Li-ion Microbatteries Research Articles

A Li-Ion Microbattery with 3D Electrodes of Different Geometries

A Li-ion microbattery comprising three-dimensional (3D) electrodes of different geometries is reported. While aluminum nanorods are used as the negative electrode a 3D carbon matrix with a larger s ...

On the electrophoretic and sol–gel deposition of active materials on aluminium rod current collectors for three-dimensional Li-ion micro-batteries

Electrophoretic deposition of titanium oxide particles, as well as sol–gel synthesis of thin films of TiO2 employing a titanium isopropoxide precursor solution, were studied as possible deposition routes for the coating of aluminium pillar current collectors intended for three-dimensional Li-ion micro-batteries. While electrophoresis of TiO2 particles was homogeneously covering the two-dimensional aluminium substrates, it was difficult to conformally coat the three-dimensional current collectors with this technique. The sol–gel approach, on the other hand, gave rise to thin and amorphous TiO2 layers on the Al rod based current collectors. The latter could be cycled for 100cycles indicating that such straightforward sol–gel approaches may be used for the manufacturing of 3D electrodes for Li-ion micro-batteries.

Design and Fabrication of an All‐Solid‐State Thin‐Film Li‐Ion Microbattery with Amorphous TiO2 as the Anode

AbstractWe have fabricated an all‐solid‐state thin film microbattery by using reactive radio frequency (RF) magnetron sputtering of the positive LiNi1/3Mn1/3Co1/3O2 (LNMC) electrode at an elevated temperature, amorphous Li3+xPO4−xNx (LiPON) electrolyte at room temperature, and in situ deposition of an amorphous titania (TiO2) film below 200 °C. Electrochemical measurement of the TiO2 half‐cell reveals a first discharge capacity of 102 μAh cm−2 μm−1 with 86 % capacity retention after 100 cycles. A capacity of 58 μAh cm−2 μm−1 from the LNMC thin film electrode can be achieved. The initial capacity of the TiO2/LiPON/LNMC full‐cell is as high as 52 μAh cm−2 μm−1 and 90 % capacity is retained after 400 cycles.

Silicon‐Microtube Scaffold Decorated with Anatase TiO2 as a Negative Electrode for a 3D Litium‐Ion Microbattery

An optimized scaffold based on silicon microtubes is designed to increase the surface capacity of 3D lithium‐ion microbatteries. High‐depth, mechanically robust microstructures are fabricated using microelectronic facilities. Conformal deposition of anatase TiO2 is achieved using atomic layer deposition, realizing the targeted improvement for microbatteries; a surface capacity of 0.2 mA h cm–2 at a charge rate of C/10 is obtained in standard liquid electrolyte. This work paves the way for the fabrication of solid‐state 3D Li‐ion microbatteries with an efficient 3D scaffold.

Laser-printing and femtosecond-laser structuring of LiMn2O4 composite cathodes for Li-ion microbatteries

Porous LiMn2O4 thick-film cathodes for Li-ion microbatteries are realized by laser-printing. The porous structure of the printed composite cathode consisting of active powder, binder, carbon black and graphite enables ionic and electronic transport through 50–60 μm thick electrodes due to its high intrinsic active surface area. In order to further improve the cycle stability and capacity retention of the laser-printed thick-film cathodes for discharging rates up to 1 C, laser-printed thick films are first calendered in a press and then structured using ultrafast femtosecond-laser radiation in order to form three-dimensional (3D) cathode architectures. It is shown that calendered/laser structured cathodes in the form of rectangular 3D grids exhibit discharge capacity retention of 68% at a 1 C rate, while calendered but unstructured cathodes retain only about 45% of their initial capacity at the same discharge rate. Overall, the improved discharge capacity retention and reduced degradation during later cycles can be attributed to the combination of increased electrical contact with shortened Li-ion pathways.

Enhanced reversible lithium storage in germanium nano-island coated 3D hexagonal bottle-like Si nanorod arrays

The rapid development of numerous microscale electronic devices, such as smart dust, micro or nano bio-sensors, medical implants and so on, has induced an urgent demand for integratable micro or nano battery supplies with high energy and power densities. In this work, 3D hexagonal bottle-like Si/Ge composite nanorod (NR) array electrodes with good uniformity and mechanical stability potentially used in micro or nano rechargeable Li-ion batteries (LIBs) were fabricated on Si substrates by a cost-effective, wafer scale and Si-compatible process. The optimized Ge nano-islands coated Si NR composite arrays as anode materials exhibit superior areal capacities and cycling performances by virtue of their favourable structural and improved conductivity features. The unique Si-based composite electrode in nanostructures can be technically and fundamentally employed to configurate all-solid-state Li-ion micro-batteries as on-chip power systems integrated into micro-electronic devices such as M/NEMS devices or autonomous wireless microsystems.

