Deep Discharge Cycles Research Articles

Rechargeability of Manganese Dioxide-Zinc Batteries

Primary alkaline batteries use electrolytic manganese dioxide (EMD) as the cathode and zinc as the anode and have been in commercial use for several decades. This chemistry is of great interest because the materials used are inexpensive, environmental friendly, and abundant. In addition, alkaline chemistry offers a better energy density and shelf life than some other aqueous batteries such as lead-acid technology. Rechargeability of EMD, however, is challenging and commercial rechargeable batteries based on this electrochemistry have faced limited success due to the limitation of cycling performance. We have investigated the causes of cycling failures using flatplate-type cathode (MnO2) and anode (Zinc) electrodes which are amenable to large scale production. Electrochemical and physiochemical characterizations were performed and will be presented. Flatplate-type electrodes were prepared by producing paste-like mixtures of cathode and anode materials and applying them onto expanded Ni (cathode) and expanded brass (anode) current collectors. The cathode mixture contained EMD, graphite, additives, SBR binder and CMC gelling agent. Anode mixtures were prepared from zinc, zinc oxide, hydrogen inhibitors, teflon binder and carbapol gelling agent. The alkaline electrolyte (9M) was prepared from DI-water and KOH salt. All the cell hardware used was developed in-house. For the cathode electrode, a number of chemical additives such as BaSO4, Sr(OH)2·8H2O, Ca(OH)2, and Bi2O3were investigated at 5 wt. %. Deep discharge cycling (to 1.1 V) reduces the initial specific capacity of 250 mAh g-1 by 50% after 20 cycles. The specific capacity reduces, although at a slower rate, to about 50 mAh g-1 after 100 cycles. Additives such as BaSO4show marginal improvement in the earlier cycles (cycles 10-50), but beyond cycle 50 no noticeable effect was observed. Deeper cycling can be combined with shallow depths of discharge (1.4 – 1.45 V) to extend the cycle life-time of the batteries. Figure 1 shows the cycling performance of RAM cells for combined deep/shallow depths of discharge at C/2 and C/10 rates. Post-cycling XRD analysis of the cathode electrode shows formation of a todorokite-like phase which could limit the cycling performance. Impedance studies show a rapid increase in the charge transfer resistance, indicating that formation of surface inactive phases also play a role in reducing the capacity upon cycling. Figure 1

In Operando X-Ray Imaging and Tracking of Degradation and Failure Phenomena inside Zinc-Air Systems

In search for the next generation of battery technology, rechargeable aqueous zinc-air systems present very attractive power sources due to high specific energy, safety, environmental compatibility and low cost of components and active materials. Nonetheless these systems have not yet been commercialised as they suffer from a short cycle life that prohibits their use for large electrical storage applications that require thousands of deep discharge cycles. One of the key factors responsible for shortened cycle life is dendritic growth occurring during the system charge. Dendrites can grow sufficiently wide to cause an internal short-circuit between the anode and the cathode. While extensive work has been carried out to study and mitigate zinc dendrite formation; real time dendritic growth mechanisms remain poorly understood X-ray micro/nano tomography methods can provide unique insights into operation, degradation and failure of electrochemical energy storage and generation devices and systems. We implemented synchrotron x-ray tomography to investigate the mechanism and kinetics of dendrite formation and dissolution during zinc-air system operation. The dendrite growth and dissolution was analysed in-operando in radiography mode while three-dimensional characterisation of dendrites on top of the zinc electrode was carried out based on set of reconstructed multiple tomographic projections (Figure 1). Additionally individual dendrites have been analysed by high resolution FIBSEM. As such, an ability to actively track the mechanisms of growth and dissolution of dendrites form a critical basis if we are to extend the cycle life of metal-air batteries. Figure 1

NiO nanoparticles supported on graphene 3D network current collector for high-performance electrochemical energy storage

Owing to the faradaic oxidation and reduction reactions mainly taking place on surface, enlarging the specific surface of redox materials is one of the most effective ways to achieve excellent electrochemical performance. Here we report a binder-free three dimensional (3D) architecture electrode consisting of a graphene 3D network (G3DN) structure growing on flexible carbon paper (CP) by chemical vapor deposition and NiO nanoparticles growing on the G3DN by in-situ thermal decomposition for high rate battery and high-performance electrochemical capacitors. Such a nanostructure provides a large specific surface and fast electronic transmission channels. The unique structure design for this electrode enables outstanding performance, showing high specific capacity of 89.1mAhcm−2 (119.2mAh/g) at current density of 0.5mAcm−2 (0.67A/g) with the NiO loading of 0.7471mgcm−2. Meanwhile the electrode displays excellent rate capability and cycling stability, which keeps 85.48% of initial capacity after 3000 deep-discharge cycles. Furthermore, a solid-state symmetric electrochemical capacitor based on two NiO/G3DN/CP electrodes with an area of 4cm2 each is fabricated, and two pieces of them in series can light up 100 green LEDs for 2min. The architecture of G3DN loaded with NiO might be generally applied to different kinds of nanomaterials for high-rate energy storage to improve their overall electrochemical performance.

