Extreme Fast Charging Research Articles

Lithium-Ion Battery Technologies for Electric Vehicles: Progress and challenges

Electric Vehicle (EV) sales and adoption have seen a significant growth in recent years, thanks to advancements and cost reduction in lithium-ion battery technology, attractive performance of EVs, governments’ incentives, and the push to reduce greenhouse gases and pollutants. In this article, we will explore the progress in lithium-ion batteries and their future potential in terms of energy density, life, safety, and extreme fast charge. We will also discuss material sourcing, supply chain, and end-of-life-cycle management as they have become important considerations in the ecosystem of batteries for the sustained growth and adoption of EVs. With significant government and private sector investments in research and development, processing, and manufacturing and advances in anodes (lithium and silicon), cathodes (high nickel), designs, supply chain development, and the circularity of lithium-ion batteries, lithium-based batteries are on track to make EVs mainstream, addressing climate concerns of fossil-fueled vehicles.

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

90 C fast-charge Na-ion batteries for pseudocapacitive faceted TiO2 anodes based on robust interface chemistry

Sodium-ion batteries are a potential candidate for next-generation energy storage devices. Unfortunately, developing an anode with improved long-term cycling stability and high-rate performance remains a substantial problem. In this work, we develop that the Na+ intercalation pseudocapacitance in faceted titanium dioxide endows extreme fast charging and long cycle life in a sodium-ion battery. Theoretical calculations and comprehensive characterization exhibit that high ionic conductivity, stable solid electrolyte interphase (SEI), and pseudocapacitive behavior are essential for fast charging. This well-designed electrode demonstrates a significantly high reversible capacity of about 135 mAh g−1 at 90 C (∼30 A g−1) for 10,000 cycles with an 87.8% retension. Coupled with a vanadium phosphate sodium Na3V2(PO4)3 cathode, and this full cell displays a specific capacity of 310 mAh g−1 at 0.2 A g−1 for 100 cycles. This study unveils the key mechanisms for fast-charging sodium storage, and can also facilitate the improvement of other titanium-based anodes secondary batteries.

End-to-End Direct-Current-Based Extreme Fast Electric Vehicle Charging Infrastructure Using Lithium-Ion Battery Storage

An urgent need to decarbonize the surface transport sector has led to a surge in the electrification of passenger and heavy-duty fleet vehicles. The lack of widespread public charging infrastructure hinders this electric vehicle (EV) transition. Extreme fast charging along interstates and highway corridors is a potential solution. However, the legacy power grid based on alternating current (AC) beckons for costly upgrades that will be necessary to sustain sporadic fast charging loads. The primary goal of this paper is to propose a sustainable, low-loss, extremely fast charging infrastructure based on photovoltaics (PV) and co-located lithium-ion battery storage (BESS). Lithium-ion BESS plays a pivotal role in our proposed design by mitigating demand charges and operating as an independent 16–18 h power source. An end-to-end direct current power network with high voltage direct current interconnection is also incorporated. The design methodology focuses on comprehensive hourly EV-load models generated for different types of passenger vehicles and heavy-duty fleet charging. Appropriate PV-BESS sizing, optimum tilt, and temperature compensation techniques based on 15 years of irradiation data were utilized in the design. The proposed grid-independent DC power networks can significantly improve well-to-wheels efficiency by minimizing total system losses for fast charging networks. The network power savings for low, medium, and high voltage use cases were evaluated. Our results demonstrate 17% to 25% power savings compared to the traditional AC case.

