Cycles For Lithium-ion Batteries Research Articles

Revealing the Thermodynamic Mechanism of Phase Transition Induced by Activation Polarization in Lithium-Ion Batteries.

Enhancing the phase transition reversibility of electrode materials is an effective strategy to alleviate capacity degradation in the cycling of lithium-ion batteries (LIBs). However, a comprehensive understanding of phase transitions under microscopic electrode dynamics is still lacking. In this paper, the activation polarization is quantified as the potential difference between the applied potential (Uabs) and the zero-charge potential (ZCP) of electrode materials. The polarization potential difference facilitates the phase transition by driving Li-ion adsorption and supplying an electron-rich environment. A novel thermodynamic phase diagram is constructed to characterize the phase transition of the example MoS2 under various Li-ion concentrations and operating voltages using the grand canonic fixed-potential method (FPM). At thermodynamic quasi-equilibrium, the ZCP is close to the Uabs, and thus is used to form the discharge curve in the phase diagram. The voltage plateau is observed within the phase transition region in the simulation, which will disappear as the phase transition reversibility is impaired. The obtained discharge curve and phase transition concentration both closely match the experimental results. Overall, the study provides a theoretical understanding of how polarization affects phase evolution in electrode dynamics, which may provide a guideline to improve battery safety and cycle life.

A Thermal Tanks-in-Series Model for Simulating over-Discharge Cycling in Lithium-Ion Batteries

Energy storage will play a crucial role in the transition to clean and renewable sources of energy production to meet future consumption demands.1 Lithium-ion (Li-ion) batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities for applications like electric vehicles and grid storage.2 Li-ion batteries for high voltage operations, where several cells are connected in series, can experience inadvertent over-discharge due to differences between cells3,4. These differences can arise due to many reasons including changes in internal resistance and deviation in electrochemical degradation that can cause divergence of cell open circuit potentials. Over-discharge is a condition when the manufacturer recommended lower voltage limit is crossed while discharging4, which results in various side effects such as electrolyte decomposition, capacity degradation, cathode morphology change and possible internal short circuit3,5. Increase in anode potential during over-discharge leads to copper dissolution from the anode current collector and subsequent plating within cell components. The Solid Electrolyte Interface (SEI) can decompose during excessive deintercalation and reform during charging, reducing the lithium inventory. Excessive heat generation during cycle life testing after occurrences of over-discharges has been found in some cases to lead to temperatures >150 °C6,7.Temperature plays a key role in the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. A physics-based modeling approach coupled with a thermal model can be employed to understand the effect of over-discharge on the electrochemical behavior of Li-ion batteries and provides insights into the interplay of various degradation mechanisms that cause capacity fade.The Thermal Tank-In-Series9,10(TTiS) model is a systematically volume-averaged form of the standard pseudo-2-dimensional (p2D)11 model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy, as it is sensitive to changes in the battery’s state of charge (SOC) and cell temperature, which helps predict the overpotential changes to the cell electrodes and thermodynamics.We use the TTiS model to identify the dominant fade mechanisms in 3 sets of experimental cycling and temperature data for the: i) normal operating window (2.5V – 4.2V), ii) 5 initial cycles of over-discharge (1.5V – 4.2V) followed by normal operation until 20% capacity fade and iii) 5 cycles of periodic over-discharge every 20 cycles, until 20% capacity fade. Analysis on the effect of C-rate, ambient temperature and voltage window of operation will facilitate understanding the temperature behavior and overpotentials in a cell sandwich. Key considerations required in extending a model to simulate over-discharge will also be examined. References S.P. S. Badwal, S. S. Giddey, C. Munnings, A. I. Bhatt, and A. F. Hollenkamp, Frontiers in Chemistry, 2, 28 (2014).G. Pistoia. Lithium-Ion Batteries: Advances and Applications. First ed. Elsevier, Amsterdam (2014).R. Guo, L. Lu., M. Ouyang, X. Feng. Sci Rep 6, 30248 (2016).G.Zhang, X. Wei, S. Chen, J. Zhu, G. Han, and H. Dai. J. Power Sources, 521, 230990. (2022).C. Fear, D. Juarez-Robles, J. A. Jeevarajan, and P. P. Mukherjee, J. Electrochem. Soc., 165, A1639–A1647 (2018).D. Juarez-Robles, Purdue Univ. Ph.D. Thesis (2019).H. Maleki and J. N. Howard, J. Power Sources, 160, 1395–1402 (2006).H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017).A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020).A. Subramaniam, S. Kolluri, C. D. Parke, M. Pathak, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 013534 (2020).M. Doyle, T. F. Fuller, and J. Newman, J. Electrochem. Soc., 140, 1526 (1993)

