Long-life Lithium Batteries Research Articles

Iterative Synthesis of Contorted Macromolecular Ladders for Fast-Charging and Long-Life Lithium Batteries.

We report here an iterative synthesis of long helical perylene diimide (hPDI[n]) nanoribbons with a length up to 16 fused benzene rings. These contorted, ladder-type conjugated, and atomically precise nanoribbons show great potential as organic fast-charging and long-lifetime battery cathodes. By tuning the length of the hPDI[n] oligomers, we can simultaneously modulate the electrical conductivity and ionic diffusivity of the material. The length of the ladders adjusts both the conjugation for electron transport and the contortion for lithium-ion transport. The longest oligomer, hPDI[6], when fabricated as the cathode in lithium batteries, features both high electrical conductivity and high ionic diffusivity. This electrode material exhibits a high power density and can be charged in less than 1 min to 66% of its maximum capacity. Remarkably, this material also has exceptional cycling stability and can operate for up to 10,000 charging-discharging cycles without any appreciable capacity decay. The design principles described here chart a clear path for organic battery electrodes that are sustainable, fast-charging, and long lasting.

Self-healing polymer electrolyte for long-life and recyclable lithium-metal batteries

Nowadays, the complex application environment requires lithium batteries to be self-healing to cope with the inevitable volume changes and breakage during use. However, only a small part of self-healing materials has been applied in lithium batteries because the introduction of self-healing components will affect the electrochemical performance. Developing a self-healing and recyclable electrolyte to pursue sustainable and long-life lithium batteries is still a great challenge. Herein, a self-healing and recyclable electrolyte has been prepared with a rigid and flexible epoxy resin as a backbone and disulfide bonds as reversible cross-linking points. The epoxy resin imparts superior mechanical abilities (tensile strength >20 MPa) to the electrolytes, while the disulfide bonds provide excellent self-healing capabilities (healing efficiency >95%). Meanwhile, the ionic conductivity (25 °C) of the rigid-flexible self-healing polymer electrolytes (RFSPEs) is as high as 10−3 S/cm, and the multiple healed RFSPE has no changes in the ionic conductivity. In addition, RFSPE has an inhibitory effect on the growth of lithium dendrites, which can cycle stably for up to 1800 h at 1 mAh/cm2. The Li/LiFePO4 cell also exhibits good cycling stability and superior rate performance.

A method for capacity prediction of lithium-ion batteries under small sample conditions

Accurate life prediction of lithium-ion battery is very important for the safe operation of battery system. At present, the data-driven life prediction method is an effective method. However, it is difficult to obtain full life cycle data of long-life lithium batteries, which leads to low accuracy of prediction results. In addition, the degradation of lithium-ion batteries has different trends in different stages, the commonly used methods are insufficient to describe global time variables which make it difficult to adapt to changes in different stages of lithium-ion battery capacity degradation. To solve the above problems, the paper proposes a deep adaptive continuous time-varying cascade network based on extreme learning machines (CTC-ELM) under the condition of small samples. First, a virtual sample generation method based on multi-population differential evolution is proposed, which uses multi-distribution overall trend diffusion technology to adaptively determine the virtual sample range, and combines with the improved differential evolution algorithm to achieve small sample data amplification. Then, a new prediction network with CTC-ELM is constructed. Finally, it is verified on different data sets. Experiments show that the method proposed can effectively expand the sample set of lithium-ion batteries and achieve high accuracy in the estimation of lithium-ion battery capacity.

High safety and long-life lithium batteries with low leakage and high wettability ceramic-polymer electrolyte

The development of ceramic-polymer electrolyte with high mechanical and electrochemical properties is the key to address the safety issue of high-performance lithium batteries due to the use of flammable organic liquid electrolytes. In this work, we designed and synthesized a flexible low liquid leakage and high wettability ceramic-polymer electrolyte (CPE) based on poly(vinylidene fluoride) (PVDF)-poly(ethylene oxide) (PEO)-γ-Al2O3 membrane with excellent mechanical and thermal stability. After being wetted by a very small amount of LiPF6-based liquid electrolyte, symmetrical Li, Li/LiFePO4 (LFP), and LFP/Li4Ti5O12 (LTO) cells with this PVDF/PEO-γ-Al2O3-LiPF6 CPE displayed much better cycling stabilities than that of commercial Celgard 2320 separator with a sufficient amount of liquid electrolyte. The CPE requires only a small amount of liquid electrolyte to achieve the desired electrochemical performance of lithium batteries. Its low liquid leakage characteristic also enhances the safety of lithium batteries, with the potential to replace the commercial separators.

