Low-cost Lithium-ion Batteries Research Articles

Creating value added nano silicon anodes from end-of-life photovoltaic modules: recovery, nano structuring, and the impact of ball milling and binder on its electrochemical performance

Recovery of silicon from end-of-life photovoltaic (PV) modules, purification, conversion to nano silicon (nano-Si), and subsequent application as an anode in lithium-ion batteries is challenging but can significantly influence the circular economy. Currently, a complete technology consisting of cross-contamination-free recovery of silicon wafers from end-of-life PV modules, a low-cost environmentally friendly purification process of the recovered PV silicon, a high yield conversion process of the recovered PV silicon into nano-Si, and its subsequent application in lithium-ion batteries is unavailable. This study provides a complete package including cross-contamination-free recovery, economical purification, reliable conversion to nano-Si, and efficient application of the end-of-life PV nano-Si in lithium-ion batteries. Hydrofluoric acid-free recovery and purification processes are demonstrated which can deliver large quantities of high-purity (≥ 99) silicon. In addition, the subsequent ball milling process produces very distinct nano-Si with different shapes and sizes. This study also creates a very effective nano-Si anode through in-situ crosslinking of water-soluble carboxymethyl cellulose and poly (acrylic acid) precursors. The integration of distinct PV nano-Si and water-soluble carboxymethyl cellulose-poly (acrylic acid) crosslink binder opens distinct possibilities to develop silicon-based practical anode for next generation low-cost lithium-ion batteries to power cell phones to electric vehicles.

Inhibit the strain accumulation for 5V spinel cathode by mitigating the phase separation during high voltage stage

LiNi0.5Mn1.5O4 (LNMO) spinel cathode is a potential cathode material for high-power, low-cost lithium-ion batteries (LIBs) due to its low raw material cost, high operating voltage and efficient lithium-ion transport channel. However, LNMO suffers from structural stability due to the two-phase-transformation during charge/discharge process, leading to poor cycling performance. To address the issues, we have constructed a homogeneous aggregated LNMO cathode with a multifaceted primary particle, namely the LNMO with single-crystal secondary particles (SSP LNMO). Ex situ and in situ characterizations including the synchrotron X-ray diffraction, the neutron diffraction and full pouch cell validated that the SSP LNMO exhibit a single solid-solution reactions with a restrained lattice evolution during the delithiation/ lithiation process. This is in contrast to the normal LNMO cathode, which demonstrates a significant two-phase transition from spinel Li1−xNi0.5Mn1.5O4 to rock-salt MnO2 at high voltage. Therefore, the SSP LNMO has greatly improved cycle life compared to the normal LNMO cathode. Overall, this study demonstrates the possibility of constructing LNMO based on primary-grain morphology modulation to improve the intrinsic stability of LIBs.

Interfacial Modulation of a Self-Sacrificial Synthesized SnO2@Sn Core-Shell Heterostructure Anode toward High-Capacity Reversible Li+ Storage.

Sn-based anodes are promising high-capacity anode materials for low-cost lithium ion batteries. Unfortunately, their development is generally restricted by rapid capacity fading resulting from large volume expansion and the corresponding structural failure of the solid electrolyte interphase (SEI) during the lithiation/delithiation process. Herein, heterostructural core-shell SnO2-layer-wrapped Sn nanoparticles embedded in a porous conductive nitrogen-doped carbon (SOWSH@PCNC) are proposed. In this design, the self-sacrificial Zn template from the precursors is used as the pore former, and the LiF-Li3N-rich SEI modulation layer is motivated to average uniform Li+ flux against local excessive lithiation. Meanwhile, both the chemically active nitrogen sites and the heterojunction interfaces within SnO2@Sn are implanted as electronic/ionic promoters to facilitate fast reaction kinetics. Consequently, the as-converted SOWSH@PCNC electrodes demonstrate a significantly boosted Li+ capacity of 961 mA h g-1 at 200 mA g-1 and excellent cycling stability with a low capacity decaying rate of 0.071% after 400 cycles at 500 mA g-1, suggesting their great promise as an anode material in high-performance lithium ion batteries.

