Cycling Stability For Lithium-ion Batteries Research Articles

Unveiling the mechanisms into Li-trapping induced (ir)reversible capacity loss for silicon anode

Commercialization of silicon (Si) anodes has been tremendously hampered by its low Coulombic efficiency and poor cycling stability in lithium-ion batteries (LIBs). As it is often the case, huge volume change of Si material, and the consequent unstable solid electrolyte interphase (SEI) formation, manifest two major attributes to a hastened electrode failure. However, this recognition is not comprehensive. In this work, we find that Li-trapping represents to be a major factor determining initial Coulombic efficiency and cycling stability for Si anodes. Moreover, through titration gas chromatography (TGC) and high-resolution transmission electron microscopy (HRTEM), we identify two existing forms of the trapped Li, which are: (1) trapped active Li due to sluggish Li+ lithiation/delithiation kinetics; (2) trapped inactive Li resulted from the pulverization of Si particles. First-off, during initial charge-discharge, trapped active Li accounts for ca. 40% of the first irreversible capacity. By further exploring the evolution of Li-trapping, it is observed that the accumulation of trapped inactive Li turns a dominant factor for the capacity decline, accounting for ∼75% of the total capacity loss after 20 cycles. We expect that the significance and fundamentals of Li-trapping elucidated herein will trigger new strategies in modifying Si anodes towards high-performance Si-based LIBs.

Dual modification of LiNi0.95Co0.04Mn0.01O2 for enhancing its cycling stability in lithium-ion batteries

A high Ni-low Co LiNi0.95Co0.04Mn0.01O2 cathode for lithium-ion batteries is modified by a combination of bulk W-doping and surface Mn-doping. Such a dual-modification is realized through a facile treatment of the W-doped precursor by KMnO4 solution. X-ray diffraction and electron scanning microscopy reveal that the crystallographic structure and morphology are not changed by the dual-modification. Electrochemical measurements prove the merits of the dual-modified cathode, including excellent cycling stability and improved rate capability. Moreover, differential capacity analysis demonstrates that the improved electrochemical properties result from the enhanced structural stability and suppressed polarization endowed by the dual-modification.

High synergetic transition metal phosphides@ nitrogen doped porous carbon nanosheets hybrids derived from silk fibroin and phytic acid self-assembly for ultra-high performance lithium storage

Transition metal phosphides (TMPs) have received widespread attention due to their high theoretical specific capacity and fast reaction kinetics. However, their poor conductivity and volume changes during the cycle limited their applications. Herein, we explore a facile and cost-effective way to prepare core–shell-like transition metal phosphides (TMPs: CoP, Ni 2 P, Cu 3 P) nanoparticles embedded into nitrogen doped porous carbon nanosheets (denoted as CoP@NDPCS, Ni 2 P@NDPCS, Cu 3 P@NDPCS) via biological material-driven assembly and self-template strategy. By self-assembled process, the amino and carbonyl groups in silk fibroin can chelate with metal ions, and then phytic acid added undergoes a coordination reaction with the metal components. Subsequently, core-shell TMPs nanoparticles supported by nitrogen doped porous carbon nanosheets were prepared by a one-step high-temperature calcination process. The obtained unique hybrid structure material with enough vacancy space to alleviate volume expansion exhibits ultra-high specific capacity and excellent cycling performance for the anode of lithium-ion batteries. The CoP@NDPCS, Ni 2 P@NDPCS and Cu 3 P@NDPCS electrodes exhibit the reversible capacities of 1014.2, 486.5 and 877 mAh g −1 at the current density of 500 mA g -1 , respectively. The remarkable lithium storage performance of TMP@NDPCS indicates that a reasonable structure designed by biological material-driven is an effective and promising method to enhance the lithium storage of transition metal phosphides. Core-shell transition metal phosphides supported by N-doped porous carbon nanosheets were prepared by one-step high temperature calcination process. The unique hybrid structure materials exhibit ultra-high specific capacity and excellent cycling stability for the anode of lithium-ion batteries, and the reasonable structure design by biological material-driven is very effective and universal method to enhance the lithium storage of transition metal phosphides. • Carbon nanosheets derived from silk fibroin can effectively alleviate the volume expansion of TMPs during the cycling process. • The TMP@NDPCS materials exhibit ultra-high specific capacity and excellent cycling stability for lithium-ion batteries. • The TMP@NDPCS hybrid materials were synthesized by one step phosphating.

