Large-capacity Lithium-ion Battery Research Articles

Construction of in situ C/N/S co-doped mesoporous Li4Ti5O12 nanosheets for high-rate and large-capacity lithium-ion batteries

The low capacity of Li4Ti5O12 (LTO) under high-rate charging/discharging limits its development in energy applications. Two-dimensional (2D) nanosheets equipped with mesopores offer promising opportunities to realize high-rate and long-term lithium-ion batteries. This paper successfully synthesized C/N/S co-doped lithium titanate nanosheets with rich oxygen vacancy concentration (CNSLTO) in a single step. C, N and S are doped into the LTO bulk phase, providing bulk oxygen vacancies and active sites. Partial Ti4+ conversion to Ti3+ is promoted by co-doping and introducing rich oxygen vacancies, improving the electrical conductivity. In addition, the effect of CTAB concentration on the morphology and electrochemical properties of the materials was studied experimentally. The optimized CNSLTO nanosheets have a relatively high specific surface area (99.38 m2 g−1) and numerous mesoporous, achieving outstanding performance and excellent cycling stability at high-rate as lithium-ion anode materials. The CNSLTO exhibits excellent rate capacity (171.7–152.6 mA h g−1 at 0.5–20 C) and cycling performance (97.6 % after 1000 cycles at 10 C). Additionally, the discharge-specific capacity of the LFP//CNSLTO full battery at 10 C (122.2 mA h g−1) was superior to the LFP//LTO (77.8 mA h g−1).

Effects of injection methods and occasions of liquid nitrogen on thermal runaway characteristics in 65 Ah LiFePO4 batteries

Lithium-ion batteries (LIBs) pose a significant risk of thermal runaway (TR), and existing methods cannot effectively prevent temperature rise and reignition. In this work, a series of experiments were carried out to investigate the TR characteristics of 65 Ah LiFePO4 batteries and explore the potential of liquid nitrogen (LN) to suppress TR. The effects of different LN injection methods (intermittent and continuous) and occasions are analyzed for the first time. The results show that the hazard of LIB TR increases with the state of charge (SOC). The self-generated heat of 100 % SOC batteries during TR is 4.6 times greater than that of 25 % SOC batteries. Both intermittent and continuous LN injection methods can effectively prevent TR, with intermittent injection yielding about a 10 % higher effective heat absorption rate than continuous injection. Injecting 1.76 kg LN can prevent TR before the safety valve opens at approximately 95 ℃. However, if TR has already occurred at around 135 ℃, 1.76 kg LN can only reduce the battery's temperature but not interrupt the TR process. By increasing the mass of LN to 6.66 kg, TR can be successfully suppressed. The work is expected to provide a guideline for suppressing TR in large-capacity LIBs.

Suppression of thermal runaway induced by thermal abuse in large-capacity lithium-ion batteries with water mist

Thermal runaway (TR), as the most critical safety problem of lithium-ion batteries (LIBs), may cause considerable accident consequences, especially for large capacity LIBs, TR hazards should be multiplied. Therefore, effective TR mitigation strategies are needed. Water mist (WM), being widely considered as a clean and efficient fire suppression method, is employed for TR control in this work. TR evolution of the multi-cell large capacity LIBs induced by thermal abuse has been clearly demonstrated for the first time, the disaster characteristics of the LIB before TR are dominated by the successive gas production behaviors of the internal cells, but the battery ultimately triggers the TR as a whole. More than that, the critical signal is identified based on the battery disaster development and is successfully used for TR suppression. Then the reason for TR being suppressed is revealed by elucidating the overall and instantaneous cooling effects of the WM on LIBs. Moreover, it is found that the disaster of large capacity LIBs develops quickly, and 15 s is sufficient to make TR uncontrollable. Even so, the WM still exhibits excellent cooling ability, taking away over 65 % of the battery heat accumulation. The results provide the first comprehensive analysis of TR evolution and clarify the ability of WM in TR suppression of multi-cell LIBs.