The impact of size effects on the electrochemical behaviour of Cu2O-coated Cu nanopillars for advanced Li-ion microbatteries

The generation of a distribution of nanoparticles upon conversion reaction of thin Cu2O layers is demonstrated to produce a wide electrochemical potential window, as well as a distinctive capacity increase in large area three-dimensional electrodes. Cu nanopillars with a 10–15 nm Cu2O coating containing traces of nanocrystalline Fe2O3 yield capacities up to 0.265 mA h cm−2 (at 61 mA g−1), excellent cycling for more than 300 cycles and an electroactive potential window larger than 2 V, due to the size effects caused by the various Cu/Cu2O nanoparticles formed during conversion/deconversion. These 3D Li-ion battery electrodes based on electrodeposited Cu nanopillars spontaneously coated with a Cu2O layer are compatible with current densities of 16 A g−1 (i.e. 61 C rates) after aerosol-assisted infiltration with an iron acetate solution followed by low-temperature pyrolysis. The capacity of the composite material increases by 67% during 390 cycles due to the growth of the electroactive area during the electrochemical milling of Cu2O forced by its repeated conversion/de-conversion. The latter generates a distribution of nanoparticles with different sizes and redox potentials, which explains the broad potential window, as well as the significant capacity contribution from double layer charging. These 3D electrodes should be well-suited for Li-ion microbatteries and Li-ion batteries in general, since they combine high capacities per footprint area with excellent power capabilities. More importantly, such electrodes grant access to fundamental understanding of the electrochemical behaviour of these active materials providing new insights into both conversion mechanisms and nanostructured interfaces more in general.

Synthesis of ion conducting LixAlySizO thin films by atomic layer deposition

Thin films of a solid electrolyte, lithium aluminosilicate, were synthesized by atomic layer deposition (ALD) for potential applications in 3D Li-ion microbatteries. The films were deposited at 290 °C via alternating the ALD growth of the constituents, LiOH, Al2O3 and SiO2. Manipulation of the cation composition and thickness was achieved through well-controlled surface reactions during each precursor pulse cycle. Various compositions were obtained by changing the number of pulse cycles for each precursor, which enabled lithium aluminate (LixAlyO), lithium aluminosilicate (LixAlySizO) and stoichiometric LiAlSiO4 materials to be prepared. The as-deposited ALD films were amorphous and formed conformal coatings over Si nanowires. Films as thin as 6 nm were found to be free of pinholes. Complex impedance measurements confirmed that the films were ionic conductors with the room temperature conductivity in the range of 10−7 to 10−9 S cm−1 and an activation energy between 0.46 and 0.84 eV, depending upon the film composition.

Nanocrystalline mesoporous LiFePO4 thin-films as cathodes for Li-ion microbatteries

Download options Please wait... Article information DOI https://doi.org/10.1039/C3TA14142J Article type Paper Submitted 15 Oct 2013 Accepted 06 Dec 2013 First published 09 Dec 2013 Download Citation J. Mater. Chem. A, 2014,2, 3038-3046 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Nanocrystalline mesoporous LiFePO4 thin-films as cathodes for Li-ion microbatteries J. Mosa, M. Aparicio, A. Durán, C. Laberty-Robert and C. Sanchez, J. Mater. Chem. A, 2014, 2, 3038 DOI: 10.1039/C3TA14142J To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Jadra Mosa Mario Aparicio Alicia Durán Christel Laberty-Robert Clement Sanchez

Energy Focus: Li-ion microbattery fabricated by 3D printing

Energy Focus: Li-ion microbattery fabricated by 3D printing

Lithium borophosphate thin film electrolyte as an alternative to LiPON for solder-reflow processed lithium-ion microbatteries

Microbatteries are energy sources well adapted to power various microsystems. To be considered as a microelectronic component, the microbatteries must be compatible with the solder-reflow treatment. During this industrial process, the temperature reaches 260 °C during few seconds. Having noticed an increase of the activation energy of the most used solid electrolyte lithium phosphate thin film (LiPON) after this type of thermal treatment, from 0.57 eV to 0.80 eV, we have investigated the correlations between composition, local structure (by XPS) and the electrical properties of lithium borophosphate solid electrolyte thin films. The lithium borophosphate thin films were prepared by radio-frequency sputtering using five different targets having the following compositions x LiBO2: (1 − x) Li3PO4 (x = 5, 10, 15, 20 and 25) in a pure argon discharge gas. In the absence of a thermal treatment, the addition of a small amount of boron (B/P ratio equal to 0.1) leads to an increase of the ionic conductivity (1.1 × 10− 6 S·cm− 1) and a decrease of the activation energy (0.52 eV) compared to a pure lithium phosphate. However, for B/P ratio higher than 0.12, the ionic conductivity decreases. The study of the local structure by X-ray photoelectron spectroscopy (XPS) shows that the borate groups have less reacted with the phosphate groups leading to a phase separation reducing the connectivity between phosphate and borophosphate networks and so the ionic conductivity. The solder-reflow type thermal treatment leads to an increase of the ionic conductivity. The best ionic conductivity, 1.9 × 10− 6 S·cm− 1, is obtained for a B/P ratio equal to 0.24 with an activation energy of 0.57 eV instead of 0.80 eV for the LiPON thin film. For a use of Li-ion microbattery at low temperature after the solder-reflow type thermal treatment, the lithium borophosphate solid electrolyte would be a potential candidate to replace LiPON with several industrial advantages.

