A Dual‐Functional Titanium Nitride Chloride Layered Matrix with Facile Lithium‐Ion Diffusion Path and Decoupled Electron Transport as High‐Capacity Anodes

Abstract

Intercalation typed electrodes are expected with low theoretical capacity, which falls behind their high rate performance and stability. In this work, α‐TiNCl, an isoelectronic system of TiO2, is designed as a promising high‐capacity intercalation anode. TiNCl features are layered TiN backbone terminated by Cl atoms. While the rocksalt TiN backbones function as electron conductors, the interlayer voids provide Cl‐coordinated Li+ sites without strong Li‐Ti repulsion, which proves to be a rapid diffusion path with a low energy barrier (0.06 vs 0.47 eV of TiO2). Therefore, a dual‐functional TiNCl matrix is established for Li+ and e– transport. To stabilize the layered structure, TiNCl is scaffolded by an in situ grown TiO2 coating, which also serves as an electron reservoir during lithiation. The TiNCl‐TiO2 anode exhibits significantly large Li+ intercalation capacity (243% of TiO2) and outstanding battery performance (231 mA h g–1 at ≈17 C for 2500 cycles, 94 mA h g–1 at ≈34 C for 10 000 cycles). The (+) LiCoO2 || TiNCl‐TiO2 (–) full battery maintains 170 mA h g–1 for 300 cycles. This work may shed light on the molecular engineering of new compounds for electrodes.

Quantitatively Tunable Anionic Vacancies of Iron Disulfide Nanorods with Superior Cyclability and Rate Capability for Li-Ion Batteries

“…It was observed that the peaks at 162.3 and 163.5 eV were related to S 2p 3/2 and S 2p 1/2 for S 2 2‑ , respectively. ,, Other peaks at 164.7 and 167.9 eV corresponded to C–S bonds and SO 4 2– , respectively. , Moreover, the intensity of the S 2p 3/2 peak for S 2 2– also decreased similar to Fe 2p 3/2 for Fe–S bonds, proving the existence of S vacancies. The high-resolution N 1s spectra of FeS 2 /C, V S -FeS 1.97 /C, V S -FeS 1.71 /C, and V S -FeS 1.65 /C nanorods in Figure e exhibited that there existed pyridinic-N and pyrrolic-N. , The high-resolution XPS spectra of C 1s for the FeS 2 /C, V S -FeS 1.97 /C, V S -FeS 1.71 /C, and V S -FeS 1.65 /C nanorods showed that two peaks at 284.6 and 285.9 eV were related to the C–C and C–S/C–N bonds (Figure f), respectively. − …”

“…40,41 Moreover, the intensity of the S 2p 3/2 peak for S 2 2− also decreased similar to Fe 2p 3/2 for Fe−S bonds, proving the existence of S vacancies. The highresolution N 1s spectra of FeS 2 /C, V S -FeS 1.97 /C, V S -FeS 1.71 /C, and V S -FeS 1.65 /C nanorods in Figure 3e exhibited that there existed pyridinic-N and pyrrolic-N. 7,42 The high-resolution XPS spectra of C 1s for the FeS 2 /C, V S -FeS 1.97 /C, V S -FeS 1.71 / C, and V S -FeS 1.65 /C nanorods showed that two peaks at 284.6 and 285.9 eV were related to the C−C and C−S/C−N bonds (Figure 3f), respectively. 43−45 To further affirm the presence and concentration of sulfur defects, EPR and ICP-OES were carried out.…”

“…As the traditional energy cannot meet the increasing consumption demand, the energy storage device with high energy density is one of the research hotspots at present. − Lithium-ion batteries (LIBs) have been applied into a variety of portable electronic devices and smart grid on account of high energy and power density, no memory effect, low self-discharge, and environmental benignity. − However, in the last three decades of exploration, only low-capacity graphite anodes (372 mA h g –1 ) can be applied in LIBs. , Conversion-type anode materials with high theoretical capacity (500–1000 mA h g –1 ), such as transition metal oxides, phosphates, nitrides, carbides, sulfides (TMSs), have been attracted extensive attention. − Among the TMSs, iron disulfide (FeS 2 ) is supposed to be the most promising candidate for the anode material with natural abundance, low cost, eco-friendliness, and high theoretical capacity (894 mA h g –1 ) based on the formation of Li 2 S with the four-electron migration. , Nevertheless, the application of FeS 2 is also limited by the following aspects: (1) sluggish diffusion kinetics of Li + due to its semiconductor properties and (2) inferior cyclicality because of volume expansion during the discharge/charge process. , …”

Designing strategies of advanced electrode materials for high-rate rechargeable batteries

“…47 The diffusion coefficient D ions can be calculated by the following eqn (1): 48 where τ represents the diffusion time, L is the diffusion length, Δ E s corresponds to the steady-state voltage change through a single-step GITT test, and Δ E τ is derived from the total change in the cell voltage to eliminate the iR drop during the constant current pulse τ of the GITT. 49,50…”

“…where s represents the diffusion time, L is the diffusion length, DE s corresponds to the steady-state voltage change through a single-step GITT test, and DE s is derived from the total change in the cell voltage to eliminate the iR drop during the constant current pulse s of the GITT. 49,50 The diffusion time s and diffusion length L are related via the following formula (2):…”