Numerical study on the fire and its propagation of large capacity lithium-ion batteries under storage

Numerical study on the fire and its propagation of large capacity lithium-ion batteries under storage

Investigation of Impulse and Continuous Discharge Characteristics of Large-Capacity Lithium-Ion Batteries

Lithium-ion batteries are one of the most popular and efficient energy storage devices. In this paper, the characteristics of high-capacity lithium-iron-phosphate batteries during the impulse and long-term operation modes of batteries with different levels of the discharge current are considered. A modified DP-model is proposed. The novelty of the model is the possibility to calculate the activation polarization parameters for different discharge currents. The state of charge is estimated using a high-order polynomial. Based on the developed model, transient processes with rapid load changes and the dependence of the battery voltage on the state of charge were obtained. Here, the model is intended to be used for the design of energy storage systems. The results showed that the DP-model is reliable under the tested conditions and can be used for the considered application.

One-step synthesis of a double conductive layer C-SiOx-TiO2 co-coated Li4Ti5O12 anode material toward a high-rate and large-capacity lithium-ion battery

The preparation of lithium titanate electrode materials with a high energy density and high rate performance is of great significance to its commercialization. In this work, we report a simple strategy to prepare a double conductive layer C-SiOx-TiO2 co-coated Li4Ti5O12(CS-TiO2/LTO) anode material by the sol–gel method to achieve more efficient lithium-ion storage. During a heat treatment process, anatase titanium dioxide was formed by the reaction between the lithium titanate surface and SiO2 layer. The SiO2 and polydopamine layers underwent a carbothermal process to form a SiOx layer. The composite material made full use of the advantages of the high-capacity SiOx coating layer and the double conductive layer combining anatase titanium dioxide with N-doped C. The C-SiOx-TiO2 co-coated Li4Ti5O12 composite exhibited significantly improving specific capacity, rate capability, and cycling stability compared to commercial Li4Ti5O12. The as-prepared CS-TiO2/LTO had a high tap density and electronic conductivity (8.45 × 10−4 S cm−1), as well as a high ionic conductivity (4.62 × 10−12 cm2 S−1), which were responsible for its excellent rate capability (221.7 mAh/g at 20C) and stable long-term cycling performance (0.008% fade per cycle after 1000 cycles at 20C).

Study of the Test Conditions and Thermostability of an Overcharge Test for Large Capacity Lithium-Ion Batteries

Abstract In this study, a lithium-ion soft-pack battery used in an electric vehicle was taken as the research object. Based on the actual working condition of the traction battery, the regularity of the evolution of the overcharge thermal runaway experiment of the sample was deeply analyzed by taking the charging rate and the ambient temperature as variables. The results showed that the larger the overcharge current was and the higher the ambient temperature was, the lower the overcharge thermal stability of the battery was. Furthermore, based on the concept of the introduction of battery energy during charging, by analyzing the total amount of energy input and the rate of energy input, a unified index was established to measure the change of the battery overcharging stability under different experimental conditions.

Synergy of a hierarchical porous morphology and anionic defects of nanosized Li4Ti5O12 toward a high-rate and large-capacity lithium-ion battery

Abstract Exploring electrode materials with a high volumetric energy density and high rate capability remains of a great challenge for nanosized-Li4Ti5O12 (LTO) batteries. Here, hierarchical porous Ti3+-C-N-Br co-doped LTO (LTOCPB-CC) is synthesized using carboxyl-grafted nanocarbon (CC) and cetylpyridinium bromide (CPB) as combined structure-directing agents. Ti4+-O-CPB/Li+-CC is designed as a new molecular chelate, in which CPB and CC promote the uniform mixing of Li+ and Ti4+ and control the morphology of TiO2 and the final product. The defects (oxygen vacancies and ion dopants) formed during the annealing process increase the electron/hole concentration and reduce the band gap, both of which enhance the n-type electron modification of LTO. As-prepared LTOCPB-CC has a large specific surface area and high tap density, as well as a high electronic conductivity (2.84 × 10−4 S cm−1) and ionic conductivity (3.82 × 10−12 cm2 s−1), which are responsible for its excellent rate capability (157.7 mA h g−1 at 20 C) and stable long-term cycling performance (0.008% fade per cycle after 1000 cycles at 20 C).

