PEO-based electrolytes are promising for solid-state lithium metal batteries, but their low ionic conductivity and unstable interfacial compatibility with electrodes are the bottlenecks restricting ...their further applications. Herein, a unique ionic liquid (Pyr14TFSI)-encapsulated cross-linked polymer electrolyte with abundant ether–oxygen repeat units (C-SPE-IL) is proposed and prepared through an in-situ thermal polymerization process. The Pyr14+ cations of ionic liquid present a stronger affinity towards ether–oxygen groups by means of tight coordinated interactions, which promotes ionic liquid encapsulated uniformly in the polymer matrix to release more mobile Li ions into ionic liquid and create multiple ionic conduction highways in both ionic liquid and polymer matrix. The C-SPE-IL shows a much higher ionic conductivity of 3.98 × 10−4 S/cm at 30 °C. Moreover, tight interfaces with LiF– and Li3N– rich components between C-SPE-IL and Li anode are constructed to ensure effective suppression of lithium dendrites during cycling. The LiFePO4/Li batteries using C-SPE-IL present stable cycling performances at both 35 °C and 60 °C. This work provides a facile and accessible approach to design novel SPE with both ionic conduction highways and good interfacial stability for high-performance solid-state lithium metal batteries.
•Ionic liquid-encapsulated cross-linked polymer electrolytes for Li metal battery.•Strong coordination between ionic liquid cation and polymer to release more Li+.•Creating multiple ion-conducting pathways to achieve high ionic conductivity.•Enhanced oxidation stability and stable interface with lithium anode.•Good rate capability and cyclability of LiFePO4/Li full cell at 35 °C and 60 °C.
An <inline-formula> <tex-math notation="LaTeX">(\boldsymbol {M},\boldsymbol {K},\boldsymbol {N},\delta _{\max }) </tex-math></inline-formula>-quasi-complementary sequence set (QCSS) is referred to as ...a set of <inline-formula> <tex-math notation="LaTeX">\boldsymbol {M} </tex-math></inline-formula> 2-D matrices of order <inline-formula> <tex-math notation="LaTeX">\boldsymbol {K}\times \boldsymbol {N} </tex-math></inline-formula> with periodic tolerance <inline-formula> <tex-math notation="LaTeX">\delta _{\max } </tex-math></inline-formula>. In a multicarrier code-division multiple-access (MC-CDMA) communication system, the set size <inline-formula> <tex-math notation="LaTeX">\boldsymbol {M} </tex-math></inline-formula> of a QCSS is equal to the maximum number of users it can support, and the periodic tolerance <inline-formula> <tex-math notation="LaTeX">\delta _{\max } </tex-math></inline-formula> determines the interference performance. For the application of a QCSS, it is desirable that the set size should be as large as possible, and the periodic tolerance should be as small as possible. In this paper, a framework of a periodic QCSS is proposed from additive and multiplicative characters associated with a specific integer set. It is then discovered that the parameters of the obtained QCSS are determined by the employed integer set. From this discovery, new classes of periodic QCSSs with large set sizes and low periodic tolerances are constructed and associated with some known integer sets.
•Electrolytes contain abundant dynamic imine bonds.•Reversible imine bonding reactions give electrolytes unique solid-state plasticity.•Reversible bonds make electrolytes achieve high ionic ...conductivity and good interfacial compatibility with lithium anode.•Full LiFePO4|V-SPE-PEG|Li cell exhibits stable cycling.
High-safety PEO-based electrolytes have attracted widespread attention, but their inefficient conduction of Li ions and poor contact with electrode interfaces deteriorate the performances of rechargeable lithium metal batteries. Herein, we design a vitrimer polymer electrolyte (V-SPE-PEG) with abundant dynamic imine bonds via Schiff base reaction between aldehyde and ammonia, which achieves high ionic conductivity and good interfacial compatibility with lithium anode. The dynamic polymer network in V-SPE-PEG exhibits solid-state plasticity because reversible imine bonding reactions enable the integrity of the polymer network to be maintained while altering the cross-linked points under external stimuli. Therefore, this 3D dynamic cross-linked network effectively facilitates the polymer chain dynamics and meanwhile enhances ionic conductivity. Additionally, dynamic bond exchange fosters electrolyte flowability and self-healing during lithium deposition, promoting a tightly integrated electrode/electrolyte interface while inhibiting lithium dendrites growth. Consequently, lithium symmetric cells utilizing the V-SPE-PEG electrolyte demonstrate exceptional long-term cycling stability, surpassing 1100 h and exhibit outstanding ionic conductivity of 2.7 × 10−4 S cm−1 at 30 °C. The LiFePO4||Li battery maintains stable cycling performance at both 40 °C and 60 °C. This study introduces an innovative approach to designing solid-state electrolytes for lithium-metal batteries.