Consequences of Deep Cycling 24 Volt Battery Strings

Abstract batteries (MIL Deep charge and discharge cycling of 24 Volt battery strings composed of two 12 Volt VRLA batteries wired in series affects reliability and life expectancy. This is a matter of interest in vehicle power source applications. These cycles include those specific operational cases requiring the delivery of the full storage capacity during discharge. The concern here is related to applications where batteries serve as a primary power source and the energy content is an issue. It is a common practice for deep cycling a 24 volt battery string to simply add the specified limit voltages during charge and discharge for the individual 12 Volt batteries. In reality, the 12 Volt batteries have an inherent capacity variability and are not identical in their performance characteristics. The actual voltages of the individual 12 Volt batteries are not identical. The experimental measurements reveal that one of the two individual batteries in the series configuration is driven to voltages exceeding the acceptable operational limits for a single 12 Volt battery. This condition results in a loss of battery capacity during cycling and results in early string failure because of cell reversals. This condition appears whenever the battery polarization is determined by a single cell rather than being shared by a number of cells that are presumed to be matched. takes place slowly over the life of the battery. During the

Silicon anode for rechargeable aqueous lithium–air batteries

A novel aqueous lithium–air rechargeable cell with the configuration of Si/1 M LiClO4 in ethylene carbonate–diethylene carbonate/Li1+x+yAlx(Ti,Ge)2−xP3−ySiyO12/5 M LiCl–1 M LiOH aqueous solution/carbon black, air is proposed. A silicon anode composed of mechanically milled silicon power with an average particle size of ca. 0.5 μm, vapor grown carbon fiber and a polyimide binder was examined. The open-circuit voltage at the charged state was 2.9 V at 25 °C. The discharge capacity of 700 mAh g-silicon−1 was retained for 40 cycles at 0.3 mA cm−2 with cut-off voltages of 3.5 and 1.5 V. Significant capacity fade was observed at deep charge and discharge cycling at 2000 mAh g-silicon−1.

Deep Discharge and Elevated Temperature Cycling of LiMn1.485Ni0.45Cr0.05O4 Spinel Cathodes: Solid-State Cell Studies

Deep Discharge and Elevated Temperature Cycling of LiMn1.485Ni0.45Cr0.05O4 Spinel Cathodes: Solid-State Cell Studies

Full open-framework batteries for stationary energy storage

New types of energy storage are needed in conjunction with the deployment of renewable energy sources and their integration with the electrical grid. We have recently introduced a family of cathodes involving the reversible insertion of cations into materials with the Prussian Blue open-framework crystal structure. Here we report a newly developed manganese hexacyanomanganate open-framework anode that has the same crystal structure. By combining it with the previously reported copper hexacyanoferrate cathode we demonstrate a safe, fast, inexpensive, long-cycle life aqueous electrolyte battery, which involves the insertion of sodium ions. This high rate, high efficiency cell shows a 96.7% round trip energy efficiency when cycled at a 5C rate and an 84.2% energy efficiency at a 50C rate. There is no measurable capacity loss after 1,000 deep-discharge cycles. Bulk quantities of the electrode materials can be produced by a room temperature chemical synthesis from earth-abundant precursors.

Detection of Soluble Mn(III) Species during Cycling of Alkaline γ-MnO2 and the Influence of Barium Hydroxide Inclusion

A series of electrochemical experiments employing a platinum sensing electrode have been carried out to investigate the relationship between Mn(III) dissolution and the rechargeable performance of the alkaline γ-MnO2 electrode. The formation of soluble Mn(III) species was first investigated in relation to the redox reactions occurring during the two-electron cycling of γ-MnO2, and its sensitivity established. The extent of Mn(III) dissolution during deep discharge cycling was then determined, and the level of soluble Mn(III) related to capacity fade, the formation of secondary phases and the implications for rechargeable performance. Finally, the inclusion of barium hydroxide in the electrode blackmix was shown to dramatically reduce the extent of Mn(III) dissolution, resulting in significant improvements in capacity retention and confirming previous suggestions as to its role in electrode rechargeability.