Optimal Configuration of Extreme Fast Charging Stations Integrated with Energy Storage System and Photovoltaic Panels in Distribution Networks

Extreme fast charging (XFC) for electric vehicles (EVs) has emerged recently because of the short charging period. However, the extreme high charging power of EVs at XFC stations may severely impact distribution networks. This paper addresses the estimation of the charging power demand of XFC stations and the design of multiple XFC stations with renewable energy resources in current distribution networks. First, a Monte Carlo (MC) simulation tool was created utilizing the EV arrival time and state-of-charge (SOC) distributions obtained from the dataset of vehicle travel surveys. Various impact factors are considered to obtain a realistic estimation of the charging power demand of XFC stations. Then, a method for determining the optimal energy capacity of the energy storage system (ESS), ESS rated power, and size of photovoltaic (PV) panels for multiple XFC stations in a distribution network is presented, with the goal of achieving an optimal configuration. The optimal power flow technique is applied to this optimization so that the optimal solutions meet not only the charging demand but also the operational constraints related to XFC, ESS, PV panels, and distribution networks. Simulation results of a use case indicate that the presented MC simulation can estimate approximate real-world XFC charging demand, and the optimized ESS and PV units in multiple XFC stations in the distribution network can reduce the annual total cost of XFC stations and improve the performance of the distribution network.

Towards extreme fast charging of 4.6 V LiCoO2 via mitigating high-voltage kinetic hindrance

High-voltage LiCoO2 (LCO) is an attractive cathode for ultra-high energy density lithium-ion batteries (LIBs) in the 3 C markets. However, the sluggish lithium-ion diffusion at high voltage significantly hampers its rate capability. Herein, combining experiments with density functional theory (DFT) calculations, we demonstrate that the kinetic limitations can be mitigated by a facial Mg2++Gd3+ co-doping method. The as-prepared LCO shows significantly enhanced Li-ion diffusion mobility at high voltage, making more homogenous Li-ion de/intercalation at a high-rate charge/discharge process. The homogeneity enables the structural stability of LCO at a high-rate current density, inhibiting stress accumulation and irreversible phase transition. When used in combination with a Li metal anode, the doped LCO shows an extreme fast charging (XFC) capability, with a superior high capacity of 193.1 mA h g−1 even at the current density of 20 C and high-rate capacity retention of 91.3% after 100 cycles at 5 C. This work provides a new insight to prepare XFC high-voltage LCO cathode materials.

Architecture for Co-Simulation of Transportation and Distribution Systems with Electric Vehicle Charging at Scale in the San Francisco Bay Area

This work describes the Grid-Enhanced, Mobility-Integrated Network Infrastructures for Extreme Fast Charging (GEMINI) architecture for the co-simulation of distribution and transportation systems to evaluate EV charging impacts on electric distribution systems of a large metropolitan area and the surrounding rural regions with high fidelity. The current co-simulation is applied to Oakland and Alameda, California, and in future work will be extended to the full San Francisco Bay Area. It uses the HELICS co-simulation framework to enable parallel instances of vetted grid and transportation software programs to interact at every model timestep, allowing high-fidelity simulations at a large scale. This enables not only the impacts of electrified transportation systems across a larger interconnected collection of distribution feeders to be evaluated, but also the feedbacks between the two systems, such as through control systems, to be captured and compared. The findings are that with moderate passenger EV adoption rates, inverter controls combined with some distribution system hardware upgrades can maintain grid voltages within ANSI C.84 range A limits of 0.95 to 1.05 p.u. without smart charging. However, EV charging control may be required for higher levels of charging or to reduce grid upgrades, and this will be explored in future work.

Implementation of EFC Charging Station by Multiport Converter with Integration of RES

Electric vehicles (EVs) are gradually becoming an integral part of the drive to accomplish sustainable energy standards. Due to their limited onboard battery capacity, EVs’ expanding popularity creates a need for widespread charging stations. However, fast charging stations, particularly Extreme Fast Charging (EFC), may impose a hassle on the electrical system due to overload during peak hours, frequent power gaps, and voltage sag. To flatten the power supply, the photovoltaic (PV) Hybrid Energy Storage Systems (HESS) and the uncertain and variable nature of PV systems always include solar and hybrid energy storage systems (HESS) such as batteries and supercapacitors. This research suggests a multi-port DC-DC converter (MPC) with a bidirectional DC-DC converter for battery ESS-integrated PV systems. The MPC can regulate the majority of active power through PV to a battery, PV to an EV charging station, HESS to an EV charging station, and PV to AC grid. Additionally, a PI controller is used for the MPC, taking both the PV and battery voltage variations into account. Therefore, the presented configuration can achieve the key benefits of greater integration, more efficiency, and reduced cost. Simulation results show the advantages of this multiport EV charging circuit with PV-HESS and design in different modes.

