Electro-chemo-mechanical analysis of the effect of bending deformation on the interface of flexible solid-state battery

Flexible solid-state battery has several unique characteristics including high flexibility,easy portability,and high safety,which may have broad application prospects in new technology products such as rollup displays,power implantable medical devices,and wearable equipments.The interfacial mechanical and electrochemical problems caused by bending deformation,resulting in the battery damage and failure,are particularly interesting.Herein,a fully coupled electro-chemo-mechanical model is developed based on the actual solid-state battery structure.Concentration-dependent material parameters,stress-dependent diffusion,and potential shift are considered.According to four bending forms(k=8/mm,0/mm,-8/mm,and free),the results show that the negative curvature bending is beneficial to reducing the plastic strain during charging/discharging,while the positive curvature is detrimental.However,with respect to the electrochemical performance,the negative curvature bending creates a negative potential shift,which causes the battery to reach the cut-off voltage earlier and results in capacity loss.These results enlighten us that suitable electrode materials and charging strategy can be tailored to reduce plastic deformation and improve battery capacity for different forms of battery bending.

分子分型与乳腺癌新辅助化疗腋窝降阶梯手术的研究

目的:探讨临床淋巴结阴性患者新辅助化疗(neoadjuvant chemotherapeutic,NAC)与前哨淋巴结活检(sentinel lymph node biopsy,SLNB)的最佳时机,评估临床淋巴结阳性患者行NAC后腋窝降阶梯手术可能获益人群。方法:回顾性分析2010年10月至2017年11月山东大学附属山东省肿瘤医院收治206例行NAC患者的临床病理资料,分析分子分型与腋窝淋巴结病理完全缓解(axillary nodal pathologic complete response,apCR)的关系。结果:206例行NAC患者中183例为临床淋巴结阳性,apCR为33.3%(61/183)。Luminal型HER-2阴性患者apCR为19.8%(17/86),与HER-2阳性行靶向治疗患者apCR的62.1%(18/29)、HER-2阳性未行靶向治疗的34.5%(10/29)及三阴性乳腺癌(triple-negative breast cancer,TNBC)的41.0%(16/39)相比显著降低,差异具有统计学意义(P<0.001)。23例临床淋巴结阴性患者行NAC后前哨淋巴结阳性率为26.1%(6/23),Luminal型HER-2阴性、TNBC和HER-2阳性患者前哨淋巴结阳性率分别为36.4%(4/11)、25.0%(1/4)和12.5%(1/8)。结论:分子分型与行NAC后的apCR相关。对临床淋巴结阴性的Luminal型HER-2阴性患者,NAC前行SLNB可避免腋窝淋巴结清扫,对临床淋巴结阴性的TNBC和HER-2阳性患者,建议NAC后行SLNB。临床淋巴结阳性且行NAC降期转阴的TNBC和HER-2阳性患者,从NAC后的腋窝降阶梯手术中可能获益更多。

High-Power and Ultralong-Life Aqueous Zinc-Ion Hybrid Capacitors Based on Pseudocapacitive Charge Storage

Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life Zn2+storage based on a pseudocapacitive storage mechanism.In the RuO2·H2O||Zn zinc-ion hybrid capacitors with Zn(CF3SO3)2 aqueous electrolyte,the RuO2·H2O cathode can reversibly store Zn2+in a voltage window of 0.4-1.6 V(vs.Zn/Zn2+),delivering a high discharge capacity of 122 mAh g?1.In particular,the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg?1 and a high energy density of 82 Wh kg?1.Besides,the zinc-ion hybrid capacitors demonstrate an ultralong cycle life(over 10,000 charge/discharge cycles).The kinetic analysis elucidates that the ultrafast Zn2+storage in the RuO2·H2O cathode originates from redox pseudocapacitive reactions.This work could greatly facilitate the development of high-power and safe electrochemical energy storage.

