Constructing a multidimensional porous structure of K/Co co-substituted Na₃V₂(PO₄)₃/C attached on the lamellar Ti₃C₂T_x MXene substrate for superior sodium storage property

Abstract

Na3V2(PO4)3 (NVP) materials emerge as prospective cathodes for sodium ion batteries (SIBs). However, its weak intrinsic conductivity has limited the deeper research. Herein, we adopt a simultaneous strategy of K/Co...

Conductive Ti3C2Tx networks to optimize Na3V2O2(PO4)2F cathodes for improved rate capability and low-temperature operation

“…4c and S9†) at room temperature (RT) and −20 °C. The corresponding D Na + values were determined by Fick's second law of diffusion: 37 where τ is the duration of the current pulse (s), m B , M B and V M are the mass loading (g), molar mass (g mol −1 ) and molar volume (cm 3 mol −1 ), respectively, of the active material, S is the surface area of the electrode (cm 2 ), and Δ E s and Δ E τ are defined as the steady-state voltage change due to current pulse and the voltage change during the constant current pulse regardless of the iR drop. The calculated average D Na + at the RT value for NVOPF/Ti 3 C 2 T x is 5.43 × 10 −11 cm 2 s −1 , larger than the value of 3.89 × 10 −11 cm 2 s −1 for NVOPF, indicating its faster apparent diffusion kinetics.…”

“…For example, serving as a continuous metallic network with good mechanical reinforcement, Ti 3 C 2 T x has been used as a conductive binder for high-capacity silicon electrodes via the slurry-casting method, 36 as well as a lamellar substrate to guide the crystal growth of K/Co co-substituted Na 3 V 2 (PO 4 ) 3 for superior sodium storage. 37 Furthermore, functional groups on the Ti 3 C 2 T x terminal facilitate the formation of a favorable solid electrolyte interphase for Si-based anodes, not only promoting the capacity release but also relieving the volume expansion effect of silicon. 38 In addition, Ti 3 C 2 T x nanosheets as multifunctional conductive binders can be used to construct a 3D flexible hard carbon film to effectively stabilize the structure of the electrode and improve the rate capability of film electrodes for Na/K-ion storage.…”