Stable cycling of LiNi0.9Co0.05Mn0.05O2/lithium metal batteries enabled by synergistic tuning the surface stability of cathode/anode

Ni-rich layered oxides (LiNi0.9Co0.05Mn0.05O2) show great potential in long-range and low-cost lithium-ion batteries. However, due to the high surface sensitivity, their practical application is hindered by interfacial instability with electrolytes under high voltage for long cyclic life. Herein, by combining both first-principle calculations and time-of-flight secondary ion mass spectrometry (TOF-SIMS), a novel surface fluorinated reconstruction (SFR) mechanism is proposed to improve the interfacial stability under high voltage, which could effectively regulate the surface fluoride species to desensitize the LiNi0.9Co0.05Mn0.05O2 interface. We demonstrate here that by tuning the ratio of fluoride species, the LiNi0.9Co0.05Mn0.05O2/Li battery could achieve excellent long-term and high voltage performance (163.5 mA h g−1 at 0.5 C for 300 cycles under 4.4 V), while the controlled sample decayed to 125.4 mA h g−1 after 300 cycles. Moreover, the favorable cross-talk effect induced by SFR further facilitates the incorporation of suitable amounts of Ni ions into the construction of stable solid electrolyte interface (SEI) layer for anode surface. Therefore, the ultra-long cycling stability under high voltage can be achieved by the robust cathode/electrolyte and Li/electrolyte interfaces, which results in excellent interfacial stability after long cycling. This work provides new insights into the surface design of cathode materials and improves the stability of the electrode-electrode interface under high voltage.

Insights into the Chemistry of the Cathodic Electrolyte Interphase for PTFE-Based Dry-Processed Cathodes.

Dry processing is a promising method for high-performance and low-cost lithium-ion battery manufacturing which uses polytetrafluoroethylene (PTFE) as a binder. However, the electrochemical stability of the PTFE binder in the cathodes and the generated chemistry of the cathode electrolyte interphase (CEI) layers are rarely reported. Herein, the CEI properties and PTFE electrochemical stability are studied via cycling the high-loading dry-processed electrodes in electrolytes with LiPF6 or LiClO4 salt. Using LiClO4 salt can eliminate other possible F sources, allowing the decomposition of PTFE to be studied. The detection of LiF in cells with the LiClO4 salt confirms that PTFE undergoes side reaction(s) in the cathodes. When compared with LiClO4, the CEI layer is much thicker when LiPF6 is used as the electrolyte salt. These results provide insights into the CEI layer and may potentially enlighten the development of binders and electrolytes for the high efficiency and long durability of DP-based LIBs.

Simpler and greener preparation of an in-situ polymerized polyimide anode for lithium ion batteries

A simplified and greener procedure for in-situ obtaining polyimide anode materials for lithium-ion battery electrodes is developed. The combined polyimide material synthesis and electrode preparation reduces the number of processing steps and treatment duration and decreases the energy required for heat treatment, solvent evaporation, and organic solvent use. More importantly, polymerization in situ on the electrode surface render the polyimide particles a sea urchin-like structure, leading to fast electrochemical kinetics, and significant improvement in discharge capacity and cycling performance compared with materials obtained using traditional procedures. Specific capacities of 1870 mAh g− 1 and 2277 mAh g− 1 at 30 °C and 60 °C, respectively, are obtained. A capacity of 1774 mAh g− 1 is retained after 500 cycles at high current density of 1000 mA g− 1 at 60 °C. This new preparation process not only simplifies the preparation process and makes it greener, but also significantly improves the battery performance, providing new possibilities for the preparation of high-performance low-cost lithium-ion battery electrodes.

Co-free/Co-poor high-Ni cathode for high energy, stable and low-cost lithium-ion batteries

Co-free/Co-poor high-Ni cathode for high energy, stable and low-cost lithium-ion batteries

Timely or early? Breaking away from cobalt-reliant lithium-ion batteries

The discovery and continual development of lithium-ion batteries (LIBs) are the keys to enabling the global implementation of smart devices and electric vehicles (EVs). On the cathode side, transitioning away from the highly priced cobalt has been a prerequisite for the grant mission of achieving complete vehicle electrification yet a major challenge for the battery research communities. In this perspective, from the aspects of material design and optimization, the current status and future contour of cathodes are sketched in pursuing the ever-increasing threshold of high-performance and low-cost LIBs.

