Dramatic Volume Change Research Articles

A Physically Cross-Linked Hydrogen-Bonded Polymeric Composite Binder for High-Performance Silicon Anodes

High-capacity silicon (Si) anodes in lithium-ion batteries require functional binders to accommodate the dramatic volume change and to improve the long-term stability during the charge/discharge cy...

A Novel Tin-Bonded Silicon Anode for Lithium-Ion Batteries.

Poor cyclic stability and low rate performance due to dramatic volume change and low intrinsic electronic conductivity are the two key issues needing to be urgently solved in silicon (Si)-based anodes for lithium-ion batteries. Herein, a novel tin (Sn)-bonded Si anode is proposed for the first time. Sn, which has a high electronic conductivity, is used to bond the Si-anode material and copper (Cu) current collector together using a hot-pressed method with a temperature slightly above the melting point of Sn. The cycling performance of the electrode is studied using a galvanostatic method. Nanoindentation and peeling tests are conducted to measure the mechanical strength of the electrodes. Direct current polarization and galvanostatic intermittent titration techniques are applied to assess the conductivity of the composites. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy are conducted to evaluate the effect of the coating layer on the cycling ability of the composites. The Sn-bonded Si anodes show superior cycling stability and high rate performance with an improved initial Coulombic efficiency. Analyses reveal that the low-melting-point Sn helps to markedly improve the electronic conductivity of the electrodes and serves as a metallic binder as well to enhance the adhesive strength of the electrode. It is hopeful that this novel Sn-bonded Si anode provides a new insight for the development of advanced Si-based anodes for LIBs.

Carbon Coating on Silicon for High-Performance Anode in Lithium-Ion Batteries

Silicon has attracted tremendous research interest as the next-generation anode material for lithium-ion batteries (LIBs) due to its approximately 10-fold higher capacity comparing to the graphite anode that is currently dominating the LIB market. Nevertheless, a critical drawback of silicon material is the dramatic volume change (>300%) during the lithiation and delithiation processes, which is a devastating destabilization factor for the silicon anode in battery cycling. Carbon coatings can serve as rigid framework to accommodate the volume change of silicon, to increase the conductivity of the silicon materials, and to protect the silicon surface from undesired side reactions. Here, we report two types of conductive carbon coatings on silicon materials through i) graphitization of a π-π stacking precursor poly(1-pyrenemethylmethacrylate) on SiO surface to encapsulate the SiO at a mild temperature, and ii) pyrolysis of polyvinylidene chloride precursor on silicon nanoparticle surface with stoichiometric ratio of sacrificial H and Cl elements that facilitate complete carbonization of the precursor. In addition, extended two‐phase transformation of carbon‐coated Si nanoparticles during electrochemical processes is examined.

Synthetic poly-dioxolane as universal solid electrolyte interphase for stable lithium metal anodes

Lithium (Li) metal is a promising anode for the next generation high-energy–density batteries. However, the growth of Li dendrites, low coulombic efficiency and dramatic volume change limit its development. Here, we report a new synthetic poly-dioxolane (PDOL) approach to constructing an artificial 'elastic' SEI to stabilize the Li/electrolyte interface and the Li deposition/dissolution behavior in a variety of electrolytes. By coating PDOL with optimized molecular weights and synthetic routes on Li metal anode, the 'elastic' SEI layer could be maintained on top of the Li metal anode to accommodate the Li deposition/dissolution. No dendrite formation was observed during the cycling process, and the interfacial side reactions were reduced significantly. Consequently, we successfully achieved 330 cycles with a CE of 98.4% in ether electrolytes and 90 cycles with a CE of 94.3% in carbonate electrolytes. Simultaneously, the Li-metal batteries with LiFePO4 as cathodes also exhibited improved cycling performance. This strategy could promote the development of dendrite-free metal anodes toward high-performance Li-metal batteries.

