Nano-Micro Lett. (2018) 10:56 https://doi.org/10.1007/s40820-018-0209-1 ARTICLE Bi Nanoparticles Anchored in N-Doped Porous Carbon as Anode of High Energy Density Lithium Ion Battery Yaotang Zhong1 . Bin Li1 . Shumin Li1 . Shuyuan Xu1 . Zhenghui Pan1 . Qiming Huang1,2 . Lidan Xing1,2 . Chunsheng Wang3 . Weishan Li1,2 Received: 23 March 2018 / Accepted: 10 May 2018 Ó The Author(s) 2018 Highlights • The Bi nanoparticles anchored in N-doped porous carbon (Bi@NC) composite was prepared by a facile replacement reaction method, in which ultrasmall Bi nanoparticles were homogeneously encapsulated in the carbon matrix • The N-doped carbon matrix enhanced the electric conductivity and alleviated the mechanical strain of Bi nanoparticles on Li insertion/extraction due to the larger void space, and Bi@NC exhibits excellent cyclic stability and rate capability for LIBs • The strategy developed in this work solves the cyclic instability issue of bismuth as anode for LIBs and provides a new approach to improve high volumetric energy density for electrochemical energy storage devices. Abstract A novel bismuth–carbon composite, in which 2.5V 2.5V Bi bismuth nanoparticles were anchored in a nitrogen-doped + i Bi@NC Li + L + carbon matrix (Bi@NC), is proposed as anode for high Li 0.90v volumetric energy density lithium ion batteries (LIBs). 0.75v + Li + BiLi@NC Li Electronic supplementary material The online version of this (Lithium insertion) Bi article (https://doi.org/10.1007/s40820-018-0209-1) contains supple- (Lithium extraction) mentary material, which is available to authorized users. + Li + Li 0.60v Li+ + Li Bi & Chunsheng Wang + [email protected] drop Voltage Li BiLi3@NC rise Voltage & Weishan Li [email protected] 0.01V 0.01V 1 School of Chemistry and Environment, South China Normal University, Guangzhou 510006, People’s Republic of China Bi@NC composite was synthesized via carbonization of 2 Engineering Research Center of MTEES (Ministry of Zn-containing zeolitic imidazolate (ZIF-8) and replace- Education), Research Center of BMET (Guangdong ment of Zn with Bi, resulting in the N-doped carbon that Province), Engineering Laboratory of OFMHEB (Guangdong Province), Key Laboratory of ETESPG (GHEI), and was hierarchically porous and anchored with Bi nanopar- Innovative Platform for ITBMD (Guangzhou Municipality), ticles. The matrix provides a highly electronic conductive South China Normal University, Guangzhou 510006, network that facilitates the lithiation/delithiation of Bi. People’s Republic of China Additionally, it restrains aggregation of Bi nanoparticles 3 Department of Chemical and Bimolecular Engineering, and serves as a buffer layer to alleviate the mechanical University of Maryland, College Park, College Park, strain of Bi nanoparticles upon Li insertion/extraction. MD 20740, USA 123 56 Page 2 of 14 Nano-Micro Lett. (2018) 10:56 With these contributions, Bi@NC exhibits excellent although its specific capacity (385 mAh g-1) is not so cycling stability and rate capacity compared to bare Bi high, as shown in Fig. 1. These features of bismuth make nanoparticles or their simple composites with carbon. This LIBs attractive in applications where high volumetric study provides a new approach for fabricating high volu- energy densities are required [19–21]. metric energy density LIBs. Like other metal anodes, however, bismuth exhibits poor cycling stability due to its large volume change during lithiation/delithiation [1]. Some efforts have been made to Keywords Porous N-doped carbon Á Bi nanoparticles Á solve this problem. For example, Park et al. [21] prepared a Anode Á Lithium-ion battery Á High energy density nanostructured Bi@C composite that delivered a relatively high capacity of 300 mAh g-1 after 100 cycles at current density 100 mA g-1 by varying the voltage from 0.0 to 2.0 V. Yang et al. [22] revealed that Bi@C microspheres as anode materials for LIBs retained capacity of 1 Introduction 280 mAh g-1 after 100 cycles at current density 100 mA g-1. The improved cycling stability of bismuth in Power sources with high volumetric and gravimetric these efforts can be attributed to the controlled coating of energy densities are urgently needed to meet the small size carbon layer on bismuth, which enhances electronic con- and long service life requirements of various applications ductivity and alleviates the mechanical strain of bismuth from information technology to transportation [1–6]. during lithiation/delithiation [23, 24]. Moreover, the con- Lithium-ion batteries (LIBs) are the dominant power trolled coating of carbon layer acts as host to stabilize the sources for these applications owing to their superior solid electrolyte interphase (SEI) on the bismuth surface energy densities and cycle lives compared to other sec- [25]. However, the above-mentioned achievements are ondary batteries, but their energy densities are still unsat- unsatisfactory for the practical