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205. An Al-doped high voltage cathode of Na4Co3(PO4)2P2O7 enabling highly stable 4 V full sodium-ion batteries.

Author

Liu, Xiaohao, Tang, Linbin, Li, Zhi, Zhang, Jianhua, Xu, Qunjie, Liu, Haimei, Wang, Yonggang, Xia, Yongyao, Cao, Yuliang, and Ai, Xinping

Abstract

The low energy density and the unsatisfactory cycling stability of cathode materials in sodium-ion battery systems have restricted their wider application. Here, a representative high voltage cathode of Na4Co3(PO4)2P2O7 (NCPP) was modified through Al doping. The as-prepared Na3.85Co2.85Al0.15(PO4)2P2O7 (Al0.15-NCPP) can deliver a discharge capacity of 99.5 mA h g−1 at 0.5C. A superior rate capability (80.3 mA h g−1 at 20C and 73.4 mA h g−1 at 50C) as well as excellent ultralong cycling stability (96.3% capacity retention after 900 cycles at 10C and 82.7% capacity retention after 8000 cycles at 30C) can be obtained. The excellent sodium storage properties are benefited from the advantages of Al doping. Al doping not only enhances ionic conductivity, but also improves the structural stability. Al0.15-NCPP, which has outstanding electrochemical properties, has been proposed as a very attractive high voltage cathode material for sodium-ion batteries. More impressively, a full cell assembled with an Al0.15-NCPP cathode and hard carbon (HC) anode exhibits distinguished rate/cycling performances (70.6 mA h g−1 at 30C and 95% capacity retention after 200 cycles at 1C) and an extremely high output voltage of 4.36 V, thus providing a preview of its practical application. In addition, our research can be used to enhance the electrochemical properties of other polyanion-based high voltage electrode materials. [ABSTRACT FROM AUTHOR]

Published
2019
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209. Highly Selective and Pollution‐Free Electrochemical Extraction of Lithium by a Polyaniline/LixMn2O4 Cell.

Author

Zhao, Along, Liu, Jincheng, Ai, Xinping, Yang, Hanxi, and Cao, Yuliang

Subjects
LITHIUM cells, NEGATIVE electrode, ELECTRIC batteries, LITHIUM, ION traps, ENERGY consumption
Abstract

Conventional lithium extraction processes are inefficient or inadaptable for application in salt‐lake brines with high Mg/Li ratios of ≥6. A new electrochemical cell, polyaniline (PANI)/LixMn2O4, was proposed to solve this problem for selective recovery of Li+ ions from brine water with high impurity cations (K+, Na+, Mg2+, etc). Benefiting from the unique selectivity of spinel LixMn2O4 for Li+ insertion and the high capacity of the PANI polymer for Cl− doping, this PANI/LixMn2O4 cell could simultaneously extract LiCl from a simulated brine with a high average current efficiency of 95 %, an energy consumption of 3.95 W h molLiCl−1, and a strong cycle ability with 70.8 % capacity retention over 200 cycles. In particular, this method avoids the use of additional chemicals, offering a highly efficient, pollution‐free technology for Li+ extraction from brine waters. Lithium extraction: A new polyaniline (PANI)/LixMn2O4 cell is proposed for the recovery of Li from brines with high Mg/Li ratios. Benefiting from the high selectivity of the spinel LixMn2O4 positive electrode for Li+ insertion and the high efficiency of the PANI negative electrode for the capture of Cl− ions, it offers a potential application for the direct recovery of LiCl from brine lakes with high Mg/Li ratios. [ABSTRACT FROM AUTHOR]

Published
2019
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225. High performance TiP2O7 nanoporous microsphere as anode material for aqueous lithium-ion batteries.

Author

Wen, Yunping, Liu, Yao, Bin, Duan, Wang, Zhuo, Wang, Congxiao, Cao, Yuliang, Ai, Xinping, and Xia, Yongyao