Synthesis of porous Si nanoparticles for high performances anode material in lithium-ion batteries

As one of the most promising candidates for anode materials, Si-based electrodes can offer specific capacity an order of magnitude beyond that of conventional graphite. However, Si usually suffers from dramatic volume changes during cycling cause pulverization and capacity fade. The key to improving cycle life is to synthesize Si-based materials with suitable architectures and a rational design. Here, we developed an economical and efficient method to obtain porous Si nanoparticles from coal ash. The Si nanoparticles with several nanometers can significantly shorten ion/electron transportation paths and further avoid the cracking and pulverization induced by large volume changes, and the porous structure makes the penetration of electrolyte easier. After carbonization, the obtained porous Si nanoparticles@C exhibits excellent electrochemical performances, and the special capacity can stable at 750 mAh g−1 at 2.0 A g−1 after 200 cycles. When current density up to 6.0 A g−1, the reversible capacity is 565 mAh g−1. We believe this method will make it possible to facilitate the large-scale and low-cost production of porous Si nanoparticles, and contribute to the development of high-performance Si-based anode materials.

A carboxymethyl vegetable gum as a robust water soluble binder for silicon anodes in lithium-ion batteries

The dramatic volume change and electrode pulverization hinder the practical utilization of silicon-based anodes for lithium-ion batteries. Studies show that binders can be an effective approach to solve these issues. Herein, the natural vegetable gum-guar gum (GG) is modified through carboxymethylation method. The carboxymethyl guar gum (CMGG) exhibits rapid water solubility, excellent thermal stability, high viscosity and robust adhesion. When it is applied as a binder for silicon anodes, the CMGG possessing affluent hydroxyl and carboxyl groups can effectively accommodate the significant volume variations of silicon particles through the formation of intensive hydrogen bonds. The Si @ CMGG electrode not only retains a high reversible capacity of 1865 mAh g−1 after 200 cycles with a capacity decay rate of 0.12% for each cycle, but also holds a capacity of 1287.1 mAh g−1 after 100 cycles with high mass loading of 1.15 mg cm−2. Furthermore, the CMGG binder can promote the lithium-ion transport like guar gum and reduce the electrode polarization, which is helpful in maintaining the electrochemical stability of Si anodes at high current density.

Carbon-Interlayer SnO2–Sb2O3 Composite Core–Shell Structure Anodes for Sodium-Ion Batteries

Although great efforts have been dedicated to improving electrochemical property of oxides anode material for sodium-ion batteries, the cycling life and rate capability of oxides anode materials are still far from its theoretical value. Herein, novel uniform SnO2@C@Sb2O3 submicrospheres with multilayer core–shell hollow structure have been synthesized as anode of sodium-ion batteries. The multilayer core–shell structure SnO2@C@Sb2O3 composite delivers a reversible capacity of 269 mAh g−1 at higher current density (1,500 mA g−1) after 100 cycles and exhibited excellent rate performance. The conductivity of the anode composite is promoted by the uniformly carbon dispersion through the whole submicrospheres. The dramatic volume change of electrode material could be mitigated by the porous core–shell structure of Sb2O3 and SnO2 during charge–discharge process. The enhanced specific capacity and rate performance are mainly ascribed to the integrity of structure and synergy effect between different metal oxides.

Self-adaptive multiblock-copolymer-based hybrid solid-state electrolyte for safe and stable lithium-metal battery

The dramatic volume change during the Li plating/stripping process has aroused brittle solid electrolyte interphase as well as weak interfacial compatibility between electrolyte and electrode, which results in capacity fading and safety hazards. We design elastic multiblock copolymers (mBCPs) with excellent extensibility up to 600% to address this problem. The best recovery rate of mBCP is 82% after 100 times of cyclic tensile tests. The mBCPs are regarded as elastomers that enable close contact with electrode surface during cycling. The elastic mBCPs are then mixed with lithium salt and high ionic conductivity inorganic ceramics to prepare hybrid solid-state electrolytes (HSSEs). The HSSEs are expected to possess self-adaptive property making good interfacial connection due to the mBCPs. The best HSSEs demonstrate high ionic conductivity of 0.14 mS cm−1 with a Li ion transference number of 0.55 and wide electrochemical window of 5.2 V at 25°C. Excellent cycling performance with long battery life is achieved by utilizing the self-adaptive HSSE: the Li metal electrode cycled for 150 times retains 96% coulombic efficiency in Li/HSSE/LiFePO4 cells, and stable cycling of 500 h is achieved in the symmetric cells.

