Lithium Storage Capacity Research Articles

Spinel-Structured, Multi-Component Transition Metal Oxide (Ni,Co,Mn)Fe2O4−x as Long-Life Lithium-Ion Battery Anode Material

Metal oxide anode materials are affected by severe volume expansion and cracking in the charging/discharging process, resulting in low capacity and poor cycle stability, which limits their application in lithium-ion batteries (LIBs). Herein, a new strategy is uncovered for a preparing spinel-structured, multi-component transition metal oxide, (Ni,Co,Mn)Fe2O4−x, with oxygen vacancies as an LIB anode material. The as-fabricated material presented excellent reversible capacity and cycling stability, delivering a discharge capacity of 1240.2 mAh g−1 at 100 mA g−1 for 200 cycles and then at 300 mA g−1 for 300 additional cycles. It presented extremely long cycle stability even at 2 A g−1, revealing 650.5 mAh g−1 after 1200 cycles. The good lithium storage capacity can be ascribed to the entropy stabilization effect, the multi-cation synergistic effect, abundant oxygen vacancies and the spinel structure. This study provides a new opportunity to fabricate and optimize conversion-type anodes for LIBs with satisfactory electrochemical performance.

Explosion Strategy Engineering Oxygen-Functionalized Groups and Enlarged Interlayer Spacing of the Carbon Anode for Enhanced Lithium Storage

Amorphous carbon monoliths with tunable microstructures are candidate anodes for future lithium-based energy storage. Enhancing lithium storage capability and solid-state diffusion kinetics are the precondition for practical applications. Transforming intrinsic oxygen-rich defects into active sites and engineering enlarged interlayer spacing are of great importance. Herein, a novel explosion strategy is designed based on oxalate pyrolysis producing CO and CO2 to successfully prepare lignin-derived carbon monolith (LSCM) with active carbonyl (C═O) groups and enlarged interlayer spacing. Explosion promotes the demethylation of methoxyl groups and cleavage of carboxyl groups to form C═O groups. CO2 etches carbon atoms in a short time to improve the heteroatom level, expanding the interlayer spacing. ZnC2O4 is decomposed at 400 °C, simultaneously producing CO and CO2, which constructs less C═O groups and large interlayer spacing. MgC2O4 is decomposed at 450 and 480 °C, staged-weakly producing CO and CO2, which constructs more C═O groups and larger interlayer spacing. CaC2O4 is decomposed at 480 and 700 °C, staged-uniformly producing CO and CO2, which constructs abundant C═O groups and largest interlayer spacing. The LSCM prepared by staged-uniform explosion exhibits high lithium storage capacity, superior rate capability, and cycling performance. The assembled lithium ion capacitor device achieves excellent energy/power densities of 78 Wh kg-1/100 W kg-1 and superior durability (capacitance retention of 8 4.6% after 20,000 cycles). This work gives a novel insight to engineer advanced oxygen-functionalized carbons for enhanced lithium storage.

Dual Modification of Olivine LiFe0.5Mn0.5PO4 Cathodes with Accelerated Kinetics for High-Rate Lithium-Ion Batteries

Developing olivine-type lithium ferromanganese phosphates with high ionic/electronic conductivity is vital to promote their practical application in long-life and high-rate lithium-ion batteries (LIBs). Herein, we propose a dual modification strategy combining C-coating and Nb-doping and apply it to enhance LiFe0.5Mn0.5PO4 cathode materials. The uniform and compact C-coating layer successfully fabricates the high-speed conductive network among primary particles and meantime prevents the attack of electrolytes. The strong Nb–O coordination can effectively accelerate ion diffusion and electron transport within the nanoparticles while suppressing the Jahn–Teller effect of Mn3+. The dual modifications synergistically improve the LiFe0.5Mn0.5PO4 cathode materials with superior lithium-storage capacities of 152 and 115 mAh g–1 at 0.1 and 5 C, respectively. Furthermore, it exhibits an impressive cycling performance with an ultrahigh capacity retention of 95.4% after 1000 cycles at 1 C. These findings extend the application of surface-to-bulk co-modification in developing novel cathode materials used in high-performance LIBs.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure by plasma for lithium and sodium storage.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure are synthesized using Ar-H2-P plasma. In situ phosphorization and graphene reduction are achieved at the same time. Benefitting from the sandwich structure and heterointerface between CoP and RGO, the electrode delivered a high reversible capacity and durable lifespan for both lithium and sodium storage.

