Lithium Titanate Battery Research Articles

Modelling of lithium‐titanate battery with ambient temperature effect for charger design

Lithium-titanate battery is a new generation of lithium-ion battery that offers an outstandingly fast charging capability. Its charging profile forms the basis for an efficient battery charger design for the battery. As a remedial solution, this study proposes a mathematical model to capture the charging profiles of the lithium-titanate battery at different charging rates and ambient temperatures. In this aspect, the charging characteristic of lithium-titanate battery is represented by a transfer function, which is applicable for small-signal analysis and large-signal simulation of battery charger design. The methodology of battery modelling is solely based on the constant-current charging profiles of a battery. Enhanced charging curve normalisation method is applied to obtain the charging characteristic of battery. A novel temperature-based equation is developed to represent the normalised charging curves at different ambient temperatures. Then, a transfer function-based model is developed to simulate the charging profiles of battery. The developed model is validated through experimental studies. Comparison of experimental and simulation results shows that the developed model is able to capture the charging behaviour of a lithium-titanate battery for various charging rates and temperatures.

Butler–Volmer-Equation-Based Electrical Model for High-Power Lithium Titanate Batteries Used in Electric Vehicles

The lithium titanate battery, which uses Li 4Ti 5O 12 (LTO) as its anode instead of graphite, is a promising candidate for fast charging and power assist vehicular applications due to its attractive battery performance in rate characteristics and chemical stability. Unfortunately, commonly used battery models, including a large number of enhanced electrical models, become problematic when describing current–voltage characteristics of lithium titanate batteries. In this paper, a novel Butler–Volmer equation-based electric model is employed to outline unique phenomena induced by changing rates for high-power lithium titanate batteries. The robustness of the proposed model for three types of lithium titanate batteries under varying loading conditions, including galvanostatic test and Federal Urban Dynamic Schedule test, is evaluated and compared against experimental data. The experimental results of three types of lithium titanate batteries with common anode materials but differentiated cathode materials show good agreement with the model estimation results with maximum voltage errors below 2%.

Heat transfer in the dynamic cycling of lithium–titanate batteries

Based on the coupled model of a three-dimensional thermal model and one-dimensional electrochemical model, the thermal behaviors of lithium–titanate battery under the discharge–charge cycling with various current are investigated. The temperature on the surface of battery increases with the increasing cycling rate. Two temperature peaks are observed during the constant-current discharge, constant-current and constant-voltage charge process based on the analysis of the heat generation. Additionally, the radiative heat transfer cannot be omitted when the battery is operated under natural convection at 0.5C cycling rate, in this case, the radiative heat transfer is estimated to contribute 42% to the total heat transfer. The results can provide basic data for the thermal management of the battery pack during the discharging and charging processes.

The Efficiency of Heptafluoropropane Fire Extinguishing Agent on Suppressing the Lithium Titanate Battery Fire

To investigate the efficiency of heptafluoropropane fire extinguishing agent on suppressing the lithium titanate battery fire, an experimental system was designed and built to perform the extinguishing test. The lithium titanate battery (50 Ah, 2.3 V) with diameter of 66 mm and length of 260 mm was used. A 5 kW electric heater was set under the battery to trigger the thermal runaway of the battery. When the battery fire occurs, the heptafluoropropane was immediately discharged by opening the agent storage tank till to the fire was extinguished. The battery temperatures, ignition time, release time of the agent, time to extinguish the fire, battery mass loss, amount of used agent and mean discharge rate of agent were obtained and analysed. The results illustrate that the single cell or small-scale battery pack fire can be extinguished by heptafluoropropane in the tests. Therefore, heptafluoropropane is a fire extinguishing agent candidate to put down the lithium titanate battery fire. However, due to the violent reactions still ongoing inner the cell and flammable gases ejecting continuously from the cell, the battery may be reignited after it is put down. So it was suggested that the heptafluoropropane agent should be applied as early as possible and with longer spray time than the usual case to avoid the reignition.