Reversibly Transforming a Highly Swollen Polyelectrolyte Hydrogel to an Extremely Tough One and its Application as a Tubular Grasper.

Poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and its copolymer hydrogels are typical polyelectrolyte gels with extremely high swelling capacity that are widely used in industry. It's common to consider these hydrogels as weak materials that are difficult to toughen. Reported here is a facile strategy to transform swollen and weak poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) [P(AAm-co-AMPS)] hydrogels to tough ones by forming strong sulfonate-Zr4+ metal-coordination complexes. The resultant hydrogels with moderate water content possess high stiffness, strength, and fracture energy, which can be tuned over 3-4 orders of magnitude by controlling the composition and metal-to-ligand ratio. Owing to the dynamic nature of the coordination bonds, these hydrogels show rate- and temperature-dependent mechanical performances, as well as good self-recovery properties. This strategy is universal, as manifested by the drastically improved mechanical properties of hydrogels of various natural and synthetic sulfonate-containing polymers. The toughened hydrogels can be converted to the original swollen ones by breaking up the metal-coordination complexes in alkaline solutions. The reversible brittle-tough transition and concomitant dramatic volume change of polyelectrolyte hydrogels afford diverse applications, as demonstrated by the design of a tubular grasper with holding force a thousand times its own weight for objects with different geometries. It is envisioned that these hydrogels enable versatile applications in the biomedical and engineering fields.

Dual‐Carbon‐Confined SnS Nanostructure with High Capacity and Long Cycle Life for Lithium‐ion Batteries

SnS with high theoretical capacity is a promising anode material for lithium‐ion batteries. However, dramatic volume changes of SnS during repeated discharge/charge cycles result in fractures or even pulverization of electrode, leading to rapid capacity degradation. To solve this problem, we construct a dual‐carbon‐confined SnS nanostructure (denoted as SnS@C/rGO) by depositing semi‐graphitized carbon layers on reduced graphene oxide (rGO) supported SnS nanoplates during high‐temperature reduction. The dual carbon of rGO and in situ formed carbon coating confines growth of SnS during the high‐temperature calcination. Moreover, during the reversible Li+ storage the dual‐carbon modification enables good electronic conductivity, relieves the volume effect, and provides double insurance for the electrical contact of SnS even after repeated cycles. Benefiting from the dual‐carbon confinement, SnS@C/rGO exhibits significantly enhanced rate capability and cycling stability compared with the bare and single carbon modified SnS. SnS@C/rGO presents reversible capacity of 1029.8 mAh g−1 at 0.2 A g−1. Even at a high current density of 1 A g−1, it initially delivers reversible capacity of 934.0 mAh g−1 and retains 98.2% of the capacity (918.0 mAh g−1) after 330 cycles. This work demonstrates potential application of dual‐carbon modification in the development of electrode materials for high‐performance lithium‐ion batteries.

Reduced graphene oxide decorated CoSnO3@ZnSnO3 with multi-component double-layered hollow nanoboxes for high energy storage and capacity retention asymmetric supercapacitors

