Power Lithium-ion Batteries Research Articles

Research on the Combined Control Strategy of Low Temperature Charging and Heating of Lithium-Ion Power Battery Based on Adaptive Fuzzy Control

A low temperature environment will lead to the decrease of chemistry reaction rate and increase of the internal resistance of the lithium battery. In addition, the excessive charging current will cause the lithium to separate out and even the permanent attenuation of battery capacity. In order to solve these problems, this paper proposes a low-temperature charging heating combined control strategy, which takes the temperature acceptable charging current of the battery at low temperature as the charging current constraint and the maximum output power of the system as the power constraint. Firstly, a scheme of combined charging and heating control system is put forward. Secondly, the low temperature charging control strategy based on adaptive fuzzy control is established and then the model is simulated and analyzed in MATLAB software. At last, a Chroma 72,001 charge and discharge tester is used to conduct a low temperature test on 18,650 lithium iron phosphate battery monomers. The results show that the low-temperature charging control strategy proposed in this paper has a more stable temperature control effect on the battery, the constant current charging time of the battery is reduced by 14% compared with the traditional threshold control method, and the overall charging energy consumption is reduced by 5.6%.

Parametric Energy Consumption Modeling for Cathode Coating Manufacturing of Lithium-Ion Batteries

In the process of manufacturing the positive electrode coating for lithium batteries, the slow and energy-consuming drying process greatly restricts the shortening of the production cycle and the improvement of energy efficiency of power lithium batteries. The purpose of this paper is to calculate the evaporation rate of N-methylpyrrolidone (NMP) solvent under different drying parameters in the first stage of evaporation and to predict the main energy consumption changes in the drying process in this stage. This research shows that, in the first evaporation stage of lithium battery coating manufacturing, when the inlet wind speed changes at 2∼12m s−1, the evaporation rate of NMP solvent obtained in the coating will change in 1.18 × 10−3 ∼2.88 × 10−3 g min−1 cm−2. For every 1m s−1 increase in wind speed, the energy consumption of electric heating increases by 57.60kW on average.

Improving LiNi0.9Co0.08Mn0.02O2’s cyclic stability via abating mechanical damages

The cyclic plummet caused by mechanical-damage-induced particle cracking is one of the key challenges to hinder the practical application of nickel-rich cathodes. Mechanical stress, roughly estimated by Δc resulted from variation of O-(Li)–O propelling forces, could be tuned up by partially deflecting oxygen charges. Herein, we propose a strategy to abate the mechanical stress of LiNi0.9Co0.08Mn0.02O2 via adjusting electrons’ distribution with appropriate cations substitution. Among the investigated species, Ti- and Al-modifications alleviate the change of lattice c by drawing the neighbor-oxygen charges to transition metal (TM) layers, and Zn-substitution aggrandizes Δc indicating that pushing effect plays the dominant role. Since it renders the largest reduction of lattice c variation, ~40% less in both regions, Ti-substituted sample retains 93.4% of the initial capacity after 200 cycles, even without particle cracking, although the other samples also deliver ~220 mAhg−1 under 0.1 ​C. Our approaches demonstrate the dependence of mechanical stress on electronic micro-structure, which is viable to develop long-life cathodes for power lithium ion batteries.

Graphene Flake-Based Electrodes for High-Energy and Power Lithium-Ion Semi-flexible Rechargeable Batteries

Developing devices and related materials for storing and producing electricity is a key issue to meet the global energy demand. Low-cost and high-performance energy-storage devices are important for sustainable energy utilization. Recently, lithium-ion battery (LIB) is emerging as a promising power source for high-performance electronics. However, their technological drawbacks have hindered the development of LIB with improved specific capacity, stable cyclic and coulombic efficiency for portable electronics application, due to the lack of availability of reliable electrode materials that provided superior electrochemical properties. As a solution to this problem, we herein demonstrated two types of few-layered graphene produced by Fenton reaction (FG) and Hummers method (HG) used for the fabrication of electrodes on flexi copper and aluminum foils in two different ways. Lithium iron phosphate (LiFePO4 or LFP) mixed with super-P carbon black (SP) and fabricated cathode, FG and HG, respectively, blended with SP and fabricated two anodes, by carefully balancing the cell composition of the anode and cathode. An optimal cell performance in terms of specific capacity and stable cyclability depends on the fabrication method of electrodes and their chemical composition. The FG electrodes showed a specific capacity of 186 mAh g−1 at 150 mA g−1 charge/discharge (C/D) current rate while HG showed a specific capacity of 195mAh g−1 at same C/D rate without capacity decay during 30 cycles and an excellent cycling stability was also observed when HG was used in cathode with SP in the same ratio at 150, 300 and 450 mA g−1 C/D rate in full LIB.

