Fast Charge Research Articles

Extreme Fast Charging of Lithium Metal Batteries Enabled by a Molten-Salt-Derived Nanocrystal Interphase.

The extreme fast charging performance of lithium metal batteries (LMBs) with a long life is an important focus in the development of next-generation battery technologies. The friable solid electrolyte interphase and dendritic lithium growth are major problems. The formation of an inorganic nanocrystal-dominant interphase produced by preimmersing the Li in molten lithium bis(fluorosulfonyl)imide that suppresses the overgrowth of the usual interphase is reported. Its high surface modulus combined with fast Li+ diffusivity enables a reversible dendrite-proof deposition under ultrahigh-rate conditions. It gives a record-breaking cumulative plating/stripping capacity of >240000 mAh cm-2 at 30mA cm-2@30 mAh cm-2 for a symmetric cell and an extreme fast charging performance at 6 C for 500 cycles for a Li||LiCoO2 full cell with a high-areal-capacity, thus expanding the use of LMBs to high-loading and power-intensive scenarios. Its usability both in roll-to-roll production and in different electrolytes indicating the scalable and industrial potential of this process for high-performance LMBs.

Deep reinforcement learning based fast charging and thermal management optimization of an electric vehicle battery pack

Existing optimal strategies for fast-charging electric vehicle batteries are predominantly at the cell level. The proposed high-fidelity methods for extending available cell models to pack level are associated with a large computational burden, making real-world implementation impossible. Further, fast charging optimization and thermal management problems are dependent. That is, the cooling system reduces battery temperature, allowing for higher charging current, while optimal current minimizes the need for cooling and, in turn, reduces thermal system power consumption. There is a lack of studies where fast charging optimization and battery thermal management problems are jointly solved. Therefore, this paper proposes a simulation study using a deep reinforcement learning (RL) approach that concurrently solves fast charging and thermal management problems for a battery pack with low computational complexity. In this regard, we formulate each cell using an electro-thermal-aging model, which accounts for the heat exchange between adjacent cells. The electro-thermal-aging model plays the role of the environment for RL and is not the focus of novelty in this work. The RL agent is then trained to output the optimal charging current and coolant mass flow rate. Moreover, the proposed methodology is examined through a numerical study where the outperformance of our model is showcased by comparing it with baseline algorithms of model predictive control (MPC) and CC–CV. Consequently, three battery packs comprising 20, 444, and 7104 cells are used, respectively. We demonstrate that RL requires less than a second to finish the simulation for 20 cells, while MPC requires more than 80 min. In addition, RL keeps the cells’ core temperature below 33 °C, but MPC results reach 40 °C. The RL performance in charging packs with 444 and 7104 cells is then compared with that of CC–CV. In terms of computation time, RL and CC–CV are nearly the same, while regarding the average core and surface temperature of the cells as well as the cell aging, RL attains better outcomes, extending the battery pack’s life by up to two years after 1000 fast charging cycles.

Over-Lithiation Regulation of Silicon-Based Anodes for High-Energy Lithium-Ion Batteries.

Mitigating the growth of dendritic lithium (Li) metal on silicon (Si) anodes has become a crucial task for the pursuit of long-term cycling stability of high energy density Si-based lithium-ion batteries (LIBs) under fast charging or other specific conditions. While it is widely known that Li metal plating on Si-based anodes may introduce inferior cycling stability and cause safety concerns, the evolution of the anode/material structure and electrochemical performance with Li metal plating remains largely unexplored. A comprehensive quantitative investigation of the hybrid Li storage mechanism, combining the Li alloying/dealloying mechanism and plating/stripping mechanism, has been conducted to explore the effect of Li plating on Si-based anodes. The findings reveal that Li plating/stripping accounts for the decay of the overall Coulombic efficiency and cycling stability of the hybrid Li storage mechanism. Furthermore, alloying reactions occurring below 0 V encourage the formation of crystalline Li15Si4, which subsequently exacerbates voltage hysteresis. The performance decay is amplified as the ratio of Li plating/stripping capacity increases, or in other words, as the over-lithiation level rises, thereby posing a threat to the battery's cycling stability. These results provide valuable insights into the design of advanced Si-based electrodes for high energy density LIBs.