Correctional DP-Based Energy Management Strategy of Plug-In Hybrid Electric Bus for City-Bus Route

Typical plug-in hybrid electric buses (PHEBs) with a fast-charged lithium titanate battery, which might fulfill about 70% of the distance of a representative city-bus route, have been adopted in many Chinese cities. Considering that the detailed information of the driving cycle could be deduced with the historical driving data and online estimation methods, there might be an opportunity for applying the dynamic programming (DP)-based global optimal energy management strategy for these PHEBs. However, road slopes or variable loads might induce transient fluctuations of the driving resistance in a given driving cycle. Meanwhile, the single-shaft parallel configuration, with automatic mechanical transmission (AMT), might constrain the implementability of the optimal energy distribution from a DP-based strategy. Therefore, in this paper, a novel correctional DP algorithm is brought forward to balance the optimization of fuel economy and drivability. Simulation results demonstrate that, integrated with the correctional logic of AMT gear shifting, the proposed energy management strategy can guarantee that the engine and the electric machine work in the high-efficiency area with optimal energy distribution, while keeping drivability in the variation of road slope and loads. The proposed method might give a technical solution to these typical PHEBs with a lower cost system configuration of the powertrain in China.

The combustion behavior of large scale lithium titanate battery.

Safety problem is always a big obstacle for lithium battery marching to large scale application. However, the knowledge on the battery combustion behavior is limited. To investigate the combustion behavior of large scale lithium battery, three 50 Ah Li(NixCoyMnz)O2/Li4Ti5O12 batteries under different state of charge (SOC) were heated to fire. The flame size variation is depicted to analyze the combustion behavior directly. The mass loss rate, temperature and heat release rate are used to analyze the combustion behavior in reaction way deeply. Based on the phenomenon, the combustion process is divided into three basic stages, even more complicated at higher SOC with sudden smoke flow ejected. The reason is that a phase change occurs in Li(NixCoyMnz)O2 material from layer structure to spinel structure. The critical temperatures of ignition are at 112–121°C on anode tab and 139 to 147°C on upper surface for all cells. But the heating time and combustion time become shorter with the ascending of SOC. The results indicate that the battery fire hazard increases with the SOC. It is analyzed that the internal short and the Li+ distribution are the main causes that lead to the difference.

A Thermal Runaway Simulation on a Lithium Titanate Battery and the Battery Module

Based on the electrochemical and thermal model, a coupled electro-thermal runaway model was developed and implemented using finite element methods. The thermal decomposition reactions when the battery temperature exceeds the material decomposition temperature were embedded into the model. The temperature variations of a lithium titanate battery during a series of charge-discharge cycles under different current rates were simulated. The results of temperature and heat generation rate demonstrate that the greater the current, the faster the battery temperature is rising. Furthermore, the thermal influence of the overheated cell on surrounding batteries in the module was simulated, and the variation of temperature and heat generation during thermal runaway was obtained. It was found that the overheated cell can induce thermal runaway in other adjacent cells within 3 mm distance in the battery module if the accumulated heat is not dissipated rapidly.

Numerical study on lithium titanate battery thermal response under adiabatic condition

To analyze the thermal behavior of 945mAh lithium titanate battery during charging and discharging processes, the experimental and numerical studies are performed in this work. The cathode and anode of the 945mAh lithium titanate soft package battery are the lithium nickel–cobalt–manganese-oxide and lithium titanate, respectively. In the experiment, an Accelerating Rate Calorimeter combined with battery cycler is employed to investigate the electrochemical–thermal behavior during charge–discharge cycling under the adiabatic condition. In numerical simulation, one electrochemical-thermal model is adopted to predict the thermal response and validated with the experimental results. From both experimental and simulated results, the profile of potential and current, the heat generation, the temperature, the temperature changing rate and the temperature distribution in the cell are obtained and thermal runaway is predicted. The analysis of the electrochemical and thermal behavior is beneficial for the commercial application of lithium titanate battery in the fields of electric vehicles and hybrid electric vehicles.