Oxygen Release Induced Chemomechanical Breakdown of Layered Cathode Materials.

Chemical and mechanical properties interplay on the nanometric scale and collectively govern the functionalities of battery materials. Understanding the relationship between the two can inform the design of battery materials with optimal chemomechanical properties for long-life lithium batteries. Herein, we report a mechanism of nanoscale mechanical breakdown in layered oxide cathode materials, originating from oxygen release at high states of charge under thermal abuse conditions. We observe that the mechanical breakdown of charged Li1- xNi0.4Mn0.4Co0.2O2 materials proceeds via a two-step pathway involving intergranular and intragranular crack formation. Owing to the oxygen release, sporadic phase transformations from the layered structure to the spinel and/or rocksalt structures introduce local stress, which initiates microcracks along grain boundaries and ultimately leads to the detachment of primary particles, i.e., intergranular crack formation. Furthermore, intragranular cracks (pores and exfoliations) form, likely due to the accumulation of oxygen vacancies and continuous phase transformations at the surfaces of primary particles. Finally, finite element modeling confirms our experimental observation that the crack formation is attributable to the formation of oxygen vacancies, oxygen release, and phase transformations. This study is designed to directly observe the chemomechanical behavior of layered oxide cathode materials and provides a chemical basis for strengthening primary and secondary particles by stabilizing the oxygen anions in the lattice.

Surface-Modified Li4Ti5O12 for High Stability and Rate Performance Anode Materials

Lithium titanium oxides have attracted great attention worldwide for use in long-life applications such as electric vehicles and energy storage systems. Because Li4Ti5O12 (LTO) operates at a higher voltage range (~1.5 V vs. Li/Li+) and experiences little volume change, excellent structural stability and safety are ensured during cycling without the formation of Li dendrites. However, it is well known that LTO materials have a drawback in rate property due to their poor electric conductivity, which has limited their practical applications to long-life lithium batteries until now [1]. So far, various approaches have been presented to overcome this issue, including different metal ion doping [2], surface treatment with conductive materials [3], synthesis of nanomaterials [4], and partial reduction of surface Ti4+ to Ti3+ by hydrogen [5]. However, most of methods are considered complicated and expensive processes in the aspect of a large scale production. In this work, we fabricate various Li4Ti5O12 materials with different Ti3+ content through a carbothermal reduction process and intensively investigate the effect of Ti3+ on their electrochemical performances. In addition, we suggest an optimal surface composition of Li4Ti5O12 materials enabling high current operation as well as high capacity.

Three-dimensional porous V2O5 hierarchical octahedrons with adjustable pore architectures for long-life lithium batteries

Three-dimensional (3D) porous V2O5 octahedrons have been successfully fabricated via a solid-state conversion process of freshly prepared ammonium vanadium oxide (AVO) octahedrons. The formation of AVO octahedrons is a result of the selective adsorption of capping reagents and the favourable supersaturation of growth species. Subsequently, 3D porous V2O5 octahedrons were obtained by simple thermolysis of the AVO octahedrons via a calcination treatment. As cathode material for lithium batteries, the porous V2O5 octahedron cathode exhibits a capacity of 96 mA·g−1 at high rate up to 2 A·g−1 in the rang of 2.4–4 V and excellent cyclability with little capacity loss after 500 cycles, which can be ascribed to its high specific surface area and tunable pore architecture. Importantly, this facile solid-state thermal conversion strategy can be easily extended to controllably fabricate other porous metal oxide micro/nano materials with specific surface textures and morphologies.

Integrated SnO2 nanorod array with polypyrrole coverage for high-rate and long-life lithium batteries.

Conversion/alloying reactions, in which more lithium ions are involved, are severely handicapped by the dramatic volume changes. A facile and versatile strategy has been developed for integrating the SnO2 nanorod array in the PPy nanofilm for providing a flexible confinement for anchoring each nanorod and maintaining the entire structural integrity and providing sustainable contact; therefore, exhibiting much more stable cycling stability (701 mA h g(-1) after 300 cycles) and better high-rate capability (512 mA h g(-1) at 3 A g(-1)) when compared with the core-shell SnO2-PPy NA.