Evaluation of LiNiO2 with minimal cation mixing as a cathode for Li-ion batteries

The electric vehicle (EV) market has grown tremendously in recent years, and is driving the development of lithium-ion batteries (LIBs) for energy storage. To meet the demand for high-energy–density and low-cost LIBs, Co-free and Ni-rich cathodes (e.g., LiNiO2; LNO) and Si anodes are being investigated. However, drawbacks of LNO, such as cation mixing, processing challenges, and safety risks significantly limit its commercialization. Increasing the oxygen partial pressure (pO2) during calcination of LNO has been shown to maintain its structural order and electrochemical performance. However, the mechanism by this observation is not well understood. In this research, three pO2 conditions were applied during the calcination of LNO cathodes. The calcination pO2 affects the sub-surface of LNO rather than the bulk region. Synchrotron spectroscopy and in-situ pressure analysis confirmed that Ni2+ and excess Li are present on the sub-surface of the LNO processed at the lowest pO2. Increasing the pO2 decreases the off-stoichiometry of LNO by providing additional oxygen to compensate for oxygen loss, especially at the sub-surface. A detailed mechanism by which the calcination pO2 affects LNO is proposed. An LIB with the LNO cathode calcined at the highest pO2 had a high initial capacity of 239.8 mA h g−1 (93.4 %), excellent fast charging cycle retention of half-cell and full cell at 55 °C, little gas evolution during cycling, and almost no weight change during storage in air. This calcining strategy prevents the cation mixing limitation of LNO, taking it one step closer to future EV application.

Dual structure engineering of SiOx-acrylic yarn derived carbon nanofiber based foldable Si anodes for low-cost lithium-ion batteries.

Silicon (Si) is attracted much attention due to its outstanding theoretical capacity (4200 mAh/g) as the anode of lithium-ion batteries (LIBs). However, the large volume change and low electron/ion conductivity during the charge and discharge process limit the electrochemical performance of Si-based anodes. Here we demonstrate a foldable acrylic yarn-based composite carbon nanofiber embedded by Si@SiOx particles (Si@SiOx-CACNFs) as the anode material. Since the amorphous SiOx and carbon (C) coating on the outside of the Si particles can provide a double buffer for volume expansion while reducing the contact between the Si core and the electrolyte to form a thin and stable solid electrolyte interface (SEI) film. Simultaneous in-situ electrochemical impedance spectroscopy (in-situ EIS) and galvanostatic intermittent titration technique (GITT) tests show that SiOx and C have higher ion/electron transport rates, and in addition, using acrylic fiber yarn and Zn(Ac)2 as raw materials reduces the manufacturing cost and enhanced mechanical properties. Therefore, the half-cell can achieve a high initial Coulombic efficiency (ICE) of 82.3% and a reversible capacity of 1358.2 mAh/g after 180 cycles. It can return to its original shape and remain intact after four consecutive folds, and the soft-pack full battery can also light up LED lights under different bending conditions.

Solid electrolyte interphase layer induced electrochemical behavior diversity of aluminum foil anode for lithium ion batteries

Metal or alloy foil anode has attracted great attention for high energy density and low-cost Lithium ion batteries (LIBs). However, the intractable challenges are still the low tolerance of volume change induced pulverization and associated solid electrolyte interphase (SEI) successive reconstruction, which leads to the fast performance degradation of LIBs. The SEI layer is supposed to play an important role in maintaining good charge transport behavior, and mechanical-electrochemical stability of the foil anode during (de) lithiation. Herein, we investigate the electrochemical behavior and corresponding structure evolution of Al foil anode, which exhibit a strong SEI dependence. The thin and robust SEI layer with much abundant LiF components and LiF/Li2CO3 heterostructures exhibits good ion transport capability. This kind of SEI layer can ease the pulverization of the Al anode during (de) lithiation at a certain extent, leading to much improved mechanical-electrochemical stability, Coulombic efficiency (CE), and depolarization phenomenon. The LIBs full-cell demonstrates a gravimetric specific capacity of 120 mAh g−1 at 1 mA cm−2 as long as 400 cycles, with a nearly 100% CE. This report offers an important compensation for systematic solution that can enable great bespoke performances of foil anode for high energy density and low-cost LIBs.

