Symmetric Cell Research Articles

High-Performance Solid-State Lithium Metal Batteries of Garnet/Polymer Composite Thin-Film Electrolyte with Domain-Limited Ion Transport Pathways.

The integrated approach of interfacial engineering and composite electrolytes is crucial for the market application of Li metal batteries (LMBs). A 22 μm thin-film type polymer/Li6.4La3Zr1.4Ta0.6O12 (LLZTO) composite solid-state electrolyte (LPCE) was designed that combines fast ion conduction and stable interfacial evolution, enhancing lithium metal interface stability and cycling performance. The ether-based molecular coordination groups/clusters formed by triethylene glycol dimethyl ether (TGDE) and anions facilitated the movement of Li+ between the polymer chain segments. These specific coordination clusters significantly "constrained" the interaction between anions and Li+, inducing the anions to follow the clusters to the Li metal and preferentially participate in solid electrolyte interface (SEI) derivatization. The inorganic salt-rich gradient SEI modulates Li+ deposition and inhibits uncontrolled dendrite growth, achieving stable cycling of Li symmetric cell at 0.2 mA cm-2 for over 2000 h. Furthermore, the Li||NCM811 cell at a rate of 0.1 C exhibits an initial discharge capacity of 194.5 mAh g-1, maintaining a capacity retention rate of over 90% after 500 cycles. This work demonstrates the importance of domain-limited ion clusters in ion transport and interfacial evolution, providing a perspective for solid-state LMBs.

High‐Entropy Electrolyte Driven by Multi‐Solvation Structures for Long‐Lifespan Aqueous Zinc Metal Pouch Cells

Aqueous zinc metal batteries (AZMBs) are promising for grid‐scale energy storage due to their low cost and high safety. However, poor stability and an unfavorable freezing point hinder their actual application. Herein, a ternary salts‐based high‐entropy electrolyte (HEE) composed of Zn0.2Na0.4Li0.4(ClO4)1.2·7H2O is proposed to address the above issues. The addition of perchlorate salts with different cations reduces the size of ion clusters, significantly increases the solvation structure species, and promotes the anion‐rich Zn2+ solvation structures, resulting in an enlarged electrochemical stability window, favorable viscosity and ionic conductivity, and low freezing point. Furthermore, characterization and calculations confirm that multiple types of solvation structures effectively increase the electrolyte entropy. As a consequence, the Zn/Zn symmetric cells in HEE can sustainably cycle for at least 1000 hours and 1500 hours under room and subzero temperatures, respectively. The Na0.33V2O5/Zn and polyaniline/Zn full cells can even last for 30000 and 20000 cycles without capacity decay at −20 °C, respectively. The pouch cells employing HEE deliver promising capacity and stability, even at high mass loading of active materials. This strategy of introducing multiple salts with different cations to construct a high‐entropy environment provides a facile approach for high‐performance and long‐lifespan AZMBs across a wide temperature range.

High-Entropy Electrolyte Driven by Multi-Solvation Structures for Long-Lifespan Aqueous Zinc Metal Pouch Cells.

Aqueous zinc metal batteries (AZMBs) are promising for grid-scale energy storage due to their low cost and high safety. However, poor stability and an unfavorable freezing point hinder their actual application. Herein, a ternary salts-based high-entropy electrolyte (HEE) composed of Zn0.2Na0.4Li0.4(ClO4)1.2·7H2O is proposed to address the above issues. The addition of perchlorate salts with different cations reduces the size of ion clusters, significantly increases the solvation structure species, and promotes the anion-rich Zn2+ solvation structures, resulting in an enlarged electrochemical stability window, favorable viscosity and ionic conductivity, and low freezing point. Furthermore, characterization and calculations confirm that multiple types of solvation structures effectively increase the electrolyte entropy. As a consequence, the Zn/Zn symmetric cells in HEE can sustainably cycle for at least 1000 hours and 1500 hours under room and subzero temperatures, respectively. The Na0.33V2O5/Zn and polyaniline/Zn full cells can even last for 30000 and 20000 cycles without capacity decay at -20 °C, respectively. The pouch cells employing HEE deliver promising capacity and stability, even at high mass loading of active materials. This strategy of introducing multiple salts with different cations to construct a high-entropy environment provides a facile approach for high-performance and long-lifespan AZMBs across a wide temperature range.

