolyte distribution, particularly under lean electrolyte conditions. The inhomogeneous reactions of S cathodes are easily mirrored by the Li anodes, resulting in exaggerated localized Li plating/stripping, Li filament formation, and eventually cell ISC. Manipulating cathode topography is proven effective to extend the cell cycle life under practical conditions. The findings of this work shed new light on the electrode design for extending cycle life of high-energy Li–S cells, which are also applicable for other rechargeable Li or metal batteries.

25 ENERGY STORAGE↗

DOE OSTI2021

A Study of Model-Based Protective Fast-Charging and Associated Degradation in Commercial Smartphone Cells: Insights on Cathode Degradation as a Result of Lithium Depositions on the Anode

The ever expanding mobile consumer electronic market has accelerated the need for safe and efficient fast-charging approaches that improve the overall speed of battery charging without hastened deterioration of the battery performance. Herein, the impact of a resource inexpensive, physics-based, electrochemically optimized fast-charging algorithm (charging time < 2 h) for mobile devices is investigated. A critical difference in the amount and morphology of lithium deposits on the anode for cells fast-charged without an optimized algorithm is observed and found to be the main cause of capacity decay. Furthermore, an in-depth study of the LiCoO 2 cathode regions opposite to pronounced lithium deposits on the anode reveals a “mirroring” phenomenon, i.e., a frozen monoclinic phase, and inactivity to relithiation. In operando hard X-ray absorption spectroscopy reveals that degraded spots on harvested cathodes seem to be activated again and participate in the intercalation process when lithiated at low rates from lithium foil counter electrodes. On the other hand, tests at higher C-rates, closer to the actual fast-charging rate, reveal only negligible oxidation state changes and therefore poor performance.

25 ENERGY STORAGE↗

DOE OSTI2022

Insights into the Effect of Heat Treatment and Carbon Coating on the Electrochemical Behaviors of SiO Anodes for Li-Ion Batteries

The use of SiO as an anode material has attracted significant interest due to its high capacity and long cycling life. Many promising approaches, including structural design and carbon coating at high temperatures, effectively improve its intrinsic low electrical conductivity and poor Coulombic efficiency. However, the “heat treatment process-composition and microstructure-electrochemical properties” relationship of the SiO anode is not fundamentally understood. Here the structure and composition evolution in amorphous SiO and graphene-coated SiO is investigated using different heat-treatment conditions. X-ray absorption near-edge structure techniques are also employed to analyze the surface and bulk composition change during the initial lithiation process, supplemented by physical or chemical characterization and electrochemical testing. Here results reveal the structural transition of SiO during heat treatment, from amorphous to disproportionated hierarchical structure, where the as-formed dielectric exterior SiO 2 shell and interior SiO 2 matrix severely polarizes electrodes, hindering the lithiation process. Carbon coating on SiO effectively restricts the growth of the SiO 2 shell and facilitates charge transfer, leading to improved electrochemical performance. A schematic model is proposed to reveal the relationship between the treatments, the resultant structural evolutions, and corresponding electrochemical behaviors.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Stable Cycling of Mg Metal Anodes by Regulating the Reactivity of Mg 2+ Solvation Species

Rationally designing stable nonaqueous electrolytes for Mg metal anodes demands a thorough understanding of their interfacial behaviors. Here, the critical role of cation–anion pairing in improving the cathodic stabilities of amine-based electrolytes against solvent reduction and H 2 evolution is identified. It is demonstrated that strong coordination between solvating amine groups and the Mg 2+ cation facilitates the dehydrogenation of the -NH 2 group, which is mainly responsible for low reversibility during Mg metal plating and stripping. Introducing ion-pairing into the primary solvation shell can effectively weaken the amine coordination such that its reduction is suppressed. A novel interfacial behavior regarding parasitic reaction product dissolution is also identified, which is responsible for the failure of interfacial passivation. An ion-pairing electrolyte is developed based on a weakly-solvated amine molecule and strongly coordinating Mg 2+ salt. This electrolyte composition delivers long-term Mg metal anode cycling with 99.6% Coulombic efficiency for 800 cycles.