Prediction of Temperature in a Penetrated Lithium-Ion Pouch Cell Using a Multi-Physics Model

Recently safety studies have been actively conducted for large capacity lithium-ion batteries (LIB) used in various industry fields, not only electric vehicle (EV) but energy storage system (ESS) and etc. However, these large LIB cells more can bring critically dangerous explosive accidents in larger scales than small LIB cells. Thermal runaway, the common event before the LIB explosion, is caused by many reasons such as overcharge, internal and external short circuits and self-reaction heating at high temperature. Many numerical studies have been conducted to thermal behaviors of LIBs for safety. However, experimental tests of the safety incidents are usually hard to be reproduced and controllable so that experimental data has been lacked. In this situation, multi-physical models can produce electrochemical responses and electrical- thermal behaviors of LIBs which experience the safety problems. Using numerical models, thermal risks in various short-circuit circumstances can be predicted. In this study, we will represent an electric- electrochemical-thermal (EECT) model to estimate thermal behaviors of LIB cells in internal short circuit situations. This multi- physics model considers charge conservation, thermal energy conservation in cell volumes and also calculates electrochemical reactions at active electrodes using the pseudo-2-dimension method (P2D). The model calculates electrical current paths through the nail penetrating the cell and Ohmic heat generated by the electric currents. Using the EECT model, a large capacity LIB cell was simulated for a nail penetration case. The design of the cell was chosen to be similar to that of the cells in the industrial fields like energy storage system (ESS) or EV. The cell has about 20Ah capacity and graphite (LiC6) and layered nickel metal oxide (LiNi0.5Co0.2Mn0.3O2, NCM523). The size of the nail was 5mm by 5mm and made of still. Also, parametric studies about nail size, location, and state of charge (SOC) of the cell were conducted and the parametric data was used for providing the safety guidelines at the short-circuit situations. Figure 1

Study on temperature characteristics of mineral ferric phosph ate lithium-ion battery

Lithium-ion battery (SE60AHA type)is the main power of mine trolleybus. It studies the characteristics of main parameters such as capacity, charging and discharging time and cycle life with temperature, which can effectively ensure safety. This paper designs charging and discharging experiments under different temperature conditions and conducts OCV-SOC curve analysis. The results show that under the charging conditions of different temperature, there is no significant change in the relative capacity of charging, but the lower the temperature is, the shorter the constant-current charging time is and the longer the constant-voltage time is. Under the discharging condition of different temperature, the change of relative discharging capacity is obvious, the voltage drops faster when the temperature is lower than 0°C, and it keeps the same voltage variation when the temperature is higher than 0°C, while the discharging time reduces with decreased temperature. Further more, according to the variation of charging and discharging voltage with different temperature, it analyze the health status and optimal working environment of mine-type lithium-ion battery adopting the characteristics of charging and discharging efficiency. The research results provide a basis of the using and maintenance of large-capacity lithium-ion battery stack in special environments of the coal mining.

Study on thermal stability of nickel-rich/silicon-graphite large capacity lithium ion battery

The nickel-rich silicon-graphite lithium-ion cells, for example the LiNi0.8Mn0.1Co0.1O2/Silicon-carbon (NMC811/Si@C), have been used in the commercial power batteries to meet the higher capacity requirements now. However, the battery with higher energy is more destructive as thermal runaway occurs. In order to improve the safety of the battery, it is essential to study the thermal stability of this kind of battery. In this work, the differential scanning calorimetry (DSC) and adiabatic rate calorimetry (ARC) have been used to conduct a detail thermal stability analysis for this type of battery of different charge state, the thermal stability mutation of Si@C material has been observed firstly when the SOC is great than 55%. Besides, a reasonable thermal runaway reaction sequence of the battery of NMC811/Si@C is proposed. Moreover, based on the time to maximum reaction rate (TMR), the effective recommendations for the use of NMC811/Si@C lithium ion battery are provided.