A Synergistic Zincophilic and Hydrophobic Supramolecule Shielding Layer for Actualizing Long‐Term Zinc‐Ion Batteries

AbstractThe zinc metal anodes are liable to experience detrimental dendrite growth and side reactions, thereby limiting the lifespan of aqueous Zn‐ion batteries. Here, a readily available supramolecule, dimethoxypillar[5]arene (DP[5]), is utilized as a shielding layer to stabilize the Zn anode by exploiting its zincophilicity derived from the ─OCH3 functional groups and its hydrophobicity from the hydrophobic backbone. The DP[5] shielding layer regulates the solvation sheath of Zn2+ and facilitates uniform zinc deposition. Swelling and dendrite formation are obviously suppressed in both the symmetric and full cells. The DP[5]‐Zn symmetrical cell cycles stably for 5500 h, and achieves a coulombic efficiency of 99.76% in a DP[5]‐Zn||Cu half‐cell after 2200 cycles. The DP[5]‐Zn||V2O5 full cell maintains 92.03% of initial capacity after 6000 cycles. Given the cost‐effective fabrication and environmental friendliness of DP[5] films, this material may pave the way for practical applications of zinc anodes.

MXene Surface Engineering Enabling High‐Performance Solid‐State Lithium Metal Batteries

AbstractSolid polymer electrolytes (SPEs) offer inherent advantages for battery applications, such as high safety and excellent processability, but their practical use is limited by challenges like low ionic conductivity, subpar mechanical properties, and instability of the electrode/electrolyte interface. Here, novel SPEs are developed by embedding 2D MXenes decorated at the surface with methoxypolyethylene glycol chains into poly(vinylidene fluoride)‐hexafluoropropylene matrices, enhanced with succinonitrile as a plasticizer. This innovative design improves the compatibility of the modified MXene in poly(vinylidene fluoride)‐hexafluoropropylene and, together with the synergistic effects of succinonitrile, promotes the dissociation of lithium salt. The SPE achieves ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, and a Li‐ion transference number of 0.59. These results are supported by comprehensive experimental characterization, COMSOL simulations, and DFT calculations. This SPE enables stable and reversible Li plating/stripping for over 2100 h in Li/Li symmetric cells, while fabricated Li/LiFePO4 full cells deliver a notable capacity of 135.4 mAh g−1 with an average Coulombic efficiency of 98.9% after 100 cycles at 0.2 C. Furthermore, the Li/LiNi0.6Co0.2Mn0.2O2 full cells also demonstrate a capacity of 140.5 mAh g−1 after over 200 cycles at 0.5 C, showcasing an impressive capacity retention rate of 99.6%.

Bi-Functional Agarose-Filled Porous Polysulfone Protective Layer for Dendrite-Free Zn Anode.

The uneven electric field and slow Zn2+ desolvation lead to rapid dendrite growth during Zn plating and stripping, which severely deteriorates the performance of Zn metal anodes (ZMAs) in Zn-ion batteries (ZIBs). Although polymer-based artificial protective (PBAP) layers are widely applied to homogenize the electric field of ZMAs, they often fail to promote the desolvation process that eventually induces Zn dendrite growth. Herein, a bi-functional protective layer, comprising a finger-like porous matrix of polysulfone (PSF) and a hydroxyl-rich filler of agarose (AG), is constructed to suppress Zn dendrite growth. COMSOL simulation demonstrates the ZMAs with bi-functional protective layers (Zn@PSF/AG) exhibit uniform electric field and Zn2+ distribution. Besides, the Zn@PSF/AG has both low desolvation energy and nucleation overpotential, effectively promoting the desolvation of Zn2+. Therefore, the Zn@PSF/AG symmetric cell exhibits excellent cycling performance, achieving 4200h at 1mA cm-2/1 mAh cm-2 and 1000h at 5mA cm-2/5 mAh cm-2. When coupling with ZnxV2O5 (ZnVO) cathode, the ZnVO‖Zn@PSF/AG full cell shows similarly high cycling stability, maintaining 72% of its capacity after 7000 cycles at 10 A g-1. This research highlights the positive roles of PBAP layer with multi-functional matrix-filler structure in developing long-life ZIBs.

