The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(...The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.展开更多
Rechargeable magnesium batteries are identified as a promising next-generation energy storage system,but their development is hindered by the anode−electrolyte−cathode incompatibilities and passivation of magnesium me...Rechargeable magnesium batteries are identified as a promising next-generation energy storage system,but their development is hindered by the anode−electrolyte−cathode incompatibilities and passivation of magnesium metal anode.To avoid or alleviate these problems,the exploitation of alternative anode materials is a promising choice.Herein,we present titanium pyrophosphate(TiP_(2)O_(7))as anode materials for magnesium-ion batteries(MIBs)and investigate the effect of the crystal phase on its magnesium storage performance.Compared with the me-tastable layered TiP_(2)O_(7),the thermodynamically stable cubic TiP_(2)O_(7) displays a better rate capability of 72 mAh g^(−1) at 5000 mA g^(−1).Moreover,cubic TiP_(2)O_(7) exhibits excellent cycling stability with the capacity of 60 mAh g^(−1) after 5000 cycles at 1000 mA g^(−1),which are better than pre-viously reported Ti-based anode materials for MIBs.In situ X-ray diffraction technology confirms the single-phase magnesiumion inter-calation/deintercalation reaction mechanism of cubic TiP_(2)O_(7) with a low volume change of 3.2%.In addition,the density functional theory calcu-lation results demonstrate that three-dimensional magnesiumion diffu-sion can be allowed in cubic TiP_(2)O_(7) with a low migration energy barrier of 0.62 eV.Our work demonstrates the promise of TiP_(2)O_(7) as high-rate and long-life anode materials for MIBs and may pave the way for further development of MIBs.展开更多
Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by unifor...Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by uniformly dis-persing amorphous Si nanodots(SiNDs)in carbon nanospheres(SiNDs/C)that are welded on the wall of the macroporous carbon framework(MPCF)by vertical graphene(VG),labeled as MPCF@VG@SiNDs/C.The high dispersity and amor-phous features of ultrasmall SiNDs(~0.7 nm),the flexible and directed electron/Li+transport channels of VG,and the MPCF impart the MPCF@VG@SiNDs/C more lithium storage sites,rapid Li+transport path,and unique low-strain property during Li+storage.Consequently,the MPCF@VG@SiNDs/C exhibits high cycle stability(1301.4 mAh g^(-1) at 1 A g^(-1) after 1000 cycles without apparent decay)and high rate capacity(910.3 mAh g^(-1),20 A g^(-1))in half cells based on industrial electrode standards.The assembled pouch full cell delivers a high energy density(1694.0 Wh L^(-1);602.8 Wh kg^(-1))and an excellent fast-charging capability(498.5 Wh kg^(-1),charging for 16.8 min at 3 C).This study opens new possibilities for preparing advanced silicon-carbon com-posite anodes for practical applications.展开更多
提出了缺陷桩-梁系统的理论模型。桩周土采用了三维连续介质模型,桩身则采用Rayleigh-love杆件,以考虑大直径桩的横向惯性效应。为了模拟桩身的缺陷段,采用了不同于正常桩身半径的桩段。通过结合阻抗函数递推法、虚土环法(ring soil pil...提出了缺陷桩-梁系统的理论模型。桩周土采用了三维连续介质模型,桩身则采用Rayleigh-love杆件,以考虑大直径桩的横向惯性效应。为了模拟桩身的缺陷段,采用了不同于正常桩身半径的桩段。通过结合阻抗函数递推法、虚土环法(ring soil pile theory,简称RSPT)和修正的阻抗函数递推法(amended impedance function transfer method,简称AIFTM),得到了桩-土系统的桩顶阻抗。桩顶梁采用了Timoshenko杆件进行模拟,同时在桩-梁连接处施加瞬态激振。成功求得了桩-梁系统动力响应在频域内的解析解,并利用离散傅里叶变换获得了时域内的半解析解。为了验证模型的合理性,将获得的半解析解与试验数据和有限元法结果进行了对比。研究结果显示,桩-梁系统较为适合的激振拾取点通常为桩梁连接处,同时需要综合考虑桩梁参数的影响。最后,通过参数分析方法探讨了在桩-梁系统上使用低应变测试的注意事项。展开更多
基金supported by the Innovation Foundation of Graduate Student of Harbin Normal University(Grant No.HSDSSCX2020-18)the Natural Science Foundation of Heilongjiang Province,China(Grant No.TD2020B001)the Opening Project of State Key Laboratory of Advanced Chemical Power Sources(Grant No.SKL-ACPS-C-25)。
文摘The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.
基金This study was supported by the National Natural Science Foundation of China(51832004,U1804253,and 51972259)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003).