Zero-strain strategy incorporating TaC with Ta2O5 to enhance its rate capacity for long-term lithium storage.

Ta2O5 holds great potential for lithium storage due to its high theoretical capacity and long-life cycling. However, it still suffers from an unsatisfactory rate capability because of its low conductivity and significant volume expansion during the charging/discharging process. In this study, a zero-strain strategy was developed to composite Ta2O5 with zero-strain TaC as an anode for lithium-ion batteries (LIBs). The zero-strain TaC, featuring negligible lattice expansion, can alleviate the volume variation of Ta2O5 when cycling, thereby enhancing the rate capacity and long-term cycling stability of the whole electrode. Further, the formation of a heterostructure between Ta2O5 and TaC was confirmed, giving rise to an enhancement in the electrical conductivity and structural stability. As expected, this anode displayed a reversible specific capacity of 395.5 mA h g-1 at 0.5 A g-1 after 500 cycles. Even at an ultrahigh current density of 10 A g-1, the Ta2O5/TaC anode delivered a high capacity of 144 mA h g-1 and superior durability with a low-capacity decay rate of 0.08% per cycle after 1000 cycles. This zero-strain strategy provides a promising avenue for the rational design of anodes, sequentially contributing to the development of high-rate capacity and long cycling LIBs.

Performance and application of Si/Ti3C2T x (MXene) composites in lithium ion battery

The excellent theoretical specific charge (lithium) storage capacity and rich abundance of silicon (Si), and the good mechanical and electrical properties of titanium based MXene (Ti3C2T x ) nanosheets promise high performance composites (Si/Ti3C2T x ) for negative electrodes (negatrodes) in future lithium ion battery (LIB) applications. In particular, the Si/Ti3C2T x composites have been preliminarily shown to offer large and stable cyclic capacity, good rate capability and a highly profitable market prospect. To better understand and help further improve the electrochemical performance of these composites, this review focuses on the electrochemical processes occurring in Si/MXene composites from a material perspective. Different cells used for electrochemical measurements, the related materials properties and the reaction processes and kinetics of Si/MXene composites as negatrode in LIB are reviewed. The perspective is also discussed for practical applications in flexible electronic devices and automobiles.

Nickel foam deposited with borophene sheets used as a self-supporting binder-free anode for lithium-ion batteries

Nickel foam-supported borophene sheets were prepared using an improved chemical vapor deposition process. The as-obtained borophene sheets have crystaline nature, where the β12phase is dominant and contributes to high capacity for lithium storage.

Enabling enhanced lithium storage capacity of two-dimensional pentagonal BN2 by aluminum doping

The highest theoretical Li storage capacity (2297 mA h g−1) to date in a pentagonal structure, achieved through aluminum-for-boron substitution in penta-BN2.

Integrating highly active graphite nanosheets into microspheres for enhanced lithium storage properties of silicon.

Integrating silicon (Si) and graphitic carbon into micron-sized composites by spray-drying holds great potential in developing advanced anodes for high-energy-density lithium-ion batteries (LIBs). However, common graphite particles as graphitic carbon are always too large in three-dimensional size, resulting in inhomogeneous hybridization with nanosized Si (NSi); in addition, the rate capability of graphite is poor owing to sluggish intercalation kinetics. Herein, we integrated graphite nanosheets (GNs) with NSi to prepare porous NSi-GN-C microspheres by spray-drying and subsequent calcination with the assistance of glucose. Two-dimensional GNs with average thickness of ∼80 nm demonstrate superior lithium storage capacity, high conductivity, and flexibility, which could improve the electronic transfer kinetics and structural stability. Moreover, the porous structure buffers the volume expansion of Si during the lithiation process. The obtained NSi-GN-C microspheres manifest excellent electrochemical performance, including high initial coulombic efficiency of 85.9%, excellent rate capability of 94.4% capacity retention after 50 repeated high-rate tests, and good cyclic performance for 500 cycles at 1.0 A g-1. Kinetic analysis and in situ impedance spectra reveal dominant pseudocapacitive behavior with rapid and stable Li+ insertion/extraction processes. Ex situ morphology characterization demonstrates the ultra-stable integrated structure of the NSi-GN-C. The highly active GN demonstrates great potential to improve the lithium storage properties of Si, which provides new opportunity for constructing high-performance anodes for LIBs.