Effect of low temperature and high-rate cyclic aging on thermal characteristics and safety of lithium-ion batteries

With the popularity of electric vehicles and climate change, it has become a typical scene to charge lithium-ion batteries (LIBs) at low temperatures at a high rate. Low temperature and high-rate charge and discharge would change the performance and then affect temperature rises, heat production and thermal runaway (TR) characteristics. This study tests the temperature rises of aging 18650 LIBs at various ambient temperatures and charge and discharge rates. The entropy and enthalpy changes of the batteries are computed based on the entropy coefficients, and subsequently, the heat productions of the batteries are computed. The TR test is carried out to explore the influence of rapid aging at low temperature environment on the thermal safety of LIBs. In this work, the heat generation mechanism and thermal runaway characteristics of lithium-ion batteries after low-temperature and high-rate cyclic aging are introduced in detail, aiming to provide a reference for the process safe design and application of lithium-ion batteries at low-temperature and fast charging scenarios.

Single-crystal TiNb2O7 materials via sustainable synthesis for fast-charging lithium-ion battery anodes

TiNb2O7 (TNO) has emerged as a promising fast-charging anode for lithium-ion batteries (LIBs). However, research on TNO anode materials has been mostly restricted to synthesis of polycrystalline with limited associated mechanistic studies. Herein, we report a novel scalable aqueous synthesis method yielding sub-micron size single-crystal TNO particles following calcination that enables fast-charging anode fabrication. The sustainable co-precipitation process yields amorphous intermediate hydroxides which upon thermal conversion induced crystallization form single crystals. The obtained TNO monocrystalline anode material under 900 °C calcination (TNO-900C) delivers a high gravimetric capacity (279 mAh/g at 1st cycle) and a high volumetric capacity (351.7 mAh/cm3 at the initial cycle) at 0.5C rate. Additionally, the TNO anode delivers a remarkable capacity of 223 mAh/g at 5C and a high retention of 81.4 % after 200 cycles. In addition, TNO-900C illustrates outstanding fast-charging performance with a reversible capacity of 200 mAh/g at 10C. The intercalation mechanism and diffusion behavior of the monocrystalline TNO anodes are elucidated by electrochemical kinetic analysis (GITT, CV, and EIS). The remarkable fast charging Li-ion storage performance can be attributed to a high Li+ diffusion coefficient (1.37 × 10−13 cm2/s), low polarization, and high structural stability.

Features of fast charging of lithium-ion batteries: electrochemical aspects (mini-review)

Features of fast charging of lithium-ion batteries: electrochemical aspects (mini-review)

Zn2+-mediated catalysis for fast-charging aqueous Zn-ion batteries

Zn2+-mediated catalysis for fast-charging aqueous Zn-ion batteries

Defect-Mediated Faceted Lithium Nucleation on Carbon Composite Substrates.

The formation of uniform, nondendritic seeds is essential to realizing dense lithium (Li) metal anodes and long-life batteries. Here, we discover that faceted Li seeds with a hexagonal shape can be uniformly grown on carbon-polymer composite films. Our investigation reveals the critical role of carbon defects in serving as the nucleation sites for their formation. Tuning the density and spatial distribution of defects enables the optimization of conditions for faceted seed growth. Raman spectral results confirm that lithium nucleation indeed starts at the defect sites. The uniformly distributed crystalline seeds facilitate low-porosity Li deposition, effectively reducing Li pulverization during cycling and unlocking the fast-charging ability of Li metal batteries. At a 1 C rate, full cells using LiNi0.8Mn0.1Co0.1O2 cathode (4.5 mA h cm-2) paired with a lithium anode grown on carbon composite films achieve a 313% improvement in cycle life compared to baseline cells. Polymer composites with carbonaceous materials rich in defects are scalable, low-cost substrates for high-rate, high-energy-density batteries.