Achieving the dendrite-free zinc anode by constructing a Sn-C interfacial layer with zincophilic and conductive network

Under the basic national policy of sustainable green development, high-performance and low-cost energy storage devices are urgently needed for intermittent generation of clean energy and storage of electrical energy. Zn metal with high capacity, abundant reserves and excellent plasticity, but the inevitable side reactions (hydrogen precipitation and corrosion, etc.) of the Zn metal anode itself have severely limited the development of aqueous Zn ion batteries (AZIBs) in the market. In this study, an artificial protective layer of polymer-derived carbon material combined with Sn is prepared to inhibit hydrogen precipitation and corrosion and prolong the lifetime of AZIBs. With these advantages, the Zn@Sn@N doped carbon (Zn@CNS) symmetric cell could achieve a stable cycle life of 1000 h at 2 mA cm-2 and low overpotential. The excellent stripping life of over 400 h is achieved in half-cells assembled with Cu foils. Furthermore, the α-MnO2//Zn@CNS full battery shows superior stability in rate capability and long-term capacity retention compared to the α-MnO2//Zn battery, indicating that the CNS coating provides excellent performance and practical value.

Synergistic effect of NASICON Na3V2(PO4)2F3 and 2D MXene for high-performance symmetric Sodium-ion batteries

Sodium fluorophosphate-based Na3V2(PO4)2F3 (NVPF) cathode materials have been widely analyzed in Sodium-ion batteries (SIB) owing to their high energy density and high working voltage. However, the low electronic conductivity of NVPF is a factor hindering their efficient use. To enhance the electronic conductivity of NVPF, in this work, a porous Na3V2(PO4)2F3 and a 2D Ti3C2-based MXene nanocomposite was synthesized using a facile sol-gel method. The NVPF, with the presence of two active redox couples, is a suitable choice for symmetric batteries. The NVPF + 2D MXene nanocomposite was analyzed for its structural and thermal characteristics, and a symmetric cell prepared from them was investigated for its electrochemical characteristics. Structural analysis of the materials developed indicates that the MXene addition has not altered the crystal structure of the NVPF. A remarkable improvement in the electrochemical performance of NVPF in the sodium symmetric cell is noticed, as indicated by its high specific discharge capacity of 92mAhg-1 at 1C for the MXene-incorporated composite structures. This improvement in electrochemical behaviour is confirmed in the rate capability curves, GCD curves, and GITT curves. The diffusion coefficient values obtained from GITT analysis showed improved kinetics in the synthesized material due to the MXene incorporation. The calculated values of the diffusion coefficient of Na+confirms the accelerated kinetics of Na+ ion migration during the intercalation/de-intercalation process in the MXene 5wt% nanocomposites, with a value of 9.57 × 10–9 cm2s-1 when compared to 4. 14 × 10–9 cm2s-1 for the pristine sample.

Synergetic bifunctional Cu-In alloy interface enables Ah-level Zn metal pouch cells

Rechargeable aqueous zinc-metal batteries, considered as the possible post-lithium-ion battery technology for large-scale energy storage, face severe challenges such as dendrite growth and hydrogen evolution side reaction (HER) on Zn negative electrode. Herein, a three-dimensional Cu-In alloy interface is developed through a facile potential co-replacement route to realize uniform Zn nucleation and HER anticatalytic effect simultaneously. Both theoretical calculations and experimental results demonstrate that this bifunctional Cu-In alloy interface inherits the merits of low Zn-nucleation overpotential and high HER overpotential from individual copper and indium constituents, respectively. Moreover, the dynamical self-reconstruction during cycling leads to an HER-anticatalytic and zincophilic gradient hierarchical structure, enabling highly reversible Zn chemistry with dendrite-free Zn (002) deposition and inhibited HER. Moreover, the improved interface stability featured by negligible pH fluctuations in the diffusion layer and suppressed by-product formation is evidenced by in-situ scanning probe technology, Raman spectroscopy, and electrochemical gas chromatography. Consequently, the lifespan of the CuIn@Zn symmetric cell is extended to more than one year with a voltage hysteresis of 6 mV. Importantly, the CuIn@Zn negative electrode is also successfully coupled with high-loading iodine positive electrode to fabricate Ah-level (1.1 Ah) laminated pouch cell, which exhibits a capacity retention of 67.9% after 1700 cycles.