The Microparticles SiOx Loaded on PAN-C Nanofiber as Three-Dimensional Anode Material for High-Performance Lithium-Ion Batteries

Three-dimensional C/SiOx nanofiber anode was prepared by polydimethylsiloxane (PDMS) and polyacrylonitrile (PAN) as precursors via electrospinning and freeze-drying successfully. In contrast to conventional carbon covering Si-based anode materials, the C/SiOx structure is made up of PAN-C, a 3D carbon substance, and SiOx loading steadily on PAN-C. The PAN carbon nanofibers and loaded SiOx from pyrolyzed PDMS give increased conductivity and a stable complex structure. When employed as lithium-ion batteries (LIBs) anode materials, C/SiOx-1% composites were discovered to have an extremely high lithium storage capacity and good cycle performance. At a current density of 100 mA/g, its reversible capacity remained at 761 mA/h after 50 charge-discharge cycles and at 670 mA/h after 200 cycles. The C/SiOx-1% composite aerogel is a particularly intriguing anode candidate for high-performance LIBs due to these appealing qualities.

Achieving ultrastability and efficient lithium storage capacity with high-energy iron(II) oxalate anode materials by compositing Ge nano-conductive sites.

Transition metal oxalates (TMOxs, represented by iron oxalate) have attracted considerable interest in anode materials due to their excellent lithium storage properties and consistent cyclic performance. Although investigations into their electrochemical capabilities and lithium storage mechanisms are gradually deepening, the complex and varied electrochemical reactions in the initial cycle, poor inherent conductivity, and high irreversible capacity constrain their further development. Herein, to solve the above-mentioned problems, we controlled the hydrothermal synthesis conditions of iron oxalate with the assistance of organic solvents, which induced the growth of iron oxalate crystals with nano Ge metal as the core. The metal Ge space sites compounded to the stacked iron oxalate particles act as conductive nodes and metal frames, which enhances both the strength of iron oxalate samples and electronic conductivity and lithium-ion diffusion inside the electrode materials. This special structure enhances the electrochemical activity of iron oxalates and improves their lithium storage capability. The iron oxalate @ nano Ge metal composite (FCO@Ge-1) exhibits an excellent cycling performance and an appreciable reversible specific capacity (1090 mA h g-1 after 200 cycles at 1 A g-1). The obvious polarization and variation of the electrochemical reaction in the initial cycle of iron oxalate are reduced by compositing nano Ge metal. It is demonstrated that nano Ge metal can promote reversible capacity retention from 67.72% to 80.69% in the early cycles. The distinctive structure of iron oxalate @ nano Ge metal composite provides a fresh pathway to enhance oxalate electrochemical reversible lithium storage activity and develop high-energy electrode material by constructing composite space conductive sites.

Functionalized two-dimensional iron boride compounds as novel electrode materials in Li-ion batteries.

MBenes, a class of two-dimensional metal borides, have emerged as a cutting-edge research frontier and a hotspot for electrode materials in ion batteries. This work presents a systematic investigation of the performance of two-dimensional iron boride (FeB) as an electrode material for lithium-ion batteries (LIBs), utilizing first-principles calculations. The results indicate that FeB exhibits remarkable structural stability and excellent conductivity, making it an extremely promising electrode material for LIBs. FeB has the capability to adsorb a monolayer of Li atoms, and exhibits a maximum theoretical capacity of 364 mA h g-1, a high average open circuit voltage (OCV) of 1.08 V, and a low diffusion barrier energy of 0.24 eV. Through the investigation of electrochemical properties of functionalized FeB, it has been discovered that surface functionalization exerts a positive impact on lithium storage. Theoretical lithium storage capacities of FeBT (T = F, O and S) are 538 mA h g-1, 555 mA h g-1 and 476 mA h g-1, respectively. However, the introduction of F and O functional groups significantly reduces diffusion barriers to 0.081 eV and 0.036 eV, respectively, while the introduction of the S functional group markedly decreases the average OCV to approximately 0.25 V. These interesting findings suggest that FeB has great potential in the future development of LIBs.

