P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this m...P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.展开更多
Well-dispersed SnO2 nanorods with diameter of 4-15 nm and length of 100-200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed...Well-dispersed SnO2 nanorods with diameter of 4-15 nm and length of 100-200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed initial discharge capacity is as high as 1778 mA.h/g, much higher than the theoretical value of the bulk SnO2 (1494 mA.h/g). During the following 15 cycles, the reversible capacity decreases from 929 to 576 mA-h/g with a fading rate of 3.5% per cycle. The fading mechanism is discussed. Serious capacity fading can be avoided by reducing the cycling voltages from 0.05-3.0 to 0.4-1.2 V. At the end, SnO2 nanorods with much smaller size are synthesized and their performance as anode materials is studied. The size effect on the electrochemical properties is briefly discussed.展开更多
Rechargeable metal-sulfur batteries with the use of low-cost sulfur cathodes and varying choice of metal anodes(Li,Na,K,Ca,Mg,and Al)represent diverse energy storage solutions to satisfy different application requirem...Rechargeable metal-sulfur batteries with the use of low-cost sulfur cathodes and varying choice of metal anodes(Li,Na,K,Ca,Mg,and Al)represent diverse energy storage solutions to satisfy different application requirements.In comparison to the highly-regarded lithium-sulfur batteries,the use of nonlithium-metal anodes in metal-sulfur batteries offers multiple advantages in terms of abundance,cost,and volumetric energy density.Although with the same sulfur cathode,metal-sulfur batteries show considerably differences in the electrochemical reaction pathway and capacity fading mechanism.Herein,we provide an overview of correlations and differences in metal-sulfur batteries,highlighting the knowledge and experience that can be transplanted from lithium-sulfur to other metal-sulfur batteries.We first discuss the historical development and the electrochemical reaction mechanism of various metal-sulfur batteries.This is then followed by an analysis of key challenges of metal-sulfur batteries including polysulfide shutting,cathode passivation,and anode stability.Finally,a short perspective is presented about the possible future development of metal-sulfur batteries.展开更多
基金financial support from the National Natural Science Foundation of China (21938005, 21573147, 22005190, 22008154, 21872163)the Science & Technology Commission of Shanghai Municipality, the Natural Science Foundation of Shanghai (19DZ1205500, 19ZR1424600, 19ZR1475100)the Sichuan Science and Technology Program (2021JDRC0015 to L.S.L)。
文摘P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.
基金Project supported by the National Key Basic Research Program of China (Grant No 2007CB310500)the Chinese Ministry of Education (Grant No 705040)the National Natural Science Foundation of China (Grant Nos 90606009, 60571044 and 10774174)
文摘Well-dispersed SnO2 nanorods with diameter of 4-15 nm and length of 100-200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed initial discharge capacity is as high as 1778 mA.h/g, much higher than the theoretical value of the bulk SnO2 (1494 mA.h/g). During the following 15 cycles, the reversible capacity decreases from 929 to 576 mA-h/g with a fading rate of 3.5% per cycle. The fading mechanism is discussed. Serious capacity fading can be avoided by reducing the cycling voltages from 0.05-3.0 to 0.4-1.2 V. At the end, SnO2 nanorods with much smaller size are synthesized and their performance as anode materials is studied. The size effect on the electrochemical properties is briefly discussed.
基金Joint International Research Laboratory of Carbon-based Functional Materials and Devices111 Project+1 种基金Collaborative Innovation Center of Suzhou Nano Science and TechnologyNational Natural Science Foundation of China,Grant/Award Numbers:U2002213,51972219。
文摘Rechargeable metal-sulfur batteries with the use of low-cost sulfur cathodes and varying choice of metal anodes(Li,Na,K,Ca,Mg,and Al)represent diverse energy storage solutions to satisfy different application requirements.In comparison to the highly-regarded lithium-sulfur batteries,the use of nonlithium-metal anodes in metal-sulfur batteries offers multiple advantages in terms of abundance,cost,and volumetric energy density.Although with the same sulfur cathode,metal-sulfur batteries show considerably differences in the electrochemical reaction pathway and capacity fading mechanism.Herein,we provide an overview of correlations and differences in metal-sulfur batteries,highlighting the knowledge and experience that can be transplanted from lithium-sulfur to other metal-sulfur batteries.We first discuss the historical development and the electrochemical reaction mechanism of various metal-sulfur batteries.This is then followed by an analysis of key challenges of metal-sulfur batteries including polysulfide shutting,cathode passivation,and anode stability.Finally,a short perspective is presented about the possible future development of metal-sulfur batteries.