The Comparison of Thermal Stability and Safety between Fresh and Aging Large Capacity Lithium Ion Battery with Silicon Carbon Anode

Due to the high energy density, lithium ion battery (LIB) plays an important role in electric vehicle (EV). However, the requirement to the energy density keeps increasing. More and more materials are selected to improve the energy density to provide more distance for EV. Silicon, as a famous anode material, provides much higher specific capacity (3579-4200 mAh/g) than graphite (372 mAh/g) does. This research focused on thermal stability and safety of a 30Ah battery with silicon carbon anode. Aging battery would also be compared with the fresh battery after several cycles to different state of health (SOH). The batteries would be analyzed by accelerating rate colorimeter (ARC) to determine the safety. The differential scanning colorimeter (DSC) evaluated the thermal stability of the batteries. The thermal stability of ARC is decided by T1, T2 and T3 which are the self-heating temperature, thermal runaway triggered temperature and the highest temperature, respectively. The scanning electron microscope (SEM) could observe the surface differences with different SOH and various silicon proportion. The research revealed an overall safety assessment of the lithium ion battery with different content of silicon anode under different SOH. Keywords: Lithium ion battery, silicon carbon, thermal runaway, thermal stability Figure 1

Facile preparation of core-shell Si@Li4Ti5O12 nanocomposite as large-capacity lithium-ion battery anode

Abstract As a promising alternative anode material, silicon (Si) presents a larger capacity than the commercial anode to achieve large capacity lithium-ion batteries. However, the application of pure Si as anode is hampered by limitations such as volume expansion, low conductivity and unstable solid electrolyte interphase. To break through these limitations, the core-shell Si@Li4Ti5O12 nanocomposite, which was prepared via in-situ self-assembly reaction and decompressive boiling fast concentration method, was proposed in this work. This anode combines the advantages of nano-sized Si particle and pure Li4Ti5O12 (LTO) coating layer, improving the performance of the lithium-ion batteries. The Si@Li4Ti5O12 anode displays a high initial discharge/charge specific capacity of 1756/1383 mAh g−1 at 500 mA g−1 (representing high initial coulombic efficiency of 78.8%), a large rate capability (specific capacity of 620 mAh g−1 at 4000 mA g−1), an outstanding cycling stability (reversible specific capacity of 883 mAh g−1 after 150 cycles) and a low volume expansion rate (only 3.3% after 150 cycles). Moreover, the synthesis process shows the merits of efficiency, simplicity, and economy, providing a reliable method to fabricate large capacity Si@Li4Ti5O12 nanocomposite anode materials for practical lithium-ion batteries.

ZIF-8-Templated Hollow Cubelike Si/SiO2@C Nanocomposites for Superior Lithium Storage Performance

Silicon-based anodes are of particular interest for the application of next generation large-capacity lithium-ion batteries (LIBs) because of their natural abundance and ultrahigh theoretical lithi...

Enhanced High Voltage Performance of Chlorine/Bromine Co-Doped Lithium Nickel Manganese Cobalt Oxide

The chlorine (Cl) and bromine (Br) co-doped lithium nickel manganese cobalt oxide (LiNi1/3Co1/3Mn1/3O2) was successfully synthesized by the molten salt method. The synthesized LiNi1/3Co1/3Mn1/3O2 compound demonstrates spherical morphology, which is formed by aggregated spherical-like or polygon primary particles. Halogen substitution would contribute to the growth of the primary particles. The LiNi1/3Co1/3Mn1/3O2 compound has the typical hexagonal layered structure, and no impurity phase is detected. The surface oxidation state of the compound is improved after Cl and Br substitution. Moreover, the Cl and Br co-doped LiNi1/3Co1/3Mn1/3O2 compound exhibits both improved rate capacity and cycle stability at a high voltage (4.6 V) compared with the pristine LiNi1/3Co1/3Mn1/3O2. The initial discharge capacities of Cl and Br co-doped LiNi1/3Co1/3Mn1/3O2 are 208.9 mAh g−1, 200.6 mAh g−1, 188.2 mAh g−1, 173.3 mAh g−1, and 157.1 mAh g−1 at the corresponding rates of 0.1C, 0.2C, 0.5C, 1C, and 3C respectively. The capacity retention at 1C after 50 cycles is increased from 81.1% to 93.2% by co-doping. The better contact between the electroactive particles of the electrode and the smaller resistance enhance the electric conductivity of the Cl and Br co-doped LiNi1/3Co1/3Mn1/3O2 cathode. The synthesized LiNi1/3Co1/3Mn1/3O2 is a promising cathode material for a high-power and large-capacity lithium-ion battery.