2D hollow leaf shaped mesoporous carbon derived from ZIF-L for efficient capacitive deionization

Electrochemical treatment of saline or brackish water by capacitive deionization (CDI) is a novel resource-saving solution to ensure the availability of freshwater resources in the environment. MOF (metal–organic framework) derived carbon as a novel carbonaceous material in CDI has received considerable research attention. Among them, ZIF-L-derived carbon (ZC) suffers from problems such as self-aggregation, poor mesoporous structure, and low electrical conductivity, which lead to poor CDI performance. In this paper, a strategy of ZIF-L coated with polydopamine (PDA) is proposed to solve the above problems. When the amount of PDA was 0.5 g, ZIF-L@PDA0.5-derived carbon composite (ZPC0.5) is obtained for efficient capacitive deionization. The ZPC0.5 composite not only maintains the 2D leaf shaped structure consistent with ZIF-L, exposing more active sites, but also has an elevated mesopore occupancy ratio to promote solution diffusion. Meanwhile, the interaction between PDA and ZIF-L makes the ZPC0.5 have a cavity structure, which improves the mass transfer capacity. The resulting ZPC0.5 composite has a specific capacitance (165.8F g−1) that is 3.86 times higher than that of ZC (42.9F g−1). Consequently, in 1.2 V, 500 mg/L NaCl solution, the symmetric CDI cell ZPC0.5//ZPC0.5 exhibits an excellent desalination capacity (29.6 mg/g), which is 2.69 times that of the ZC//ZC.

A two-pronged strategy to boost the capacitive deionization performance of nitrogen-doped porous carbon nanofiber membranes

Carbon-based capacitive deionization (CDI) systems are universally subject to the limited desalination capacity, due to the electrosorption characteristics and undesirable pore structures. Herein, a two-pronged strategy is proposed to boost the desalination performance of the electrospun carbon nanofibers (CNFs), where silicalite-1 nanoparticles as the internal porogen create mesopores and macropores, and zeolitic imidazolate framework (ZIF-L) leaves as the external carbon source provide micropores and mesopores. This combination results in the large surface area, well-developed graded pore structure, and increased nitrogen content of the core-shell polyacrylonitrile/silicalite-1@ZIF-L-derived CNFs (defined as PCNFs-SZ) electrode, which delivers a superior specific capacitance of 145.4 F g−1 in a neutral electrolyte. The symmetric CDI cell assembled by the self-supporting PCNFs-SZ membrane electrodes holds a prominent desalination capacity of 37.09 mg g−1 and a rapid salt removal rate of 10.36 mg g−1 min−1 at 1.2 V (initial NaCl concentration: 500 mg L−1), and demonstrates significant potential for real-world applications in the desalination and purification of reclaimed water. Furthermore, theory calculations confirm the enhanced Na+-capture capability of PCNFs-SZ. The present work highlights an effective and viable approach to enhance the desalination performance of carbon-based CDI cells.

An active and stable PrOx-modified open-straight pore (La0.8Sr0.2)0.98MnO3-δ-Sc0.18Zr0.82O2-δ air electrode for reversible solid oxide cells

Air electrode supported reversible solid oxide cells (RSOCs) have drawn increasing attention for the capability of fuel flexibility and well bonding between the air electrode and electrolyte. However, the high concentration polarization and sluggish oxygen reduction/evolution reaction (ORR/OER) has significantly restricted the practical applications. Herein, finger-like (La0.8Sr0.2)0.98MnO3-δ-Sc0.18Zr0.82O2-δ (LSM98-SSZ) air electrode supported symmetrical and single cells are successfully fabricated by phase inversion tape-casting technology. The open-straight pores formed on the air electrode support can facilitate the gas transport and catalyst impregnation. The ORR/OER activity of LSM98-SSZ air electrode is largely increased with the introduction of impregnated PrOx nano catalyst, showing a low polarization resistance (Rp) of 0.06 Ω cm2 and great stability for 550 h at 700 oC. Furthermore, the LSM98-SSZ supported cell with PrOx modification shows a remarkable peak power density of 1.0 W cm-2 and electrolysis current density of 1.09 A cm-2 at 1.3 V at 750 oC. The enhanced performance is primarily ascribed to the facilitated oxygen surface exchange.