25 ENERGY STORAGE↗

DOE OSTI2024

A Comprehensive Experimental Study on Microstructure‐Graded Graphite Anodes for Enhancing Fast‐Charging Capability of Lithium‐Ion Batteries

Lithium‐ion batteries with high gravimetric capacity density and improved cycle life performance under fast‐charging conditions are crucial for widespread electric vehicle (EV) adoption. This study investigates how designing graphite anode microstructure, specifically porosity, and particle‐size gradients, improves lithium‐ion (Li + ) transport during fast‐charging conditions. Three‐layered graphite anodes with varying porosity (24%, 36%, 46%) and particle size gradients (3, 5, 10 μm) were compared to a conventional single‐layered electrode in half‐cell configurations. At room temperature and high discharge rate (2C), both gradient structures showed significantly enhanced capacity retention (80% and 67% vs. 50%) compared to the conventional electrode, highlighting the effectiveness of microstructure engineering for fast charging. The study also investigated the temperature's impact on cycle life. After 200 cycles at 2°C and 45°C, all gradient structures demonstrated superior capacity retention (≈80%) compared to the conventional electrode (35%), suggesting the gradients mitigate degradation rate at high temperatures. Electrochemical impedance spectroscopy confirmed superior Li+ diffusion and lower resistivity in gradient electrodes. Simulations explored the influence of gradient profiles on reaction kinetics across the electrode thickness. Overall, this research demonstrates that the fast‐charging capability of graphite electrodes can be greatly enhanced by engineering the electrode microstructure, thereby making EV technology more accessible and appealing.

Ahmadi, Soma↗

DOE OSTI2022

A Carboranyl Electrolyte Enabling Highly Reversible Sodium Metal Anodes via a “Fluorine‐Free” SEI

Abstract Realization of practical sodium metal batteries (SMBs) is hindered due to lack of compatible electrolyte components, dendrite propagation, and poor understanding of anodic interphasial chemistries. Chemically robust liquid electrolytes that facilitate both favorable sodium metal deposition and a stable solid‐electrolyte interphase (SEI) are ideal to enable sodium metal and anode‐free cells. Herein we present advanced characterization of a novel fluorine‐free electrolyte utilizing the [HCB 11 H 11 ] 1− anion. Symmetrical Na cells operated with this electrolyte exhibit a remarkably low overpotential of 0.032 V at a current density of 2.0 mA cm −2 and a high coulombic efficiency of 99.5 % in half‐cell configurations. Surface characterization of electrodes post‐operation reveals the absence of dendritic sodium nucleation and a surprisingly stable fluorine‐free SEI. Furthermore, weak ion‐pairing is identified as key towards the successful development of fluorine‐free sodium electrolytes.

Tomich, Anton W.↗

DOE OSTI2025

A Universal Design of Lithium Anode via Dynamic Stability Strategy for Practical All‐Solid‐State Batteries

Abstract All‐solid‐state Li‐metal battery (ASSLB) chemistry with thin solid‐state electrolyte (SSE) membranes features high energy density and intrinsic safety but suffers from severe dendrite formation and poor interface contact during cycling, which hampers the practical application of rechargeable ASSLB. Here, we propose a universal design of thin Li‐metal anode (LMA) via a dynamic stability strategy to address these issues. The ultra‐thin LMA (20 μm) is in situ constructed with uniform highly Li‐ion conductive solid‐electrolyte interphase and composite‐polymer interphase (CPI) via electroplating process. As a result, the passivation layer with poor Li‐ion conduction on Li anode can be dissolved and small surface resistance can be achieved due to the good compatibility of CPI to SSEs. The cycling of Li symmetric cell with Li 6 PS 5 Cl thin film electrolyte (<100 μm) shows a high critical current density of >2.0 mA cm −2 with excellent cycling stability at 1.0 mA cm −2 . The ASSLBs paring with Ni‐rich LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathode demonstrated the feasibility of engineered LMA design by presenting good rate capability from 0.1 C to 1.0 C at room temperature, as well as long‐term cycling stability (81 % retention after 100 cycles). This work represents a general pathway to make thin dendrite‐free LMA available for high‐energy‐density ASSLBs.

Deng, Tao [Department of Chemical and Biomolecular↗

DOE OSTI2022

Impacts of Dissolved Ni 2+ on the Solid Electrolyte Interphase on a Graphite Anode

Transition metal (e.g. Ni) ions dissolved from layered-structured Ni-rich cathodes can migrate to the anode side and accelerate the failure of lithium-ion batteries. The investigations of the impact and distribution of Ni species on the solid electrolyte interphase (SEI) on the anode are crucial to understand the failure mechanism. Herein, we used time-of-flight secondary ion mass spectroscopy (TOF-SIMS) coupled with multivariate curve resolution (MCR) analysis to intuitively characterize the distribution of Ni species in the SEI. We find that the SEI on the graphite electrode using an EC-based electrolyte exhibits a multi-stratum structure. During accelerated aging of the LiNi 0.88 Co 0.08 Mn 0.04 O 2 /graphite full cell, the dissolution of Ni aggravates significantly upon cycling. A strong correlation between the dissolved-Ni and organic species in the SEI on graphite is illustrated. Here, the ion-exchange reaction between Ni 2+ and Li + ions in the SEI is demonstrated to be the main reason for the increase of SEI resistivity.