Cost-Benefit Analysis Model of Single and Hybrid Energy Storage System in Active Distribution Network

The active distribution network is an effective approach to solve the problem such as the high penetration of intermittent renewable energy. This paper constructs single and hybrid energy storage battery systems in the active distribution network, calculates the economic benefits of the single and hybrid energy storage systems from six aspects in annual electricity sale revenue, ancillary revenue, investment cost, maintenance cost, landed cost and power shortage punishment cost. Take the lithium iron phosphate battery as single system, the lithium iron phosphate battery and Lithium titanate battery as the hybrid system to compute the cost benefit. The results show that the storage systems have effects to the intermittent renewable energy in peak shaving. Since the hybrid energy storage system can obtain more annual ancillary revenue, and the batteries’ work life is longer, it has more advantage in economic benefits than the single energy storage system.

Recovery of Ti and Li from spent lithium titanate cathodes by a hydrometallurgical process

Despite the potential application of lithium titanate (Li4Ti5O12) battery, recovering Ti and Li from the spent batteries remains a largely unexplored but important topic. In this contribution, a process including leaching, extraction for the separation of titanium from leaching liquor and synthesizing TiO2 nano-particles by a homogeneous precipitation method is presented as a successful strategy. Various operating parameters were optimized, affording more than 97% leaching efficiency of both Ti and Li at a sulfuric acid solution of 4M, H2O2 of 20vol.%, solid-to-liquid ratio of 0.025gmL−1, leaching temperature of 80°C and leaching time of 4h. In the case of the extraction, the solvent extraction efficiency of titanium about 99% can be achieved with 30vol.% primary amine N1923 as an extractant and kerosene as a diluent at highly acidic condition, organic phase/aqueous phase (O/A) ratio 2:1 within 10min of contact time in ambient temperature, while the solvent extraction efficiency of lithium is only 1.4%. The raffinate was concentrated from 0.74gL−1 to 1.11gL−1 by evaporation, then lithium carbonate was precipitated by adding saturated solution of sodium carbonate affording 85% recovery. Finally, the stripping was fast with equilibrium time of 10min with 2M H2SO4 and titanium stripping of 98%. The results of XRD and SEM show that the size of as-prepared TiO2 powders is 100–200nm from the stripped solution by the homogeneous precipitation method.

钛酸锂电池在城市公交电动产业化中的应用

近年来，钛酸锂电池由于具有长寿命、安全的特点而引起人们极大的兴趣。用固相合成法合成的钛酸锂材料颗粒在几十到几百纳米之间，电池的充放电平台电压为1.57 V；采用钛酸锂作为电池负极，采用三元材料为正极制造的电池，在不同充放电倍率、大倍率和高温条件下分别做了测试，发现电池具有较高的性能；电池首次在重庆得到大规模应用，测试了电池的典型工况、充电电流、充电时间与能耗水平，证明钛酸锂负极电池可应用与城市公交电动化中具有较高的市场前景。The great interest for lithium titanate battery with features of long life and safety has grown in recent years. Lithium titanate material particles ranging from dozens to hundreds nanometer in diameter were prepared using solid phase synthesis method; voltage of the charge and discharge platform was 1.57 V. Using lithium titanate as battery cathode and ternary materials as anode, tests were made under different charge-discharge rates, zoom time and high temperature respectively, indicating that the battery offers higher performance. This battery has been put into large- scale application in Chongqing, and typical operating conditions, charging current, recharging time and energy consumption level were tested, proving that lithium titanate battery has a promising market prospect of application in industrialization of urban transit electric vehicles.

Forklift with a lithium-titanate battery during a lifting/lowering cycle: Analysis of the recuperation capability

Abstract Opportunities of storing electric energy recovered from an electro-hydraulic forklift truck are studied with a lithium-titanate battery as energy storage. Instead of a traditional valve control, the lifting system is controlled directly with an electric servo motor drive and a hydraulic pump capable of operating also as a hydraulic motor during potential energy recovery. The paper describes the proposed speed control method of forks to improve the energy efficiency characteristics of the forklift, including the operation time and lifetime of the energy storage device. The analysis results for the proposed systems are compared for different battery sizes from the life cycle point of view.

