A Review: Enhanced Anodes of Li/Na-Ion Batteries Based on Yolk-Shell Structured Nanomaterials

Abstract

Lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) have received much attention in energy storage system. In particular, among the great efforts on enhancing the performance of LIBs and SIBs, yolk-shell (YS) structured materials have emerged as a promising strategy toward improving lithium and sodium storage. YS structures possess unique interior void space, large surface area and short diffusion distance, which can solve the problems of volume expansion and aggregation of anode materials, thus enhancing the performance of LIBs and SIBs. In this review, we present a brief overview of recent advances in the novel YS structures of spheres, polyhedrons and rods with controllable morphology and compositions. Enhanced electrochemical performance of LIBs and SIBs based on these novel YS structured anode materials was discussed in detail.

Keywords: Lithium-ion batteries; Sodium-ion batteries; Yolk–shell structure.

Fig. 1

Graphical illustration of yolk–shell structure: a single shell with single yolk, b double shells with a single yolk, c multiple shells with a single yolk, and d single shell with multiple yolks. Reprinted with permission from Refs. [21, 55, 133]. TEM images of: e single shell with single yolk, f double shells with single yolk, and g single shell with multiple yolks. h SEM, i TEM, j HRTEM and k element mapping images of triple shells with single yolk. Reprinted with permission from Refs. [58, 60, 62, 68]

Fig. 2

Schematic demonstration of novel YS structure of: a polystyrene spheres (PS)@NiCo₂S₄. Reprinted with permission from Ref. [71]; b urchin-like Bi₂S₃@polypyrrole(ppy). Reprinted with permission from Ref. [72]; c rough VO₂ microspheres. Reprinted with permission from Ref. [73]; and d pomegranate-like Si@C. Reprinted with permission from Ref. [75]. The corresponding TEM images of e PS@NiCo₂S₄, and f Bi₂S₃@ppy. Reprinted with permission from Ref. [71, 72]. g₁ FESEM and g₂ TEM images of VO₂ microspheres. Reprinted with permission from Ref. [73]. h SEM image of pomegranate-like Si@C particles. Inset shows the spherical morphology in overall. i Details of sub-YS nanospheres in a single pomegranate-like Si@C particle. Reprinted with permission from Ref. [75]

Fig. 3

a Schematic illustration YS Fe₃O₄@C nanobox following 1-, 2- and 3-h etching time. The TEM images (b₁, b₂, b₃) of Fe₃O₄@C nanobox are shown in the dashed box corresponding to 1-, 2- and 3-h etching, respectively. Reprinted with permission from Ref. [84]. Graphical illustrations of c YS nanoprism of Ni–Co mixed oxide, d YS octahedral Fe₂P@C, and e YS octahedral Au nanorod@Cu₇S₄. f TEM image of YS Ni–Co mixed oxide nanoprism. g₁ SEM image and g₂ TEM octahedral Fe₂P@C. h TEM octahedral Cu₇S₄ shell with Au nanorod yolk. Reprinted with permission from Refs. [80, 82, 88]

Fig. 4

a₁–a₅ Schematic illustration of synthesis process of YS Au@TiO₂ nanorod. The corresponding TEM images of synthesis process: b–d the as-prepared Au@TiO₂ nanorod with different aspect ratios. Reprinted with permission from Ref. [92]

Fig. 5

TEM images and electrochemical performance of LIB assembled with YS structure anode: a Sn@C nanocube, the corresponding b cyclic voltammetry curves and c cyclic performance. Reprinted with permission from Ref. [87]. d Ni₂P wrapped by graphene networks, the corresponding e rate performance at different current densities, and f long-term cycle performance. Reprinted with permission from Ref. [124]. g urchin-like Bi₂S₃@ppy, the corresponding h galvanostatic profiles and i long-term cyclic performance. Reprinted with permission from Ref. [72]. j Fe₃O₄@Fe₃C nanospindle and k the corresponding long-term cyclic performance. Reprinted with permission from Ref. [93]. l Schematic illustration of volume expansion of YS structure yolk after lithiation. Reprinted with permission from Ref. [104]

Fig. 6

a TEM image and b HRTEM image of FeS₂@C with 45-minute etching. Element mapping images of: c FeS₂@C-0 and d FeS₂@C-45. e Comparison of rate performance of FeS₂@C-0 and FeS₂@C-45 at various current densities. f Variation of capacity retention of FeS₂@C-0 and FeS₂@C-45 in 100 cycles performance at 100 mA g⁻¹. g Long-term cyclic performance of FeS₂@C-0 and FeS₂@C-45. Reprinted with permission from Ref. [86]