文摘Rechargeable magnesium batteries are identified as a promising next-generation energy storage system,but their development is hindered by the anode−electrolyte−cathode incompatibilities and passivation of magnesium metal anode.To avoid or alleviate these problems,the exploitation of alternative anode materials is a promising choice.Herein,we present titanium pyrophosphate(TiP_(2)O_(7))as anode materials for magnesium-ion batteries(MIBs)and investigate the effect of the crystal phase on its magnesium storage performance.Compared with the me-tastable layered TiP_(2)O_(7),the thermodynamically stable cubic TiP_(2)O_(7) displays a better rate capability of 72 mAh g^(−1) at 5000 mA g^(−1).Moreover,cubic TiP_(2)O_(7) exhibits excellent cycling stability with the capacity of 60 mAh g^(−1) after 5000 cycles at 1000 mA g^(−1),which are better than pre-viously reported Ti-based anode materials for MIBs.In situ X-ray diffraction technology confirms the single-phase magnesiumion inter-calation/deintercalation reaction mechanism of cubic TiP_(2)O_(7) with a low volume change of 3.2%.In addition,the density functional theory calcu-lation results demonstrate that three-dimensional magnesiumion diffu-sion can be allowed in cubic TiP_(2)O_(7) with a low migration energy barrier of 0.62 eV.Our work demonstrates the promise of TiP_(2)O_(7) as high-rate and long-life anode materials for MIBs and may pave the way for further development of MIBs.
基金All authors acknowledge fund support from Guangdong Basic and Applied Basic Research Foundation(2020A1515110762)National Natural Science Foundation of China(52172084).
文摘Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by uniformly dis-persing amorphous Si nanodots(SiNDs)in carbon nanospheres(SiNDs/C)that are welded on the wall of the macroporous carbon framework(MPCF)by vertical graphene(VG),labeled as MPCF@VG@SiNDs/C.The high dispersity and amor-phous features of ultrasmall SiNDs(~0.7 nm),the flexible and directed electron/Li+transport channels of VG,and the MPCF impart the MPCF@VG@SiNDs/C more lithium storage sites,rapid Li+transport path,and unique low-strain property during Li+storage.Consequently,the MPCF@VG@SiNDs/C exhibits high cycle stability(1301.4 mAh g^(-1) at 1 A g^(-1) after 1000 cycles without apparent decay)and high rate capacity(910.3 mAh g^(-1),20 A g^(-1))in half cells based on industrial electrode standards.The assembled pouch full cell delivers a high energy density(1694.0 Wh L^(-1);602.8 Wh kg^(-1))and an excellent fast-charging capability(498.5 Wh kg^(-1),charging for 16.8 min at 3 C).This study opens new possibilities for preparing advanced silicon-carbon com-posite anodes for practical applications.
文摘提出了缺陷桩-梁系统的理论模型。桩周土采用了三维连续介质模型,桩身则采用Rayleigh-love杆件,以考虑大直径桩的横向惯性效应。为了模拟桩身的缺陷段,采用了不同于正常桩身半径的桩段。通过结合阻抗函数递推法、虚土环法(ring soil pile theory,简称RSPT)和修正的阻抗函数递推法(amended impedance function transfer method,简称AIFTM),得到了桩-土系统的桩顶阻抗。桩顶梁采用了Timoshenko杆件进行模拟,同时在桩-梁连接处施加瞬态激振。成功求得了桩-梁系统动力响应在频域内的解析解,并利用离散傅里叶变换获得了时域内的半解析解。为了验证模型的合理性,将获得的半解析解与试验数据和有限元法结果进行了对比。研究结果显示,桩-梁系统较为适合的激振拾取点通常为桩梁连接处,同时需要综合考虑桩梁参数的影响。最后,通过参数分析方法探讨了在桩-梁系统上使用低应变测试的注意事项。
文摘采用金属有机物化学气相沉积(Metal organic chemical vapor deposition,MOCVD)技术在101.6 mm(4英寸)半绝缘SiC衬底上开展太赫兹用GaN肖特基势垒二极管(Schottky barrier diode,SBD)外延材料应力演进及缺陷密度控制的研究。提出了一种基于AlGaN过渡层的应力调控方案,实现了外延材料的应力调控;采用低温脉冲式掺杂技术生长n+-GaN层,降低了外延材料的缺陷密度,提升了晶体质量。研制的101.6 mm GaN SBD外延材料的弯曲度(Bow)/翘曲度(Warp)为-12/18μm,(002)/(102)面半高宽为148/239 arcsec,方阻9.2Ω/□,方阻片内不均匀性1.1%,并基于自研材料实现了截止频率为1.12 THz的GaN SBD器件的研制。