Novel Insights into Energy Storage Mechanism of Aqueous Rechargeable Zn/MnO2 Batteries with Participation of Mn2+

Aqueous rechargeable Zn/MnO2 zinc-ion batteries(ZIBs)are reviving recently due to their low cost,non-toxicity,and natural abundance.However,their energy storage mechanism remains controversial due to their complicated electrochemical reactions.Meanwhile,to achieve satisfactory cyclic stability and rate performance of the Zn/MnO2 ZIBs,Mn2+ is introduced in the electrolyte(e.g.,ZnSO4 solution),which leads to more complicated reactions inside the ZIBs systems.Herein,based on comprehensive analysis methods including electrochemical analysis and Pourbaix diagram,we provide novel insights into the energy storage mechanism of Zn/MnO2 batteries in the presence of Mn2+.A complex series of electrochemical reactions with the coparticipation of Zn2+,H+,Mn2+,SO42-,and OH-were revealed.During the first discharge process,co-insertion of Zn2+ and H+ promotes the transformation of MnO2 into ZnxMnO4,MnOOH,and Mn2O3,accompanying with increased electrolyte pH and the formation of ZnSO4·3 Zn(OH)2-5 H2O.During the subsequent charge process,ZnxMnO4,MnOOH,and Mn2O3 revert to a-MnO2 with the extraction of Zn2+ and H+,while ZnSO4·3Zn(OH)2·5H2O reacts with Mn2+ to form ZnMn3O7·3 H2O.In the following charge/discharge processes,besides aforementioned electrochemical reactions,Zn2+ reversibly insert into/extract from α-MnO2,ZnxMnO4,and ZnMn3O7·3H2O hosts;ZnSO4·3Zn(OH)2·5 H2O,Zn2Mn3O8,and ZnMn2O4 convert mutually with the participation of Mn2+.This work is believed to provide theoretical guidance for further research on high-performance ZIBs.

分子分型对乳腺癌新辅助化疗后肿瘤退缩模式的影响

目的:探讨乳腺癌新辅助化疗(neoadjuvant chemotherapy,NAC)后不同分子分型的乳腺原发病灶退缩模式。方法:选取2008年7月至2017年10月山东大学附属山东省肿瘤医院收治的108例ⅡA~ⅢC期乳腺浸润性导管癌行新辅助化疗后手术患者的临床病理资料,手术标本制作次连续病理大切片,电子显微镜下勾画残余肿瘤范围,三维重建残余肿瘤,评价新辅助化疗后原发肿瘤临床病理退缩模式。结果:108例患者新辅助化疗后向心性退缩(concentric shrinkage mode,CSM)与非向心性退缩(non-concentric shrinkage mode,NCSM)中Luminal A型分别占47.4%(9/19)与52.6%(10/19),Luminal B HER-2阴性型、HER-2阳性型分别占53.6%(15/28)、72.7%(16/22)与46.4%(13/28)、27.3%(6/22),HER-2阳性型分别占84.6%(11/13)与15.4%(2/13),三阴性乳腺癌分别占80.8%(21/26)与19.2%(5/26)。结论:Luminal B HER-2阳性型、HER-2阳性型及三阴性乳腺癌的原发肿瘤更易出现CSM,Luminal A型、Luminal B型HER-2阴性型的原发肿瘤临床病理退缩模式无显著性差异。分子分型可用于预测乳腺癌新辅助化疗后原发肿瘤的临床病理退缩模式,有助于选择新辅助化疗后适合保乳治疗的患者、降低局部复发率。

β-MnO_(2) with proton conversion mechanism in rechargeable zinc ion battery

Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,the under-debate proton reaction mechanism and unsatisfactory electrochemical performance limit their applications.Nanorod b-MnO_(2) synthesized by hydrothermal method is used to investigate the reaction mechanism.As cathode materials for RAZIB,the Zn//b-MnO_(2) delivers 355 mA h g^(-1)(based on cathode mass)at0.1 A g^(-1),and retain 110 mA h g^(-1) after 1000 cycles at 0.2 A g^(-1).Different from conventional zinc ion insertion/extraction mechanism,the proton conversion and Mn ion dissolution/deposition mechanism of b-MnO_(2) is proposed by analyzing the evolution of phase,structure,morphology,and element of b-MnO_(2) electrode,the pH change of electrolyte and the determination of intermediate phase MnO OH.Zinc ion,as a kind of Lewis acid,also provides protons through the formation of ZHS in the proton reaction process.This study of reaction mechanism provides a new perspective for the development of Zn//MnO_(2) battery chemistry.