Smart Extreme Fast Portable Charger for Electric Vehicles-Based Artificial Intelligence

Due to the increase in the number of electric vehicles (EVs) in the world, there is a need to design superior performance and lower operating costs of charging infrastructures to serve these vehicles. Merging extreme fast charging technology with the portable feature can provide a user-friendly and cost-effective structure for charging EVs. This brief proposes a Smart Extreme Fast Portable Charger (SEFPC) for Electric Vehicles which have several input ports (e.g., the power grid or Renewable Energy Sources (RESs)/Energy Storage Systems (ESSs)) and an output port with an optimal charging operation mode based on considering the condition of the available power sources and battery of EVs for saving the energy and time charging. Moreover, a model-free sliding mode controller-based machine learning algorithm is applied to find optimal charging operation mode based on the battery state and power of sources condition to increase battery life and overall system efficiency. Finally, real-time results based on the OPAL-RT are provided to validate the efficacy and feasibility of the proposed SEFPC and model-free sliding mode controller.

Analysis and design of battery thermal management under extreme fast charging and discharging

Thermal management is critical for the safety of electric vehicle (EV) battery packs, especially under ultra-fast and extreme fast charging and discharging use conditions. Liquid cooling is particularly attractive over other battery thermal management technologies due to its high heat transfer coefficient and low power usage. This paper systematically studies a liquid-cooled battery thermal management system for limiting the maximum temperature and voltage excursions of a standard 18650 lithium-ion battery pack. Considering two different coolant flow configurations, the influences of coolant flow rate, inlet temperature, battery capacity, charge rate, and discharge rate are investigated through a detailed computational study. Based on the simulations, design windows are developed for keeping the maximum temperature during charging below 45 °C and during discharging within 60 °C, as well as maintaining the cell voltage < 4.2 V. The design windows provide the maximum charge and discharge rates that can be achieved with a given coolant flow rate and inlet temperature for a battery capacity. Equivalently, the design windows may be utilized for a desired charge and discharge rate to obtain the required coolant flow design. The study provides valuable insight into advancing the ultra and extreme fast charge and discharge capabilities of battery packs for EV applications.

One-Step Synthesis of Three-Dimensional Na3V2(PO4)3/Carbon Frameworks as Promising Sodium-Ion Battery Cathode.

Sodium-ion batteries (SIBs) are essential for large-scale energy storage attributed to the high abundance of sodium. Polyanion Na3V2(PO4)3 (NVP) is a dominant cathode candidate for SIBs because of its high-voltage and sodium superionic conductor (NASICON) framework. However, the electrochemical performance of NVP is hindered by the inherently poor electronic conductivity, especially for extreme fast charging and long-duration cycling. Herein, we develop a facile one-step in-situ polycondensation method to synthesize the three-dimensional (3D) Na3V2(PO4)3/holey-carbon frameworks (NVP@C) by using melamine as carbon source. In this architecture, NVP crystals intergrown with the 3D holey-carbon frameworks provide rapid transport pathways for ion/electron transmission to increase the ultrahigh rate ability and cycle capability. Consequently, the NVP@C cathode possesses a high reversible capacity of 113.9 mAh g-1 at 100 mA g-1 and delivers an outstanding high-rate capability of 75.3 mAh g-1 at 6000 mA g-1. Moreover, it shows that the NVP@C cathode is able to display a volumetric energy density of 54 Wh L-1 at 6000 mA g-1 (31 Wh L-1 for NVP bulk), as well as excellent cycling performance of 65.4 mAh g-1 after 1000 cycles at 2000 mA g-1. Furthermore, the NVP@C exhibits remarkable reversible capabilities of 81.9 mAh g-1 at a current density of 100 mA g-1 and 60.2 mAh g-1 at 1000 mA g-1 even at a low temperature of -15 °C. The structure of porous carbon frameworks combined with single crystal materials by in-situ polycondensation offers general guidelines for the design of sodium, lithium and potassium energy storage materials.

