Grid-scale energy storage technologies is important and in urgent need for the renewable energy applications. Among the most energy storage technologies, electrochemical energy storage technologies, such as batteries, shows the great advantages of simple structure and high efficiency, which is developing quickly and widely applicated for varied fields of EES. For the electrochemical energy storage technologies, the electrode/electrolyte play the most important roles for the mass and ion transport. The ionic conductivity and mechanical strength of electrode/electrolyte layers directly influence the energy/power densities and cycling stability of the batteries. Thus, engineering a stable artificial SEI layer with sufficient strength and high interface energy is an efficient strategy to accelerate the ion/electron transfer kinetics as well as guarantee the stable and reversible redox reactions.

Plasma is generated by high voltage ionization, constituted of highly reactive species, which can easily form a large number of active sites on the material surface to construct interface layers with certain components. Lithium metal is considered as the most ideal anode for high energy batteries due to its ultrahigh theoretical capacity. However, the low coulombic efficiency and lithium dendrites lead to the poor cycling stability of lithium metal batteries. To solve these problems, artificial SEI layers with certain species of LiF, Li₂C₂ and polythiophene are prepared through the plasma treatment. Benefiting from the high mechanical strength of LiF, low Li⁺ diffusion barrier of Li₂C₂ and flexible structure of the polythiophene, modified Li anodes exhibit an long-term cycling stability of 8000 h with dendrite free structure. When coupling with LiFePO₄, the cell using P-PTh-Li can obtain a reversible capacity of 94% after 500 cycles, compared to that of 62% capacity retention of Li. Furthermore, CF₄ plasma was further employed for the treatment of PP separator. The grafted polar groups enhance the ionic conductivity and lithium-ion transference number of the separator. Moreover, the introduction of fluorine-containing functional groups participates in the formation of LiF-rich SEI film, which can regulate the uniform deposition of lithium ions and inhibits lithium dendrite growth.

Liquid metal batteries (LMBs) are highly promising for grid-scale energy storage due to their outstanding kinetics, scalability, and long lifespan enabled by their unique three-liquid-layer structure. However, challenges remain with the positive electrode, including fluctuations at the electrode/electrolyte interface during charge and discharge cycles, as well as poor wettability on the current collector. These issues introduce excess electrical resistance and hinder rate capability, ultimately compromising cycling stability. To address the rate capability, we propose an operando strategy for the formation of Li₂Te with a multi-channel structure. This engineered structure enhances ion transport during cycling, significantly improving rate performance. The Li || Sb-Bi-Te₅ cell demonstrated exceptional capacity retention of 84.4% at 1000 mA cm⁻², compared to only 43.8% for the Li || Sb-Bi cell. To enhance electrode wettability, we incorporated 4 mol% Se into a Bi-based metal, forming a highly surface-active interface layer. This layer effectively reduced the contact angle with 304 stainless steel (SUS304) from 144.7° to 74.3°, significantly improving adhesion. The resulting 20 Ah Li || Bi-Se₄ cell (where Se constitutes 4 mol% of Bi) exhibited remarkable cycling stability, achieving 1200 cycles with a minimal capacity fade rate of just 0.00174% per cycle.This straightforward and efficient approach provides a viable pathway to producing stable LMBs with extended lifespans, advancing their practical implementation for large-scale energy storage.

Present-day technologies contribute significantly to environmental strain through the emission of exhaust gases, underscoring the need for cleaner alternatives. Electrocatalysis offers promising solutions to replace traditional processes in both the manufacturing and energy sectors. More precisely, various electrocatalyst surface modifications have proven effective in improving the Oxygen Reduction Reaction (ORR), a reaction of critical interest in fuel cell technology. Nonetheless, several obstacles impede the commercialization of electrocatalyst surface modifications, one being inadequate quantification of active sites.

Here, we focus on enhancing electrocatalytic interfaces by electrochemically modifying the polycrystalline platinum (Pt-poly) surface to create a more favorable environment for electrocatalytic reactions. We achieve surface modification by electrochemical biasing in the presence of dicyanamide anions (DCA) and then characterize the modified electrode electrochemically. Using rotating disc electrode (RDE) measurements, we analyze surface probe reactions, including N₂O reduction (Potential of Zero Total Charge determination), Oxygen Reduction Reaction (ORR), and Hydrogen Oxidation Reaction (HOR).

Our findings indicate that the newly formed species, transforming platinum into a +2 oxidation state, partially block the platinum surface. Nevertheless, sufficient free active sites remain available for proton, hydrogen, oxygen, and nitrous oxide adsorption and manifest higher catalytic activity towards corresponding reactions. This is likely due to electrostatic interactions, which inhibit water discharge and adsorption of anions. Furthermore, we present a new, non-destructive surface area determination method based on N₂O reduction probing. Overall, the selective nature of this modification holds significant promise for applications in electrocatalytic reactions.

Understanding the electronic and ionic transport properties inside active cathode materials and through its surroundings in lithium-ion battery cathodes is crucial for optimizing battery performance. Such studies are most often done by EIS measurements in combination with rate performance and cyclability. However, these measurements can at most link changes in performance with changes in average resistance values which can, with at least some ambiguity, be attributed to certain interfaces and interphases. For a particle composite electrode with intrinsic distribution in porosity, particle size and tortuosity, the number of interfaces and their variations are innumerable. The number and positions of the electronic contacts made to one single active material particle alone is difficult to predict. The distance between the carbon nanoparticle chains wrapped around the particle determine the resistive drop and current/potential distributions. Furthermore, the electrical contact of the (semiconductor) active material with current collector and carbon black is simply assumed to be Ohmic with inconsequential contact resistance independent of the state-of-charge. Especially at high C-rates, these electronic effects might affect battery operation. We present a methodology to build experimental models to characterize and quantify the individual interfaces using thin-film stacks and patterning of metallic contacts with controlled area and pitch. The quantitative characterization of single interfaces can be used as input parameters for mathematical modeling of simulated electrode structures.  