TiO2 hierarchical hollow microspheres with different size for application as anodes in high-performance lithium storage

Nowadays, the safety issue has greatly hindered the development of large capacity lithium-ion batteries (LIBs), especially in electric vehicles applications. TiO2 is a kind of potential anode candidate for improving the safety of LIBs. However, it still needs to understand how to improve the performance of TiO2 anode in the practical applications. Herein, we design a contrast experiment by using three sizes of TiO2 hierarchical hollow microspheres (TiO2-HSs). The research results indicated that the cycling performance of TiO2-HSs anode can be affected by the size of microspheres, and the nanoparticles size of microspheres and crystallinity of TiO2 can affect their initial discharge capacity and lithium ion diffusion. And, the influence of microspheres size is more significant. This may provide a new strategy for improving the lithium-ion storage property of TiO2 anode material in the practical applications.

Nano/micro-structured silicon@carbon composite with buffer void as anode material for lithium ion battery

A novel nano/micro-structured pSi@C composite with buffer void was successfully synthesized via a simple and scalable process with combination of the calcination, spray drying, carbonization and HF etching. The obtained pSi@C composite with this particular structure exhibits high reversible capacity of ca. 2200mAhg−1 and excellent cycling stability with 90.3% capacity retention after 300 cycles, which benefits from its void spaces between silicon and carbon layer and highly conductive carbon-layer. The simple and scalable synthesis technique and good electrochemical performance of this nano/micro-structured pSi@C composite make it a promising candidate for large capacity lithium ion battery anode material.

Safety of large-capacity lithium-ion battery and evaluation of battery system for telecommunications

In backup power sources for telecommunications equipment, it is desirable that the lithium-ion (Li-ion) cells have large capacity to minimize installation size of backup systems and to improve reliability of them by reducing a number of cells and accompanying protective devices. On the other hand, large-capacity Li-ion cell is difficult to manage safety problems. Therefore, safety improvement must be done to replace lead-acid batteries in conventional backup power sources. Improvement of lifetime has also to be achieved under the float-charging condition.We have been developing large-capacity Li-ion cells of which safety are improved by adding phosphazene flame retardant. In this work, 200-Ahs cell is fabricated and several safety tests under the assumption of telecommunications backup use are carried out. The results show no explosion, ignition, or thermal runaway. Forced thermal runaway test of a cell in the module which involves 13 cells are also carried out. There is no explosion, ignition, or thermal runaway in other 12 cells. In addition, 36-kW Li-ion battery system consisted of the 200-Ahs cells and battery management system (BMS). The system was operated for about 400 days in a state of floating charge. More than 95% of initial capacity is obtained.

Fail-safe design for large capacity lithium-ion battery systems

A fault leading to a thermal runaway in a lithium-ion battery is believed to grow over time from a latent defect. Significant efforts have been made to detect lithium-ion battery safety faults to proactively facilitate actions minimizing subsequent losses. Scaling up a battery greatly changes the thermal and electrical signals of a system developing a defect and its consequent behaviors during fault evolution. In a large-capacity system such as a battery for an electric vehicle, detecting a fault signal and confining the fault locally in the system are extremely challenging. This paper introduces a fail-safe design methodology for large-capacity lithium-ion battery systems. Analysis using an internal short circuit response model for multi-cell packs is presented that demonstrates the viability of the proposed concept for various design parameters and operating conditions. Locating a faulty cell in a multiple-cell module and determining the status of the fault's evolution can be achieved using signals easily measured from the electric terminals of the module. A methodology is introduced for electrical isolation of a faulty cell from the healthy cells in a system to prevent further electrical energy feed into the fault. Experimental demonstration is presented supporting the model results.

Safety Evaluation Explained with an Example of Development of Space Use Large Capacity Lithium-Ion Battery(Practice of Safety Engineering)

Safety Evaluation Explained with an Example of Development of Space Use Large Capacity Lithium-Ion Battery(Practice of Safety Engineering)