Rapid microwave synthesis of Zn3(OH)2V2O7·2H2O nanosheets for enhanced lithium storage performances

Zn3V2O7(OH)2·2H2O has attracted much attention due to its fascinating properties. However, the reported methods need a long reaction time. Little attention has been paid to the energy consumption cost and time saving in the manufacturing process. This paper develops the microwave approach to synthesize Zn3V2O7(OH)2·2H2O nanosheets with about 25 nm thickness only in 10 min, which greatly saves the energy compared to the traditional routes, and easily be extended to fabricate other metal pyrovanadate compounds. Nanosheets shape implies a totally different reaction in the similar microwave system. As cathode of lithium-half cells, The as-prepared Zn3V2O7(OH)2·2H2O nanosheets holds the high capacity of 962.4 mAh g−1 after 100 cycles at 20 mA g−1. It can retain 98.9% of the eighth reversible capacity and shows a promising application in cathode of lithium power batteries. In comparison, the capacity is 392.6 mAh g−1 after 100 cycles and the retention is only 50.9% of the eighth for the thicker plate-like Zn3V2O7(OH)2·2H2O. The electrochemical impedance spectroscopy reveals that Li+ (de) intercalation process in this system is mix-controlled by charge-transfer and diffusion steps, which indicates that 2 dimensional structure plays a vital role in improving the electrochemical performances of Zn3V2O7(OH)2·2H2O.

A Layered Bidirectional Active Equalization Method for Retired Power Lithium-Ion Batteries for Energy Storage Applications

The power from lithium-ion batteries can be retired from electric vehicles (EVs) and can be used for energy storage applications when the residual capacity is up to 70% of their initial capacity. The retired batteries have characteristics of serious inconsistency. In order to solve this problem, a layered bidirectional active equalization topology is proposed in this paper. Specifically, a bridge-type equalization topology based on an inductor is adopted in the bottom layer, and the distributed equalization topological structure based on the bidirectional BUCK-BOOST circuit is adopted in the top layer. State of charge (SOC) is used as the equalization target variable, and the bottom layer equalization algorithm based on a “partition” idea and route optimization is proposed. The static equalization experiments and charge equalization experiments are performed by the 12 retired batteries selected from an electric sanitation vehicle. The results show that the proposed equalization method can reduce the SOC difference between retired batteries and can effectively improve the inconsistency of the retired battery pack with a faster equalization speed.

Evaluation of lithium battery thermal management using sealant made of boron nitride and silicone

In this study, a battery thermal management (BTM) system immersed in a silicone sealant (SS) is designed for an 18650-type lithium-ion power battery. When compared with a general water-cooled BTM system, the novel BTM system with a simple structure can provide effective heat dissipation and long-term corrosion protection. The thermal performance of the three battery modules prepared using SS packaging are analyzed in detail, including an air-cooled battery module, a pure SS battery module, and an SS/BN module composited with 10 wt% BN (SS/BN). The charge and discharge measurements are carried out under various conditions such as the natural air cooling, forced ventilation cooling, and immersion cooling methods. The experimental results indicate that the immersion SS/BN system can significantly reduce the maximum temperature of the battery module and balance the temperature in the module at different discharge rates. The maximum temperature of the three immersion SS modules is less than 35 °C during the 3C discharge process. Moreover, the temperature difference of the immersion SS/BN module can be maintained within 0.5 °C. This research can provide insights into the design and optimization of BTM systems, especially under water or moisture conditions.