High-Performance Aqueous Zinc-Ion Batteries Realized by MOF Materials

Rechargeable aqueous zinc-ion batteries(ZIB s) have been gaining increasing interest for large-scale energy storage applications due to their high safety,good rate capability,and low cost.However,the further development of ZIB s is impeded by two main challenges:Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity,and meanwhile,unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs.In this paper,metal-organic framework(MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIB s with Mn(BTC) MOF cathodes and ZIF-8-coated Zn(ZIF-8@Zn) anodes.Various MOF materials were synthesized,and Mn(BTC) MOF was found to exhibit the best Zn^2+-storage ability with a capacity of 112 mAh g^-1.Zn^2+ storage mechanism of the Mn(BTC) was carefully studied.Besides,ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils.Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes.As a result,the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors,with 8 times longer cycle life than bare Zn foils.Based on the above,high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes,which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles.This work provides a new opportunity for high-performance energy storage system.

Towards High-Energy and Anti-Self-Discharge Zn-Ion Hybrid Supercapacitors with New Understanding of the Electrochemistry

Aqueous Zn-ion hybrid supercapacitors(ZHSs)are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance,high safety and low cost.Herein,high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups.Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage,but also optimizes ion transport kinetics.Consequently,the cathodes show a high gravimetric capacity of 156 mAh g^(−1),superior rate capability(79 mAh g^(−1)with a very short charge/discharge time of 14 s)and exceptional cycling stability.Meanwhile,hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg−1,a high power density of 15.3 kW kg^(−1)and good anti-self-discharge performance.Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn_(4)SO_(4)(OH)_(6)·5H_(2)O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes.The roles of these reactions in energy storage of ZHSs are elucidated.This work not only paves a way for high-performance cathode materials of ZHSs,but also provides a deeper understanding of ZHS electrochemistry.

Few-layer Ti3C2Tx MXene delaminated via flash freezing for high-rate electrochemical capacitive energy storage

Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are induced to rearrange and produce volume expansion,thus notably expand the MXenes’interlayer distance to form few-layer MXene.The synthesized few-layer Ti3C2Tx MXene nanosheets display a very small thickness(less than 5 Ti3C2 atom-layers)and expanded interlayer spacing.Consequently,the few-layer Ti3C2Tx exhibits enhanced capacitance(255 F g^-1 vs.177 F g^-1 for the multi-layered Ti3C2Tx)and significantly optimized rate capability(150 F g^-1 at 200 mV s^-1 vs.25 F g^-1 for the multi-layered Ti3C2Tx),because redox-active sites in the few-layer MXene are easily accessible to electrolyte ions.Moreover,an asymmetric supercapacitor is constructed using the few-layer Ti3C2Tx negative electrode and an activated carbon fiber positive electrode.The asymmetric supercapacitor presents a high energy density of 17.9 Wh kg^-1 and a high power density of 14 kW kg^-1,which is inseparable from its wide voltage window of 1.4 V and the good rate performance of the few-layer Ti3C2Tx MXene electrode.Overall,the flash freezing-assist delamination provides an effective and environmental-friendly strategy to synthesize few-layer MXene materials for high-rate electrochemical energy storage.