Metal-oxide/carbon composites with remarkable dielectric-magnetic properties are promising as microwave absorption materials, but achieving high-attenuation and broadband microwave absorption ...properties still remains challenging. Herein, we develop a one-step carbonization of the ferric gluconate precursor to manufacture two-dimensional oxygen-vacancy-rich Fe3O4/carbon nanosheets (Fe3O4/C) for high-attenuation microwave absorption. The key to the synthesis is employing the Fe3+-gluconate complex as the precursor, which has the ability to release small molecules within the viscosity foaming window to spontaneously obtain a 3D self-foamed material. Followed by high-temperature annealing, the as-obtained Fe3O4/C hybrid composite features large lamellar (>20 μm) carbon nanosheets with abundant yolk–shell heterostructures and highly dispersed and high-loaded (∼44%) oxygen-vacancy-rich Fe3O4 nanocrystals. The unique 2D structure could facilitate multiple scattering absorption and interconnect into a 3D conductivity-loss network. Meanwhile, the abundant yolk–shell heterostructures could trigger extra interfacial polarization. And density functional theory calculation results demonstrate that oxygen vacancies endow magnetic Fe3O4 nanocrystals with charge-separation induced polarizations. Consequently, Fe3O4/C exhibit superior microwave absorption capability with an impressive reflection loss (RL) of −65.4 dB and an ultra-broad effective absorption bandwidth of 6.24 GHz. The spontaneous foaming strategy in this work could provide feasible technological approaches for the practical fabrication of microwave absorption materials.
Mutually orthogonal complementary sets (MOCSs) have found a number of practical applications in wireless communications and radar owing to their perfect aperiodic auto-correlation and ...cross-correlation properties. Recently, toward the challenge of designing MOCSs with non-power-of-two lengths, direct constructions were presented by Wu et al. using generalized Boolean functions (GBFs). In this letter, a new construction of MOCSs is proposed based on GBFs, which leads to MOCSs with flock size 2 k+1 and length 2 m + 2 t , whose set size is 1/2 of the flock size, where integers 0 ≤ t <; k ≤ m. In addition, the constructed MOCSs can yield column sequence peak-to-mean envelope power ratio (PMEPR) of at most 2.
An <inline-formula> <tex-math notation="LaTeX">(M,K,N,\delta _{\mathrm {max}}) </tex-math></inline-formula>-quasi-complementary sequence set (QCSS) is referred to as a set of <inline-formula> ...<tex-math notation="LaTeX">M </tex-math></inline-formula> two-dimensional matrices of size <inline-formula> <tex-math notation="LaTeX">K\times N </tex-math></inline-formula> with maximum periodic correlation magnitude <inline-formula> <tex-math notation="LaTeX">\delta _{\mathrm {max}} </tex-math></inline-formula>. It can be applied to a multi-carrier code-division multiple-access communication system to achieve low-interference performance. Compared with perfect complementary sequence sets, QCSSs with maximum periodic correlation magnitudes achieving or asymptotically achieving the correlation lower bounds have the advantage of supporting more users. In this paper, two constructions of periodic QCSSs from additive characters and multiplicative characters of finite fields are developed. In the first construction, new QCSSs with constituent sequence length <inline-formula> <tex-math notation="LaTeX">N=p </tex-math></inline-formula> are proposed by using cyclic classes, where <inline-formula> <tex-math notation="LaTeX">p </tex-math></inline-formula> is a prime. In the second construction, QCSSs with constituent sequence length <inline-formula> <tex-math notation="LaTeX">N=q-1 </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">N=r^{2}-1 </tex-math></inline-formula> are presented by employing almost difference sets and special sets proposed by Katz, respectively, where <inline-formula> <tex-math notation="LaTeX">q>5 </tex-math></inline-formula> is an odd prime power and <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula> is a prime power. Notably, the parameters of QCSSs derived from the second construction are flexible and have not been covered in the literature. In addition, all the proposed periodic QCSSs are asymptotically optimal with respect to the correlation lower bounds.
