Fast Charging Of Lithium-ion Batteries Research Articles

(Invited) Enabling Fast Charging of Lithium-Ion Batteries without Lithium Plating

Today’s Li-ion technology is highly optimized for performance at relatively slow charging operation. However, significant challenges still present for fast charging conditions (> 4C). In state-of-the-art Li-ion batteries (LIBs) with high energy densities, the electrodes are relatively thick (> 100 μm), which leads to a tradeoff between energy density and high-power performance. In addition, the electrochemical potential of the anode can easily become more negative than Li/Li+ during fast charging, resulting in Li plating [1]. Therefore, new approaches are needed to overcome these energy/power tradeoffs in LIBsIn this talk, I will introduce three strategies to enable fast charging LIBs, using industrially-relevant pouch cells with thick (>3 mAh/cm2) electrode loadings. In the first strategy, vertical channels are introduced into post-calendared electrodes using laser ablation patterning [2]. The resulting 3-D anode architecture consists of a hexagonal close-packed array of vertical channels that serve as linear pathways for rapid ionic diffusion through the electrode thickness. This allows for a more homogeneous flux of Li throughout the volume of the electrode. As a result, the accessible capacity of the electrode during fast charging increases, and Li plating is eliminated.In the second strategy, the energy/power tradeoffs in carbonaceous anode materials are overcome by forming hybrid blends of graphite and hard carbon [3]. This allows for a balance between the higher energy density of graphite with the faster rate performance of hard carbon. By controlling the graphite/hard carbon ratio, we identify an optimal blend for fast charging.In the third strategy, we demonstrate the potential to eliminate Li plating and enabling 4C fast charging purely through interfacial control. This is achieved by coating the surface of graphite with a solid-state electrolyte material using Atomic Layer Deposition (ALD) [4]. These coatings eliminate electrolyte decomposition during the formation cycle, resulting in an “artificial SEI” with a resistance that is 75% lower than the natural SEI that forms in carbonate electrolytes. This challenges the fundamental assumption that fast charging of thick graphite anodes must be solved by improving mass transport, highlighting the critical role of the SEI on fast-charge performance.[1] Y. Chen, K.-H. Chen, A. J. Sanchez, E. Kazyak, V. Goel, Y. Gorlin, J. Christensen, K. Thornton, N. P. Dasgupta, J. Mater Chem. A 9, 23522 (2021).[2] K.-H. Chen, M. Namkoong, V. Goel, C. Yang, S. Kazemiabnavi, S. M. Mortuza, E. Kazyak, J. Mazumder, K. Thornton, J. Sakamoto, N. P. Dasgupta, J. Power Sources 471, 228475 (2020).[3] K.-H. Chen, V. Goel, M. J. Namkoong, M. Wied, S. Müller, V. Wood, J. Sakamoto, K. Thornton, N. P. Dasgupta, Adv. Energy Mater. 11, 2003336 (2020).[4] E. Kazyak, K.-H. Chen, Y. Chen, T. H. Cho, N. P. Dasgupta, Adv. Energy Mater, In Press (2021).

Superior Fast-Charging Lithium-Ion Batteries Enabled by the High-Speed Solid-State Lithium Transport of an Intermetallic Cu6 Sn5 Network.

Superior fast charging is a desirable capability of lithium-ion batteries, which can make electric vehicles a strong competition to traditional fuel vehicles. However, the slow transport of solvated lithium ions in liquid electrolytes is a limiting factor. Here, a Lix Cu6 Sn5 intermetallic network is reported to address this issue. Based on electrochemical analysis and X-ray photoelectron spectroscopy mapping, it is demonstrated that the reported intermetallic network can form a high-speed solid-state lithium transport matrix throughout the electrode, which largely reduces the lithium-ion-concentration polarization effect in the graphite anode. Employing this design, superior fast-charging graphite/lithium cobalt oxide full cells are fabricated and tested under strict electrode conditions. At the charging rate of 6 C, the fabricated full cells show a capacity of 145 mAh g-1 with an extraordinary capacity retention of 96.6%. In addition, the full cell also exhibits good electrochemical stability at a high charging rate of 2 C over 100 cycles (96.0% of capacity retention) in comparison to traditional graphite-anode-based cells (86.1% of capacity retention). This work presents a new strategy for fast-charging lithium-ion batteries on the basis of high-speed solid-state lithium transport in intermetallic alloy hosts.