A high-rate and long cycle life aqueous electrolyte battery for grid-scale energy storage

New types of energy storage are needed in conjunction with the deployment of solar, wind and other volatile renewable energy sources and their integration with the electric grid. No existing energy storage technology can economically provide the power, cycle life and energy efficiency needed to respond to the costly short-term transients that arise from renewables and other aspects of grid operation. Here we demonstrate a new type of safe, fast, inexpensive, long-life aqueous electrolyte battery, which relies on the insertion of potassium ions into a copper hexacyanoferrate cathode and a novel activated carbon/polypyrrole hybrid anode. The cathode reacts rapidly with very little hysteresis. The hybrid anode uses an electrochemically active additive to tune its potential. This high-rate, high-efficiency cell has a 95% round-trip energy efficiency when cycled at a 5C rate, and a 79% energy efficiency at 50C. It also has zero-capacity loss after 1,000 deep-discharge cycles.

Copper hexacyanoferrate battery electrodes with long cycle life and high power

Short-term transients, including those related to wind and solar sources, present challenges to the electrical grid. Stationary energy storage systems that can operate for many cycles, at high power, with high round-trip energy efficiency, and at low cost are required. Existing energy storage technologies cannot satisfy these requirements. Here we show that crystalline nanoparticles of copper hexacyanoferrate, which has an ultra-low strain open framework structure, can be operated as a battery electrode in inexpensive aqueous electrolytes. After 40,000 deep discharge cycles at a 17 C rate, 83% of the original capacity of copper hexacyanoferrate is retained. Even at a very high cycling rate of 83 C, two thirds of its maximum discharge capacity is observed. At modest current densities, round-trip energy efficiencies of 99% can be achieved. The low-cost, scalable, room-temperature co-precipitation synthesis and excellent electrode performance of copper hexacyanoferrate make it attractive for large-scale energy storage systems.

Conceptual design for 12 V “lead-free” accumulators for automobile and stationary applications

Conceptual design for 12 V lead-free accumulators is presented using basic research results on lithium insertion materials. Among possible materials, Li[Li 1/3Ti 5/3]O 4 is selected for a negative-electrode material, and Li[Ni 1/2Mn 3/2]O 4, LiMn 2O 4, LiCo 1/3Ni 1/3Mn 1/3O 2, and LiFePO 4 are specifically considered as positive-electrode materials. Combination of these materials with Li[Li 1/3Ti 5/3]O 4 gives a 2, 2.5 or 3 V lithium-ion battery. Series connection of such a lithium-ion battery makes 12 V lead-free accumulators possible. Characteristic features of the lead-free accumulators are discussed in terms of energy density for deep charge and discharge cycles, power density for short period of time, material economy, environmental friendliness, and safety compared with those of lead-acid batteries currently hold a position in automobile, large uninterruptible power supply, and off-grid solar home systems.

Lithium insertion into the composites of acid-oxidized carbon nanotubes and tin oxide

Lithium intercalation into the composites of acid-oxidized carbon nanotubes and tin oxide was studied in an electrolyte system, 1 M solution of LiPF 6 dissolved in a 50:50 mixture by volume of ethylene carbonate (EC) and dimethyl carbonate (DMC). The electrochemical method that is constant current charge–discharge test was used for electrochemical properties of the acid-oxidized carbon nanotubes and tin oxide. The nanocomposites show higher specific capacities than the acid-oxidized carbon nanotubes and better cyclability than SnO 2, and the improvement is believed to be due to the improved maintainability of high dispersion of SnO 2 in the carbon nanotubes. The second cycle de-lithiation capacity of 255 mAh/g from the nanocomposites was nevertheless reduced to 250 mAh/g after 50 deep charge and discharge cycles, and the nanocomposites of acid-oxidized carbon nanotubes and SnO 2 may be considered as a candidate anode material for Li-ion batteries.