Ultrathin inorganic-nanoshell encapsulation: TiO2 coated polyimide nanofiber membrane enabled by layer-by-layer deposition for advanced and safe high-power LIB separator

Separators with superior thermal stability, excellent electrolyte uptake and high ionic conductivity are imperative for developing high-power lithium ion batteries (LIBs). Yet it is not easy to build a separator possessing excellent performances in every aspect. For addressing this issue, herein, a novel in-situ growth-bonded titania (TiO2) nanolayer is coated on the polyimide (PI) nanofiber membrane via a novel layer-by-layer deposition (LBLD) strategy. Despite the tiny TiO2 content (2.2%), the resulting hybrid nano-fabric demonstrates improved performance and great potential for high-power LIBs. Benefited from the advantages of LBLD, the TiO2 nanolayer coated on PI nanofibers is ultrathin with neither sacrificing the porosity nor increasing the total thickness, which indicates that the strategy reported herein is a tremendous progress in comparison with conventional coating methods. After coated by the TiO2 nanolayer, the nanofibrous PI membranes exhibit superb heating-endurance, great flame-retardance, excellent wettability and high Li ion transmission, which would enhance the security of LIBs. More importantly, a unique bonding nanostructure is introduced into the nanofibrous PI membrane accompanied by TiO2 nanolayer, leading to strong interactions among PI nanofibers and promoted mechanical performance, which would improve the operability of the separators in LIBs assembly. The electrochemical tests show that cells assembled with the TiO2 coated PI separators have better high-rates performance, higher discharge capacity and great long-term running stability even at 120 °C. These characters suggest that the TiO2 coated PI membrane might play an important role in the forthcoming advanced power LIBs.

Synthesis of Hollow Microspheres LiNi0.5Mn1.5O4 Coated With Al2O3 and Characterization of the Electrochemical Capabilities

AbstractSpinel LiNi0.5Mn1.5O4 (LNMO) has become one of the most practical power lithium-ion battery cathode materials due to its advantages of three-dimensional Li+ diffusion channel, higher potential window (3.5–5V), high-energy density (∼660 Wh/kg), and high-power density. In this manuscript, a hollow spherical LNMO material with large size and high crystallinity is prepared by a modified coprecipitation method using ethyl alcohol as a peptizator. Subsequently, the prepared LNMO material is further modified by an Al2O3 coating to improve its cycle stability. Results show that the initial discharge-specific capacity of LNMO material with 1 wt% Al2O3 coating is 133.7 mAh g−1 at 0.2 C rate, and the capacity retention rate is 97.7% after 100 cycles. The effective increase in the cycle life of the battery can be attributed to the uniform and dense Al2O3 coating on the surface of the material.

Estimation method of SOC for power lithium battery based on improved EKF algorithm adaptive to various temperature

Estimation method of SOC for power lithium battery based on improved EKF algorithm adaptive to various temperature

Research on thermal equilibrium performance of liquid-cooled lithium-ion power battery system at low temperature

The development of electric vehicles is an important trend in the automotive industry, in which the performance of power batteries is greatly affected by temperature. In recent years, it has been widely concerned that the performance of power batteries at low temperature will lead to the vehicle failure to start because of the bad thermal equilibrium of power battery heating system. This paper studies the thermal equilibrium performance of battery liquid heating system at low temperature. Inlet temperature, heating time, ambient temperature, and their coupling relationship to battery thermal equilibrium performance are studied by orthogonal experimental design method. It is expected that this study can provide reference for the parameter selection of battery heating system.

Analysis and optimization control of finned heat dissipation performance for automobile power lithium battery pack

To cope with the problem of global warming and improve the performance of electric vehicles, the power source of electric vehicles is researched. First, the CFD simulation analysis method is utilized to analyze the heat dissipation effect under the changes of the air intake speed, the number of fins, and the thickness of the fins between lithium batteries. Then, the orthogonal experiment is utilized to select the optimal solution between the lithium batteries. The simulation results show that the heat dissipation effect is optimal under the conditions that the inlet air speed is 8 m/s, the number of fins is seven, and the thickness of fins is 2.5 mm. Then, the orthogonal experiment determines the optimal heat dissipation scheme of the lithium battery pack the air inlet speed is 8 m/s, the number of fins is six, and the thickness of the fins is 2 mm. This optimal scheme can effectively improve the heat dissipation performance of lithium batteries, enhance the performance of electric vehicles, and reduce CO2 emissions.