Atomic-Scale Laminated Structure of O-Doped WS2 and Carbon Layers with Highly Enhanced Ion Transfer for Fast-Charging Lithium-Ion Batteries.

WS2 anode materials show huge potential for fast-charging lithium-ion batteries (LIBs) due to the naturally good 2D diffusion pathways but suffer from large Li+ diffusion barrier energy and poor intrinsic electrical conductivity. Here, a defect-rich atomic-scale laminated structure of WS2 and C (D-WS2 -C) with O doping and enlarged interlayer distance from 0.62 to 1.06nm of WS2 is first fabricated, which is assembled into micron-sized spheres to prepare WS2 /C composite microspheres. D-WS2 -C with maximized molecular layer contact area between WS2 and carbon and large interlayer spacing greatly enhances the electrical conductivity of WS2 and reduces Li-ion diffusion energy barrier, confirmed by density functional theory calculations. Besides, the unique D-WS2 -C enables the formation of vast superfine W nanoparticles (1-2nm) during the conversation reaction, resulting in the construction of a space charge zone on W surface. Based on these characteristics of D-WS2 -C, the prepared WS2 /C composite microspheres show superior fast-charging capability with a high capacity of 647.8 mAh g-1 at 20 C in half cells. For full cells, a high-energy density of 100.9Wh kg-1 is achieved at a charge time of only 8.5min at 5 C, representing the best fast-charging performances in WS2 -based anode materials to date.

A Nonstoichiometric Niobium Oxide/Graphite Composite for Fast-Charge Lithium-Ion Batteries.

Electrification of transportation has spurred the development of fast-charge energy storage devices. High-power lithium-ion batteries require electrode materials that can store lithium quickly and reversibly. Herein, the design and construction of a Nb2 O5-δ /graphite composite electrode that demonstrates remarkable rate capability and durability are reported. The presence of graphite enables the formation of a dominant Nb12 O29 phase and a minor T-Nb2 O5 phase. The high rate capability is attributed to the enhanced electronic conductivity and lower energy barriers for fast lithium diffusion in both Nb12 O29 and T-Nb2 O5 , as unraveled by density functional theory calculations. The excellent durability or long cycling life is originated from the coherent redox behavior of Nb ions and high reversibility of lithium intercalation/deintercalation, as revealed by operando X-ray absorption spectroscopy analysis. When tested in a half-cell at high cycling rates, the composite electrode delivers a specific capability of 120 mAh g-1 at 80 C and retains over 150 mAh g-1 after 2000 cycles at 30 C, implying that it is a highly promising anode material for fast-charging lithium-ion batteries.

Liquid cooling vs hybrid cooling for fast charging lithium-ion batteries: A comparative numerical study

Lithium-ion batteries (LIBs) rely on efficient thermal management systems for their safe and reliable operation. Issues like overheating of LIBs due to excessive heat generation, thermal runaway and thermal propagation are still a challenge for engineers. To address the challenge, numerous cooling methods viz. liquid cooling, air cooling, cooling using phase change materials (PCMs), hybrid cooling (i.e., combining liquid and PCM cooling), etc., have been proposed by different authors in the past. Though all the above methods are best suited for LIBs under normal charging/discharging operations, their suitability for cooling fast charging LIBs remains unexplored. In general, the heat generation and risks due to thermal runaway in LIBs are relatively more during fast charging than normal charging. As regards hybrid cooling employing PCMs, the method is yet to be benchmarked, as PCMs themselves suffer from low thermal conductivity issues that may affect their overall thermal performance. The present work is an attempt to address the above-stated aspects. Detailed 3D numerical simulations on three different design configurations (D1-D3) of a prismatic LIB module consisting of four 10 Ah batteries fast charged at 8C rate are reported herein. Two different cooling methods viz. (i) liquid cooling employing a dielectric liquid coolant (STO-50) and (ii) hybrid cooling combining liquid dielectric and a PCM (RT35) are investigated, and their performances compared. The results reveal interesting facts on the ability of liquid cooling (D2) over hybrid cooling (D3) for fast charging LIBs. Parametric studies show that the coolant flow direction (horizontal/vertical) and thermal conductivity of the PCM (kpcm) have a profound influence on the cooling obtained compared to PCM’s melting temperature (Tm) and latent heat (λ). It is concluded that PCM based hybrid cooling is not suitable for cooling LIBs under fast charging unless kpcm is enhanced to 1 W/mK or above. A minimum coolant flow rate of 2 lpm is needed to limit the battery temperatures to 40 °C or below for the module under fast charging conditions. An increase in PCMs latent heat from 160 to 200 kJ/kg has no significant influence on the cooling achieved.