New manganese dioxides for lithium batteries

Lithium/manganese dioxide primary batteries use heat treated manganese dioxide (HEMD), a defect pyrolusite structure material as the cathode active material. Ion exchange of the structural protons in electrolytic manganese dioxide (EMD) with lithium before heating results in formation of a lithium containing γ-MnO 2. Increased lithium hydroxide concentration and increased temperature lead to increased lithium levels. At 80 °C with a combination of LiOH and LiBr, almost all of the structural protons in MnO 2 are replaced by lithium resulting in a γ-MnO 2 phase substantially free of protons and containing about 1.8% Li. This highly substituted lithium containing MnO 2 is reduced at between 3.5 and 1.8 V and has a capacity of 250 mAh g −1. There are two reduction processes, one at 3.25 and the other at 2.9 V. TGA studies reveal two processes during heat treatment. Heating the lithium substituted MnO 2 to 350–400 °C results in a partially ordered HEMD-like MnO 2 (LiMD) phase with higher running voltage and superior discharge kinetics. Continued heating of the lithiated manganese dioxide to 450–480 °C under oxygen partial pressure can result in formation of a mixed phase containing both HEMD and a new, ordered MnO 2 phase (OMD). The intimately mixed HEMD/OMD composition has a discharge voltage near 2.9 V with a capacity about 220 mAh g −1. Heating exhaustively lithiated MnO 2 to 350–400 °C results in formation of the partially ordered LiMD MnO 2 phase as with the previous partially lithium substituted MnO 2. Additional heating of the highly lithium substituted MnO 2 to 450–480 °C under oxygen results in formation of the new OMD phase in substantially pure form. Discharge of the new OMD phase shows it has a discharge capacity near 200 mAh g −1 between 3.4 and 2.4 V versus lithium in a single, well-defined discharge process. OMD demonstrated good cycling against Li with no indication of formation of LiMn 2O 4 spinel after 80 deep discharge cycles.

Electrochemical lithiation and de-lithiation of carbon nanotube-Sn 2Sb nanocomposites

Nanocomposites of carbon nanotubes (CNTs) with Sn 2Sb alloy nanoparticles were prepared by KBH 4 reduction of SnCl 2 and SbCl 3 precursors in the presence of CNTs. SEM and TEM examinations showed that most of the Sn–Sb alloy nanoparticles were present in high dispersion in the CNT web, while others were deposited directly on the outside surface of the carbon nanotubes. Constant current charge and discharge tests using the nanocomposites as Li + storage compounds showed higher specific capacities than pristine CNTs and better cyclability than unsupported Sn 2Sb particles. The first cycle de-lithiation capacity of 580 mAh/g from a CNT–56 wt%Sn 2Sb nanocomposite was nevertheless reduced to 372 mAh/g after 80 deep charge and discharge cycles. The uniform dispersion of Sn 2Sb alloy in the CNT web and on the surface of CNTs have substantially improved the usability of the Sn 2Sb particles to the extent that the nanocomposites of CNTs and Sn 2Sb may be considered as a candidate anode material for Li-ion batteries.

A Vanadium‐Based Cathode for Lithium‐Ion Batteries

A vanadium‐based oxide system has been developed as a cathode for use in a lithium‐ion battery. The lithiated material was made in two steps, i.e., 1, making a Li‐V‐O and, 2, introducing lithium into the intercalation host by reducing the V(V) with ions in the form of lithium sulfide. The stoichiometry of the final product corresponds approximately to . This material has shown excellent resistance to dissolution in ethylene carbonate/dimethyl carbonate electrolyte. The capacity of the material cycling at a C/3 rate over the voltage range of 3.8–2.0 V is ∼220 mAh/g. has demonstrated some stability in an ambient environment. This new cathode is capable of storing large amounts of energy, 630 mWh/g. has exhibited long cycle life, greater than 100 deep discharge cycles vs. lithium metal. © 2000 The Electrochemical Society. All rights reserved.

99/03808 Reliability of rechargeable batteries in a photovoltaic power supply system: Urbina, A. et al. J. Power Sources, 1999, 80, (1/2), 30–38

We investigate the reliability If a rechargeable battery acting as the energy storage component in a photovoltaic power supply system. A model system was constructed for this that includes the solar resource, the photovoltaic power supp Iy system, the rechargeable battery and a load. The solar resource and the system load are modeled as SI ochastic processes. The photovoltaic system and the rechargeable battery are modeled deterministically, imd an artificial neural network is incorporated into the model of the rechargeable battery to simulate dartage that occurs during deep discharge cycles. The equations governing system behavior are solved simultaneously in the Monte Carlo framework and a fwst passage problem is solved to assess system reliability.

Reliability of rechargeable batteries in a photovoltaic power supply system

We investigated the reliability of a rechargeable battery acting as the energy storage component in a photovoltaic power supply system. A model system was constructed for this that includes the solar resource, the photovoltaic power supply system, the rechargeable battery and a load. The solar resource and the system load are modelled as stochastic processes. The photovoltaic system and the rechargeable battery are modelled deterministically, and an artificial neural network is incorporated into the model of the rechargeable battery to simulate damage that occurs during deep discharge cycles. The equations governing system behaviour are solved simultaneously in the Monte Carlo framework, and a first passage problem is solved to assess system reliability.