Aqueous aluminide ceramic coating polyethylene separators for lithium-ion batteries

A new type of aqueous aluminide ceramic coating polyethylene (ACP) separators is prepared by a simple spreader coating process using aluminum oxide (Al2O3) and boehmite (AlOOH) as the ceramic coating particles. During the preparation of the separator, water is used as the solvent and BYK (Beck Chemical Co., Ltd.) additives are used as the aqueous assistant. The as-prepared ACP separators present more outstanding synthetic properties than commercial polyethylene (PE) separators. In addition, compared with Al2O3-coated PE (PE-Al2O3) separators, AlOOH-coated PE (PE-AlOOH) separators have superior synthetic properties, including a better interface stability and a higher liquid electrolyte uptake due to the presence of hydroxyl groups (-OH). As a consequence, the LiNi0.3Co0.3Mn0.3O| Li metal half-cells with PE-AlOOH separators have a good cycling stability and a high rate performance. The advantages of the PE-AlOOH separators make them promising candidates for applications in high power lithium-ion batteries.

Research on Modeling and Characteristic Parameters Consistency of Retired Lithium Power Batteries

For retired power batteries, it is difficult for single cell to meet the power requirements, and there is a problem of poor consistency between multiples. Therefore, re-grouping and consistency assessment are required for cascade utilizaton of retired batteries. In this paper, the remaining capacity test and HPPC test of retired lithium power batteries were carried out. And then the consistency of characteristic parameters of retired batteries under different SOC conditions was compared and analyzed based on capacity, internal resistance and other parameters. The results show that as the battery discharges, the ohmic internal resistance increases, and the consistency of polarization resistance and polarization capacitance are obviously deteriorated. Therefore, it is more reasonable to group them into consistent groups according to the electrochemical parameters of retired batteries at high discharge depth. Moreover, there is no strong correlation among the characteristic parameters such as open-circuit voltage, internal resistance and capacitance. Multiple parameters are required to evaluate the consistency of retired lithium batteries.

Nanocrystalline silicon embedded highly conducting phosphorus doped silicon thin film as high power lithium ion battery anode

In a search of high capacity anode for lithium ion batteries, nano architecture silicon appears as an interesting material despite of its volume change issues. Herein, we report phosphorous doped (n‒type) nanocrystalline silicon using plasma enhanced chemical vapor deposition technique exhibiting superior electrochemical performance. Systematically optimized as grown nanocrystalline silicon shows better electrical conductivity of 35 S cm−1. As anode for lithium-ion storage, nanocrystalline silicon exhibits initial discharge capacity of 3090 mAh g−1 at C/5 rate and retains around 2250 mAh g−1 after 50 cycles. Moreover, it displays high rate capability, viz., at 1C rate it delivers an initial discharge capacity of 1830 mAh g−1 with 70% capacity retention after 250 cycles. At 5C (21 A g−1) rate, discharge capacity greater than 650 mAh g−1 with good cycling stability (65% capacity retention) for 500 cycles. The enhanced capacity retention and high rate performance is attribute to unique nanoarchitecture where silicon nanocrystallites are entrench in amorphous silicon matrix. Besides, phosphorous doping improves the electronic conductivity while restricting the volume change by limiting lithium reactivity and phase transition. Hence, n-type silicon thin film comprising highly conducting nanocrystalline islands embed in amorphous silicon matrix is suitable for high power Li-ion battery applications.

