In situ Observation of Li Deposition-Induced Cracking in Garnet Solid Electrolytes

Lithium(Li)penetration through solid electrolytes(SEs)induces short circuits in Li solid-state batteries(SSBs),which is a critical issue that hinders the development of high energy density SSBs.While cracking in ceramic SEs has been often shown to accompany Li penetration,the interplay between Li deposition and cracking remains elusive.Here,we constructed a mesoscale SSB inside a focused ion beam-scanning electron microscope(FIB-SEM)for in situ observation of Li deposition-induced cracking in SEs at nanometer resolution.Our results revealed that Li propagated predominantly along transgranular cracks in a garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO).Cracks appeared to initiate from the interior of LLZTO beneath the electrode surface and then propagated by curving toward the LLZTO surface.The resulting bowl-shaped cracks resemble those from hydraulic fracture caused by high fluid pressure on the surface of internal cracks,suggesting that the Li deposition-induced pressure is the major driving force of crack initiation and propagation.The high pressure generated by Li deposition is further supported by in situ observation of the flow of filled Li between the crack flanks,causing crack widening and propagation.This work unveils the dynamic interplay between Li deposition and cracking in SEs and provides insight into the mitigation of Li dendrite penetration in SSBs.

Stratified-structural hydrogel incorporated with magnesium-ion-modified black phosphorus nanosheets for promoting neuro-vascularized bone regeneration

Angiogenesis and neurogenesis play irreplaceable roles in bone repair.Although biomaterial implantation that mimics native skeletal tissue is extensively studied,the nerve-vascular network reconstruction is neglected in the design of biomaterials.Our goal here is to establish a periosteum-simulating bilayer hydrogel and explore the efficiency of bone repair via enhancement of angiogenesis and neurogenesis.In this contribution,we designed a bilayer hydrogel platform incorporated with magnesium-ion-modified black phosphorus(BP)nanosheets for promoting neuro-vascularized bone regeneration.Specifically,we incorporated magnesium-ion-modified black phosphorus(BP@Mg)nanosheets into gelatin methacryloyl(GelMA)hydrogel to prepare the upper hydrogel,whereas the bottom hydrogel was designed as a double-network hydrogel system,consisting of two interpenetrating polymer networks composed of GelMA,PEGDA,andβ-TCP nanocrystals.The magnesium ion modification process was developed to enhance BP nanosheet stability and provide a sustained release platform for bioactive ions.Our results demonstrated that the upper layer of hydrogel provided a bionic periosteal structure,which significantly facilitated angiogenesis via induction of endothelial cell migration and presented multiple advantages for the upregulation of nerve-related protein expression in neural stem cells(NSCs).Moreover,the bottom layer of the hydrogel significantly promoted bone marrow mesenchymal stem cells(BMSCs)activity and osteogenic differentiation.We next employed the bilayer hydrogel structure to correct rat skull defects.Based on our radiological and histological examinations,the bilayer hydrogel scaffolds markedly enhanced early vascularization and neurogenesis,which prompted eventual bone regeneration and remodeling.Our current strategy paves way for designing nerve-vascular network biomaterials for bone regeneration.

Gadolinium-hyaluronic acid nanoparticles as an efficient and safe magnetic resonance imaging contrast agent for articular cartilage injury detection

Accurate detection of cartilage injuries is critical for their proper treatment because these injuries lack the selfhealing ability and lead to joint dysfunction.However,the low longitudinal T1 relaxivity(r1)and non-specificity of contrast agents(such as gadolinium(III)-diethylenetriamine-pentaacetic acid(Gd-DTPA))significantly limit the efficiency of clinical magnetic resonance imaging(MRI)applications.To overcome these drawbacks,we integrated hyaluronic acid(HA)with Gd to synthesize a Gd-DTPA-HA composite,which was subsequently freeze-dried to produce nanoparticles(NPs).The resultant Gd-HA NPs demonstrated a greater r1 value(12.51 mM^-1 s^-1)compared with the bulk Gd-DTPA-HA(8.37 mM^-1 s^-1)and clinically used Gd-DTPA(3.88 mM^-1 s^-1).Moreover,the high affinity of HA to the cartilage allowed these NPs to penetrate deeper beyond the cartilage surface.As a result,Gd-HA NPs considerably increased the quality of cartilage and lesion MR images via their intra-articular injection in vivo.Specifically,2 h after NP administration,the signal-to-noise ratio at the injured cartilage site was 2.3 times greater than the value measured before the injection.In addition,Gd-HA NPs exhibited good biosafety properties due to the absence of adverse effects in the blood or on the main organs.It was also showed that Gd NPs were first metabolized by the kidney and liver and then excreted from the body with urine.Thus,Gd-HA NPs can potentially serve as an efficient MRI contrast agent for improved detection of cartilage injuries.