Magnesium doped LiNixMnyCozO2 cathode- structural properties

High energy density and low-cost lithium-ion batteries (LIBs) are the most efficient energy storage devices. Moreover, LIBs with nickel-rich LiNixMnyCozO2 (N-NMC) cathodes provide an attractive candidate for electric vehicle applications due to their performance metrics. In the N-NMC, each element offers different properties, including high capacity, good cycling, and excellent conductivity. But, ion mixing, metal-ion dissolution, oxygen loss, etc., on the cathode surface cause severe effects on the electrode. Consequently, magnesium (Mg) doping on the NMC cathode eliminates these drawbacks, ensures high thermal stability, inhibits cation mixing, and prevents irreversible capacity loss. Additionally, the low-cost co-precipitation method aids in the highly efficient synthesizing of homogeneous Mg-doped NMC cathode materials. Here, X-ray diffraction (XRD) confirms the phase and crystallinity of the materials, with I(003)/I(104) ratios of 1.4942, 0.9790, and 0.9148 for NMC, NMC1, and NMC2. The morphology of the layered pristine and doped NMC has been detected using a field emission scanning electron microscope (FESEM). Raman spectra determine the crystal chemistry of layered transition metals, while Fourier Transform Infrared Spectroscopy (FTIR) detects the vibration spectra of a substance. Based on these results, an improved N-NMC cathode may represent the best electrode material for energy storage devices.

Realizing high energy-density lithium-ion batteries: High Ni-content or high cut-off voltage of single-crystal layered cathodes?

• The electrochemical properties of SC-NCM613 and SC-NCM811 are systematically studied under the similar Li + deintercalation/intercalation. • The SC-NCM613 has an improved structural and air stability along with reduced cost compared with that of SC-NCM811. • Increasing the upper cut-off voltage of layered cathodes with relatively low Ni-content is a better choice for high-energy and low-cost LIBs. Improving Ni-content or upper cut-off voltage is usually utilized to boost the specific capacity of cathodes and the energy-density of lithium-ion batteries (LIBs). However, the performance comparison and structural evolutions between the aforementioned strategies have not been reported yet, especially under the same state of charge (SOC) of single-crystal layered ternary cathodes. Herein, the properties of single-crystal LiNi 0.6 Co 0.1 Mn 0.3 O 2 (SC-NCM613) and LiNi 0.8 Co 0.1 Mn 0.1 O 2 (SC-NCM811) are systematically studied under the similar Li + deintercalation/intercalation. Both single-crystal cathodes deliver a specific capacity of about 200 mAh g −1 with a median-voltage of 3.8 V. The SC-NCM613 under the cut-off of 4.5 V shows improved cycling life than that of SC-NCM811 under 4.3 V. Both single-crystal cathodes exhibit a similar rate property at 25 °C while SC-NCM613 has enhanced high-rate capacities as testing temperature drops to 0 °C. XRD results demonstrate that the enhanced stability of SC-NCM613 is ascribed to the reduced structural distortion at high SOC. Besides, SC-NCM613 has a decreased content of Ni 3+ ions, suggesting the improved air and storage stability. And Ni substituted by Mn in SC-NCM613 will reduce the cost of cathode. These results suggest that increasing the upper cut-off voltage of layered cathodes with relatively low Ni-content is a better choice for designing high-energy and low-cost LIBs.

Stabilization of Dual Interfaces for High-Capacity Sulfurized Polyacrylonitrile through Electrolyte Selection

Sulfurized polyacrylonitrile (SPAN) is considered as a promising cathode for the increasing need of high energy density and low-cost lithium-ion batteries. By chemically attaching sulfur to the conductive polymer backbone, SPAN system can promote a solid-solid conversion during the lithiation/delithiation process of sulfur, which avoids the polysulfide “shuttle effect”, and thus renders a better cycling stability compared to Li-sulfur system. However, due to the dissolving nature of long-chain polysulfide in ether-based electrolyte, SPAN annealed at high temperature is preferred in many Li-SPAN systems, which sacrifices the specific capacity in exchange for a higher cycling stability.Here, a new design strategy for Li-SPAN batteries is reported. We manipulate a multistage approach by selecting SPAN and compatible electrolyte to achieve high specific capacity and outstanding cycling stability. In this work, optimally annealed SPAN is selected to increase the capacity, and localized high-concentration electrolyte (LHCE) is chosen in consideration of stabilizing the interfaces on both cathode and anode. Compared with commonly used carbonated-based electrolyte, LHCE shows a great advantage on capacity and cycling stability. Moreover, the long cycling performance of the high-mass-loading full cells under room (23°C) and high (60°C) temperature is demonstrated with a great potential for high-energy and low-cost batteries.

