Lithium-ion batteries(LIBs)suffer from float charge failure in the grid-scale storage market.However,the lack of a unified descriptor for the diverse reasons behind float charge failure poses a challenge.Here,a quanti...Lithium-ion batteries(LIBs)suffer from float charge failure in the grid-scale storage market.However,the lack of a unified descriptor for the diverse reasons behind float charge failure poses a challenge.Here,a quantitative analysis of active lithium loss is conducted across multiple temperatures into float charge of Li(Ni_(0.5)Co_(0.2)Mn_(0.3))O_(2)–graphite batteries.It is proposed that the active lithium loss can be used as a descriptor to describe the reasons for float charge quantitatively.Approximately 6.88%and 0.96%of active lithium are lost due to solid electrolyte interphase thickening and lithium deposition,which are primary and secondary failure reasons,respectively.These findings are confirmed by X-ray photoelectron spectroscopy depth profiling,scanning electron microscope,and accelerating rate calorimeter.Titration-gas chromatography and nuclear magnetic resonance are utilized to quantitatively analyze active lithium loss.Additionally,electrolyte decomposition at high temperatures also contributes to active lithium loss,as determined by Auger electron spectrum and nondestructive ultrasound measurements.Notably,no failure is detected in the cathode due to the relatively low working voltage of the float charge.These findings suggest that inhibiting active lithium loss can be an efficient way of delaying failure during high-temperature float charge processes in LIBs.展开更多
A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The t...A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.展开更多
The electrochemical stability of lithium-ion batteries strongly depends on the thickness of the solid electrolyte interphase(SEI)formed on graphite anodes.Nevertheless,electrolyte decomposition at the anode surface,es...The electrochemical stability of lithium-ion batteries strongly depends on the thickness of the solid electrolyte interphase(SEI)formed on graphite anodes.Nevertheless,electrolyte decomposition at the anode surface,espe-cially at 65℃,leads to uncontrolled SEI growth.We have designed a hybrid negative electrode by incorporating hard carbon(HC)into graphite to increase the surface work function,which effectively hinders electron escape,thereby reducing electrolyte reduction and inhibiting thick SEI formation at 65℃.The disordered structure of HC faciitates lithiumion diffusion and prevents lithium plating on the electrode surface.As a result,a hybrid negative electrode containing 50%HC has an especially high capacity(98 mAh/g)at 8 C and long cycle life at 0.5 C at room temperature.Further-more,in a full battery it has an excellent capacity(128.54 mAh/g)and stable floating charge for 144 h at 65℃.The electrode achieves a balance between high energy density and high-power density for lithium-ion batteries,thus maintaining stability even during a floating charge at a temperature of 65℃.This is attributed to the formation of a thinner and more robust SEI.This study provides a mechanistic understanding of how the electrode work function governs electrolyte decomposition and SEI evolution,offering a practical strategy for slowing the degradation of lithium-ion batteries at 65℃.展开更多
基金supported by the National Key Research and Development(R&D)Program of China(2022YFB4101600)Key Research and Development(R&D)Projects of Shanxi Province(202102040201003,202202040201007)+1 种基金the Fundamental Research Program of Shanxi Province(20210302123008)the ICC CAS,SCJC-XCL-2023-13,CAS Project for Young Scientists in Basic Research(Grant No.YSBR-102).
文摘Lithium-ion batteries(LIBs)suffer from float charge failure in the grid-scale storage market.However,the lack of a unified descriptor for the diverse reasons behind float charge failure poses a challenge.Here,a quantitative analysis of active lithium loss is conducted across multiple temperatures into float charge of Li(Ni_(0.5)Co_(0.2)Mn_(0.3))O_(2)–graphite batteries.It is proposed that the active lithium loss can be used as a descriptor to describe the reasons for float charge quantitatively.Approximately 6.88%and 0.96%of active lithium are lost due to solid electrolyte interphase thickening and lithium deposition,which are primary and secondary failure reasons,respectively.These findings are confirmed by X-ray photoelectron spectroscopy depth profiling,scanning electron microscope,and accelerating rate calorimeter.Titration-gas chromatography and nuclear magnetic resonance are utilized to quantitatively analyze active lithium loss.Additionally,electrolyte decomposition at high temperatures also contributes to active lithium loss,as determined by Auger electron spectrum and nondestructive ultrasound measurements.Notably,no failure is detected in the cathode due to the relatively low working voltage of the float charge.These findings suggest that inhibiting active lithium loss can be an efficient way of delaying failure during high-temperature float charge processes in LIBs.
文摘A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.
基金supported by National Key Research and Development(R&D)Program of China(2022YFF0609802,2022YFF0609801)Fundamental Research Program of Shanxi Province(202403021222485,202403021222486)Talent Projects for Outstanding Doctoral Students to Work in Shanxi Province(2023SHB002)。
文摘The electrochemical stability of lithium-ion batteries strongly depends on the thickness of the solid electrolyte interphase(SEI)formed on graphite anodes.Nevertheless,electrolyte decomposition at the anode surface,espe-cially at 65℃,leads to uncontrolled SEI growth.We have designed a hybrid negative electrode by incorporating hard carbon(HC)into graphite to increase the surface work function,which effectively hinders electron escape,thereby reducing electrolyte reduction and inhibiting thick SEI formation at 65℃.The disordered structure of HC faciitates lithiumion diffusion and prevents lithium plating on the electrode surface.As a result,a hybrid negative electrode containing 50%HC has an especially high capacity(98 mAh/g)at 8 C and long cycle life at 0.5 C at room temperature.Further-more,in a full battery it has an excellent capacity(128.54 mAh/g)and stable floating charge for 144 h at 65℃.The electrode achieves a balance between high energy density and high-power density for lithium-ion batteries,thus maintaining stability even during a floating charge at a temperature of 65℃.This is attributed to the formation of a thinner and more robust SEI.This study provides a mechanistic understanding of how the electrode work function governs electrolyte decomposition and SEI evolution,offering a practical strategy for slowing the degradation of lithium-ion batteries at 65℃.