Ion-irradiation induced structural, electronic, and optical properties modification in a few layered MoS2

Two-dimensional MoS2 is a promising candidate due to its layered structure, high conductivity, and fast charge transfer kinetics. In this work,the structural, electronic, and optical properties of pristine MoS2 have to be done by the ion irradiation technique with different ion fluences.The structural quality of the film has been confirmed by Raman spectroscopy, with peak positions of A1g and E12g indicating a few MoS2 layers. Fourier-transform infrared (FTIR) spectroscopy revealed the conformal fabrication of MoS2 nanosheets. Defect engineering by ion irradiation is an effective approach to tuning the intrinsic properties of Layered MoS2, as analyzed by photoluminescence spectroscopy.

Impact of fast charging and low-temperature cycling on lithium-ion battery health: A comparative analysis

Fast charging and low temperatures create harsh conditions that promote lithium deposition on graphite anodes, which significantly accelerates the degradation of the battery's state of health (SoH) and eventually could result in safety concerns. In this work, commercial lithium-ion batteries are investigated under fast charging conditions and at low environmental temperatures. The findings are compared with lithium-ion battery cycled under ambient temperature conditions. The fast charging and low temperatures result in dead lithium formation, which is then characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The low-temperature cycled battery exhibits significant growth of series resistance by an average of 73 %. In comparison, growth in charge transfer resistance is 16 %, and no significant change was observed in solid electrolyte interface (SEI) resistance due to the formation of dead lithium, compared to the battery cycled at ambient temperature. SEM images also confirm the dead lithium formation. The results provide insight into battery degradation in the case of high current due to low temperature and could lead to a better understanding of the degradation mechanism.

Sequential Effect of Dual-Layered Hybrid Graphite Anodes on Electrode Utilization During Fast-Charging Li-Ion Batteries.

To recharge lithium-ion batteries quickly and safely while avoiding capacity loss and safety risks, a novel electrode design that minimizes cell polarization at a higher current is highly desired. This work presents a dual-layer electrode (DLE) technology via sequential coating of two different anode materials to minimize the overall electrode resistance upon fast charging. Electrochemical impedance spectroscopy and distribution of relaxation timesanalysis revealed the dynamic evolution of electrode impedances in synthetic graphite (SG) upon a change in the state of charge (SOC), whereas the natural graphite (NG) maintains its original impedance regardless of SOC variation. This disparity dictates the sequence of the NG and SG coating layers within the DLE, considering the temporal SOC gradient developed upon fast charging. Simulation and experimental results suggest that DLE positioning NG and SG on the top (second-layer) and bottom (first-layer), respectively, can effectively reduce the overall resistance at a 4C-rate (15-min charging), demonstrating two times higher capacity retention (61.0%) over 200 cycles than its counterpart with reversal sequential coating, and is higher than single-layer electrodes using NG or NG/SG binary mixtures. Hence, this study can guide the combinatorial sequence for multi-layer coating of various active materials for a lower-resistivity, thick-electrode design.

The principle and amelioration of lithium plating in fast-charging lithium-ion batteries

Fast charging is restricted primarily by the risk of lithium (Li) plating, a side reaction that can lead to the rapid capacity decay and dendrite-induced thermal runaway of lithium-ion batteries (LIBs). Investigation on the intrinsic mechanism and the position of Li plating is crucial to improving the fast rechargeability and safety of LIBs. Herein, we investigate the Li plating behavior in porous electrodes under the restricted transport of Li+. Based on the theoretical model, it can be concluded that the Li plating on the anode-separator interface (ASI) is thermodynamically feasible and kinetically advantageous. Meanwhile, the prior deposition of metal Li on the ASI rather than the anode-current collector interface (ACI) is verified experimentally. In order to facilitate the transfer of Li+ among the electrode and improve the utilization of active materials without Li plating, a bilayer asymmetric anode composed of graphite and hard carbon (GH) is proposed. Experimental and simulation results suggest that the GH hybrid electrode homogenizes the lithiated-rate throughout the electrode and outperforms the pure graphite electrode in terms of the rate performance and inhibition of Li plating. This work provides new insights into the behavior of Li plating and the rational design of electrode structure.