Malic acid additive with a dual regulating mechanism for high-performances aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are widely used in energy storage devices due to their high safety and low cost. However, the practical application of AZIBs is constrained by the formation of dendrites and the occurrence of severe side reactions. Herein, these problems are addressed by introducing malic acid (MA) as a multifunctional additive into electrolyte. Theoretical calculations, finite element simulations and experimental tests show that MA can adsorb on the surface of the Zn anode and change the solvated structure of Zn2+ and promote the desolvation of [Zn (H2O)6]2+, thus inhibiting the hydrogen evolution reaction (HER) and the generation of by-products, and promoting the uniform deposition of Zn. Additionally, benefiting from this dual effect of solvent structure and interface adsorption regulation, a high Coulombic efficiency of 99.83 % can be achieved for the Zn//Cu half cell in an electrolyte containing a small amount of MA, and an excellent lifetime of beyond 4000 h can be achieved in a Zn//Zn symmetric cell at 5 mA cm−2 and 1 mAh cm−2. Even under deep plating/stripping conditions (5 mA cm−2 and 5 mAh cm−2), it is still capable of stabling operation for 600 h. In addition, the Zn//V2O5 full cell with MA also exhibited higher capacity and better rate performance. The incorporation of MA improves the electrochemical performance of zinc ion batteries to a great extent relative to the pure ZnSO4 electrolyte.

Optimizing Interface Chemistry with Novel Covalent Molecule for Highly Sustainable and Kinetics-Enhanced Sodium Metal Batteries

Metallic sodium has attracted increasing attention as an ideal anode material for next-generation high energy density and low-cost secondary batteries. However, it is highly desired yet remains challenging to improve their cycling stability and safety due to unstable solid electrolyte interphase and dendrite growth. Herein, a hybrid interface layer composed of Na2Se and Na3P is constructed on the surface of Na (Na@NPS) via in situ spontaneous reaction. The hybrid interface layer with merits of high sodiophilicity and high Na-ion conductivity can effectively induce homogeneous Na-ion flux distribution, accelerate the reaction kinetics and suppress decomposition of electrolyte components. Benefitting from the above advantages, the Na@NPS symmetric cell delivers a long cycle life (1000 h at 1 mA cm–2 and 1 mAh cm–2). Furthermore, the full cell coupling with Na3V2(PO4)3-based cathode provides an exceptionally long lifespan (1500 cycles) at 20 C with a capacity retention of 98.2% and high energy density (226 Wh kg–1). Therefore, the enhanced electrochemical performance illustrates the feasibility of the covalent molecule derived hybrid multifunctional interfaces in solving the irregular deposition of Na-ion and expediting reaction kinetics in Na metal batteries.

Breath inspired multifunctional low-cost inorganic colloidal electrolyte for stable zinc metal anode

The practical application of aqueous zinc-ion batteries (AZIBs) is primarily constrained by issues such as corrosion, zinc dendrite formation, and the hydrogen evolution reaction occurring at the zinc metal anode. To overcome these challenges, strategies for optimizing the electrolyte are crucial for enhancing the stability of the zinc anode. Inspired by the role of hemoglobin in blood cells, which facilitates oxygen transport during human respiration, an innovative inorganic colloidal electrolyte has been developed: calcium silicate-ZnSO4 (denoted as CS-ZSO). This electrolyte operates in weak acidic environment and releases calcium ions, which participate in homotopic substitution with zinc ions, while the solvation environment of hydrated zinc ions in the electrolyte is regulated. The reduced energy barrier for the transfer of zinc ions and the energy barrier for the desolvation of hydrated ions imply faster ion transfer kinetics and accelerated desolvation processes, thus favoring the mass transfer process. Furthermore, the silicate colloidal particles act as lubricants, improving the transfer of zinc ions. Together, these factors contribute to the more uniform concentration of zinc ions at the electrode/electrolyte interface, effectively inhibiting zinc dendrite formation and reducing by-product accumulation. The Zn//CS-ZSO//Zn symmetric cell demonstrates stable operation for over 5000 h at 1 mA cm−2, representing 29-fold improvement compared to the Zn//ZSO//Zn symmetric cell, which lasts only 170 h. Additionally, the Zn//CS-ZSO//Cu asymmetric cell shows stable average Coulombic efficiency (CE) exceeding 99.6% over 2400 cycles, significantly surpassing the performance of the ZSO electrolyte. This modification strategy for electrolytes not only addresses key limitations associated with zinc anodes but also provides valuable insights into stabilizing anodes for the advancement of high-performance aqueous zinc-ion energy storage systems.