Effects of Vapor Grown Carbon Fiber Substitution for Conductive Carbon in Anode Systems for LiB Applications

ABSTRACTIsotropic and anisotropic conductive carbon particles, carbon black (CB) and vapor grown carbon fiber (VGCF), were incorporated into a Lithium Titanate (LTO) battery anode material composition, and their effect on conductivity and electrochemical properties investigated. Nanocomposite electrodes comprised of LTO, polyvinyldine floride (PVDF) and as little as 5 wt% VGCF are reported to manifest more than one order of magnitude enhancement in conductivity over their CB counterparts. VGCF-based anodes are also found to exhibit more stable voltage discharge profiles and as much as 20% improvement in capacity retention during extended electrochemical cycling at charge/discharge rates as high as 2.625 A/g (15 C). Remarkably, we find that the benefits of VGCF relative to CB conductivity aids diminish at higher particle loadings and that a LTO anode formulation containing 5 wt% CB | 5 wt% VGCF yields optimal capacity retention. At 5C, this composite system outperformed both the 10 wt% VGCF and 10 wt% CB electrode systems by delivering 20% higher capacity during extended charge/discharge cycling. We explain this finding in terms of two synergetic effects: enhanced electrode conductivity facilitated by incorporation of a percolated network of anisotropic VGCF particles; and shorter transport distances between the insulative LTO and high surface area CB.

Experimental study of an air-cooled thermal management system for high capacity lithium–titanate batteries

Lithium–titanate batteries have become an attractive option for battery electric vehicles and hybrid electric vehicles. In order to maintain safe operating temperatures, these batteries must be actively cooled during operation. Liquid-cooled systems typically employed for this purpose are inefficient due to the parasitic power consumed by the on-board chiller unit and the coolant pump. A more efficient option would be to circulate ambient air through the battery bank and directly reject the heat to the ambient. We designed and fabricated such an air-cooled thermal management system employing metal-foam based heat exchanger plates for sufficient heat removal capacity. Experiments were conducted with Altairnano's 50 Ah cells over a range of charge-discharge cycle currents at two air flow rates. It was found that an airflow of 1100 mls−1 per cell restricts the temperature rise of the coolant air to less than 10 °C over ambient even for 200 A charge-discharge cycles. Furthermore, it was shown that the power required to drive the air through the heat exchanger was less than a conventional liquid-cooled thermal management system. The results indicate that air-cooled systems can be an effective and efficient method for the thermal management of automotive battery packs.

Willenhall Energy Storage System: Europe's largest research-led lithium titanate battery

The Willenhall Energy Storage System is one of the largest research-led lithium titanate, grid-tied electrical storage systems in Europe. It took nearly 2 years from procurement through to final commissioning and cost £3.3 M. From its location in the West Midlands it forms a test bench for current and future grid support methodologies not possible previously with co-generation methods such as diesel and pumped-hyro. This study details the logistical challenges of construction, initial results from commissioning trials and the technical obstacles to the wider adoption of such systems.

Battery powered electric vehicles charged via solar photovoltaic arrays developed for light agricultural duties in remote hilly areas in the Southern Mediterranean region

In the Southern Mediterranean region hilly and remote areas are afflicted with the high cost of diesel fuel, problematic supply, poor or non-existent grid connections and lack of maintenance technicians to service farm grid generation systems and machinery. A prototype Battery Powered Electric Vehicle (BPEV) charged using a solar photovoltaic array (10 kWp) was installed at a monastery situated at Achkout (Lebanon) with a total agricultural area of 50 ha, 10 ha of which was devoted to viticulture. The purpose of this was to investigate the potential for the cleaner production of power hence reducing the use of diesel fuels in agriculture. Data collected from the test site is presented and used to validate a numerical model. The numerical model was then used to extend the study further to the other countries bordering the Mediterranean Sea which have different levels of solar irradiance. Currently the average cost of diesel fuel within the EU is at an all-time high of 1.32 €/L. A life cycle costing determined that if the current trends in inflation in the EU continue and that fuel costs increase by 7.5% per annum, then battery powered electric vehicles charged using solar photovoltaics are economically viable in areas of high solar irradiance. The numerical model was then used to determine the outcome of using lithium titanate batteries instead of conventional lead-acid batteries. Adoption of the described system for a 10 ha vineyard would result in annual fuel saving of 4200–5200 L of diesel depending on which location in the Mediterranean area a system such as this is installed.