In this work, we will present a strategy for patterning Lithium Manganese Oxide (LMO) thin films, while preserving both the electrochemical activity and the structural morphology of the films. Having successfully established this process, we patterned metallic test structures on top of LMO films. Furthermore, employing the transmission line method [1], we calculated the conductivity of LMO and the contact resistance between LMO and the metal test structures. This approach enabled us to effectively benchmark the electron transport capabilities of different materials that serve as current collectors. Next to quantification of contact resistance, our results provided insights in the effect of grain or crystal size on conductivity of the LMO films. The grain size is controlled by the thermal budget during crystallization of the deposited films

In a further example, we address the use of titanium dioxide (TiO2) protective coating, deposited via atomic layer deposition (ALD) on our LMO films. The few nanometers thin film thickness permits lithium ions to traverse the film, while it slows down cathode degradation and suppress side reactions with electrolytes [2]. Although TiO2 is a dielectric and generally not expected to enhance electron transport directly, it can significantly affect the interface where electron transfer occurs. Our study aimed to determine the impact of TiO2 presence on contact resistance and to establish how its thickness could influence both electron transport characteristics and lithium-ion insertion/extraction dynamics. This analysis provides insights into the optimal thickness of TiO2 layers before they begin to compromise the cathode’s performance, offering a refined understanding of how such protective layers interact with both the electron and ionic transport.

The developed methodology already provides valuable insights into the effects of coatings and allows for the benchmarking and exploration of new materials. Looking ahead, this approach will enhance our understanding of the processes occurring within the composite cathode.

Silicon monoxide (SiO)-based anode materials are one of the most intensively investigated class of materials for use as high-capacity anodes in lithium-ion batteries. However, their low initial Coulombic efficiency (ICE), resulting from the irreversible electrochemical reaction of the amorphous SiO₂ (a-SiO₂) phase in the SiO, restricts the wide-spread adoption of SiO-based anode materials in lithium-ion batteries. In this work, we deomonstrate Si/M-silicate(M: Li, Mg, Ca) nanocomposite materials based on the dehydorgenation reaction of metal hydrides to improve the electrochemical performance of SiO. The resulting Si/M-silicate nanocomposite materials showed much improved electrochemical performance compared to pristine SiO. Laser-assisted atom probe tomography(LA-APT) combined with high resolution transmission microscopy(HR-TEM) clearly revealed that two exothermic reactions during prelihitation process related to microstructural evolution are key in optimizing the domain size of Si active phase and metal silicate buffer phase, and their topological arrangements in prelithiated SiO materials. We also report that the pre-emptive formation of irreversible phase combined with high-energy mechanical milling (HEMM) process can simultaneously improve both the ICE and long-term cycle performance by effectivley mitigating the volume expansion of Si during cycling, resulting in improved long-term cycle stability.

        Electrocatalysts is essential for the commercilization of fuel cells. Currently, Pt is the key element on both anode and cathode. Since Pt is costly and scarce, it poses a question of how to lower the Pt loading and increase the efficiency. Most of previous studies focused on Pt alloyed with some 3d-transition metals, such as Fe, Co, Ni, etc. However, the activity and stability are not good enough for fuel cell applications. Recently, ordered intermetallic nanoparticles have attracted some attention, since the ordered intermetallic phase provides definite composition and structure. They can provide predictable controls over structural, geometric, and electronic effects, which are not afforded by alloys. However, previous reports on ordered intermetallic are mainly used as anode catalysts, such as formic acid oxidation. And the synthesis procedure is very complex. More importantly, the particles are unsupported and it is not easy to clean the particle surface. In our studies, we present that carbon supported ordered intermetallic nanoparticles can be easily formed using a simple impregnation-reduction method followed by high temperature pretreatment. Besides, by selecting special 3d-transition metals, Pd-based ordered intermetallics can also be formed. When used as electrocatalysts for fuel cells, the ordered imtermetallics exhibit both the enhanced activities and stabilties.

Lithium metal all-solid-state batteries promise to deliver a step-change in cell energy density and safety.[1,2] However, at charge/discharge rates on the order of 1 mA cm², plating of lithium results in growth of lithium filaments through the solid electrolyte (dendrites),[3,4] and stripping of Li leads to contact loss between the lithium anode and solid electrolyte (voids).[5-7] This talk will cover our recent findings on the mechanisms of dendrite growth and voiding, and the testing protocols used to determine the maximum failure-free rates of charge/discharge.

Mechanism: Synchrotron-source X-ray computed tomography enables us to image the evolution of interfaces in a solid-state battery during operation. Visualization of the formation of dendrites and voids, in combination with modelling, provides insights into how these failure mechanisms might be prevented.[3,4,6]

Testing protocols: As solid-state batteries move towards commercialisation, it is increasingly important to determine the maximum rates at which they can be charged/discharged without formation of dendrites/voids. Our recent work investigates some conventionally used testing protocols, and identifies how these can be improved to increase accuracy and reproducibility.