Application of novel Dy0.06Gd0.02Er0.02Bi1.9O3 oxide ion electrolyte for intermediate-temperature reversible solid oxide cells

Bismuth-based oxides are promising electrolyte materials for Reversible Solid Oxide Cells (RSOCs) due to their high ion conductivity and rapid surface oxygen exchange kinetics. In this work we propose a multi-element doping strategy to obtain a novel Dy0.06Gd0.02Er0.02Bi1.9O3 (DGESB) quaternary oxide bismuth material whose ionic conductivities and crystal structure are characterized by AC impedance and X-ray diffraction technique in the temperature range from 600 to 700 °C. Along with promising structure stability and durability, our novel DGESB showed a remarkable ionic conductivity that is 65 times higher than the commercial yttria-stabilized zirconia (YSZ) electrolyte at 700 °C. With composite electrode of DGESB + LCN (LaCo0.6Ni0.4O3) and DGESB/YSZ bilayer electrolyte consisting of RSOC symmetric cell, which achieves a high peak power density (PPD) of 1.62 W/cm2 in fuel cell mode which is 2.7 times higher than that of YSZ single-layer electrolyte, while the electrolysis current density is as high as 1.66 A/cm2 at 1.3 V under H2/H2O:50/50 in electrolysis mode at the same operation temperature of 700 °C. The electrochemical performance measurements revealed a certain stable operation for 200 h in fuel cell mode. The performance degradation can be attributed to the microstructure evolution at the interface between electrolyte and electrodes. The high ionic conductive DGESB proves to be an excellent intermediate electrolyte layer for improving cell performance in RSOCs

A near-single-ion conducting polymer-in-ceramic electrolyte for solid-state lithium metal batteries with superior cycle stability and rate capability

Composite solid-state electrolytes (CSE) represent a promising alternative to conventional porous separators and organic liquid electrolyte systems in commercialized lithium metal battery (LMBs), offering effective dendrite suppression, high interfacial compatibility and enhanced cycle life. This study introduces a polymer-in-ceramic electrolyte, which is synthesized by blending perovskite-type inorganic electrolyte Li1.5La1.5TeO6 (LLTeO) with polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF), denoted as PMMA/PVDF-LLTeO. The resulting CSE features a dense, non-porous structure, high mechanical strength, excellent thermal stability, and a broad electrochemical window. Notably, with the incorporation of a high ceramic filler content (up to 70 %), the CSE promotes a hybrid ion transport mechanism, yielding a near-single-ion conducting behavior with an ion transference number of 0.833, and a high elastic modulus of approximately 1 GPa. These attributes collectively contribute to the suppression of dendrite growth, as analyzed through multiphysics-based simulations. Li//Li symmetric cells using PMMA/PVDF-LLTeO-70 exhibit robust lithium stripping-plating stability, with a critical current density of 0.45 mA cm−2. Furthermore, the corresponding Li//LiFePO4 cells exhibit superior rate performance and cyclic stability, achieving over 150 cycles with a capacity retention rate of 92.2 % at high temperatures (60 °C). This research highlights the potential of the proposed CSE with high-temperature applications, significantly improving the safety and performance of LMBs

Regulating the space charge at interface by negative polar biomolecule enabling ultrastable Zn anode chemistry