Stable Hydroborate Solid-State Lithium Battery with High-Voltage NMC811 Cathode

Hydroborate solid electrolytes offer high ionic conductivity and are stable in contact with alkali metal anodes, but are challenging to integrate into batteries with high-voltage cathodes [1-3]. Here, we demonstrate stable dis-/charge cycling of solid-state lithium-ion batteries combining a Li3(CB11H12)2(CB9H10) hydroborate electrolyte with a 4 V-class LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, exploiting the enhanced kinetic stability of the LiCB11H12-rich and LiCB9H10-poor electrolyte composition [4]. Cells with lithium metal and indium/lithium anodes achieve a discharge capacity at C/10 of ~145 mAh g–1 at room temperature and ~175 mAh g–1 at 60 °C. Indium/lithium cells retain 98% of their initial discharge capacity after 100 cycles at C/5 and 70% after 1000 cycles at C/2. Capacity retention of 97% after 100 cycles at C/5 and 75% after 350 cycles at C/2 is also achieved with a graphite anode without any excess lithium. The energy density per cathode composite weight of 460 Wh kg–1 is on par with the best solid-state batteries reported to date.[1] L. Duchêne, A. Remhof, H. Hagemann, D. Battaglia, Energy Storage Materials, 2020, 225, 782[2] L. Duchêne, R.-S. Kühnel, E. Stilp, E. Cuervo Reyes, A. Remhof, H. Hagemann, C. Battaglia, Energy & Environ. Science, 2017, 10, 2609[3] R. Asakura, D. Reber, L. Duchêne, S. Payandeh, A. Remhof, H. Hagemann, C. Battaglia, Energy & Environ. Science, 2020, 13, 5048[4] H. Braun, Ryo Asakura, A. Remhof, C. Battaglia, ACS Energy Lett. in press

Nonsolvating Fluoroaromatic Cosolvent Enabled Long-Term Cycling of High-Voltage Lithium-Ion Batteries with Organosulfur Electrolytes.

The structure-activity relationships of nonsolvating cosolvents for organosulfur-based electrolyte systems were revealed. The performance of nonsolvating dilutant fluorobenzene (FB) was compared to various fluorinated ether dilutants in high-voltage electrolytes containing a concentration of 1.2 M LiPF6 dissolved in fluoroethylene carbonate (FEC), ethyl methyl sulfone (EMS), and the dilutant. In a high-voltage and high-loading LiNi0.8Mn0.1Co0.1O2 (NMC811) full cell configuration, the organosulfur-based electrolyte containing FB dilutant enabled superior electrochemical performance compared to the electrolytes using other nonsolvating fluorinated ether formulations. Moreover, the FB-containing electrolyte exhibited the highest ionic conductivity and lowest viscosity among all organosulfur-based electrolytes containing nonsolvating dilutant. These improvements are attributed to the enhanced physical properties of electrolyte and lithium-ion mobility. Furthermore, by employing first-principles simulations, the observed suppression of side reactions at high voltage is linked to FB's lower reactivity toward singlet dioxygen, which is likely produced at the NMC interface. Overall, FB is considered an excellent diluent that does not impede cell operation by mass decomposition at the cathode.

Adding CNTs into Anthracite towards High Performance Anode Materials for Lithium Ion Batteries

AbstractCommercial graphite anodes face the problems of high preparation temperature and limited specific capacity in lithium‐ion batteries (LIBs). Amorphous carbon anode materials are prepared at low temperatures and have abundant sources and modes of preparation. As a low‐cost carbon source material, anthracite has a practical application value in storing lithium as anode electrodes of LIBs. However, the capacity is not enough to meet the present increasing demand. We added CNTs to enhance the performance of anthracite‐based carbon anodes. The addition of CNTs significantly improves the electrical properties of amorphous carbon anode materials due to their good electronic conductivity. This anthracite‐based carbon with CNTs (A−C) anode displays a specific cycling capacity of 360 mAh ⋅ g−1 at the current density of 200 mA ⋅ g−1 after 200 cycles in LIBs. We believe that the work has far‐reaching significance for improving the practicability of amorphous carbon anode materials.