Structure-Performance relationship guided design and strategic synthesis of lithiated oxa-graphene for high lithium storage

Graphene derivative materials are widely used as anode component in lithium-ion batteries. However, there is still a lack of reliable and foresighted guides helpful for designing high-performance graphene-based electrode materials. To this end, we strategically chose challenging graphite fluoride as starting material for the derivatization of graphene in order to exclude interference factors. As a result, graphene framework was functionalized with oxygen-containing carboxylate and sulfonate groups and oxygen-free aniline units at a similar functionalization degree. Due to the strong effect of lithiation, out-of-plane p-aminobenzoic acid blocks boosted the lithium-storage capacity of graphene matrix to 636 mAh g−1 at 0.1 A/g, and sulfanilic acid blocks maximized this value to 873 mAh g−1. Sadly, oxygen-free aniline functionalized graphene material only delivered a specific capacity of 88 mAh g−1. Meanwhile, spatial lithiated carboxylate and sulfonate units endowed graphene framework with better rate capability and cycling stability. Such a structure-performance relationship established herein was beneficial for the design and preparation of high-performance graphene derivative electrode materials.

Overall Carbon-neutral Electrochemical Reduction of CO2 in Molten Salts using a Liquid Metal Sn Cathode.

An overall carbon-neutral CO2 electroreduction requires enhanced conversion efficiency and intensified functionality of CO2-derived products to balance the carbon footprint from CO2 electroreduction against fixed CO2. A liquid Sn cathode is herein introduced into electrochemical reduction of CO2 in molten salts to fabricate core-shell Sn-C spheres (Sn@C). An in-situ generated Li2SnO3/C directs a self-template formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core-shell structure of Sn@C, a CO2-fixation current efficiency higher than 84% and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO2 conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO2.

Facile Synthesis of Nb-Doped CoTiO3 Hexagonal Microprisms as Promising Anode Materials for Lithium-Ion Batteries

Bimetallic oxides are demonstrated to show better electrochemical performance than single transition metal oxides. Recently, ilmenite-type transition metal titanate (MTiO3, M = Fe, Co, Ni, etc.) is emerging as a promising anode for lithium-ion batteries (LIBs) due to its comparable theoretical capacity and small volumetric change during cycling. However, the practical electrochemical performance is still harmed by its poor electronic conductivity. Herein, for the first time, a Nb-doping strategy is adopted to modify CoTiO3 hexagonal microprisms by a facile solvothermal method combined with an annealing treatment. Benefiting from the unique 1D morphology and the ameliorated conductivities induced by Nb-doping, the optimized Nb-doped CoTiO3 anode exhibits an improved lithium-storage capacity of 233 mA h g−1 at 100 mA g−1 after 100 cycles and excellent rate capability, which are superior to that of pure CoTiO3. This work sheds light on the potential application of titanium containing bimetallic oxide in the next-generation advanced rechargeable LIBs.

Local structure transformations promoting high lithium diffusion in defect perovskite type structures

Defect perovskites, AxBO3 such as (Li3xLa2/3-x)TiO3, are attracting attention as high capacity electrodes in lithium-ion batteries. However, the mechanism enabling high lithium storage capacities has not been fully investigated. In this work, the reversible insertion and removal of lithium up to an average A-site cavity occupancy of 1.71 in the defect perovskite (Li0.18Sr0.66)(Ti0.5Nb0.5)O3 is investigated. It was shown that subtle lithium reorganization during lithiation has a significant impact on enabling high capacity. Contrary to previous studies, lithium was coordinated to triangular faces of Ti/Nb oxygen octahedra and offset from O4 windows between A-site cavities in the as-synthesised material. Upon electrochemical lithiation Li-Li repulsion redistributes of all the lithium towards the O4 window position resulting in a loss of lithium mobility. Surprisingly, the mobility is regained during over-lithiation and following multiple electrochemical cycles. It is suggested that lithium reorganisation into the center of the O4 window alleviates the Li-Li repulsion and modifies the diffusion behavior from site percolation to bond percolation. The results obtained provide valuable insight into the chemical drivers enabling higher capacities and enhanced diffusion in defect perovskites. More broadly the study delivers fundamental understanding on the non-equilibrium structural transformations occurring within electrode materials during repeated electrochemical cycles.