High performance hydrovoltaic devices based on asymmetrical electrode design

As a promising method for energy harvesting, water evaporation can generate electrical energy without additional mechanical energy input. In the evaporation power generation unit based on the principle of flow potential, the low charge collection efficiency is the key factor limiting the energy output, which limits the practical application of water evaporation equipment. Based on the principle of evaporation potential, an asymmetric sandwiched hydrovoltaic device based on metallic aluminum plate and carbon cloth electrodes is designed, which not only matches the electrode, but also reduces the carrier migration route and realizes fast charge transfer and collection. The device achieves an open-circuit voltage (Voc) of 730 mV and a short-circuit current density (Jsc) of 558 μA cm−2, capable of producing output power density exceeding 61.7 μW cm−2. Micro-nano electronic devices with low power consumption can be powered by integration of multiple devices. This study proposes a strategy for clean energy collection based on water evaporation.

One-pot synthesis of g-C3N4/N-doped CeO2 nanocomposites and their potential visible light-driven photocatalytic degradation of methylene blue dye.

In the pursuit of efficient photocatalytic materials for environmental applications, a new series of g-C3N4/N-doped CeO2 nanocomposites (g-C3N4/N-CeO2 NCs) was synthesized using a straightforward dispersion method. These nanocomposites were systematically characterized to understand their structural, optical, and chemical properties. The photocatalytic performance of g-C3N4/N-CeO2 NCs was evaluated by investigating their ability to degrade methylene blue (MB) dye, a model organic pollutant. The results demonstrate that the integration of g-C3N4 with N-doped CeO2 NCs reduces the optical energy gap compared to pristine N-doped CeO2, leading to enhanced photocatalytic efficiency. It is benefited from the existence of g-C3N4/N-CeO2 NCs not only in promoting the charge separation and inhibits the fast charge recombination but also in improving photocatalytic oxidation performance. Hence, this study highlights the potential of g-C3N4/N-CeO2 NCs as promising candidates for various photocatalytic applications, contributing to the advancement of sustainable environmental remediation technologies.

High Capacitance Porous Ruthenium Nitride Films with High Rate Capability for Micro-Supercapacitors.

The demand for high-performance energy storage devices to power Internet of Things applications has driven intensive research on micro-supercapacitors (MSCs). In this study, RuN films made by magnetron sputtering as an efficient electrode material for MSCs are investigated. The sputtering parameters are carefully studied in order to maximize film porosity while maintaining high electrical conductivity, enabling a fast charging process. Using a combination of advanced techniques, the relationships among the morphology, structure, and electrochemical properties of the RuN films are investigated. The films are shown to have a complex structure containing a mixture of crystallized Ru and RuN phases with an amorphous oxide layer. The combination of high electrical conductivity and pseudocapacitive charge storage properties enabled a 16µm-thick RuN film to achieve a capacitance value of 0.8Fcm-2 in 1m KOH with ultra-high rate capability.

Solvation Effect: The Cornerstone of High-Performance Battery Design for Commercialization-Driven Sodium Batteries.

Sodium batteries (SBs) emerge as a potential candidate for large-scale energy storage and have become a hot topic in the past few decades. In the previous researches on electrolyte, designing electrolytes with the solvation theory has been the most promising direction is to improve the electrochemical performance of batteries through solvation theory. In general, the four essential factors for the commercial application of SBs, which are cost, low temperature performance, fast charge performance and safety. The solvent structure has significant impact on commercial applications. But so far, the solvation design of electrolyte and the practical application of sodium batteries have not been comprehensively summarized. This review first clarifies the process of Na+ solvation and the strategies for adjusting Na+ solvation. It is worth noting that the relationship between solvation theory and interface theory is pointed out. The cost, low temperature, fast charging, and safety issues of solvation are systematically summarized. The importance of the de-solvation step in low temperature and fast charging application is emphasized to help select better electrolytes for specific applications. Finally, new insights and potential solutions for electrolytes solvation related to SBs are proposed to stimulate revolutionary electrolyte chemistry for next generation SBs.