Frontispiece: Unlocking Charge Transfer Limitations for Extreme Fast Charging of Li‐Ion Batteries

Lithium Ion Batteries. Fast charging of high-energy Li-ion batteries is achieved by simultaneously reducing the anode and cathode charge transfer energy barriers through electrolyte engineering, as reported by Chong Yan, Qiang Zhang et al. in their Research Article (e202214828).

Extreme Fast Charging Capability in Graphite Anode via a Lithium Borate Type Biobased Polymer as Aqueous Polyelectrolyte Binder

Desolvation of lithium ions and diffusion of Li+ through the solid electrolyte interface (SEI) play an important role in determining the extreme fast-charging ability of graphite for electric vehicle (EV) application. For this reason, a novel aqueous borate type bio-based polymer with inherent Li ions was designed as an SEI forming binder for graphite. The low lying LUMO energy level enabled the preferential reduction of the binder prior to the degradation of the electrolyte or salt to form a thinner and highly conducting borate rich SEI. A robust boron rich SEI and a binder with inherent Li ions improved the kinetics with low activation energy for lithiation/desolvation (22.56 kJ/mol), lower SEI resistance, and a high Li+ diffusion coefficient across the graphite galleries (7.24 × 10–9 cm2 s–1). Anodic half-cells with the novel binder delivered a discharge capacity of 73 mAh/g at 10 C, which is three times higher than the those of the polyvinylidene fluoride (PVDF) and sodium carboxymethyl cellulose/polystyrene-polybutadiene rubber (CMC-SBR) counterparts, with a high capacity retention for more than 1000 cycles.

Unlocking Charge Transfer Limitations for Extreme Fast Charging of Li-Ion Batteries.

Extreme fast charging (XFC) of high-energy Li-ion batteries is a key enabler of electrified transportation. While previous studies mainly focused on improving Li ion mass transport in electrodes and electrolytes, the limitations of charge transfer across electrode-electrolyte interfaces remain underexplored. Herein we unravel how charge transfer kinetics dictates the fast rechargeability of Li-ion cells. Li ion transfer across the cathode-electrolyte interface is found to be rate-limiting during XFC, but the charge transfer energy barrier at both the cathode and anode have to be reduced simultaneously to prevent Li plating, which is achieved through electrolyte engineering. By unlocking charge transfer limitations, 184 Wh kg-1 pouch cells demonstrate stable XFC (10-min charge to 80 %) which is otherwise unachievable, and the lifetime of 245 Wh kg-1 21700 cells is quintupled during fast charging (25-min charge to 80 %).

Unlocking Charge Transfer Limitations for Extreme Fast Charging of Li‐Ion Batteries

AbstractExtreme fast charging (XFC) of high‐energy Li‐ion batteries is a key enabler of electrified transportation. While previous studies mainly focused on improving Li ion mass transport in electrodes and electrolytes, the limitations of charge transfer across electrode–electrolyte interfaces remain underexplored. Herein we unravel how charge transfer kinetics dictates the fast rechargeability of Li‐ion cells. Li ion transfer across the cathode–electrolyte interface is found to be rate‐limiting during XFC, but the charge transfer energy barrier at both the cathode and anode have to be reduced simultaneously to prevent Li plating, which is achieved through electrolyte engineering. By unlocking charge transfer limitations, 184 Wh kg−1 pouch cells demonstrate stable XFC (10‐min charge to 80 %) which is otherwise unachievable, and the lifetime of 245 Wh kg−1 21700 cells is quintupled during fast charging (25‐min charge to 80 %).