Double-layered hollow nanostructure composed of CoSn(OH)6@ZnSn(OH)6 which are derived from CoSn(OH)6 nanoboxes wrapped by ZnSn(OH)6 cover layers is prepared by a controlled alkali etching method, followed by heating treatment to prepare reduced graphene oxide (rGO) decorated CoSnO3@ZnSnO3 nanoboxes. The results revealed that the specific surface area of CoSnO3@ZnSnO3 reached 70.29 m2 g−1, which is much higher than that of CoSnO3 (44.25 m2 g−1). The enlargement in specific surface area of the double-layered hollow structure can responsible to provide sufficient buffer space for the dramatic volume change during the cycle. Moreover, rGO can effectively promote the transmission of ions or electrons and can provides a large reaction interface for electrochemical reaction. In addition, it can avoid CoSnO3@ZnSnO3 agglomeration and further improve storage capacity and stability. When the current density is 0.5 A g−1, the capacitance of material is 400.2 F g−1, which is higher than CoSnO3 and CoSnO3@ZnSnO3. Besides, the capacity retention rate of CoSnO3@ZnSnO3/rGO reaches 85% after 1100 cycles at a current density of 3 A g−1. This work demonstrates the interaction between the modification of the rGO network and the multi-layered hollow structure with the high specific surface areas can provide large spaces to effectively buffer volume changes and facilitate electron and electrolyte ion transport.

Black phosphorus composites with engineered interfaces for high-rate high-capacity lithium storage.

High-rate lithium (Li) ion batteries that can be charged in minutes and store enough energy for a 350-mile driving range are highly desired for all-electric vehicles. A high charging rate usually leads to sacrifices in capacity and cycling stability. We report use of black phosphorus (BP) as the active anode for high-rate, high-capacity Li storage. The formation of covalent bonds with graphitic carbon restrains edge reconstruction in layered BP particles to ensure open edges for fast Li+ entry; the coating of the covalently bonded BP-graphite particles with electrolyte-swollen polyaniline yields a stable solid-electrolyte interphase and inhibits the continuous growth of poorly conducting Li fluorides and carbonates to ensure efficient Li+ transport. The resultant composite anode demonstrates an excellent combination of capacity, rate, and cycling endurance.

Engineering phosphorous anodes

Batteries A focus of battery research has been the development of a range of lithium, sodium, and potassium cathodes, but improving anode materials is also an important goal. Silicon has shown some promise for replacing graphite because of its exceptional capacity, but the dramatic volume change during lithiation-delithiation processes often leads to failure. Jin et al. developed a composite that is made of black phosphorous and graphite in its core and covered with swollen polyaniline. In contrast to previous efforts, bonding between the carbon and phosphorous allows for a high charging rate without sacrifices in capacity and cycling stability. Science , this issue p. [192][1] [1]: /lookup/doi/10.1126/science.aav5842

Rational design of titanium oxide-coated dual Core–Shell sulfur nanocomposite cathode for highly stable lithium–sulfur batteries

Lithium-sulfur batteries (LSBs) have been considered as one of the promising next-generation energy storage systems due to their high specific capacity and energy density compared to intercalated metal oxide-based lithium-ion batteries (LIBs). However, the bottleneck that prevents commercialization of LSBs is how to tackle the polysulfide shuttle (PSS) effect, including low conductivity and dramatic volume change of the cathode material, which lead to rapid capacity fading and poor cycle life. In this paper, a new LSB cathode material with a nano-sized structure of sulfur encapsulated TiO2-coated dual core–shell hollow carbon sphere (S@HCS@TiO2) has been developed. The inner hollow carbon sphere (HCS) with a foamy carbon shell provides space for volumetric expansion, good electronic and ionic conductivity; while the outside TiO2 shell is not only a physical barrier to polysulfide species, but also possesses a strong chemical interaction with polysulfides. As a result, the obtained Li–S cells with S@HCS@TiO2 cathode material display a high initial capacity (751.6 mA h g−1) and low capacity decay (0.039% per cycle) for 800 cycles at a high current density (1C).