Promoting electrochemical rates by concurrent ionic-electronic conductivity enhancement in high mass loading cathode electrode

Enhancing the fast charging capacity of thick electrodes with high mass loading is imperative in expediting the widespread adoption of electric vehicles. Nonetheless, the insufficient charge transfer kinetics of thick electrodes hinder the movement of effective electrons and ions, hence diminishing capacity at high current rates. Herein, we applied sustainable and biodegradable cellulose nanocrystals (CNCs) as electrode additives. It is the first time to simultaneously improve the electronic conductivity by optimizing the carbon dispersion and establishing electron transfer networks, as well as boosting the ionic conductivity of electrodes by shortening the ion transfer pathway. Specifically, the LiNi0.6Mn0.2Co0.2O2 electrodes incorporating 1% dual functional CNCs additive exhibit improved effective electrical conductivity from 0.11 to 0.16 S/m and risen effective ionic conductivity from 0.36 to 0.62 S/m, in comparison to counterpart electrodes without CNCs. Therefore, the 1% CNC electrode with a high mass loading of 27.0 mg/cm2 delivers a discharge capacity of 128 mAh/g at 1 C, which is superior to that of the CNC-free electrodes (95 mAh/g). In short, this study presents a novel environmentally friendly, economically viable, and dual-functional electrode additive that enhances both electronic and ionic conductivities with the aim of facilitating the widespread adoption of fast-charging high mass loading electrodes.

Low-Temperature and Fast-Charging Lithium Metal Batteries Enabled by Solvent–Solvent Interaction Mediated Electrolyte

Low-Temperature and Fast-Charging Lithium Metal Batteries Enabled by Solvent–Solvent Interaction Mediated Electrolyte

In Situ Interphasial Engineering Enabling High‐Rate and Long‐Cycling Li Metal Batteries

AbstractThe practical implementation of Li metal anode has long been hindered by the significant challenges of notorious dendritic Li growth and severe interphase instability during repeated cycling. Herein, a highly lithiophilic NiSe‐modified host has rationally been constructed to stabilize Li metal by the facile mechanical rolling strategy. The in situ configurated high‐flux Li2Se‐enriched interphase layer can facilitate the fast interfacial charge transfer, high Li plating/stripping reversibility and homogeneous Li nucleation/growth. Consequently, the achieved modified Li metal demonstrates ultrahigh rate capability (10 mA cm−2) and ultralong‐term cycling stability (6600 cycles) with dendrite‐free Li deposition. The Li|LiFePO4 (LFP) cell exhibits an extraordinarily long lifespan cycling stability over 500 cycles with an ultra‐low decay rate of only ≈0.0092% per cycle at 1 C. Furthermore, the 4.5 V high‐voltage Li|LiCoO2 pouch cell with a high areal capacity (≈1.9 mAh cm−2) still reveals an impressively prolonged cyclability over 200 cycles even under the harsh test condition of low negative‐to‐positive‐capacity (N/P) ratio of ≈3.4 and lean electrolyte of ≈5.5 µL mAh−1. This work provides a facile and scalable strategy toward a highly stable Li metal anode for reliable practical usage.

Bifunctional energy materials based on cellulose ionic complexes toward low-grade heat and photon energy storage

Discovering energy materials for low-grade heat and photon energy storage would advance the energy utilization from natural resources. Here, the ionic complexes based on cellulose and azobenzene-containing surfactant are presented as a new class of phase change materials for achieving this objective. Such materials could accomplish the energy charging in two different ways. Under UV light, the ionic complexes store photon energy and low-grade heat via the photoisomerization of azobenzene and the induced isothermal phase change at room temperature. While, without light condition, they could be employed for storing low-grade heat through a gradual phase change below 100 °C, by taking advantage of the intermolecular interaction changes. In the two different energy charging ways, the gravimetric energy densities for low-grade heat storage upon heating and photoinduced energy storage are up to 202 J/g and 152 J/g, respectively. The stored energy could be fast released as heat under Vis light irradiation. In addition, the fabrication of gold nanoparticles is proved to be a highly effective method for the fast energy charging under UV light. This work provides a new physicochemical principle for the development of energy storage materials based on biomolecules, which would also advance the economic value of cellulose as biomass resource.