Superior electrochemical properties of porous Mn2O3-coated LiMn2O4 thin-film cathodes for Li-ion microbatteries

Thin-film LiMn2O4 cathodes coated with Mn2O3 overlayer were prepared by a sol–gel method for Li-ion microbattery tests. The double-layered structure was fabricated on Pt(111) substrate through spin-coating the precursor solution for LiMn2O4 followed by that for Mn2O3. The Mn2O3 overlayer exhibited granular morphology with significant volume of pores while the LiMn2O4 film consisted of compacted grains. The electrochemical properties of the porous Mn2O3-coated LiMn2O4 (Mn2O3/LiMn2O4) cathodes characterized by charge–discharge (C–D) cycling performance, cyclic voltammetry, and rate capability were compared with those of the pristine LiMn2O4 cathodes. The Mn2O3/LiMn2O4 cathodes exhibited good cycle-life, only 0.007% capacity loss per cycle at 25°C, thereby achieved discharge capacity retention of 80% after 3000 cycles, while the pristine LiMn2O4 cathodes retained only 35% of the initial capacity under the same C–D condition. The Mn2O3/LiMn2O4 cathodes also exhibited better rate capabilities compared to the pristine LiMn2O4 cathodes. The improved electrochemical performance is ascribed to the porous Mn2O3 overlayer that not only protects the underlying LiMn2O4 film from direct exposure to the electrolyte but also provides efficient Li+ diffusion path during the C–D cycling.

High energy and power density TiO2 nanotube electrodes for 3D Li-ion microbatteries

Highly ordered anodic TiO2 nanotube arrays with a tube length of 9 μm are shown to provide areal capacities of 0.24 mA h cm−2 (i.e. 96 mA h g−1) at a charge/discharge current density of 2.5 mA cm−2 (corresponding to a rate of 5 C) and 0.46 mA h cm−2 (i.e. 184 mA h g−1) at 0.05 mA cm−2, when used as 3D free-standing anodes in Li-ion microbatteries. The present nanotube electrodes, which could be cycled for 500 cycles with only 6% loss of capacity, exhibited significantly higher energy and power densities, as well as an excellent cycling stability compared to previously reported TiO2-based Li-ion microbattery electrodes. The influence of parameters such as ordering, geometry and crystallinity of the nanotubes on the microbattery performance was investigated. A two-step anodization process followed by annealing of the nanotubes was found to yield the best microbattery performance. It is also demonstrated that the rate capability of the electrode depends mainly on the rate of the structural rearrangements associated with the lithiation/delithiation reaction and that the areal capacity at various charge/discharge rates can be increased by increasing the tube wall thickness or the length of the nanotubes, up to 0.6 mA h cm−2 for 100 cycles.

Sulfidated TiO2nanotubes: A potential 3D cathode material for Li-ion micro batteries

In this work, self-organized titania nanotubes are sulfidated by an annealing treatment to produce TiOxSy nanotubes. Morphological, structural and electrochemical analyses show that this 3D nanostructured electrode is a potential cathode material for Li-ion microbatteries.

Architecturing Hierarchical Function Layers on Self-Assembled Viral Templates as 3D Nano-Array Electrodes for Integrated Li-Ion Microbatteries

This work enables an elegant bottom-up solution to engineer 3D microbattery arrays as integral power sources for microelectronics. Thus, multilayers of functional materials were hierarchically architectured over tobacco mosaic virus (TMV) templates that were genetically modified to self-assemble in a vertical manner on current-collectors, so that optimum power and energy densities accompanied with excellent cycle-life could be achieved on a minimum footprint. The resultant microbattery based on self-aligned LiFePO(4) nanoforests of shell-core-shell structure, with precise arrangement of various auxiliary material layers including a central nanometric metal core as direct electronic pathway to current collector, delivers excellent energy density and stable cycling stability only rivaled by the best Li-ion batteries of conventional configurations, while providing rate performance per foot-print and on-site manufacturability unavailable from the latter. This approach could open a new avenue for microelectromechanical systems (MEMS) applications, which would significantly benefit from the concept that electrochemically active components be directly engineered and fabricated as an integral part of the integrated circuit (IC).