Investigation of Cellulose-Based Separators for Secondary Lithium Metal Batteries

Lithium-ion batteries (LIBs) have been the predominant energy storage technology for a variety of applications such as portable electronic devices and wireless power tools. However, the rising demand for emerging technologies such as long-range electric vehicles and grid-level energy storage and delivery has drastically increased the necessity for low-cost LIBs with enhanced performance and safety.Improvements in the modern LIB technology can be achieved through improvements in different, individual components of the battery. Among the key components of the battery, the separator plays a vital role. To date, polypropylene (PP)/polyethylene (PE) membranes have been used as separators in LIBs due to their desired electrochemical stability. However, these separator materials suffer from low thermal stability, which results in their deformation or decomposition at elevated temperatures upon high charging rates1. A dangerous consequence of this material degradation is an electrical short, leading to an aggressive discharge of the battery and subsequent fire. Moreover, PP/PE separators possess relatively low electrolyte wettability and an expensive and eco-unfriendly fabrication process. Hence, alternative separator materials for future LIB technology are indispensable.Among alternative separator materials, cellulose is a promising candidate2. Cellulose is derived from biomass which is one of the most abundant and renewable resources on Earth. It also is non-toxic and has high mechanical and chemical stability. Additionally, with an initial decomposition temperature of 270°C, cellulose offers a major advantage in thermal stability compared to its polymeric competitors3. The thermal and electrochemical stability, electrolyte wettability, and performance of cellulose-based separators in LIBs have been studied3,4. However, those reports mostly consider the conventional LIB electrode materials– Li transition metal oxide and graphite; and focus on the separator/electrolyte compatibility. Therefore, to be considered for future generations of high-performance Li-based batteries, cellulose-based separators must be investigated in batteries with new electrode chemistries.This work presents new insights on the interaction of cellulose-based separator and metallic Li – the leading candidate for future anodes. Coin cells were prepared using various cathode materials, Li metal anode, and a commercial cellulose-based separator. The cycling performance of the cells was tested at different C rates. Results were compared with the cycling performance of the coin cells with similar electrodes but a commercial PP/PE separator. Comparable discharge profiles were observed in the two groups of cells, but the cellulose separator hampered the charging process. Additional electrochemical analysis suggested an undesired interaction between the cellulose-based separator and metallic Li. To further understand this interaction, various protective coatings on the separator were investigated, the results of which suggest a mechanical degradation in the cellulose separator during cycling and consequently a soft short. These results are expected to provide a new understanding regarding the stability of cellulose-based separators in Li metal-containing batteries, which can help with their implementation in the next generation of Li-based batteries with enhanced performance and safety.

High reversible capacity silicon anode by segregated graphene-carbon nanotube networks for lithium ion half/full batteries

Micron-sized Si-based materials have gained much attention recently in the pursuit of high-performance and low-cost lithium-ion battery (LIBs). However, huge volume variation and poor conductivity induce a rapid performance decline of Si microparticles. Herein, porous silicon microsphere segregated in graphene and carbon nanotube network (pSi/HCNT/rGO) is constructed by one-step hybrid and reduction self-assembly strategy. Carbon nanotubes provide the “safety belt” for the entire structure to block aggregation between rGO layers. The hierarchical porous structure composed by intrinsic pore structure of pSi and flexible carbon network effectively buffers the volume expansion and ensures the structural and interface stability in the lithium storage process, which also delivers multiple conductive pathways to boost Li+/e− migration efficiency. Proper configuration design leads to high charging capacity of 2319 mAh g−1 at 0.1 A g−1, exceptional initial Coulombic efficiency of 87.5 % (vs pSi of 55.8 %) and stable long cycle performance of 583 mAh g−1 after 400 cycles at 5 A g−1 when pSi/HCNT/rGO applying in half battery. The pSi/HCNT/rGO||LiFePO4 (LFP) full battery also shows the capacity maintenance of 96 % after 150 cycles at 1 C.