Abstract

This work developed a facile way to mass-produce a carbon-coated TiP2O7 nanoporous microsphere (TPO-NMS) as anode material for aqueous lithium-ion batteries via solid-phase synthesis combined with spray drying method. TiP2O7 shows great prospect as anode for aqueous rechargeable lithium-ion batteries (ALIBs) in view of its appropriate intercalation potential of −0.6 V (vs. SCE) before hydrogen evolution in aqueous electrolytes. The resulting sample presents the morphology of secondary microspheres (ca. 20 μm) aggregated by carbon-coated primary nanoparticles (100 nm), in which the primary nanoparticles with uniform carbon coating and sophisticated pore structure greatly improve its electrochemical performance. Consequently, TPONMS delivers a reversible capacity of 90 mA h/g at 0.1 A/g, and displays enhanced rate performance and good cycling stability with capacity retention of 90% after 500 cycles at 0.2 A/g. A full cell containing TPO-NMS anode and LiMn2O4 cathode delivers a specific energy density of 63 W h/kg calculated on the total mass of anode and cathode. It also shows good rate capacity with 56% capacity maintained at 10 A/g rate (vs. 0.1 A/g), as well as long cycle life with the capacity retention of 82% after 1000 cycles at 0.5 A/g. [ABSTRACT FROM AUTHOR]

Published
2019
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226. A high voltage cathode of Na2+2xFe2−x(SO4)3 intensively protected by nitrogen-doped graphene with improved electrochemical performance of sodium storage.

Author

Wang, Wei, Liu, Xiaohao, Xu, Qunjie, Liu, Haimei, Wang, Yong-Gang, Xia, Yongyao, Cao, Yuliang, and Ai, Xinping

Abstract

As a high-voltage and earth-abundant element, in recent years, alluaudite, Na2+2xFe2−x(SO4)3, has been regarded as a highly promising cathode material of sodium ion batteries with higher energy density. However, the critical environmental sensitivity and limited conductivity of this kind of sulfate-based (SO42−) polyanionic material has led to its poor crystal stability and inferior intercalation ability. Herein, we report the design of nitrogen-doped graphene under low temperature conditions as an evolutionary modification approach to prepare the Na2+2xFe2−x(SO4)3; namely, an alluaudite sulfate Na2+2xFe2−x(SO4)3@N-rGO composite was prepared by a facile co-precipitation method assisted by the nitrogen-doped graphene. It is therefore surprising that the three-dimensional graphene-based network provides continuous electron pathways; thus, the Na2+2xFe2−x(SO4)3@N-rGO composite exhibits improved electronic conductivity and excellent sodium insertion capability, as well as the electrochemical performance. As a result, it delivers a reversible capacity of 93.2 mA h g−1 with average redox potential of 3.8 V (vs. Na+/Na) at 0.05C; when the discharge rate increased to 10C, it delivers 56.3 mA h g−1 and an amazing capacity retention of 83% is achieved after 400 cycles. On the other hand, the doped nitrogen species plays a huge role on improving the electron-donating ability of the graphene layer, which effectively protects the easily oxidized host material from deterioration, giving the material longer stability in a normal oxygen-containing atmosphere. We believe that this work may lead to a promising, low cost, suitable sodium ion battery material for next-generation large-scale energy storage devices. [ABSTRACT FROM AUTHOR]

Published
2018
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227. In Situ Formation of Co9S8Nanoclusters in Sulfur-Doped Carbon Foam as a Sustainable and High-Rate Sodium-Ion Anode

Author

Wang, Yunxiao, Wang, Yanxia, Wang, Yun-xia, Feng, Xiangming, Chen, Weihua, Qian, Jiangfeng, Ai, Xinping, Yang, Hanxi, and Cao, Yuliang

Abstract

Transition-metal sulfides hold great promise as anode materials for sodium-ion batteries due to the high theoretical capacity and excellent redox reversibility based on multielectron conversion reactions. In this work, an elaborate composite, cobalt sulfide nanoclusters embedded in honeycomb-like sulfur-doped carbon foam (Co9S8@S-CF), is prepared via a facile sulfur-assisting calcination strategy, which tactfully induces the co-occurrence of in situ pore-forming, sulfidation, sulfur doping, and carbonization. Notably, sulfur-doped carbon foam (S-CF) possesses abundant voids, which are subject to construction of three-dimensional ionic/electronic pathways, leading to high sodium-ion accessibility and ultrafast sodium-ion/electron transportation toward Co9S8nanoclusters. When worked as an anode in sodium-ion batteries, it delivers a remarkable capacity of 373 mA h g–1over 1000 cycles at 0.25 C, achieving superior capacity retention of 80%. Furthermore, this anode could achieve unprecedented rate capability with a reversible capacity of 180 mA h g–1at 50 C (20 A g–1), which significantly precedes those reported previously.