VO2 Nanowires Assembled into Hollow Microspheres for High-Rate and Long-Life Lithium Batteries

Development of three-dimensional nanostructures with high surface area and excellent structural stability is an important approach for realizing high-rate and long-life battery electrodes. Here, we report VO2 hollow microspheres showing empty spherical core with radially protruding nanowires, synthesized through a facile and controllable ion-modulating approach. In addition, by controlling the self-assembly of negatively charged C12H25SO4(-) spherical micelles and positively charged VO(2+) ions, six-armed microspindles and random nanowires are also prepared. Compared with them, VO2 hollow microspheres show better electrochemical performance. At high current density of 2 A/g, VO2 hollow microspheres exhibit 3 times higher capacity than that of random nanowires, and 80% of the original capacity is retained after 1000 cycles. The superior performance of VO2 hollow microspheres is because they exhibit high surface area about twice higher than that of random nanowires and also provide an efficient self-expansion and self-shrinkage buffering during lithiation/delithiation, which effectively inhibits the self-aggregation of nanowires. This research indicates that VO2 hollow microspheres have great potential for high-rate and long-life lithium batteries.

A high-rate long-life Li4Ti5O12/Li[Ni0.45Co0.1Mn1.45]O4 lithium-ion battery

Lithium batteries are receiving considerable attention as storage devices in the renewable energy and sustainable road transport fields. However, low-cost, long-life lithium batteries with higher energy densities are required to facilitate practical application. Here we report a lithium-ion battery that can be cycled at rates as high as 10 C has a life exceeding 500 cycles and an operating temperature range extending from -20 to 55 °C. The estimated energy density is 260 W h kg(-1), which is considerably higher than densities delivered by the presently available Li-ion batteries.

Implantable monitoring systems: Design considerations and challenges

The use of electrocardiographic (ECG) information in the diagnosis and follow-up evaluation of cardiac patients has evolved from the simple limb lead surface ECG to more sophisticated instruments using advanced recording and diagnostic methods. Advances in electronic technology have provided continued improvement in the performance of ECG monitoring equipment such as the i2-1ead resting and stress ECG, the interpretive electrocardiograph, the signal-averaged ECG, ambulatory ECG monitors, and body surface potential mapping systems. Holter I reported in 1961 the use of a portable ECG recording device. With the introduction of this first ambulatory monitor, clinicians had the opportunity to identify the presence of various cardiac rhythms while the patient was performing his or her normal daily activities. Applications of these ambulatory monitors have included identification of arrhythmias, evaluation of patient symptoms, quantification of ischemia (for both anginal and silent episodes), and performance evaluation of implantable pacemakers and defibrillators. 2 Ambulatory monitors are presently available with magnetic tape, digital random access memory, or min i -ha rd disk drives as their data storage medium. Some digital recorders also include real-time E C G analysis,3 which allows the ambulatory monitor to store higher-resolution ECG data during detected events. Variants of ambulatory monitors include event recorders and loop monitors. These monitors are typically used by the patients over longer periods of time, primarily for the identification of less frequent arrhythznias. However, their operation requires that any cardiac events be symptomatic to be recorded, because the patient must direct the storage of the event into memory for future retrieval and clinical review. In a similar manner, pacemaker technology has evolved from the simple nonprogrammable single-chamber pulse generators to dual-chamber rate-modulated pacemakers. The 1970s saw the introduction of the first programmable pacemakers, the use of the long-life lithium batteries, and basic memory storage with the storage of paced and sensed events. The 1980s were highlighted by the introduction

Radioisotope thermoelectric generators for implanted pacemakers

This paper discusses the development and application of long-life lithium batteries and the problems associated with miniature radioisotope thermoelectric generators (RITEG) with service lives of 10 years or longer. On eof the main problems encountered when devising a radioisotope heat source (RHS) for an RITEG is to obtain biomedical /sup 238/PuO/sub 2/ with a specific neutron yield of 3.10/sup 3/-4.10/sup 3/ (g /SUP ./ sec)/sup -1/, equivalent to metallic Pu 238, and with a content of gamma impurities sufficient to ensure a permissible exposure a permissible exposure does rate (EDR) of a mixture of neutron and gamma radiation. After carrying out the isotope exchange and purifying the initial sample of its gamma impurity elements, the authors obtain biomedical Pu 238 satisfying the indicated requirements king suitable for use in the power packs of medical devices. Taking the indicated specifications into account, the Ritm-1o and gamma radioisotope heat sources were designed, built, tested in models and under natural conditions, and then into production as radioisotope thermoelectric generators designed to power the electronic circuits of implanted pacemakers. The Ritm-MT and Gemma radioisotope thermoelectric generators described are basic units, which can be used as self-contained power supplies for electronic equipment with power requirementsmore » in the micromilliwatt range.« less