Extremely fast-charging lithium ion battery enabled by dual-gradient structure design.

Extremely fast-charging lithium-ion batteries are highly desirable to shorten the recharging time for electric vehicles, but it is hampered by the poor rate capability of graphite anodes. Here, we present a previously unreported particle size and electrode porosity dual-gradient structure design in the graphite anode for achieving extremely fast-charging lithium ion battery under strict electrode conditions. We develop a polymer binder–free slurry route to construct this previously unreported type particle size-porosity dual-gradient structure in the practical graphite anode showing the extremely fast-charging capability with 60% of recharge in 10 min. On the basis of dual-gradient graphite anode, we demonstrate extremely fast-charging lithium ion battery realizing 60% recharge in 6 min and high volumetric energy density of 701 Wh liter−1 at the high charging rate of 6 C.

State of health estimation for fast-charging lithium-ion battery based on incremental capacity analysis

Recently, lithium-ion batteries with fast-charging capability up to 3C rate are progressively equipped in modern consumer products. State of health (SOH) estimation specifically developed for fast-charging batteries is still an open-question, and the majority of the published methods is for batteries under lower charging rate below 1C. This study proposes a novel SOH method in particular for fast-charging batteries based on the incremental capacity (IC) analysis and Gaussian process regression (GPR). Firstly, the battery aging under fast-charging conditions is discussed according to the IC analysis, and a different characteristic of the IC curve is found for fast-charging batteries beyond the one observed under a lower charging rate. Then a novel feature extracted from the IC curves is introduced for SOH estimation of fast-charging batteries, and this novel feature is further identified and verified both from physical mechanism analysis and from quantitative comparison with classical features on battery aging correlation. Finally, a GPR model is established and trained with the dataset of extracted features for SOH estimation of fast-charging batteries. The proposed method is demonstrated on two fast-charging batteries Datasets, in which one of them simulates the real-life application, and the proposed method can achieve more than 90% reduction on mean absolute percentage error.

Introducing a Pseudocapacitive Lithium Storage Mechanism into Graphite by Defect Engineering for Fast-Charging Lithium-Ion Batteries.

The extreme fast-charging capability of lithium-ion batteries (LIBs) is very essential for electric vehicles (EVs). However, currently used graphite anode materials cannot satisfy the requirements of fast charging. Herein, we demonstrate that intrinsic lattice defect engineering based on a thermal treatment of graphite in CO2 is an effective method to improve the fast-charging capability of the graphite anode. The activated graphite (AG) exhibits a superior rate capability of 209 mAh g-1 at 10 C (in comparison to 15 mAh g-1 for the pristine graphite), which is attributed to a pseudocapacitive lithium storage behavior. Furthermore, the full cell LiFePO4||AG can achieve SOCs of 82% and 96% within 6 and 15 min, respectively. The intrinsic carbon defect introduced by the CO2 treatment succeeds in improving the kinetics of lithium ion intercalation at the rate-determining step during lithiation, which is identified by the distribution of relaxation times (DRT) and density functional theory (DFT) calculations. Therefore, this study provides a novel strategy for fast-charging LIBs. Moreover, this facile method is also suitable for activating other carbon-based materials.