Thermal analysis and management of lithium–titanate batteries

Battery electric vehicles and hybrid electric vehicles demand batteries that can store large amounts of energy in addition to accommodating large charge and discharge currents without compromising battery life. Lithium–titanate batteries have recently become an attractive option for this application. High current thresholds allow these cells to be charged quickly as well as supply the power needed to drive such vehicles. These large currents generate substantial amounts of waste heat due to loss mechanisms arising from the cell's internal chemistry and ohmic resistance. During normal vehicle operation, an active cooling system must be implemented to maintain a safe cell temperature and improve battery performance and life. This paper outlines a method to conduct thermal analysis of lithium–titanate cells under laboratory conditions. Thermochromic liquid crystals were implemented to instantaneously measure the entire surface temperature field of the cell. The resulting temperature measurements were used to evaluate the effectiveness of an active cooling system developed and tested in our laboratory for the thermal management of lithium–titanate cells.

城市公共交通电动化的快速充电技术应用 Fast Charging Technology Used in Electrical Applications for Urban Public Transport

现有电池技术条件下，电动汽车面临着“买不起，用不起”的窘况。快速充电技术可以减少电池数量，可改变这一现状。新型钛酸锂电池可快速充电，寿命长，应用于此电池的快速充电技术在公共交通电动化应用中已得到较好的应用，快速充电站也具有较高的投资收益，本应用技术值得推广。 Under the existing battery technology, the development of electric Vehicle faces a new problem, that “It is easy to buy an electrical vehicle, however it is difficult use”. And this problem slow down the development of the electric vehicle until fast charging technology rises up recently, which can reduce the number of battery cells installed in the electric vehicles. In addition, novel fast charge lithium titanate battery, long life, can be applied to the urban public transport, and have a better Demonstration Application, meanwhile, the fast charging station also has a high return on investment, the application of technology should be promoted.

Battery powered electric vehicles developed for light agricultural duties in remote areas in the southern Mediterranean region

SYNOPSIS Hilly and remote areas in the Southern Mediterranean region suffer a high cost of diesel fuel, problematic supply, poor or non-existent grid connections and lack of maintenance technicians to service farm grid generation systems and machinery. A prototype battery powered electric vehicle using a solar photovoltaic array (10 kWp) was installed at a monastery situated at Achkout (Lebanon) with a total agricultural area of 50 hectares, 10 hectares of which was under viticulture. The monastery and associated farmland previously relied on a diesel powered generator (35 kVA) and a diesel fuelled tractor (20 kW) for meeting electrical loads and motive power. This prototype battery powered electric vehicle or Renewable Energy Agricultural Multipurpose System (RAMseS) for Farmers has been developed under the European Union's FP6 programme to investigate the potential for the cleaner production of power, hence reducing the use of diesel fuels in agriculture. Data collected from the test site is presented. An economic analysis determined that if the current trends in inflation in the EU continue and fuel costs increase by 10% per annum, then the original RAMseS system will be economically viable. A further analysis looking at the adoption of new lithium titanate batteries reveals that these systems would be cost effective if these new batteries can be produced at a similar cost to lead acid batteries. Adoption of the RAMseS system for a 10 hectare vineyard would result in annual fuel and carbon dioxide saving of 4000 litres and 2.9 tonnes respectively. The use of alternative non-lead based batteries would save the use of nearly 21 tonnes of lead over the system's lifetime.

A precise scaling length for depleted regions : R. D. Schrimpf and R. M. Warner, Jr.Solid-St. Electron.28 (8) 779 (1985)

Based on the coupled model of a three-dimensional thermal model and one-dimensional electrochemical model, the thermal behaviors of lithium–titanate battery under the discharge–charge cycling with various current are investigated. The temperature on the surface of battery increases with the increasing cycling rate. Two temperature peaks are observed during the constant-current discharge, constant-current and constant-voltage charge process based on the analysis of the heat generation. Additionally, the radiative heat transfer cannot be omitted when the battery is operated under natural convection at 0.5 C cycling rate, in this case, the radiative heat transfer is estimated to contribute 42% to the total heat transfer. The results can provide basic data for the thermal management of the battery pack during the discharging and charging processes.