Effects of compression on recombinant battery separator mats in valve-regulated lead–acid batteries

The spring characteristics of a typical recombinant battery separator mat (RBSM) material used in valve-regulated lead–acid (VRLA) batteries have been monitored at several stages during repetitive deep-discharge cycling service (C3/3, 100% DoD). Through the controlled application of a range of compressive loads, accurate plots of separator thickness vs. compressive force have been recorded for both dry and acid-saturated material. From subsequent analysis, several important properties have been established. Dry RBSM accepts some `crush' during the first application of pressure. At high levels of force (≥60 kPa), RBSM suffers a second stage of crush that can be permanent. Saturation with sulphuric acid solution produces a discernible shrinkage of the material. Thus, for a given thickness of RBSM, an acid-saturated separator will apply less force to the plates than a dry equivalent. This has important consequences for the manufacture of VRLA batteries. In particular, with present separator technology, it would appear that even the use of relatively high levels of compression during the assembly of RBSM VRLA cells is not an effective strategy for attaining the levels of compression required to prevent significant expansion of the positive plates. The difficulties of setting, and then maintaining, adequate levels of plate group compression are further underlined by the promising performance of a constant-compression RBSM VRLA cell. By means of a feedback-controlled system that applies a pressure of close to 40 kPa, this first-of-its-kind cell has displayed relatively stable cycling behaviour.

Battery pack having memory

In an exemplary embodiment, a battery conditioning system monitors battery conditioning and includes a memory for storing data based thereon; for example, data may be stored representative of available battery capacity as measured during a deep discharge cycle. With a microprocessor monitoring battery operation of a portable unit, a measure of remaining battery capacity can be calculated and displayed. Where the microprocessor and battery conditioning system memory are permanently secured to the battery so as to receive operating power therefrom during storage and handling, the performance of a given battery in actual use can be accurately judged since the battery system can itself maintain a count of accumulated hours of use and other relevant parameters. In the case of a nonportable conditioning system, two-way communication may be established with a memory associated with the portable unit so that the portable unit can transmit to the conditioning system information concerning battery parameters (e.g. rated battery capacity) and/or battery usage (e.g. numbers of shallow discharge and recharge cycles), and after a conditioning operation, the conditioning system can transmit to the portable unit a measured value of battery capacity, for example. A battery pack having memory stores battery history and identifying data to be retrieved by a portable battery powered device. Battery status information may be utilized in conjunction with characteristic battery history data in order to optimize charging and discharging functions and to maximize the useful life of a battery pack.

Redox Processes at the Manganese Dioxide Electrode: III. Detection of Soluble and Solid Intermediates during Reduction

The soluble and solid‐state intermediates formed during redox cycling of electrodeposited manganese dioxide (EMD), birnessite and chemically modified EMD (Bi‐CMEMD), and birnessite (Bi‐birnessite) electrodes were investigated using a stationary detector electrode (soluble intermediates) and x‐ray diffraction (solid‐state intermediates). Reduction of each electrode type can be divided into a homogeneous stage followed by a heterogeneous stage. For all electrode types, homogeneous reduction was a solid‐state process involving proton and electron insertion into the manganese dioxide structure, causing a lattice expansion. Toward the end of homogeneous EMD reduction, soluble species were detected, presumably due to an equilibrium shift between solid and solution phase species. The homogeneous/heterogeneous transition was also electrode dependent; i.e., for EMD and Bi‐CMEMD, for birnessite, and for Bi‐birnessite. Heterogeneous electrochemical behavior was also electrode dependent. Initial heterogeneous reduction of EMD, Bi‐birnessite, and Bi‐CMEMD proceeded through a soluble intermediate to form . Electrolyte concentration effects were more pronounced in this stage, since more concentrated KOH electrolytes lead to greater solubility. The composition at which was first detected in the Bi‐birnessite electrode suggested that the Mn(IV) to Mn(III) and Mn(III) to Mn(II) reduction processes occurred simultaneously. Heterogeneous reduction of birnessite was a solid‐state process that resulted in , which is electrochemically inactive. oxidation resulted in formation of birnessite, the exact nature of which depended on the presence or absence of ions. Under these deep discharge cycling conditions, the EMD electrode behaved poorly due to the eventual formation of . However, the Bi‐birnessite and Bi‐CMEMD electrodes are rechargeable due to the presence of ions, which prevent formation.