Nano-Co3O4 anchored helical carbon nanofibers as an anode material for Li-ion batteries

Co 3 O 4 /HCNFs were firstly prepared successfully via a simple and inexpensive oil-bath method. Within the hybrid composite, the HCNFs and Co 3 O 4 show a synergistic effect to improve the specific capacity and cycling stability of Lithium-ion batteries. • A novel Co 3 O 4 /HCNFs anode composite was first introduced for lithium-ion batteries. • A simple two-step approach was successfully used to prepare the Co 3 O 4 /HCNFs composite material. • Co 3 O 4 /HCNFs composites make an obvious advantage as an anode material for lithium-ion batteries. In the current work, the Co 3 O 4 /helical carbon nanofibers (Co 3 O 4 /HCNFs) composite was successfully obtained by using a simple and inexpensive two-step method and applied as an anode material for lithium-ion batteries (LIBs). The results showed that Co 3 O 4 nanoparticles (the nanoparticle size of 10–20 nm) were anchored on the surface of helical carbon nanofibers. The Co 3 O 4 /HCNFs anode displays an excellent cyclability of 853 mAh/g after 200 cycles under the current density of 200 mA/g (327.7 %, 183.7 %, and 172.0 % higher than the pure HCNFs, pure Co 3 O 4 , and Co 3 O 4 -HCNFs respectively). The superior electrochemistry capability of the Co 3 O 4 /HCNFs composites are mainly thankful to the specific 3D helical structure of HCNFs, which can not only accommodate the volume expansion of nano-Co 3 O 4 during charge–discharge process, but also greatly enhance the conductivity of Co 3 O 4 . Therefore, this research provides a novel method to exploiting an excellent and stable anode material for enhanced LIBs.

Fully coating of Mg3B2O6 in nonaqueous solution on Ni-rich LiNi0.8Co0.1Mn0.1O2 secondary particles to improve cycling stability of lithium-ion batteries

Surface coating is an effective strategy to suppress side reactions at the electrode/electrolyte interface and improve cycling stability of the Ni-rich LiNixCoyMn1-x-yO2 electrodes. It is difficult to prepare a complete coating layer on the secondary particles by traditional methods, due to the alkaline substances and oxidative property on surface. In this work, a coating process of Mg3B2O6 running counter to traditional routes was designed to modify LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material. In a weak polar ethanol medium, BH4- ions are uniformly lain on particle surface by the interaction between its electronegativity and oxidizing surface, which also change the charge state into negative atmosphere around the NCM811 surface. Then Mg2+ ions are also completely dispersed by the mutual attraction between metal cations and the hydrolyzed BO3-. Then a full surface coverage of Mg3B2O6 was prepared in situ on the NCM811 secondary particles. The complete coating layer protects the surface crystal structure of the NCM811 and limits the irreversible phase transition. The optimized composite with a suitable coverage of 1 % Mg3B2O6 exhibits enhanced rate capability and excellent cycling performance. At a high current density of 10C, it delivers a specific capacity of 162.7 mAh g−1. Especially, it maintains 160.6 mAh g−1 after 400 cycles at a high cut-off voltage of 4.5 V at 1C with a retention of 80.3 %. In addition, Mg3B2O6 is a non-toxic and non-polluting material. The simple coating process with low-cost raw materials as well as mild operating conditions endow this technology with potential practical application value.

Enabling Long-Cycling Life of Si-on-Graphite Composite Anodes via Fabrication of a Multifunctional Polymeric Artificial Solid-Electrolyte Interphase Protective Layer.

The energy density of lithium-ion batteries (LIBs) can be meaningfully increased by utilizing Si-on-graphite composites (Si@Gr) as anode materials, because of several advantages, including higher specific capacity and low cost. However, long cycling stability is a key challenge for commercializing these composites. In this study, to solve this issue, we have developed a multifunctional polymeric artificial solid-electrolyte interphase (A-SEI) protective layer on carbon-coated Si@Gr anode particles (making Si@Gr/C-SCS) to prolong the cycling stability in LIBs. The coating is made of sulfonated chitosan (SCS) that is crosslinked with glutaraldehyde promoting good ionic conduction together with sufficient mechanical strength of the A-SEI. The focused ion beam-scanning electron microscopy and high-resolution transmission electron microscopy images show that the SCS is uniformly coated on the composite particles with thickness in nanometer. The anodes are investigated in Li metal cells Si@Gr/C-SCS||Li metal) and lithium-ion full-cells (LiNi0.6Co0.2Mn0.2O2 (NCM-622)||Si@Gr/C-SCS) to understand the material/electrode intrinsic degradation as well as the impact of the polymer coating on active lithium losses because of the continuous SEI (re)formation. The anode composites exhibit a high capacity reaching over 600 mAh g-1, and even without electrolyte optimization, the Si@Gr/C-SCS illustrates a superior long cycle life performance of up to 1000 cycles (over 67% capacity retention). The excellent long-term cycling stability of the anodes was attributed to the SCS polymer coating acting as the A-SEI. The simple polymer coating process is highly interesting in guiding the preparation of long-cycle-life electrode materials of high-energy LIB cells.