Heterogeneous interface of Se@Sb@C boosting potassium storage

The development of potassium ion batteries is restricted by the intrinsic large ion radius, resulting in dramatic volume change of electrodes and slow faradic reaction in kinetics. High requirements are proposed for the structure design of anodes. In this work, Se coating-Sb nanocrystalls-three dimensional interconnected carbon networks (3D [email protected]@C) heterogeneous structure was prepared by a low-temperature template-assisted CVD method. The network and sandwich structure can not only shorten the solid-state diffusion path of K+, but also alleviate the volume change of Sb. Moreover, the hetero interface between Se and Sb can form chemical bonding and further generate heterogeneous junctions in electrochemical reactions, providing more electron states at the Fermi energy level and reducing the ionic diffusion barrier of K+. Benefiting from it, the 3D [email protected]@C electrode possess an optimized energy storage mechanism and exhibits an outstanding rate performance and an ultra-long lifespan of more than 5000 cycles with 87% of capacity retention, which is rarely reported for PIB anodes. It reveals the important role of heterogeneous structure in potassium storage, which can inspire other researchers to achieve superior electrochemical performance by interface engineering for electrode materials.

Edge-Plane Exposed N-Doped Carbon Nanofibers Toward Fast K-Ion Adsorption/Diffusion Kinetics for K-Ion Capacitors

Sluggish kinetics severely limit the development of potassium-ion hybrid capacitors (PIHCs). Exposing active sites is recognized as an ideal strategy to resolve this issue, but the corresponding ma...

Strain engineering by atomic lattice locking in P2-type layered oxide cathode for high-voltage sodium-ion batteries

Abstract Developing high-voltage cathode materials is the key to overcome the obstacles of low energy density for sodium-ion batteries (SIBs). P2-type manganese-rich layered oxides are considered as an appealing cathode material for SIBs, but still suffer from severe capacity and voltage decay. As the underlying cause, inhomogeneous interlaminar stress originated from the intrinsic structural transition brings out the generation and propagation of surface cracks, and should be tackled. Herein, we construct an interlocking spinel-like/layered heterostructure via boric acid treatment approach. The well-designed epitaxial spinel-like nanolayer effectively inhibits the unfavorable P2-OP4 phase transition associated with dramatic volume change over 4.1 V, preventing the accumulation of inhomogeneous stress as well as the lattice distortion. The generation and propagation of intragranular cracks are fundamentally prohibited, resulting in improved structural durability and capacity stability. This present work sheds light on the importance of interface engineering of high-voltage cathode materials for SIBs.

In situ fabrication of hierarchical iron oxide spheres@N-doped 3D porous graphene aerogel for superior lithium storage

To improve the electronic conductivity and dramatic volume change of iron oxide as anode for lithium-ion batteries, we finally fabricate a hierarchical aerogel composite of FeOx spheres encapsulated in porous N-doped three-dimensional graphene (FeOx@N-3DG) via a facile in situ electrostatic self-assembly strategy assisted with hydrothermal. In the hierarchical architecture, the distributed FeOx spheres that consist of Fe2O3 and Fe3O4 crystals are intimately wrapped by N-3DG acting as protective elastomer to buffer the volume change during cycling. Moreover, the integrally interconnected porous structure is beneficial for fast electron transfer and penetration of the electrolyte. More importantly, the abundant grain boundaries of Fe2O3 and Fe3O4 crystals inside FeOx spheres provide smooth channels for fast lithium-ion transport and increase lithium storage sites. Therefore, FeOx@N-3DG anode material exhibits high specific capacity (1100 mAh g−1 after 200 cycles at 0.5 A g−1), excellent rate performance (550 mAh g−1 at 5 A g−1) and outstanding long cycling stability (81.6% of capacity retention after 1000 cycles at 1 A g−1), which is attributed to the superior surface capacitance behavior in the hierarchical architecture during charging and discharging. Thus, the hierarchical FeOx@N-3DG aerogel has potential to be an advanced anode material for lithium-ion batteries.