High-performance zinc-ion batteries enabled by electrochemically induced transformation of vanadium oxide cathodes

Rechargeable aqueous zinc-ion batteries(ZIBs) have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electrochemical properties of ZIBs,cathode materials with prominent Zn^(2+) storage capability are highly needed.Herein,we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides.Specifically,K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes.The cathode presented superior Zn^(2+) storage capability in Zn(OTf)_(2) aqueous electrolyte,including high capacity of 321 mAh/g,fast charge/discharge ability(96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance.Mechanism analysis evidenced that in Zn(OTf)_(2) electrolyte,Zn^(2+) intercalation in the first discharge process promoted K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers to transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O nanoflakes,and the latter served as the Zn^(2+)-storage host in subsequent charge/discharge processes.Benefiting from open-framework crystal structure and sufficiently exposed surface,the Zn_(3+x)V_(2) O_7(OH)_(2)·2_H2 O nanoflakes exhibited high Zn^(2+) diffusion coefficient,smaller charge-transfer resistance and good reversibility of Zn^(2+) intercalation/de-intercalation,thus leading to superior electrochemical performance.While in ZnS04 aqueous electrolyte,the cathode material cannot sufficiently transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O thereby corresponding to inferior electrochemical behaviors.Underlying mechanism and influencing factors of such a transformation phenomenon was also explored.This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides,but also provides new insights into Zn^(2+)-storage electrochemistry.

Group VB transition metal dichalcogenides for oxygen reduction reaction and strain-enhanced activity governed by p-orbital electrons of chalcogen

Developi ng alter native oxyge n reducti on reactio n (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challe nge of commercial application of fuel cells. Owing to their various compositi ons and tun able electronic properties, transition metal dichalcogenides (TMDs) have the great potential to realize high-efficiency catalysts for ORR. Here, various 3R-phase dichalcogenides of group VB and VIB transition metals (MX2, M = Nb, Ta, Mo, W;X = S, Se, Te) are investigated for ORR catalysts by using density functional theory calculations. The computed over-potentials of group VB TMDs are much less than those of group VIB TMDs. For group VB TMDs, a volcano-type plot of ORR catalytic activity is established on the adsorption energies of *OH, and NbS2 and TaTe2 exhibit best ORR activity with an oveepotential of 0.54 V. To achieve even better activity, strain engineering is performed to tune ORR catalytic activity, and the minimum over-potential of 0.43 V can be realized. We further dem on strate that the shift of p orbital center of surface chalcoge n elements under strain is responsible for tuning the catalytic activity of TMDs.

Flexible supercapacitors

Flexible supercapacitors show a great potential for applications in wearable, miniaturized, portable, large- scale transparent and flexible consumer electronics due to their significant, inherent advantages, such as being flexible, lightweight, low cost and environmentally friendly in comparison with the current energy storage devices. In this report, recent progress on flexible supercapacitors, flexible electrodes and electrolytes is reviewed. In addition, the future challenges and opportunities are discussed.

Reversible aqueous zinc-ion battery based on ferric vanadate cathode

Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety.However,the relationship between structure change of cathode and the zinc ion storage mechanism is still complex and challenging.Herein,open-structured ferric vanadate(Fe_(2)V_(4)O_(13))has been developed as cathode material for aqueous zinc-ion batteries.Intriguingly,two zinc ion storage mechanism can be observed simultaneously for the Fe2V4O13 electrode,i.e.,classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe_(2)V_(4)O_(13),and reversible phase transformation from ferric vanadate to zinc vanadate,which is verified by combined studies using various in-situ and ex-situ techniques.As a result,the Fe_(2)V_(4)O_(13) cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g,and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2-1.6 V with 2 mol/L Zn(CF_(3)SO_(3))_(2) aqueous solution.Moreover,the assembled Fe_(2)V_(4)O_(13)//Zn flexible quasi-solid-state battery also exhibits a relatively high mechanical strength and good cycling stability.The findings reveal a new perspective of zinc ion storage mechanism for Fe_(2)V_(4)O_(13),which may also be applicable to other vanadate cathodes,providing a new direction for the investigation and design of zinc-ion batteries.