Suppressing lithium dendrite growth on lithium-ion/metal batteries by a tortuously porous γ-alumina separator

The challenges of dendrite propagation limit the operational safety and long-term cycling stability of lithium-ion batteries and development of high energy density lithium-metal batteries. Solid state electrolytes may eliminate the propagation of dendrites, but they fail to achieve high Li-ion conductivity and charge transfer rate at room temperature resulting in undesired cell performance. Here we report the usage of electrode-coated plate-structured γ-alumina separators with liquid electrolyte for high performance, safe lithium-ion batteries. The γ-alumina separators, made of γ-alumina plates of high aspect ratio, are mechanically strong and tortuously porous, and therefore effective in preventing passage of dendrites. Nickel-manganese-cobalt-oxide/lithium cells with a plate-structured γ-alumina separator show stable cycle performance without passage of dendrites up to 3 C-rate of charging and discharging. Same cells with commercial polypropylene (PP-2500) separator or spherical-structured α-alumina separator of similar pore size to γ-alumina separator, could not achieve the above-mentioned dendrite free cycling even at much lower C-rates (0.2 C and 1.0 C respectively). A comparison of the three cells with different separators clearly shows that the hardness and high tortuosity of the separator are effective in preventing dendrite propagation. This work results in the development of a lithium-ion-battery with improved safety and shows a new direction in the design and fabrication of high performance and safe lithium-metal batteries.

Bio-inspired synthesis of transition-metal oxide hybrid ultrathin nanosheets for enhancing the cycling stability in lithium-ion batteries

Bio-inspired synthesis of transition-metal oxide hybrid ultrathin nanosheets for enhancing the cycling stability in lithium-ion batteries

Carbon quantum dot‐laminated stepped porous Al current collector for stable and ultrafast lithium‐ion batteries

Designing an interfacial architecture between the current collector and electrode plays a serious role in developing the specific capacity with cycling stability of lithium-ion batteries (LIBs). Consequently, an original approach to enhance the structure of the interface between the current collector and electrode is necessary. Thus, we developed a novel interface architecture based on carbon quantum dots (CQDs)-laminated on a stepped porous Al (SP-Al) current collector to attain stable and ultrafast-discharge LIBs and CQD-SP-Al for application as LIB cathodes. To this end, the electrochemical etching and ultrasonic spray coating methods were employed. The cathode assembled with CQD-SP-Al displayed the adhesion enhancing, an increased redox reaction kinetics, and the magnificent interfacial stability of the current collector//electrode interface because of the increased surface roughness, stepped pores with N-doped CQD, and uniform CQD lamination layer. The resultant cathode with CQD-SP-Al showed an enhanced specific capacity of 78.2 mAh/g and capacity retention of 92.6% at a high C-rate of 10C after 500 cycles. This great cycling stability is due to an expanded interfacial contact area of current collector//electrode with improved adhesion, as well as to the CQD lamination layer, while the excellent ultrafast discharge capacity is ascribed to the risen number of charge supplying/collecting sites, the stepped porous structure, and the highly conductive N-doped CQD lamination layer.

Improving interfacial stability of high voltage LiCoO2-based cells with 4-methylmorpholine-2,6-dione additive

An novel electrolyte additive, 4-methylmorpholine-2,6-dione (MMD) with anhydride and amine functional groups, is come up with, which can not only construct a dense and stable cathode-electrolyte-interface (CEI) film on solid and electrolyte interphase that can automatically improve the cycling stability of lithium-ion batteries (LIBs) at high temperature and high voltage, but also effectively capture hydrofluoric acid and water in the electrolyte that can adequately inhibit carbonate decomposition and protect LiCoO2 (LCO) internal structure. The capacity retention rate of Li||LCO cells increases from 65.8% to 83.5% after 200 cycles at 1C between 3.0 and 4.6 V after just adding a trace amount of 0.03% MMD to the baseline electrolyte. Even at ultra-high voltages of 4.7 V, the retained capacity of MMD-containing Li||LCO half-cell is improved from 91 to 122 mAh g−1 after 200 cycles at 1C. Both theoretical calculation and experiments reveal that MMD can be preferentially oxidized ahead of those solvent through C–C bond breaking to construct a thin and robust CEI layer on LCO surface. Such a combination of anhydride and amine functional groups opens up a direction to exploit novel electrolyte additives for prolonging the cycle life of higher energy density LCO.