application of bismuth as isfactory for quickly developing society [7–11]. anode in LIBs. Graphite is the most commonly used anode in com- Various carbon materials have been extensively studied mercial LIBs because of its superior cycling stability and for performance improvement of anode or cathode mate- high coulombic efficiency. However, the low theoretical rials in LIBs [26–30]. Metal organic frameworks (MOFs) capacity of the graphitic anode (372 mAh g-1) limits the characterized by diverse skeletal structures, high surface development of graphite-based LIBs. Therefore, it is nec- areas, tunable pore sizes, and open metal sites in the essary to look for high energy density LIBs anodes. skeleton have been demonstrated as promising templates or Several metals including Al, Si, Sn, Sb, Ge, and Bi have precursors for fabricating nanostructured carbon for vari- captured attention as anode materials due to their high ous applications [31–37]. Except for the advantages men- theoretical capacities compared to graphite, which has been tioned above, MOFs can also be designed and synthesized used as anode since the invention of LIBs. Al, Si, Sn, Sb, in a straightforward and cost-effective manner by and Ge have far higher theoretical gravimetrical capacities than that of graphite (372 mAh g-1) through the formation (1383,994,0.26) -1 -1 (2190,4200,0.25) of LiAl (994 mAh g ), SiLi4.4 (4200 mAh g ), SnLi4.4 Al -1 -1 0.25 Si (993 mAh g ), SbLi3 (660 mAh g ), and Li2.2Ge5 (1600 mAh g-1), but cannot give correspondingly high (2180,1600,0.21) 0.20 (1889,660,0.19) Ge volumetric capacities, which is only respective 1383, 2190, Sb 1991, 1889, and 2180 mAh cm-3 compared to -3 0.15 (1991,993,0.14) 756 mAh cm of graphite [12, 13]. Besides, these metals Sn yield potential hysteresis of 0.26, 0.25, 0.14, 0.19, and (756,372,0.11) 0.10 C 0.21 V for lithiation/delithiation, respectively, which are (3430,384,0.11) Bi Potential hysteresis (V) hysteresis Potential not only larger than in graphite (0.11 V), but also are 0.05 energy inefficient [1]. Although Bi is a diagonal element of 4500 Sn and in the same group as Sb, it has unique layered 4000 0.00 3500 -1 ) 500 3000 1000 2500 crystal structure that can provide larger interlayer spacing Volumetric1500 ca 2000 (mAh g 2000 1500 to accommodate Li ions (such as Li3Bi) [14–16]. Most 2500 paci 3000 1000 apacity ty (m 500 importantly, bismuth gives a volumetric capacity of A 3500 ific c h cm -3 4000 0 3430 mAh cm-3, which is far higher than those of other ) Spec metal anodes and about five-bold than that of graphite [17]. Fig. 1 Lithium storage performances of various metals in compar- It also yields potential hysteresis the same as graphite [18] ison to graphite 123 Nano-Micro Lett. (2018) 10:56 Page 3 of 14 56 assembling varied metal ions/clusters and organic ligands thoroughly washed with methanol, followed by drying in a under mild conditions [38]. Therefore, without any pro- vacuum oven overnight. cessing equipment, it can be simply mass-produced just by To obtain N-doped porous carbon with dispersed zinc increasing the amounts of raw materials. In addition, it has nanoparticles (Zn@NC), carbonization process was carried been noted that nitrogen-containing MOFs yield nitrogen- out. The as-obtained ZIF-8 was heated at 500, 600, 700, -1 doped carbon that exhibits enhanced electronic conduc- and 800 °C for 3 h at the rate 2 °C min under H2/Ar tivity and activity toward reactions on carbon [39, 40]. atmosphere with slow flow. Finally, a tan product was Zeolitic imidazolate framework (ZIF-8), a kind of nitrogen- produced after high temperature calcination. containing MOFs, combines high stability of inorganic Bismuth nanoparticles were anchored in N-doped por- zeolite with high surface area and porosity, and is a good ous carbon matrices by galvanic replacement reaction. precursor for preparing carbon matrices to enhance cycling Typically, 1 mmol as-obtained Zn@NC and 1 mmol BiCl3 stability of some electrode materials for LIBs [41–43]. For were homogeneously dispersed in 75 mL mixed solvent of example, Si@ZIF8 composites were prepared by Han et al. glycerin and methanol (2:1 in volume) under ultrasonic [44] via in situ mechanochemical synthesis, which shows treatment at room temperature for 30 min. The mixture superior electrochemical properties with lithium storage was sealed in a 100 mL Teflon-lined autoclave, main- capacity up to 1050 mAh g-1 and excellent cycle stability tained at 120 °C for a certain period of time and then ([ 99% capacity retention after 500 cycles). cooled naturally. To obtain the product (Bi@NC), the In this work, a novel carbon/bismuth composite is precipitation was thoroughly washed with methanol via introduced through a novel synthetic strategy wherein ZIF- centrifugation–redispersion cycles at 9000 rpm for 5 min 8 was used as precursor for N-doped porous carbon to and finally dried in a vacuum oven overnight.