A practical semi-empirical model for predicting the SoH of lithium-ion battery: A novel perspective on short-term rest

In this paper, the semi-empirical battery degradation prediction model proposed considers electrochemical degradation characteristics and represents degradation effects under various conditions, including different states of charge (SoC) areas. This model is specifically designed to address degradation during cycling and short-term rest periods in lithium-ion batteries using liquid electrolytes. Cycle aging incorporates the impact of solid electrolyte interphase (SEI) growth, a known dominant factor, and the model for short-term resting periods captures potential aging impacts on subsequent cycles due to internal material concentration gradients, moving away from the traditionally used calendar life approach. The derivation of the model presented in this paper is based on 14 data sets under different SoC conditions and 8 data sets under various Crates, explaining the degradation effects at 10 % SoC intervals and three different Crate points. Moreover, the model's performance was validated through capacity prediction for two data sets experimented with dynamic operational schedules of actual energy storage systems (ESS), including various conditions. The results showed a root mean square error (RMSE) of 0.564 and a mean absolute percentage error (MAPE) of 0.346. The superiority of this model is demonstrated by comparing its performance with four other types of degradation models derived through the same process in the validation data.

Experimental assessment of high-energy high nickel-content NMC lithium-ion battery cycle life at cold temperatures

An essential element for the diffusion and environmental impact assessment of electrochemical storage systems is their lifetime. This lifetime also impacts the overall cost of the equipment in which the storage system is used. At the same time, a number of applications, e.g. electric vehicles, do not allow a temperature control of the batteries, although the performances of the latter are very strongly linked to them. The phenomena investigated, such as aging, behavior at low temperature and rapid charge for low temperature, are complex and difficult to model. Only the establishment of databases representative of the conditions of use can lead to elements of response. The exploitation of these databases by artificial intelligence tools is certainly relevant but requires a learning on data representative of the conditions of use and of the phenomena to be evaluated.The work presented in this paper is in this context and is intended to model the influence of the rapid charge at low temperature (0 °C, −10 °C, −20 °C) on the lifetime (initial capacity loss) of lithium-Ion NMC elements. The problem with data-based approaches is the large number of tests required and the development in relevant experimental designs. Faced to this challenge, a consortium of French laboratories and manufacturers has been working together since the 2000s to carry out this type of work. The paper proposes to present a test campaign and summarizes the main results to assess the service life (loss of capacity) for a fast-charging application at low temperature and position them against the manufacturer data established at 25 °C. The impact of two partial discharge processes (50 %) will also be assessed. In a last part, we show that for low temperatures, even for the nominal charge current the life time is reduced to few dozens of cycles and a mechanical destruction of the cell with no activation of the current interrupt device is achieved. This study demonstrates and quantifies the very important impact of low-temperature charging processes on the lifetime of high energy lithium-ion NMC batteries.

Lithium Plating at the Cell Edge Induced by Anode Overhang during Cycling in Lithium-Ion Batteries: Part I. Modeling and Mechanism

The anode overhang is usually cited to prevent lithium plating at the cell edges of lithium-ion batteries. Still, numerous reports in the literature show lithium plating at the cell edge, which is typically referred to as edge plating. Edge plating is often attributed to inhomogeneous lithium distribution, thermal gradients, or pressure-dependent effects. This work presents an easy-to-implement two-dimensional electrochemical model demonstrating inhomogeneous lithiation induced by the anode overhang, which can explain experimentally observed edge plating. First, the mechanism of inhomogeneous lithiation due to the anode overhang is explained in detail. Then, a parameter study on charge protocol and geometric cell properties is presented, and the implications for cell applications are analyzed. Finally, the findings are discussed and put into a broader perspective of cell design, manufacturing, and fast charging application. In Part II of this work, the simulation is validated experimentally using multi-reference electrode single-layer pouch cells.

An Ultralow-concentration and Moisture-resistant Electrolyte of Lithium Difluoro(oxalato)borate in Carbonate Solvents for Stable Cycling in Practical Lithium-ion Batteries.