One-step synthesis of WO3 coating-modified LiNi0.8Co0.15Al0.05O2 cathode material with long cycling stability for lithium-ion batteries

One-step synthesis of WO3 coating-modified LiNi0.8Co0.15Al0.05O2 cathode material with long cycling stability for lithium-ion batteries

Fully Coating of Mg3b2o6 in Nonaqueous Solution on Ni-Rich Lini0.8co0.1mn0.1o2 Secondary Particles to Improve Cycling Stability of Lithium-Ion Batteries

Fully Coating of Mg3b2o6 in Nonaqueous Solution on Ni-Rich Lini0.8co0.1mn0.1o2 Secondary Particles to Improve Cycling Stability of Lithium-Ion Batteries

Nanocrystalline Cellulose Supported MnO2 Composite Materials for High-Performance Lithium-Ion Batteries.

The rate capability and poor cycling stability of lithium-ion batteries (LIBs) are predominantly caused by the large volume expansion upon cycling and poor electrical conductivity of manganese dioxide (MnO2), which also exhibits the highest theoretical capacity among manganese oxides. In this study, a nanocomposite of nanosized MnO2 and pyrolyzed nanocrystalline cellulose (CNC) was prepared with high electrical conductivity to enhance the electrochemical performance of LIBs. The nanocomposite electrode showed an initial discharge capacity of 1302 mAh g−1 at 100 mA g−1 and exhibited a high discharge capacity of 305 mAh g−1 after 1000 cycles. Moreover, the MnO2-CNC nanocomposite delivered a good rate capability of up to 10 A g−1 and accommodated the large volume change upon repeated cycling tests.

Improvement of long-term cycling performance of high-nickel cathode materials by ZnO coating

Abstract The high-nickel cathode material of LiNi0.8Co0.15Al0.05O2 (LNCA) has a prospective application for lithium-ion batteries due to the high capacity and low cost. However, the side reaction between the electrolyte and the electrode seriously affects the cycling stability of lithium-ion batteries. In this work, Ni2+ preoxidation and the optimization of calcination temperature were carried out to reduce the cation mixing of LNCA, and solid-phase Al-doping improved the uniformity of element distribution and the orderliness of the layered structure. In addition, the surface of LNCA was homogeneously modified with ZnO coating by a facile wet-chemical route. Compared to the pristine LNCA, the optimized ZnO-coated LNCA showed excellent electrochemical performance with the first discharge-specific capacity of 187.5 mA h g−1, and the capacity retention of 91.3% at 0.2C after 100 cycles. The experiment demonstrated that the improved electrochemical performance of ZnO-coated LNCA is assigned to the surface coating of ZnO which protects LNCA from being corroded by the electrolyte during cycling.

A key strategy to form a LiF-based SEI layer for a lithium-ion battery anode with enhanced cycling stability by introducing a semi-ionic C[sbnd]F bond

A solid electrolyte interphase (SEI) on an anode is a critical issue in lithium-ion batteries because it is related to cycling stability. In this study, we introduce a semi-ionic CF bond on the surface of graphite (SICF) via plasma fluorination to introduce a LiF-based SEI layer on the anode during the first cycle. In the charge-discharge profiles and cyclic voltammetry curves, a peak related to the LiF-based SEI formation was clearly observed for SICF. In particular, SICF had an excellent long-term cycling stability of 98.8% for 100 cycles (1.0 C-rate). From the anodes of the disassembled coin cells, it was found that semi-ionic CF bonds improved the formation of a stable LiF-based SEI layer and decreased the number of side reactions with HF, which was produced from PF5. Moreover, SICF exhibited a lower volume expansion compared to that of the pristine anode and the anode with covalent CF bonds. Therefore, introducing a semi-ionic CF bond via plasma fluorination is a key strategy for forming a LiF-based SEI layer on the graphite anode surface that enhances the cycling stability of lithium-ion batteries.