The demand for flexible lithium-ion batteries (FLIBs) has witnessed a sharp increase in the application of wearable electronics, flexible electronic products, and implantable medical devices. ...However, many challenges still remain towards FLIBs, including complex cell manufacture, low-energy density and low-power density. To address these issues, researchers have widely conducted studies on the structure and material design of flexible batteries. Among these efforts, the anode-free lithium metal battery (AFLMB) stands out as a promising solution, offering potential new avenues for research in flexible battery design. The anode-free full cell configuration removes excess lithium and combines the fully lithiated cathode with a bare current collector (CC), which not only simplifies the production process and lowers the cost, but also achieves light weight and high-energy-density. Nevertheless, AFLMBs are still confronted by challenges including diminished coulombic efficiency (CE), shortened cycle longevity, and lithium dendrite growth, which substantially impede the practical application of AFLMBs towards flexible batteries. This review provides an overview of the latest developments in anode-free batteries, particularly focusing on research strategies in electrolyte design and current collector modification. Considering the characteristics of flexible batteries, the article also points out the challenges and feasible research directions for the development of flexible AFLMBs. It is concluded that although there are significant challenges in developing flexible AFLMBs, the design of gel electrolytes and polymer artificial solid electrolyte interphases (SEIs) can expedite practical advancements, aiming to achieve safe, light weight, cost-effective, and high-energy-density flexible batteries.
The anode-free lithium metal battery is characterized by light weight, low cost, high-energy density, and high safety and shows great potential for the application of flexible devices.
Codebooks with small inner product correlation have wide applications in many fields, such as direct spread code-division multiple access communications, signal processing, and compressed sensing. It ...is extremely hard to produce optimal codebooks with respect to the Welch bound or the Levenstein bound. This letter focuses on constructing asymptotically optimal codebooks with additive characters of finite fields. Following the proposed constructions, two classes of asymptotically optimal codebooks with respect to the Welch bound are obtained. In addition, the resulting codebooks could have a small alphabet size.
Solid polymer electrolytes (SPEs) with good flexibility and low cost are very promising for all-solid-state lithium metal batteries, but they suffer from the trade-off between ionic conductivity at ...room temperature and mechanical stability. Herein, a robust composite polymer electrolyte is prepared by thermal lamination of PEO polymer electrolyte films onto a lithiated organic nanofiber membrane (LOF), which could combine the merits of 3D Li-ion conduction highways for high ionic conductivity and nanofiber-reinforced networks for good mechanical properties. The intimate combination between the nanofibers and the PEO matrix endows the LOF-reinforced PEO composite (LOF-CPE) with homogeneous structure, leading to an enhanced ultimate tensile stress of 8.9 MPa. Furthermore, the introduction of the LOF significantly decreases the crystallinity of the polymer matrix, which accelerates polymer segmental motion. The well-designed LOF also constructs an interfacial percolation network with additional active Li
+
, resulting in the formation of high-speed Li-ion conduction pathways. Therefore, the as-prepared LOF-CPE delivers an excellent ionic conductivity of 7.41 × 10
−5
S cm
−1
at 30 °C. While used as a SPE in LiFePO
4
|Li solid-state batteries, the batteries exhibit good cyclability with a capacity retention of 82% after 500 cycles under 0.5C. This work provides a very promising strategy for solid polymer electrolytes to simultaneously achieve high ionic conductivity and excellent mechanical properties towards high-performance solid-state lithium metal batteries.
A robust composite polymer electrolyte is prepared by thermal lamination of PEO electrolyte films onto lithiated organic nanofibers, combining the merits of 3D Li-ion conduction highways and good nanofiber-reinforced mechanical properties.