The electrolyte concentration not only impacts the battery performance but also affects the battery cost and manufacturing. Currently, most studies focus on high-concentration (>3 M) or localized high-concentration electrolytes (~1 M); however, the expensive lithium salt imposes a major concern. Most recently, ultralow concentration electrolytes (<0.3 M) have emerged as intriguing alternatives for battery applications, which feature low cost, low viscosity, and extreme-temperature operation. However, at such an early development stage, many works are urgently needed to further understand the electrolyte properties. Herein, we introduce an ultralow concentration electrolyte of 2 wt % (0.16 M) lithium difluoro(oxalato)borate (LiDFOB) in standard carbonate solvents. This electrolyte exhibits a record-low salt/solvent mass ratio reported to date, thus pointing to a superior low cost. Furthermore, this electrolyte is highly compatible with commercial Li-ion materials, forming stable and inorganic-rich interphases on the lithium cobalt oxide (LiCoO2) cathode and graphite anode. Consequently, the LiCoO2-graphite full cell demonstrates excellent cycling performance. Besides, this electrolyte is moisture-resistant and effectively suppresses the generation of hydrogen fluoride, which will markedly facilitate the battery assembly and recycling process under ambient conditions.

Unveiling voltage evolution during Li plating-relaxation-Li stripping cycling of lithium-ion batteries

The unwanted Li plating on graphite anode surface in lithium-ion batteries causes poor cycling performance along with raised safety risk once Li dendrites penetrate separator. Voltage characteristics during relaxation and discharging have been recognized as the most direct and convenient indictor for Li plating detection, where unveiling voltage evolution during plating-relaxation-stripping cycling needs to be emphasized to facilitate Li plating detection. This study fabricates Li|graphite cells to implement Li plating-relaxation-stripping protocols through over-lithiation before internal short circuit, and the Li nucleation-growth process is linked to voltage evolution assisting with the post-mortem approaches. The Li plating voltage initially displays continuous decline indicated as Li nucleation, until the formation of Li plating plateau indicated as Li growth. The plating-relaxation-stripping voltage patterns show highly correlation that the occurrence of Li plating plateau exactly corresponds to the appearance of a mixed relaxation plateau attributed to the equilibrium of Li stripping and Li re-intercalation into graphite, while the disappearance of the mixed relaxation plateau just corresponds to the advent of Li stripping plateau. Three stages are finally divided associated with characteristic Li plating -relaxation-stripping voltage patterns, where Stage I indicates the occurrence of Li plating plateau behaving as predominant LixC6; Stage II is characterized as the occurrence of mixed relaxation plateau manifested as Li coexisting with LixC6; Stage III is distinguished by the appearance of Li stripping plateau indicated as predominant Li and dead Li. This work proposes underlying evolution mechanism of Li plating-relaxation-stripping cycling, which contributes to sufficient evidence for reliable Li plating detection.

Trifluoromethylated Lithium Borates as Electrolyte Salts for High‐Energy‐Density Lithium‐Ion Batteries with High‐Voltage LiNi0.5Mn1.5O4 Positive Electrodes

AbstractLiNi0.5Mn1.5O4 (LNMO) is a promising positive electrode material for high‐energy‐density lithium‐ion batteries (LIBs) because of its high working voltage; however, its practical application is hindered by the insufficient oxidation resistance of LIB electrolytes. In this study, we aimed to address this issue by evaluating two trifluoromethylated lithium borate compounds lithium difluoro (perfluoropinacolato) borate (PFP‐F2) and lithium difluoro(2‐hydroxy‐3,3,3,3′,3′,3′‐hexafluoroisobutylato) borate (HHIB‐F2) as electrolyte salts for high‐potential LIBs (4.8 V vs. Li/Li+) with LNMO positive electrodes. In full‐cell tests, the cyclability of LIBs containing these salts is superior (60 °C) to that of the cell with lithium tetrafluoroborate (LiBF4) as the reference electrolyte salt, which is ascribed to the formation of a positive electrode passivation layer that inhibits the oxidative decomposition of the electrolyte salt and solvent in the former case. Moreover, the oxidative decomposition of trifluoromethylated borates at 4.8 V affords a passivation layer on the negative electrode. Thus, the examined borates hold great promise for the commercialization of high‐energy‐density LNMO‐based LIBs, and the formation of a solid electrolyte interphase (SEI) at the negative electrode resulting from the oxidative decomposition products of electrolyte salts is a promising new way to enhance the performance of high‐potential positive electrode LIBs beyond existing levels.

Stable cycling and low-temperature operation utilizing amorphous carbon-coated graphite anodes for lithium-ion batteries.