Durable Fast Charging of Lithium-Ion Batteries Based on Simulations with an Electrode Equivalent Circuit Model

Fast charging of lithium-ion batteries is often related to accelerated cell degradation due to lithium-plating on the negative electrode. In this contribution, an advanced electrode equivalent circuit model is used in order to simulate fast-charging strategies without lithium-plating. A novel parameterization approach based on 3-electrode cell measurements is developed, which enables precise simulation fidelity. An optimized fast-charging strategy without evoking lithium-plating was simulated that lasted about 29 min for a 0–80% state of charge. This variable current strategy was compared in experiments to a conventional constant-current–constant-voltage fast-charging strategy that lasted 20 min. The experiments showed that the optimized strategy prevented lithium-plating and led to a 2% capacity fade every 100 fast-charging cycles. In contrast, the conventional strategy led to lithium-plating, about 20% capacity fade after 100 fast-charging cycles and the fast-charging duration extended from 20 min to over 30 min due to increased cell resistances. The duration of the optimized fast charging was constant at 29 min, even after 300 cycles. The developed methods are suitable to be applied for any given lithium-ion battery configuration in order to determine the maximum fast-charging capability while ensuring safe and durable cycling conditions.

Intrinsic electrochemical activity of Ni in Ni3Sn4 anode accommodating high capacity and mechanical stability for fast-charging lithium-ion batteries

Fast interfacial kinetics derived from bicontinuous three-dimensional (3D) architecture is a strategic feature for achieving fast-charging lithium-ion batteries (LIBs). One of the main reasons is its large active surface and short diffusion path. Yet, understanding of unusual electrochemical properties still remain great challenge due to its complexity. In this study, we proposed a nickel–tin compound (Ni3Sn4) supported by 3D Nickel scaffolds as main frame because the Ni3Sn4 clearly offers a higher reversible capacity and stable cycling performance than bare tin (Sn). In order to verify the role of Ni, atomic-scale simulation based on density functional theory systematically addressed to the reaction mechanism and structural evolution of Ni3Sn4 during the lithiation process. Our findings are that Ni enables Ni3Sn4 to possess higher mechanical stability in terms of reactive flow stress, subsequently lead to improve Li storage capability. This study elucidates an understanding of the lithiation mechanism of Ni3Sn4 and provides a new perspective for the design of high-capacity and high-power 3D anodes for fast-charging LIBs.

Crystallographic engineering to reduce diffusion barrier for enhanced intercalation pseudocapacitance of TiNb2O7 in fast-charging batteries

Improving the ion/electron transport of TiNb2O7 composite is of great significance for achieving fast-charging lithium-ion batteries. Herein, we firstly report a rare-earth element engineering to tailor the bandgap and crystallographic structure for the dual function of electronic and ionic conductivity. Tb-doped TiNb2O7 (denoted as Tbx-TNO, x=0, 0.005, 0.010, 0.015) are successfully fabricated through a one-step solid-state reaction strategy. The Rietveld refinement technology of X-ray diffraction (XRD) demonstrates an effective substitution of Tb in the central sites of Nb-O octahedral. Significantly, in-situ XRD and ex-situ TEM techniques reveal the positive influence of Tb doping on the underlying ion transport behavior, which is verified by the increased unit cell volume, decreased mechanic effects, and promoted Li+-diffusion kinetics. DFT calculations demonstrate a narrow down of bandgap (from insulators to semiconductors) and reduction of ion-diffusion barrier in various migration modes, which lead to substantially enhanced ion/electron conductivities of Tb-TiNb2O7 microrod. Benefiting from the structural merits, the Tb0.01-TiNb2O7 presented outstanding rate capability (a reversible capacity of 192.8 mA h g−1 at 50 C) and an impressive cycle lifespan, corresponding to an ultra-high retention ratio of 98.9% (203.2 mA h g−1) over 1000 cycles. A pouch cell based on LiNi0.8Co0.1Mn0.1O2 cathodes and the Tb0.01-TiNb2O7 anodes exhibits potential application with superior rate capability and cycling stability. This work provides a simple strategy to enhance the rate-performance of TiNb2O7, making a guideline to construct fast-charging batteries with long cycling life.

