Post-annealing tailored 3D cross-linked TiNb2O7 nanorod electrode: towards superior lithium storage for flexible lithium-ion capacitors

Abstract

TiNb 2 O 7 anode materials (TNO) have unique potential for applications in Li-ion capacitors (LICs) due to their high specific capacity of ca. 280 mA h g −1 over a wide anodic Li-insertion potential window. However, their highrate capability is limited by their poor electronic and ionic conductivity. In particular, studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported. Herein, a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported. This binder-free TNO anode exhibits superior rate performance (~66.3% capacity retention as the rate increases from 1 to 40 C), which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods, facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network. Furthermore, the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility (no capacity loss after continuous bending for 500 times). Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities (~100.6 W h kg −1 /4108.8 W kg −1 ; 10.7 mW h cm −3 / 419.3 mW cm −3 ), more superior to previously reported hybrid supercapacitors. The device also efficiently powers an LED light upon 180°bending. Figure 1 Schematic illustration of the merits of TNO electrode architecture for Li-ion storage.

Nitrogen and phosphorous co-doped hierarchical meso—microporous carbon nanospheres with extraordinary lithium storage for high-performance lithium-ion capacitors

“…The Ragone plots in Fig. 6g show that the energy and power densities of the as-fabricated LIC are highly comparable or even exceeded those of many LICs that have been reported (Table S3), including Li 4 Ti 5 O 12 (LTO)// AC [48], Li 4 Ti 5 O 12 /C//porous graphene macroform (PGM) [49], graphitic carbon (GC)//AC [50], Li 2 TiSiO 5 (LTSO)/C//AC [51], m-Nb 2 O 5 -C//AC [52], SnO 2 -C//C [53], H 2 Ti 6 O 13 //CMK-3 [54], Fe 3 O 4 /C@MXenes//AC [55], Fe 2 TiO 5 /super conducting carbon black (SCCB) [56], N-doped carbon//AC [57], TiNb 2 O 7 //AC [58], Ti 3 C 2 T x /rGO//AC [59], and soft carbon (SC)//AC [60].…”

Recent Advances in Titanium Niobium Oxide Anodes for High-Power Lithium-Ion Batteries

“…Improvements regarding TNO-based anodes were previously discussed. Figure summarizes the energy densities and power densities of representative TNO-based LIC systems. ,,,− It should be noted that the energy densities and power densities reported in the literatures are based on the masses of active materials, which are between the values of LIBs and supercapacitors. , …”

“…Ragone plots of the TNO-based LICs systems with commercial energy storage devices. Data from the LICs, LIBs, supercapacitors, and capacitors are calculated based on the total mass of active materials: (1) TiNb 2 O 7 @MS/C||AC, (2) TiNb 2 O 7 -750–7 h||AC, (3) TiNb 2 O 7 /HG||AC, (4) TiNb 2 O 7 ||graphene, (5) HG-TiNb 24 O 62 ||CN, (6) TiNb 2 O 7 @C||CFs, (7) TiNb 2 O 7 fibers||AC …”

Hybrid Li-Ion Capacitor Operated within an All-Climate Temperature Range from −60 to +55 °C

“…A capacity of 35 mA h g –1 is achieved at 10 C, and the capacity of 18 mA h g –1 at 50 C corresponds to 36% of that at 1 C. Moreover, it can be detected that such an LIC can be well-operated even at the ultra-high rates of 80 and 100 C (Figure S11). Based on the capacity and voltage, the Ragone plot of the TNO@EG||AC device in Figure d shows the obtained power density and energy density and comparison with those of some reported TNO-based LICs, also given in Table S2. − It can be detected that a much higher energy of 119 W h kg –1 is realized with a specific power of 151 W kg –1 . With the power density increasing to 5110 W kg –1 , a considerable energy of 26 W h kg –1 is retained owing to the superior rate capability and extended voltage window.…”