The irreversibility of Zn metal anode arising from uncontrollable dendrite growth and hydrogen evolution reaction, especially at high current densities, has challenged the commercialization application of aqueous Zn-ion batteries. Here we report biomolecule additive, named xanthan gum, to solve these issues through making use of dissociated electronegative groups to reduce space charge near the anode-electrolyte interface, tuning solvation structure and form H2O-poor electrical double layer to regulate the Zn deposition behaviors. Meanwhile, the dissolved xanthan gum with multiple polar groups can break the association between H2O and Zn2+ to reconstruct solvated structures of Zn ions to suppress hydrogen evolution reaction (HER). Therefore, the Zn//Zn symmetric cells in ZnSO4 electrolyte with xanthan gum deliver an ultra-long cycle life (>4700 h), and also present excellent cycling performances in other electrolytes (Zn(OAc)2 and Zn(OTf)2). More importantly, a high coulombic efficiency of 99.7 % is achieved using Zn//Cu half cells tested and excellent cycling life for KVO//Zn full cells. This work provides a guidance to design the electrolyte additive for highly reversible Zn metal batteries.

Multifunctional Composite Separator Based on NiS2/NiSe2 Homologous Heterostructure Polyhedron Promotes Polysulfide Conversion for High Performance Lithium-Sulfur Batteries.

The shuttle effect significantly hinders the industrialization of high-energy-density lithium-sulfur batteries. To address this issue, NiS2/NiSe2 homologous heterostructure polyhedron (HHP) composite separators were developed to immobilize polysulfides and promote their swift conversion. An in-situ visualization symmetrical cell was specifically designed to show the rapid polysulfide adsorption capability of NiS2/NiSe2 HHP, while the electrolyte-separator interfacial contact behavior was simulated to elucidate the mechanism of action of the composite separator in affecting the homogeneous nucleation of lithium metal surfaces. The electrochemical experimental result highlights the substantial enhancement in the reaction kinetics of polysulfides facilitated by NiS2/NiSe2 HHP, owing to its high Li+ diffusion coefficient and Li2S deposition capacity. The NiS2/NiSe2 HHP cells demonstrate high initial specific capacity (1224.1 mAh g-1) at 0.2 C and minimal decay rates (0.073%) at 2 C. The NiS2/NiSe2 HHP separator has high electrochemical catalytic activity with multiple adsorption sites, enabling the rapid polysulfide conversion and contributing to the preparation of high-performance lithium-sulfur batteries.

Chitosan-based gel polymer electrolytes for high performance Li-ion battery

This study explores the use of glutaraldehyde-crosslinked chitosan-based gel polymer electrolytes (GPEs) in lithium-ion batteries (LIBs). GPEs are prepared by solution casting using two different molecular weights of chitosan including 150 kDa as medium and 400 kDa as high molecular weight (MMWCS and HMWCS, respectively) with varying amounts of crosslinker. Degree of crystallinity was 25.9 and 24.1 % for HMWCS and MMWCS, respectively that was decreased to 18.3 and 22.7 % by using 5 % crosslinker and 17.8 and 21.1 % by using 10 % crosslinker, and 17.2 and 17.6 % by using 20 % crosslinker. The obtained ionic conductivity for HMWCS and MMWCS was 3.1 × 10−3 and 2.9 × 10−3 S.cm−1. After crosslinking by 5, 10, and 20 % crosslinker, the ionic conductivity was obtained to 0.9 × 10−3 and 0.3 × 10−3 S.cm−1, 6.3 × 10−3 and 5 × 10−3 S.cm−1, and 1.1 × 10−3 and 0.5 × 10−3 S.cm−1 for high and medium molecular weight, respectively. Lithium-ion transfer number was obtained between 0.34 and 0.83 and the highest t+ value was obtained for the MMWCS-GA10. Electrochemical stability window of the prepared polymer electrolytes was >5 V and samples showed no remarkable dendrite growth after cycling analyses. The symmetric cells demonstrated reliable performance, operating for over 300 h without any short-circuiting, which indicates excellent reversible cycling stability for chitosan-based lithium-ion batteries. Furthermore, the Gr/GPE cell exhibited very low voltage polarization, with the over-potential decreasing from 10 mV initially to 6 mV after 300 h at the same current density. Discharge capacity was obtained higher than 170 mAh/g at 0.2C with CE = 97 % for both HMWCS-GA20 and HMWCS-GA20.