Potentiometric entropy and operando calorimetric measurements reveal fast charging mechanisms in PNb9O25

The Wadsley–Roth compound PNb9O25 is a promising fast charging lithium ion battery anode material with high operating voltage to prevent solid electrolyte interface formation. Here, we present potentiometric entropy measurements featuring signatures of semiconductor-to-metal transition and intralayer ordering upon lithiation in the anode material PNb9O25 that could not be observed with in situ X-ray diffraction. In addition, the instantaneous heat generation rates at the PNb9O25 working electrode and at the lithium metal counter electrode during galvanostatic cycling were measured individually for the first time by operando isothermal calorimetry. The heat generation rate decreased at the PNb9O25 electrode upon lithiation due to the decrease in electrical resistivity caused by the semiconductor-to-metal transition observed in potentiometric entropy measurements. Furthermore, the heat generation rate at the lithium metal electrode was positive during delithiation due to the exothermic plating of Li+ ions on the lithium metal counter electrode associated with dendrite formation. Furthermore, calorimetric measurements established that the entropy change dominated the reversible heat generation rate at each electrode. Finally, the contribution of enthalpy of mixing was relatively small even at high C-rates thanks to the high Li+ ion mobility in Pnb9O25 confirming its promises as a fast charging anode material.

Interplay of Electrode Heterogeneity and Lithium Plating

Lateral microstructure heterogeneity in anodes is known to induce nonuniform current density, state of charge, and lithium plating. This means that such electrode heterogeneity can limit the fast charging of lithium-ion batteries. In this work, a combination of experiments and simulation is employed to understand the effect of mm scale lateral heterogeneity on cell aging. A previously developed model was extended to efficiently simulate SEI formation and Li plating for independent regions of an electrode. The model consists of three parallel regions each described under a P2D framework and with a distinct ionic resistance and possibly active material loading. The results suggest that during fast charge when the active material is uniformly distributed across the three regions, the region with the highest resistance reaches the end of life sooner than the other regions. There is also positive feedback from Li metal filling the pores near the separator interface that further accelerates lithium plating. Finally, when there is a non-uniform active material distribution associated with the ionic resistance heterogeneity, tight competition between regions can occur, leading to less overall lithium plating and plating that is more uniform between regions.

Research progress on electrolytes for fast-charging lithium-ion batteries

Fast-charging is considered to be a key factor in the successful expansion and use of electric vehicles. Current lithium-ion batteries (LIBs) exhibit high energy density, enabling them to be used in electric vehicles (EVs) over long distances, but they take too long to charge. In addition to modifying the electrode and battery structure, the composition of the electrolyte also affects the fast-charging capability of LIBs. This review provides a comprehensive and in-depth overview of the research progress, basic mechanism, scientific challenges and design strategies of the new fast-charging solution system, focusing on the influences that the compositions of liquid and solid electrolytes have on the fast-charging performance of LIBs. Finally, new insights, promising directions and potential solutions for the electrolytes of fast-charging systems are proposed to stimulate further research on revolutionary next-generation fast-charging LIB chemistry.

Multimodal quantification of degradation pathways during extreme fast charging of lithium-ion batteries

Using a unique combination of advanced characterization techniques, we identify specific degradation mechanisms and quantify degradative species formed during fast charge cycling of lithium-ion battery pouch cells.

Constrained Bayesian Optimization for Minimum-Time Charging of Lithium-Ion Batteries

The fast charging of lithium-ion batteries while minimizing battery degradation is a key challenge to battery community. Difficulties in this optimization are the high dimensionality of parameter space of charging strategies, significant variability between batteries (even from the same production line), and limited quantitative information on battery degradation mechanisms. Current approaches to addressing these challenges are model-based optimization and grid search. Model-based methods are limited by the insufficient complexity and accuracy of electrochemical models – especially in the early stage of development when a new battery chemistry is being introduced to the market – and grid search methods are expensive in terms of testing time and cells. This article proposes a data-driven Bayesian optimization (BO) approach for minimum charging time problem, in which an acquisition function of constrained expected improvement is employed to explicitly handle constraints that limit degradation. In addition, continuous-varied-current charging protocols are introduced into the proposed BO approach by utilizing the technique of polynomial function expansions. The effectiveness of the proposed approach is demonstrated on the LIONSIMBA, a porous electrode theory-based battery simulator. The simulation results show that the proposed BO-based charging approach with continuous current profile outperforms the commonly used constant current constant voltage (CC-CV) method for the minimum charging time problem. Moreover, the decrease in the minimum charging time and increase in its variance with increasing number of degrees of freedom used in charging protocols is also quantified.