With the continuous expansion of the lithium-ion battery market, addressing the critical issues of stable cycling and low-temperature operation of lithium-ion batteries (LIBs) has become an urgent necessity. The high anisotropy and poor kinetics of pristine graphite in LIBs contribute to the formation of precipitated lithium dendrites, especially during rapid charging or low-temperature operation. In this study, we design a graphite coated with amorphous carbon (GC) through the Chemical Vapor Deposition (CVD) method. The coated carbon layer at the graphite interface exhibits enhanced reaction kinetics and expanded lithium-ion diffusion pathways, thereby reduction in polarization effectively alleviates the risk of lithium precipitation during rapid charging and low-temperature operation. The pouch cell incorporating GC‖LiCoO2 exhibits exceptional durability, retaining 87% of its capacity even after 1200 cycles at a high charge/discharge rate of 5C/5C. Remarkably, at -20 °C, the GC-2 maintains a specific capacity of 163 mA h g-1 at 0.5C, higher than that of pristine graphite (65 mA h g-1). Even at -40 °C, the GC-2‖LiCoO2 pouch cell still shows excellent capacity retention. This design realizes the practical application of graphite anode in extreme environments, and have a promising prospect of application.

Fluoride scavengeable Sb2O3-functionalized poly(imide) separators for prolonged cycling of lithium-ion batteries.

Nanosize-controlled antimony oxides (Sb2O3) that can effectively scavenge fluoride species in a cell are incorporated into a PI separator to regulate its porous structure. The incorporation of the Sb2O3 layer onto the PI separator surface prevents the internal short circuit and efficiently removes fluoride species via chemical scavenging reactions, thereby resulting in stable cycling behaviors upon cycling.

Rapid Test and Assessment of Lithium-ion Battery Cycle Life Based on Transfer Learning

Rapid Test and Assessment of Lithium-ion Battery Cycle Life Based on Transfer Learning

Speciation of Transition Metal Dissolution in Electrolyte from Common Cathode Materials

Significant capacity loss has been observed across extended cycling of lithium-ion batteries to high temperatures and high voltages. This occurs due to transition metal dissolution from the high voltage spinel or layered oxide cathode material, ion migration through the electrolyte, and deposition on the solid-electrolyte interphase (SEI) on the anode. While much research has been done to track the oxidation state of the transition metal in the cathode material or deposited on the anode, there have been mixed reports on the chemical state of the transition metal ions dissolved in the electrolyte depending on the type of cathode used. X-ray absorption near edge spectroscopy (XANES) was performed on electrolytes extracted from full cells built with four different cathode materials that were cycled at either high or standard voltages to determine the chemical state of Mn and Ni in solution. Inductively coupled plasma-mass spectrometry (ICP-MS) was performed on the anodes from these cells to determine the concentration of deposited metal ions.

Significance of electrolyte additive molecule structure in stabilizing interphase in LiNi0.8Co0.1Mn0.1O2/artificial graphite pouch cells at high temperature

Electrolyte additives are pivotal for stable cycling of rechargeable lithium ion batteries (LIBs), which dictate the creation of the protective interphases on electrodes. Many additives have been proposed but less knowledge is available on the relationship between their molecular structure and interphase stability. This research compares three electrolyte additives with systematic changes in their cyclic ethylene sulfate structures, i.e. 1,3,2−dioxathiolane−2,2−dioxide (DTD), 4−methyl−1,3,2−dioxathiolane−2,2− dioxide (MDTD) and 4−propyl−[1,3,2] dioxathiolane−2,2−dioxide (PDTD) to investigate their effects on the performance of LiNi0.8Co0.1Mn0.1O2/artificial graphite lithium ion pouch cells at high temperature. Comprehensive characterizations reveal that all these additives exhibit similar oxidative and reductive activity, but they lead to diverse long−term cycling performance at 55 °C. The sulfate species derived from the propyl functionalized PDTD form the most effective cathode and anode interphases in preventing electrolyte decomposition and improving cycling capabilities, with capacity retention of 85 % after 900 cycles at 55 °C. Meanwhile, a super stable (3000 cycles), high−capacity (1668 mAh) pouch cell is constructed at 25 °C. This work paves a road to design electrolyte additive more efficiently for high−energy−density LIBs at elevated temperature.

Speciation of Transition Metal Dissolution in Electrolyte from Common Cathode Materials.