The In-situ Characterization of Fast-charging Degradation Modes in Li-ion Batteries Using High-resolution Neutron Imaging

Extreme fast charging (XFC) of lithium-ion batteries (LIBs) in 10 minutes is one of the main goals of the US Advanced Battery Consortium for low-cost, fast-charged electric vehicles by 2023. However, existing LIBs cannot achieve these XFC goals without significant capacity fade over cycling due to complex XFC degradation modes. One of the key XFC failure mechanisms is dead Li plating on the graphite anode. While numerous methods have detected Li plating, they lack three-dimensional non-invasive visualization of dead Li on graphite anodes in full cells during battery cycling. Herein, we demonstrate the viability of high-resolution (spatial resolution: 10–15 μm) neutron micro-computed tomography (μCT) for in-situ characterization of dead Li on graphite anodes (thickness: ~130 μm) in full cells containing NMC cathode, that were cycled at 1C and 6C.

Design, development, and techno-economic analysis of extreme fast charging topologies using Super Capacitor and Li-Ion Battery combinations

In the past few decades, it has been observed that Renewable Energy System (RES) coupled with a grid is a potential option for fulfilling the fast-growing load demand. However, the intermittent nature of renewable energy resources limits the performance of RES and prevents it from being properly utilized. This results in power quality issues and grid system instability. To address this issue, it is a common practice to combine RES with effective energy storage technologies, including the latest storage system based on Lithium-Ion Batteries (LIB) and Super Capacitors (SC). However, the fast charging of LIB and slow discharging of SC are still debatable. Time taken for charging LIB is usually sky-high that the Cost of Energy (CoE) becomes unprofitable. On the other side, although the charging of SC is faster, but undergoes quick discharging. Hence, in this paper, a cutting-edge model of LIB, i.e., an extreme Fast Charging LIB (FCLIB) is developed, where LIB is integrated with fast charging SC. This reduces the charging time of storage systems in comparison with conventional systems. In the current paper, six alternative topologies of FCLIB are developed and analyzed for CoE estimation, using real commercial load profiles and resource data. It is observed that the proposed FCLIB with the best topology is achieving 80 % of its State of Charge (SoC) in 5.84 min and 100 % of SoC in 13.5 min. The Optimized Electric Renewable Model (OERM) was employed to analyze the techno-economic analysis of the proposed FCLIB. It is estimated that the proposed topology of FCLIB has a CoE of 0.32$/kWh with fast charging, which is approximately equal to the CoE of a conventional slow charging LIB (estimated as 0.33$/kWh). Thus, the designed FCLIB provides an optimal storage solution for RES to overcome the intermittent nature of renewable energy resources to meet the load demand.

Extreme Fast Charging: Effect of Positive Electrode Material on Crosstalk

Extreme fast charging (XFC) is a key requirement for the adoption of battery-based electric vehicles by the transportation sector. However, XFC has been shown to accelerate degradation, causing the capacity, life, and safety of batteries to deteriorate. We tested cells containing five positive electrode chemistries, LFP (olivine structure), LMO (spinel), LCO (layered), NMC811 (layered) and NCA (layered), using fast-charging protocols. After testing, the negative electrodes from cells containing positive electrodes crystallizing with a layered structure were found to have more lithium deposited on their surfaces. Those crystallizing with a layered structure also tended to have a larger increase in impedance than those crystallizing with a spinel or olivine structure. Characterization of the negative electrodes by X-ray photoelectron spectroscopy showed that using the concentrations of LiF and LixPOyFz as metrics, the concentration of LiF in the SEI from the cell with different positive electrodes is LFP > LMO > LCO ∼ NMC811 > NCA; and for LixPOyFz, the order is LMO > LFP > NCA > NMC811 > LCO. Clearly, the positive-electrode material was influencing the amounts of these materials formed.