Towards the Intercalation and Lithium Plating Mechanism for High Safety and Fast-Charging Lithium-ion Batteries: A Review

The ever-increasing demand of portable electronics and electric vehicles has consistently promoted the development of lithium-ion batteries (LIBs) in the direction of higher energy density, higher safety, and faster charging. However, present high-energy LIBs are insufficient to sustain extra-fast power input without adverse consequences, which is mainly affected by the lithium (Li) plating on graphite electrode. The goal of this review is to enable graphite anode to support higher current and improve safety by ameliorating undesired Li plating from fundamentals and detections. Hence, the interaction, containing solid electrolyte interphase formation, Li+ intercalation/plating behavior, between graphite and Li+ be discussed in depth. Besides, the cognitive process of Li+ intercalation/plating kinetics as well as the inner mechanisms of Li plating especially in 3 extreme conditions (high state-of-charge, high charging-rate, and low temperature) are highly desirable to investigate Li plating comprehensively. Meanwhile, issues induced by Li plating, detection methods of Li deposition and knowledge gaps are identified for the follow-up research directions of Li plating in LIBs.

Synchronous Manipulation of Ion and Electron Transfer in Wadsley-Roth Phase Ti-Nb Oxides for Fast-Charging Lithium-Ion Batteries.

Implementing fast‐charging lithium‐ion batteries (LIBs) is severely hindered by the issues of Li plating and poor rate capability for conventional graphite anode. Wadsley–Roth phase TiNb2O7 is regarded as a promising anode candidate to satisfy the requirements of fast‐charging LIBs. However, the unsatisfactory electrochemical kinetics resulting from sluggish ion and electron transfer still limit its wide applications. Herein, an effective strategy is proposed to synchronously improve the ion and electron transfer of TiNb2O7 by incorporation of oxygen vacancy and N‐doped graphene matrix (TNO− x @N‐G), which is designed by combination of solution‐combustion and electrostatic self‐assembly approach. Theoretical calculations demonstrate that Li+ intercalation gives rise to the semi‐metallic characteristics of lithiated phases (Li y TNO− x ), leading to the self‐accelerated electron transport. Moreover, in situ X‐ray diffraction and Raman measurements reveal the highly reversible structural evolution of the TNO− x @N‐G during cycling. Consequently, the TNO− x @N‐G delivers a higher reversible capacity of 199.0 mAh g−1 and a higher capacity retention of 86.5% than those of pristine TNO (155.8 mAh g−1, 59.4%) at 10 C after 2000 cycles. Importantly, various electrochemical devices including lithium‐ion full battery and hybrid lithium‐ion capacitor by using the TNO− x @N‐G anode exhibit excellent rate capability and cycling stability, verifying its potential in practical applications.

Beneficial Effects of Three-Dimensional Structured Electrodes for the Fast Charging of Lithium-Ion Batteries

Beneficial Effects of Three-Dimensional Structured Electrodes for the Fast Charging of Lithium-Ion Batteries

Photochemically driven solid electrolyte interphase for extremely fast-charging lithium-ion batteries

Extremely fast charging (i.e. 80% of storage capacity within 15 min) is a pressing requirement for current lithium-ion battery technology and also affects the planning of charging infrastructure. Accelerating lithium ion transport through the solid-electrolyte interphase (SEI) is a major obstacle in boosting charging rate; in turn, limited kinetics at the SEI layer negatively affect the cycle life and battery safety as a result of lithium metal plating on the electrode surface. Here, we report a γ-ray-driven SEI layer that allows a battery cell to be charged to 80% capacity in 10.8 min as determined for a graphite full-cell with a capacity of 2.6 mAh cm−2. This exceptional charging performance is attributed to the lithium fluoride-rich SEI induced by salt-dominant decomposition via γ-ray irradiation. This study highlights the potential of non-electrochemical approaches to adjust the SEI composition toward fast charging and long-term stability, two parameters that are difficult to improve simultaneously in typical electrochemical processes owing to the trade-off relation.