25 ENERGY STORAGE↗

DOE OSTI2025

A Universal Design of Lithium Anode via Dynamic Stability Strategy for Practical All‐Solid‐State Batteries

Deng, Tao [Department of Chemical and Biomolecular↗

DOE OSTI2020

Highly Ordered Carbon Coating Prepared with Polyvinylidene Chloride Precursor for High‐Performance Silicon Anodes in Lithium‐Ion Batteries

Abstract A highly ordered carbon structure based on polyvinylidene chloride precursor has been developed to host silicon nanoparticles. The stoichiometric ratio of sacrificial H and Cl elements facilitated full utilization of the carbon content of the precursor that produced robust carbon coatings on silicon nanoparticles with excellent mechanic properties and electrochemical stabilities. The optimal sintering temperature and carbon content have been investigated. When evaluated as the anode of a lithium‐ion battery (LIB), the Si : C 1 : 2 composite sintered at 800 °C (SiC12‐800) provided excellent capacity retention of 85 % at 0.1 C after 50 cycles with an enhanced CE, which reached 99 % only after 10 cycles. The SiC12‐800 electrode maintained a specific capacity of 709.2 mAh/g after 300 cycles at 0.3 C, and delivered a high rate performance of 737.9 mAh/g and 485.6 mAh/g at 5 C and 10 C, respectively. The results indicate that polymer precursors with stoichiometric ratio of sacrificial elements have high potential for generating highly robust carbon coatings for silicon anodes in high energy density LIBs.

Zhou, Shuo↗

DOE OSTI2024

Interface Modifications of Lithium Metal Anode for Lithium Metal Batteries

Lithium metal batteries (LMBs) enable much higher energy density than lithium–ion batteries (LIBs) and thus hold great promise for future transportation electrification. However, the adoption of lithium metal (Li) as an anode poses serious concerns about cell safety and performance, which has been hindering LMBs from commercialization. To this end, extensive effort has been invested in understanding the underlying mechanisms theoretically and experimentally and developing technical solutions. In this review, we devote to providing a comprehensive review of the challenges, characterizations, and interfacial engineering of Li anodes in both liquid and solid LMBs. Finally, we expect that this work will stimulate new efforts and help peer researchers find new solutions for the commercialization of LMBs.

25 ENERGY STORAGE↗

DOE OSTI2026

A Dendrite-Resistant Sodium/Porous-Carbon Anode for Solid-State Batteries – Strategies and Challenges for Low-Pressure Operation

Sodium solid-state batteries (Na-SSB) have gained interest recently due to the abundance of Na over Li, but they still tend to fail due to dendrites under practical current densities and cycling capacities. To overcome this, Na-SSBs are frequently tested with impractically high applied pressure. In this work, a porous carbon interfacial layer is utilized in conjunction with Na-ß”-Al2O3 solid electrolytes to enable Na-cycling at milder cell pressures. This sodium/porous carbon layer enables improved solid-state Na cycling in symmetric cells, up to a current density of 10 mA cm-2 at 25 °C. Cycling up to 1 mAh cm-2 is challenging with low pressure, but 1 mAh cm-2 capacity can be reliably cycled at 1 mA cm-2 at an elevated temperature of 60 °C in symmetric cells. Finally, the evolution of the interface and sodium/carbon anode is evaluated with cryogenic ion-milling and cross-sectional imaging revealing that, depending on testing temperature, pressure, current density, and capacity, void formation, Na-extraction from porous carbon, delamination of the porous carbon matrix, or a combination of these occurs at the interface between Na-metal and BASE. Despite this, excellent dendrite resistance is achieved, and a full-cell design utilizing a Na-transition metal oxide cathode is still able to achieve an areal capacity of ~ 2.7 mAh cm-2 at 0.125 mA cm-2. This work demonstrates an alternative pathway toward a Na-metal anode for Na-SSBs without the requirement of excessive stack pressure.

low-cost↗

DOE OSTI2021

Exploring the Role of Humidity, Temperature, and Mixed Ionic and Electronic Conductivity on SOFC Anode Electrocatalysis

Infiltration of nanoscale electrocatalysts into Ni/yttria-stabilized zirconia (Ni-YSZ) cermets has been shown to improve the electrochemical performance of solid oxide fuel cell (SOFC) anodes. While infiltrated electrodes in SOFCs result in improved cell performance, long-term operation leads to coarsening of the infiltrated nanoparticles and negates the short-term performance improvements. This study explores the roles of humidity, temperature, and number of cycles of nanocatalyst infiltration in improving mixed conduction within the Ni-YSZ electrode. Two mixed conduction phases were studied: Gd 0.1 Ce 0.9 O 2-δ (GDC) as an infiltrant into Ni-YSZ electrodes, and Ni/transition metal doped-YSZ electrodes infiltrated with Ni. Analysis of impedance data from these cells shows improved electrochemical performance in infiltrated cells with mixed conduction compared with infiltrated cells containing purely ionic and electronic conducting phases. Improved anode performance is attributed to the availability of electronic pathways through predominantly ionic-conducting phases to connect distant Ni nanoparticles and/or Ni grains.