In Situ Characterization of Lithium Deposition and Microstructure Evolution of Silicon Anodes By Synchrotron X-Ray Imaging

Advanced lithium batteries are crucial for next-generation energy storage systems such as portable electronics and electric vehicles. Due to a low specific capacity (372 mAh/g) batteries using traditional graphite-based anode materials can hardly meet the increasing demands of light weight and high energy density. With theoretical specific capacities that are approximately 10 times higher than that of conventional graphite anodes metallic lithium (3860 mAh/g) and silicon (4200 mAh/g) anodes are regarded as two excellent candidates. Specifically, the energy density of batteries could be dramatically increased approximately from 250 Wh/kg to 440 Wh/kg by replacing graphite with lithium anodes.[1] However these two promising anodes suffer from the dramatic volume change due to microstructure degradation and low coulombic efficiency derived from unstable solid electrolyte interphase (SEI) during cycling. In addition, the dendritic and/or fiber-like deposition on lithium anode could initiate an internal short circuit and thus leads to a fast battery failure. Despite great progress recently achieved on improving electrochemical performance, a clear picture of the microstructure degradation of electrode and battery failure mechanisms is still elusive, largely due to a lack of feasible in situ characterization techniques. Synchrotron X-ray imaging has evolved into a tool of choice allowing in situ or operando analysis of the internal morphology/structure evolution non-invasively.[2, 3] With this technique the internal microstructure of a silicon electrode in a lithium ion battery was visualized during battery operation.[4] The silicon particles were found to change their sizes upon lithiation/delithiation and the changes could be quantified. An expansion prolongation phenomenon of Si particle was discovered involving that some particles continue expanding even after switching the battery current direction and shrinkage would be expected. In addition, Li deposition at the Li/separator interface as well as within a porous carbon matrix was visualized and quantified three dimensionally. The study provides new basic insights into expansion/shrinkage processes inside Si particles and uncovers the Li deposition behavior that can hardly be probed by surface imaging techniques. Finally investigations on Li anode degradation mechanisms are presented.[5] References [1] D. Lin, Y. Liu, Y. Cui, Reviving the lithium metal anode for high-energy batteries. Nature Nanotechnology, 2017, 12, 194. [2] M. Ebner, F. Marone, M. Stampanoni, V. Wood, Visualization and quantification of electrochemical and mechanical degradation in Li ion batteries. Science, 2013, 342, 716-720. [3] K. J. Harry, D. T. Hallinan, D. Y. Parkinson, A. A. MacDowell, N. P. Balsara, Detection of subsurface structures underneath dendrites formed on cycled lithium metal electrodes. Nat Mater, 2014, 13, 69-73. [4] K. Dong, H. Markötter, F. Sun et al., In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X-ray Imaging. ChemSusChem, doi:10.1002/cssc.201801969. [5] Fu Sun, Xin He, Xiaoyu Jiang, et al., Advancing Knowledge of Electrochemically Generated Lithium Microstructure and Performance Decay of Lithium Ion Battery by Synchrotron X-ray Tomography, Materials Today, accepted.

An environmental friendly cross-linked polysaccharide binder for silicon anode in lithium-ion batteries

Silicon is a promising anode material for the next generation of lithium-ion batteries. Binder plays an essential role in maintaining electrode integrity when Si undergoes dramatic volume change during lithiation/delithiation processes. Herein, an environmental friendly water-soluble binder of oxidized starch cross-linked sodium carboxymethyl cellulose (OS-CMC) possessing three-dimensional (3D) network structure is designed. The abundant hydroxyl and carboxyl groups and the 3D structure of the cross-linked binder not only enhance the bonding with Si nanoparticles surface but also greatly alleviate the mechanical stress, thus maintaining the integrity of electrode and conductive network. In addition, it can facilitate faster lithium-ion transportation at the interface of Si/OS-CMC. As a result, the Si anodes with OS-CMC binder show good electrochemical stability and better mechanical properties than that of Si anodes with OS or CMC binder. The Si anodes with OS-CMC binder exhibit a discharge capacity of 1922 mAh g−1 after 100 cycles at a current density of 0.4 A g−1 with a high initial discharge capacity of 3424 mAh g−1 and maintain a superior capacity of 1667 mAh g−1 at a high current density of 8 A g−1. Our work provides a novel binder design for high-performance Si-based anodes.