Simultaneous neutron and X-ray tomography for visualization of graphite electrode degradation in fast-charged lithium-ion batteries

Advanced battery characterization using neutron and X-ray-based imaging modalities is crucial to reveal fundamental degradation modes of lithium-ion batteries (LIBs). Taking advantage of the sensitivity of neutrons to some low-Z (Li) and X-rays to high-Z materials (Cu), here we demonstrate the viability of simultaneous neutron- and X-ray-based tomography (NeXT) as a non-destructive imaging platform for ex situ 3D visualization of graphite electrode degradation following extreme fast charging (XFC). In addition, we underscore the benefits of the simultaneous nature of NeXT by combining the neutron and X-ray data from the same sample location for material identification and segmentation of one pristine and two XFC-cycled graphite electrodes (9C charge for 450 cycles). Our ex situ results and methodology development pave the way for the design of NeXT-friendly LIB geometries that will allow operando and/or in situ three-dimensional (3D) visualization of electrode degradation during XFC. • Simultaneous neutron and X-ray tomography (NeXT) is a non-invasive imaging method • NeXT enables visualization of graphite electrode degradation after fast charging • NeXT overlaps neutron and X-ray data from same sample area to identify materials • NeXT shows qualitative correlation between electrode degradation and plated Li Advanced battery characterization is critical to reveal fundamental degradation modes of lithium-ion batteries. Using the sensitivity of neutrons to lithium and X-rays to copper, Yusuf et al. demonstrate the viability of simultaneous neutron and X-ray tomography as a non-invasive imaging modality for visualization of graphite electrode degradation following fast charging.

Mitigating Heterogeneities in Lithium-Ion Battery Modules Under Fast Charging

Temperature control is essential for fast-charging performance of Li-ion battery. Cold temperature leads to sluggish ion transportation of electrolyte, brittle polymeric cell components, changes in solid electrolyte interface (SEI) properties and associated resistance build-up, and Li plating and dendrite growth [1]. High temperature boosts fast charging but can also accelerate battery degradation and increase the rise of battery thermal failure. This is caused by the increased rate of side-reactions, resulting in loss of cyclable lithium and higher rate of attrition of active materials at higher temperatures.Temperature and its gradient in a battery unit strongly affect performance and life of battery units [2]. It is recommended that pack temperature uniformity of a li-ion battery pack in electric vehicles shall be less than 3 ºC [3]. Battery thermal management systems (BTMS) are important for controlling battery pack temperature and minimizing temperature gradients to prevent thermal-related issues in Battery Energy Storage Systems (BESS). This thermal management goal is more critical for fast charging of battery modules made of large format, high-energy-density cells. Current BTMS in battery electric vehicles (BEVs) are inadequate in limiting the maximum temperature rise of the battery during extreme fast charge (i.e., 6C charge). To achieve fast-charge, the size of the battery thermal management system needs to increase from today’s BEV average size of 1–5 kW to around 15–25 kW [4].A combined experimental and modelling approach is employed to access thermal and electrochemical heterogeneities of a battery module under extreme fast charge conditions and develop corresponding mitigation approaches. The electrochemical-thermal model was built based on electrical characterization of 32 mAh pouch cells, including constant-current 1C to 9C rates of charging at varying temperatures. Predictive performance of the model in heat generation was validated by comparing results against measurements conducted using a microcalorimeter. Thereafter, the validated model is used to predict performance of a battery module consisting of six large format pouch cells. The large pouch cell has a capacity of 25 Ah and the identical electrode design of the 32 mAh cells. 3D simulation results suggest significant temperature and charge differences can be produced. The heterogeneous behavior was enlarged along charging. As shown in Figure 1, it was found that electrodes close to the tabs were preferentially charged.Cell electrochemical heterogeneity can be reduced by reducing cell temperature difference. Two potential solutions are investigated using the developed 3D model, including the enhancement of heat transfer within cells, such as increasing cell thermal conductivities with thicker current collectors, and the optimal design of thermal management systems. The feasibility of state-of-the-art thermal management strategies for fast charging is evaluated, including liquid cooling using cold plate devices and direct liquid cooling.