Ni-decorated Sn(HPO4)2 anchored on reduced graphene oxide boosting initial Coulombic efficiency and cyclic stability for lithium-ion batteries

Layered Sn(HPO4)2 with perfect crystal structure and large interlayer spacing shows considerable lithium storage capacity worthy of study, but its intrinsic poor conductivity and low initial Coulombic efficiency (ICE) as anode material for lithium-ion batteries need to be enhanced. Herein, Sn(HPO4)2 is first decorated by Ni nanoparticles through electroless plating, then anchored on reduced graphene oxide (rGO). The well-conductive Ni nanoparticles distributed uniformly on the surface of Sn(HPO4)2 can help to inhibit the irreversible sites on the surface and reduce electrochemical kinetic impedance, thus the Ni/Sn(HPO4)2 anode exhibits improved ICE and capacity retention ratios, which are almost twice that of bare Sn(HPO4)2 anode. Meanwhile, the conductive network formed by rGO in rGO/Ni/Sn(HPO4)2 composite not only weakens the electrochemical reaction polarization, but also keeps the electrode structure stable and provides extra lithium storage sites, so rGO/Ni/Sn(HPO4)2 anode delivers higher ICE of 60.29%, superior cyclic stability of 79.7% capacity retention after 120 cycles with at 0.1 A g−1.

Micron SiOx encapsulated into amorphous B, N Co-doped carbon nanotube network for high-capacity and long-durable Li-ion half/full batteries

Micron silicon suboxide (m-SiOx) with low-cost and advantageous capacity has been proposed as a prospective candidate for lithium-ion battery anodes, yet huge volumetric fluctuation and poor inherent conductivity should be addressed urgently. Herein, encapsulation of m-SiOx particles into amorphous B, N co-doped carbon nanotube network (SSBCN) via metal cation-assisted carbonization is shown. Rational preparation process enables in-situ synthesis of 3D porous carbon nanotubes network around m-SiOx, guaranteeing slight volume variation during cycling, effective electrical contact, fast electron and Li-ion transfer and speedy electrolyte penetration. In-situ Raman spectra confirm the additional utilization rate of m-SiOx. Heteroatomic active sites (Sn, N, B) further enhance lithium storage capacity. As anodes in half batteries, the SSBCN exhibits ultrahigh reversible capacities of 2072.8 mAh/g at 0.1 A/g, excellent rate performance of 501.8 mAh/g at 10 A/g and prominent long-term cycle stability of 400 and 1000 cycles at 1 and 5 A/g, respectively. Moreover, SSBCN//LiFePO4 (LFP) full batteries also display remarkable cycle durability with a 92.72% capacity retention after 600 cycles at 1C. This work outperforms most of the recently reported SiOx-based anodes and renders a new opportunity of m-SiOx in high-performance LIBs.

Two-dimensional black phosphorus modified by aluminum element: A feasible way to enhance lithium storage performance

• The maximum lithium storage capacity of Al-2D-BP is 46% higher than that of 2D-BP. • Al-2D-BP has higher capacity retention than 2D-BP after 100 cycles. • The mechanism of lithium storage in Al-2D-BP is mainly diffusion-controlled. Two-dimensional black phosphorus (2D-BP) has attracted much attention in electrochemical lithium storage due to its special wrinkled structure and great theoretical capacity, and it is a two-dimensional energy storage material with great application potential. However, the low electronic conductivity of phosphorus-based materials also greatly limits their application and development. In order to improve the lithium storage performance of 2D-BP, it was modified by the high electron mobility of aluminum element using hydrothermal synthesis method in this study, and the material morphology and chemical composition were investigated through a series of physical characterization, while the long cycling and rate performance tests also showed that the electrode has superior lithium storage capacity and cycling stability, thus proving the feasibility of this scheme. It lays a theoretical and practical foundation for the future research of 2D-BP in lithium storage and promotes the practical application of 2D-BP in this field in the future.

Microstructure Engineered Silicon Alloy Anodes for Lithium‐Ion Batteries: Advances and Challenges

AbstractDue to the high theoretical lithium storage capacity and moderate voltage platform, silicon is expected to substitute graphite and serves as the most promising anode material for lithium‐ion batteries (LIBs). However, substantial volume change during cycling subjects the silicon anode to electrode pulverization and conductive network damage, extensively limiting its commercial purpose. Strategies, such as alloying, nano‐crystallization, and compositing, are developed against these problems. This review introduces the attractive alloying modification method and summarizes the recent advances in microstructure‐engineered silicon alloy anodes for LIBs. The electrochemical performances of silicon alloy anodes with various morphologies, such as nanoparticles, nanowires, two‐dimensional layered structures, porous structures, and thin films, are discussed in detail. The challenges for the commercial application of silicon alloy anodes are elaborated in the end. This review provides a comprehensive overview and concerns of microstructure‐engineered silicon alloy anodes for potential applications in LIBs.