Facile fabrication of cuprous oxide nanocomposite anode films for flexible Li-ion batteries via thermal oxidation

In the present work, nanostructured Cu2O films are directly grown from a Cu metal foil by means of a rapid thermal oxidation process. The structural characteristics of the films are investigated by field emission scanning electron microscopy, X-ray diffraction and attenuated total reflectance Fourier-transformed infrared spectroscopy. The electrochemical behaviour is investigated in both lithium (liquid electrolyte) and all-solid lithium polymer cells. At a discharge/charge rate of C/5, the films can provide a specific capacity greater than 220 mAh g-1 in the all-solid configuration, with excellent cycling stability and capacity retention after prolonged cycling. High surface area, short diffusion path and good conduction of the Cu2O films are considered to be responsible for the good electrochemical performance, along with the use of the polymeric electrolyte which is directly formed in situ on the electrode film surface. The present findings can provide a new and easy approach to fabricate nanocomposite films with interesting performance as negative electrode particularly for the next generation of flexible all-solid-state Li-ion microbatteries.

Li4Ti5O12 thin-film electrodes by sol–gel for lithium-ion microbatteries

Spinel Li4Ti5O12 has been considered as one of the most prospective anode materials for Li-ion microbatteries. Homogeneous, transparent and crack-free Li4Ti5O12 coatings with thickness around 110 nm have been prepared by dipping gold-coated quartz substrates in sols prepared using titanium isopropoxide and lithium acetate. The influence of the thermal treatment on the phase composition, structure and electrochemical behavior was studied. Rutile TiO2 (considered as an impurity in this study) is only detected in the coatings treated at 700 °C. XPS and TOF-SIMS depth profiles show a homogeneous distribution, with a Li increase and Ti reduction at the surface. Electrochemical characterization of samples treated at 600 °C presents a redox reaction around 1.55 V indicating that the film is simple phase of Li4Ti5O12. The shift to slightly lower voltage in samples treated at 700 °C is a consequence of Rutile impurities. Larger capacity and good reversibility in the sample heat-treated at 600 °C can be attributed to high crystallinity of Li4Ti5O12 and phase purity. RBS analysis specifies a composition close to Li4Ti5O12 in the case of the pristine and charged samples, and Li7Ti5O12 for the discharged sample. Surface XPS study confirms the presence of an outermost layer containing LiF and Li2CO3.

Laser-Printed and Processed LiCoO2 CathodeThick Films for Li-Ion Microbatteries

Thick-film electrodes (LiCoO2 cathode and carbon anode) are laser-printed onto metallic current collectors for fabricating Li-ion microbatteries. Microbatteries fabricated with these laser-printed thick-film electrodes demonstrate a significantly higher discharge capacity and power density than those made by sputter-deposited thin-film techniques. This increased performance is attributed to the porous structure of the laser-printed electrodes that allows improved ionic and electronic transport through the thick electrodes (up to ~100 µm) without a significant increase in internal resistance. Laser structuring process is applied to increase active surface area of the laser-printed LiCoO2 cathode films for improving cycle stability of microbatteries at high charging/discharging currents. Laser structuring parameters, including laser pulse number and laser fluence, are optimized for improving surface morphology of the films.

Novel multiphase electrode/electrolyte composites for next generation of flexible polymeric Li-ion cells

An innovative multiphase electrode/electrolyte composite is proposed here, which is obtained by a fast, versatile and easily scalable UV-induced free-radical photo-polymerisation technique. This novel configuration consists of a methacrylic-based polymer electrolyte directly formed in situ at the interface of different electrode films (i.e. commercial graphite and hydrothermally synthesized LiFePO4). Conformal coatings are confirmed by SEM analysis which indicates an intimate interfacial adhesion between the electrode material particles and the polymer electrolyte. Laboratory-scale lithium pouch cells assembled by contacting a lithium metal counter electrode over the as-prepared electrode/electrolyte composites display good ambient temperature charge/discharge characteristics, at the level of the corresponding lithium cells in liquid electrolyte, along with very stable cyclability even at high current rates. In addition, preliminary results of a laboratory-scale Li-ion polymer cell, assembled by contacting the LiFePO4 cathode with the graphite anode, both in situ coated with the polymer electrolyte, are presented. The obtained findings outline the practical relevance of the novel procedure adopted which leads to the preparation of composite films with interesting performance, particularly for the next generation of flexible all-solid-state Li-ion microbatteries.

Transition Metal Oxide Particles Deposited onto Titania Nanotubes as High Performance Electrodes for Li-Ion Microbatteries

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