Published
2019
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228. 3D graphene decorated Na4Fe3(PO4)2(P2O7) microspheres as low-cost and high-performance cathode materials for sodium-ion batteries

Author

Yuan, Tianci, Wang, Yanxia, Zhang, Jiexin, Pu, Xiangjun, Ai, Xinping, Chen, Zhongxue, Yang, Hanxi, and Cao, Yuliang

Abstract

Sodium-ion battery has emerged as one of most promising technologies for large-scale energy storage system, and hence has stimulated extensive exploration of applicable electrode materials with low cost and superb electrochemical properties. Herein, 3D graphene decorated Na4Fe3(PO4)2(P2O7) microspheres as a low-cost and environmentally friendly cathode material are synthesized by using a facile spray-drying method. The as-prepared NFPP@rGO composite exhibits a high reversible capacity of 128 mAh g−1at 0.1 C, a superior rate capability (35 mAh g−1at 200 C), and a long cycling life (62.3% capacity retention over 6000 cycles at 10 C). The excellent electrochemical performance is attributed to combined advantages of graphene coating on the surface of nanoparticles and the flexible 3D graphene network, which not only improve the electronic conductivity, but also accommodate the structural stress of the material during charging and discharging. Therefore, the NFPP@rGO microsphere with superior electrochemical performances, low-cost raw materials, simple synthetic route and high thermal stability is considered as a very attractive cathode electrode for sodium ion battery.

Published
2019
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231. Covalently Bonded Silicon/Carbon Nanocomposites as Cycle-Stable Anodes for Li-Ion Batteries

Author

Fan, Sijia, Wang, Hui, Qian, Jiangfeng, Cao, Yuliang, Yang, Hanxi, Ai, Xinping, and Zhong, Faping

Abstract

Carbon coating is a popular strategy to boost the cyclability of Si anodes for Li-ion batteries. However, most of the Si/C nanocomposite anodes fail to achieve stable cycling due to the easy separation and peeling off of the carbon layer from the Si surface during extended cycles. To overcome this problem, we develop a covalent modification strategy by chemically bonding a large conjugated polymer, poly-peri-naphthalene (PPN), on the surfaces of nano-Si particles through a mechanochemical method, followed by a carbonization reaction to convert the PPN polymer into carbon, thus forming a Si/C composite with a carbon coating layer tightly bonded on the Si surface. Due to the strong covalent bonding interaction of the Si surface with the PPN-derived carbon coating layer, the Si/C composite can keep its structural integrity and provide an effective surface protection during the fluctuating volume changes of the nano-Si cores. As a consequence, the thus-prepared Si/C composite anode demonstrates a reversible capacity of 1512.6 mA h g–1, a stable cyclability over 500 cycles with a capacity retention of 74.2%, and a high cycling Coulombic efficiency of 99.5%, providing a novel insight for designing highly cyclable silicon anodes for new-generation Li-ion batteries.

Published
2024
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232. Self-actuating protection mechanisms for safer lithium-ion batteries

Author

Luo, Yang, Sang, Chunchun, Le, Kehan, Chen, Hao, Li, Hui, and Ai, Xinping

Abstract

This review summarizes the research progresses, current states and issues, key challenges, and future trends of self-actuating reaction control mechanisms for Li-ion batteries (LIBs), aiming at providing insight for developing safety-enhancing technologies for LIBs.

Published
2024
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233. A novel Na8Fe5(SO4)9@rGO cathode material with high rate capability and ultra-long lifespan for low-cost sodium-ion batteries

Author

Liu, Changyu, Chen, Kean, Xiong, Huiqian, Zhao, Along, Zhang, Haiyan, Li, Qingyu, Ai, Xinping, Yang, Hanxi, Fang, Yongjin, and Cao, Yuliang

Abstract

Sodium-ion batteries (SIBs) are regarded as the most promising technology for large-scale energy storage systems. However, the practical application of SIBs is still hindered by the lack of applicable cathode materials. Herein, a novel phase-pure polyanionic Na8Fe5(SO4)9is designed and employed as a cathode material for SIBs for the first time. The Na8Fe5(SO4)9has an alluaudite-type sulfate framework and small Na+ion diffusion barriers. As expected, the as-synthesized Na8Fe5(SO4)9@rGO exhibits a high working potential of 3.8 ​V (versus Na/Na+), a superior reversible capacity of 100.2 mAh g−1at 0.2 ​C, excellent rate performance (∼80 mAh g−1at 10 ​C, ∼63 mAh g−1at 50 ​C), and an ultra-long cycling life (91.9% capacity retention after 10,000 cycles at 10 ​C, 81% capacity retention after 20,000 cycles at 50 ​C). We use various techniques and computational methods to comprehensively investigate the electrochemical reaction mechanisms of Na8Fe5(SO4)9@rGO.

Published
2024
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