Melamine-templated TiO2 nanoparticles as anode with high capacity and cycling stability for lithium-ion batteries

Titanium dioxide (TiO2) plays a vital role especially in the field of sustainable energy including photovoltaic, environmental remediation, energy storage devices, and secondary rechargeable batteries. Herein, we report melamine as an efficient soft template to produce gram-scale TiO2 nanoparticles as anode material in lithium-ion batteries (LIBs). The X-ray diffraction confirms the formation of anatase phase with high crystallinity, while FESEM and HRTEM reveal a spherical morphology with average size of 10–20 nm. Tested as anode material in LIBs, it demonstrates an excellent electrochemical performance with high discharge capacity of 316 mAh g−1 and 272 mAh g−1 at 0.1C and 1C rates, respectively, with long-term cycle life stability over 1000 cycles. The TiO2 anode when coupled with LiNi0.33Mn0.33Co0.33O2 (NMC) cathode in full cell delivered capacity of 95 mAh g−1 after 30th cycle with about 2 V. The high discharge capacity could originate from high interparticles contact and nanosize features which could permit fast Li-ion diffusion and fast kinetics.

Li2O-2B2O3 coating decorated Li4Ti5O12 anode for enhanced rate capability and cycling stability in lithium-ion batteries

Li2O-2B2O3 (LBO) ionic conductor with high conductivity plays an important role in boosting the rate performance and cycling stability of Li4Ti5O12 (LTO) anode for lithium-ion batteries by preventing direct exposure of LTO to the electrolyte. Herein, the effect of LBO coating layer on lithium ion (Li+) storage performance is investigated in detail by adjusting the adding amount of LBO precursor dispersion. LTO coated with 2 wt% LBO achieves an optimum performance with a specific capacity of 172.9 mA h g−1 at a current density of 0.1 A g−1, an improved rate capability (specific capacity of 127.9 mA h g−1 is maintained when the current density is 20 times than 0.1 A g−1) and a remarkable cycling stability (capacity retention of 94.2% after 4000 cycles at 2.0 A g−1). These LBO-LTO composites are competitive and promising candidates for electrochemical energy storage and other applications.

In Situ Observation of Interface Evolution on a Graphite Anode by Scanning Electrochemical Microscopy.

A well-formed solid electrolyte interface (SEI) is critical for achieving long-term cycling stability in lithium-ion batteries (LIBs). However, the SEI remains the poorly understood component in LIBs especially under dynamic conditions. Here, scanning electrochemical microscopy (SECM) was applied to study the spontaneous reaction on a graphite electrode, SEI formation in the first cycle, SEI evolution during 10 cycles, and the stability of the as-formed SEI in the electrolyte. The conversion, dissolution, stabilization, and growth behaviors of the SEI were determined. Moreover, the SECM results were analyzed in combination with ex situ material characterization to understand the SEI on the graphite electrode comprehensively.

Covalent Assembly of MoS2 Nanosheets with SnS Nanodots as Linkages for Lithium/Sodium-Ion Batteries.

Weak van der Waals interactions between interlayers of two-dimensional layered materials result in disabled across-interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS2 nanosheets to realize unique MoS2 /SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all-inorganic and carbon-free concept enables effective across-interlayer electron transfer, facilitated ion diffusion kinetics, and outstanding mechanical stability, which are evidenced by experimental characterization, DFT calculations, and mechanical simulations. Consequently, the MoS2 /SnS HSs exhibit superb rate performance and long cycling stability in lithium-ion batteries, representing the best comprehensive performance in carbon-free MoS2 -based anodes to date. Moreover, the MoS2 /SnS HSs also show excellent sodium storage performance in sodium-ion batteries.

MnSe/ZnSe encapsulated in N-doped carbon electrospinning nanofibers for high-performance lithium ion batteries

To realize high capacity and long cycling stability for lithium-ion batteries (LIBs), a new type bimetal selenides MnSe/ZnSe encapsulated in nitrogen-doped carbon nanofibers (MZS@N-CNFs) have been fabricated for lithium ion battery via electrospinning and selenization processes. Synergistic effect of the ultrafine bimetal selenides nanoparticles provides a high specific capacity while the 1D carbon nanofibers can shorten the ions pathways and improve the conductivity. When assembled as anodes for LIBs, the MZS@N-CNFs demonstrate an extremely high capacity of 1369.1 mA h g−1 and excellent cycle stability of 826.1 mA h g−1 at 1 A g−1 after 300 cycles.