25 ENERGY STORAGE↗

DOE OSTI2024

Amorphous Iridium Oxide-Integrated Anode Electrodes with Ultrahigh Material Utilization for Hydrogen Production at Industrial Current Densities

Herein, ionomer-free amorphous iridium oxide (IrO x ) thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells (PEMECs) via low-cost, environmentally friendly, and easily scalable electrodeposition at room temperature. Combined with a Nafion 117 membrane, the IrO x -integrated electrode with an ultralow loading of 0.075 mg cm –2 delivers a high cell efficiency of about 90%, achieving more than 96% catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane (2 mg cm –2 ). Additionally, the IrO x electrode demonstrates superior performance, higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes. Notably, the remarkable performance could be mainly due to the amorphous phase property, sufficient Ir 3+ content, and rich surface hydroxide groups in catalysts. Overall, due to the high activity, high cell efficiency, an economical, greatly simplified and easily scalable fabrication process, and ultrahigh material utilization, the IrO x electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.

08 HYDROGEN↗

DOE OSTI2024

Zero-strain high entropy spinel oxide (FeNiCuCrMn) 3 O 4 @rGO as high-performance anode for sodium ion battery

High entropy spinel oxides (HEOs), as a new type of anode material with at least five transition metal elements and high theoretical specific capacity, have enormous promise in sodium ion batteries (SIBs). However, the influence of different transition metal elements on the structure and electrochemical performances of HEOs is not clear. Here, in this study, the addition of Mn to HEO can increase the surface oxygen vacancy (O v ) concentration, shorten the band gap, and enhance the electrochemical performance of (FeNiCuCrMn) 3 O 4 @rGO. XPS results show (FeNiCuCrMn)3O4@rGO has the highest surface O v concentration. Ab initio calculations demonstrate that the indirect band gap of (FeNiCuCrMn)3O4@rGO is 0.068 eV. In situ X-ray diffraction and synchrotron X-ray absorption spectroscopy reveal that (FeNiCuCrMn) 3 O 4 @rGO exhibits a zero-strain characteristic with an inconsequential unit cell volume change of 0.2 %. Specifically, (FeNiCuCrMn) 3 O 4 @rGO as anode materials for SIBs show good cyclic stability (with a capacity retention of 84 % at 500 mA g −1 after 3000 cycles). Overall, this work provides a new direction for optimizing transition metal elements in HEOs.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Controlling MoO 2 and MoO 3 phases in MoO x /CNTs nanocomposites and their application to anode materials for lithium-ion batteries and capacitors

Molybdenum oxides (MoO 2 and MoO 3 ) are attractive anode materials for Li- and Na- ion batteries. Although there have been extensive studies on them individually, systematic and comparative studies are still lacking. Here, we demonstrate a facile and straightforward synthesis method to control the phase and oxidation state in the MoO x /CNTs nanocomposites via hydrothermal reaction followed by heat-treatment. By changing the gas atmosphere during the annealing process, well-dispersed MoO 2 /CNTs and MoO 3 /CNTs nanocomposites are formed without altering their overall morphology. This strategy enables us to investigate the true structure-property correlation of MoO x /CNTs nanocomposites by comparing the structure and electrochemical properties of MoO 2 /CNTs and MoO 3 /CNTs. When tested as anode materials for lithium-ion batteries, both HT-MoO 2&3 /CNTs electrodes show much-improved cycling stability and rate performance compared to the rod-shaped bulk MoO 3 electrode. In situ Mo K-edge x-ray absorption spectroscopy (XAS) has been further employed to compare and elucidate Li + storage mechanisms of both electrodes. When employed to the negative electrode of a high-power lithium-ion capacitor (LIC), the LIC full-cell composed of HT-MoO 3 /CNTs negative and activated carbon positive electrodes demonstrates impressive energy and power densities (~ 90 Wh kg –1 with 2000 W kg –1 ) and excellent cycling stability (96.8 % capacity retention after 300 cycles), revealing the versatility of the MoO x /CNTs electrodes in energy applications.

25 ENERGY STORAGE↗