Enhanced mechanical behavior and electrochemical performance of composite separator by constructing crosslinked polymer electrolyte networks on polyphenylene sulfide nonwoven surface

In this study, a new composite separator was fabricated by constructing crosslinked polymer electrolyte networks on polyphenylene sulfide (PPS) nonwoven substrate to enhance mechanical behavior and cell performance. According to chemical reactions of C–F bonds with amine groups, crosslinked polymer electrolyte networks were firstly formed between polymer poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and hyperbranched polyethylenimine (PEI). The composite separator was given systematic investigations ranging from basic physical properties, electrochemical behavior and cell performance. It was found that the designed membrane exhibited higher electrolyte uptake, superior wetting behavior, improved ionic conductivity and interfacial compatibility, which finally weakened ohmic polarization phenomenon in device, and gave rise to the enhancement of discharge capacities at various C-rates as well as the strengthen of cyclic stability. Moreover, the incorporation of crosslinked networks in this system was confirmed to boost mechanical property prominently by tensile test. At the same time, this composite separator was observed to display remarkable heat resistance even after treated at 200 °C and broaden the electrochemical window considerably. Accordingly, this designed separator can meet the safety and performance requirements in the development of high power lithium ion battery.

Characteristics of Power Lithium-Ion Batteries at Extreme Cold Environment

Characteristics of Power Lithium-Ion Batteries at Extreme Cold Environment

Coupling Niobia Nanorods with a Multicomponent Carbon Network for High Power Lithium-Ion Batteries.

High power lithium-ion batteries require highly conductive electrodes. For an active electrode material that has limited electron conductivity, it is critical to build a carbon network that is not only highly conductive itself but also highly compatible with the electroactive material for efficient interfacial charge transfer. Herein, we design a multicomponent carbon network that is optimized for electrical coupling with the electroactive Nb2O5 nanorods for efficient electron injection. The self-support electrode is constructed by using 0D polypyrrole-derived (Ppy) carbon nanoparticles as glue to bind the Nb2O5 nanorods with 1D carbon nanotubes (CNTs) and 2D graphene nanosheets (GNSs). The 0D carbon nanoparticles also cross-link 1D CNTs with 2D GNSs, which can effectively prevent the GNSs from aggregation and form the 3D CNT/GNS network that provides continuous electronic and ionic pathways. This 3D Nb2O5@C self-support electrode exhibits a high discharge capacity of 246.3 mA h g-1 at 0.5 C and 100 mA h g-1 at 20 C and excellent Coulombic efficiency of 99.98% at 20 C. Even increasing the mass loading to 7.1 mg cm-2, the Nb2O5@C electrode can still reach a discharge capacity of 172.4 mA h g-1 at 0.5 C after 100 cycles. A high power density of 1043 W kg-1 can be achieved at an energy density of 104.3 W h kg-1 based on the electrode weight, which is among the highest values demonstrated so far for Nb2O5 electrodes. The results pave the way toward practical applications of Nb2O5 anodes in high-power lithium-ion batteries.

Multi-Scale Multi-Field Coupled Analysis of Power Battery Pack Based on Heat Pipe Cooling

Based on the study of the relationship between micro and macro parameters in the actual microstructure of the electrodes, a new multi-scale multi-field coupling model of battery monomer is established and the heat generation rate of the battery is obtained by detailed numerical simulation. According to the parameters of a certain electric vehicle and battery selected, the structure of the power battery pack and heat pipe cooling system is designed. Through multi-field coupling computational fluid dynamics simulation, the temperature difference of the battery pack is gained. By changing the fin spacing, the cooling scheme of the heat pipe is optimized, which ensures that the temperature difference is less than 5 K and the maximum temperature of the battery system is 306.26 K. It is found that increasing the discharge rate, the temperature difference increases rapidly. Increasing the air inlet velocity can improve the thermal uniformity of the battery pack, but changing the air inlet temperature only determines the range of temperature, it cannot improve the thermal uniformity. The method proposed and results gained can provide a reference for the research of heat management systems with heat pipe of lithium-ion power battery pack for vehicles.

Research on Performance Optimal Control of New Energy Vehicle Cooling System

The application and popularization of new energy vehicles have become the strategic trend of the development of China’s automobile industry. The cooling system of new energy vehicles is used to maintain the temperature of the vehicle system in a reasonable range to prevent the high temperature from affecting the life of the vehicle or causing faults and accidents. This paper introduces the present situation of the cooling system of new energy vehicles, studies the calculation model of battery cooling, and optimizes and simulates the liquid cooling structure of power lithium battery pack, which verifies the calculation model well and accumulates a lot of practical data.