Industrial waste micron-sized silicon use for Si@C microspheres anodes in low-cost lithium-ion batteries

As the energy demands of our society increase, more and more high-energy-density lithium-ion batteries (LIBs) are required to satisfy them. Silicon-based anodes are very promising for future electrical energy storage equipment. However, their commercial applications are limited by their expensiveness and the detrimental volume expansion during the battery cycling. This work describes the fabrication of low-cost silicon nanoparticles (SiNPs) by high-energy mechanical milling (HEMM) using industrial waste micron-sized Si sheets as the initial material. The produced SiNPs were encapsulated by carbon microspheres derived from sucrose. Carbon-coated SiNPs (Si@C) were incorporated as LIB anodes, which delivered high specific capacity (equal to 948 mAh g−1) even after 500 cycles at 0.5C. Even the full-cell with the prelithiated Si@C microsphere-based anode and the Li(Ni1/3Co1/3Mn1/3)O2 cathode exhibited very high energy density (equal to 439.8 Wh Kg−1) and 90% capacity retention after 300 cycles. We believe that the recycling and utilization of the solid industrial waste might play a crucial role in the next-generation energy storage applications based on low-cost Si LIB anodes.

Fundamentals of metal oxide/oxyfluoride electrodes for Li-/Na-ion batteries

Lithium-ion batteries provide the development of a clean and sustainable society based on renewable energy resources. To further enhance energy density and reduce the cost of batteries, innovations on electrode materials and high-performance nickel-/cobalt-free materials are necessary. In this review, lithium-excess manganese-based electrode materials with layered/rock salt oxides/oxyfluorides are emphasized because of their potential ability to be utilized as advanced and low-cost lithium-ion batteries in the near future. For these emerging electrode materials, higher energy density is realized, compared with traditional layered materials based on nickel/cobalt ions, relying on anionic and/or cationic redox as multi-electron reactions. Although, currently, anionic redox suffers from degradation of reversibility on continuous cycles, significant progress on theoretical understanding and material design concepts has been made in the past several years. Recently, as alternatives to traditional layered materials, many disordered rock salt oxides, including metastable and nanosized oxyfluorides, have been also found as a new class of high-capacity electrode materials with anionic/cationic redox. In the later part, these new trends for the material design are also extended to the development of electrode materials for sodium-ion batteries. By reviewing the fundamental and recent research progress in metal oxide/oxyfluoride electrodes, a valuable guide for materials scientists in the field of batteries is provided to accelerate the industrial development of high-performance nickel-/cobalt-free electrode materials.

Unveiling the role of trivalent cation incorporation in Li-rich Mn-based layered cathode materials for low-cost lithium-ion batteries

Unveiling the role of trivalent cation incorporation in Li-rich Mn-based layered cathode materials for low-cost lithium-ion batteries

Tunnel elasticity enhancement effect of 3D submicron ceramics (Al2O3, TiO2, ZrO2) fiber on polydimethylsiloxane (PDMS)

Some polymers are flexible, foldable, and wearable. Structural—functional composite is fabricated by adding inorganic fillers with functional properties. Up to date, compared with the polymer matrix, the composite prepared by polymer-inorganic fillers has lower flexibility, higher brittleness, and higher modulus of elasticity. In this paper, three-dimensional (3D) net-shaped submicron α-Al2O3, orthorhombic ZrO2, and rutile TiO2 fiber were fabricated by solution blowing spinning on a large scale. On the contrary, the elastic modulus (E) of the composite prepared by this 3D ceramic fiber was greatly reduced, and the flexibility of the composite was higher than that of the polymer matrix. When the strain was 75%, the E of the 3D net-shaped Al2O3 fiber-polydimethylsiloxane (PDMS) composite was 20% lower than that of PDMS. When the strain was 78%, the E of the 3D net-shaped TiO2 fiber-PDMS and 3D net-shaped ZrO2 fiber-PDMS composites decreased by 20% and 25%, respectively. This abnormal effect, namely the tunnel elastic enhancement effect, has great practical significance. In all-solid-state lithium-ion batteries, the composite inhibits lithium dendrite growth and the 3D inorganic network contributes to lithium ion transport. It is possible to promote the industrial production of low-cost and large-scale flexible solid-state lithium-ion batteries and it can enhance the energy storage density of energy storage materials. This novel idea also has bright prospects in flexible electronic materials.