Significant capacity loss has been observed across extended cycling of lithium-ion batteries cycled to high potential. One of the sources of capacity fade is transition metal dissolution from the cathode active material, ion migration through the electrolyte, and deposition on the solid-electrolyte interphase on the anode. While much research has been conducted on the oxidation state of the transition metal in the cathode active material or deposited on the anode, there have been limited investigations of the oxidation state of the transition metal ions dissolved in the electrolyte. In this work, X-ray absorption spectroscopy has been performed on electrolytes extracted from cells built with four different cathode active materials (LiMn2 O4 (LMO), LiNi0.5 Mn1.5 O4 (LNMO), LiNi0.8 Mn0.1 Co0.1 O2 (NMC811), and (x Li2 MnO3 *(1-x) LiNia Mnb Coc O2 , with a+b+c=1) (LMRNMC)) that were cycled at either high or standard potentials to determine the oxidation state of Mn and Ni in solution. Inductively coupled plasma-mass spectrometry has been performed on the anodes from these cells to determine the concentration of deposited transition metal ions. While transition metal ions were found dissolved in all electrolytes, the oxidation state(s) of Mn and Ni were determined to be dependent on the cathode material and independent of cycling potential.

Interfacial Engineering of MoS2/V2O3@C-rGO Composites with Pseudocapacitance-Enhanced Li/Na-Ion Storage Kinetics.

Molybdenum sulfide has been widely investigated as a prospective anode material for Li+/Na+ storage because of its unique layered structure and high theoretical capacity. However, the enormous volume variation and poor conductivity limit the development of molybdenum sulfide. The rational design of a heterogeneous interface is of great importance to improve the structure stability and electrical conductivity of electrode materials. Herein, a high-temperature mixing method is implemented in the hydrothermal process to synthesize the hybrid structure of MoS2/V2O3@carbon-graphene (MoS2/V2O3@C-rGO). The MoS2/V2O3@C-rGO composites exhibit superior Li+/Na+ storage performance due to the construction of the interface between the MoS2 and V2O3 components and the introduction of carbon materials, delivering a prominent reversible capacity of 564 mAh g-1 at 1 A g-1 after 600 cycles for lithium-ion batteries and 376.3 mAh g-1 at 1 A g-1 after 450 cycles for sodium-ion batteries. Theoretical calculations confirm that the construction of the interface between the MoS2 and V2O3 components can accelerate the reaction kinetics and enhance the charge-ionic transport of molybdenum sulfide. The results illustrate that interfacial engineering may be an effective guide to obtain high-performance electrode materials for Li+/Na+ storage.

Study of temperature cycling of commercial rechargeable lithium-ion batteries

Lithium-ion batteries, a popular electric energy storage device, have high energy density and impressive working performance. However, the temperature affects its life cycle, capacity, and performance. Different effects are generated inside the battery for the different temperature conditions. It is necessary to study their thermal and electric characteristics in various thermal conditions since electric energy storage devices are used in various applications at low or high temperatures. In this study, the experimental analysis was performed to observe how a battery cell behaves above room temperature for a different 18650 cylindrical battery cell with a capacity of 5200 mAh. The testing temperature for this experiment was at 28˚C, 50˚C, 60˚C, 70˚C, and 100˚C. It is noted that the capacity of the battery cell fades drastically at high temperatures compared to low temperatures due to internal short circuits occurring at high temperatures.

Hollow sea urchin-like microspheres of the dual transition metal oxides NiO/Co3O4 immobilized on rGO enhance lithium-ion battery cycling and rate performance

The serious volume expansion and unsatisfying electronic conductivity during charge/discharge of transition metal oxides with relatively high capacity and low cost have limited their development as anode materials for lithium-ion batteries (LIBs). Herein, elaborately designed dual transition metal oxides NiO/Co3O4 immobilized on reduced graphene oxide (NiO/Co3O4 @rGO) with unique hollow sea urchin-like microspheres are employed as a modulated material for satisfying structural integrity and high capacity. On the one hand, the radioactive spines outside of sea urchin material inhibit its’ agglomeration, enlarge surface area for electrolyte infiltration, and shorten the Li+ transport path during the lithiation/delithiation process, but they also alleviate the side effects caused by volume change during cycling. On the other hand, rGO, with its good electronic conductivity and flexibility, provides physical protection for the material structure. Thanks to these merits, the NiO/Co3O4 @rGO anode exhibited a remarkable reversible discharge (1845 mAh g−1 upon 100 cycles at 0.1 A g−1), outstanding rate capacity, and desirable cycling stability (1252 mAh g−1 up to 400 cycles at 1 A g−1) in LIBs, demonstrating the enormous potential of NiO/Co3O4 @rGO for feasible synthesis, high performance, and inexpensive LIBs.