An Advanced All Phosphate Lithium-Ion Battery Providing High Electrochemical Stability, High Rate Capability and Long-Term Cycling Performance

Abstract

High rate capability and long-term cycling spindle-like LiTi 2 (PO 4 ) 3 /C anode and needle-like Li 3 V 2 (PO 4 ) 3 cathode have been evaluated in half-cell, and combined to fabricate an advanced fast cyclable all phosphate lithium-ion battery. The electrode materials with well-defined morphology were prepared by a solvothermal reaction followed by annealing, delivering capacities of 115.0 and 118.1 mAh · g −1 at 25 • C over 200 cycles at 0.5 C, respectively. For the full cell assembly, no prelithiation process is needed for the selected electrode pair due to their mutually matched capacity and stoichiometric amount of lithium-ions. The fabricated full cell, with an output voltage of more than 1.5 V, inherits a superior rate capability and cycling performance of its electrodes. A discharge capacity of 36 mAh · g −1 at 30 C (about 30% of the initial discharge capacity at 0.1 C) and a capacity retention of ∼35% at 5 C over 1000 cycles has been achieved. Furthermore, one of the most important reasons for the capacity fading in the full cell during long-term cycling is found to be a decomposition and structural degradation of Lithium-ion batteries are widely used in portable electronics and are a promising energy storage system for electric vehicles because of their high energy density and long cycle life.1,2 However, current lithium-ion battery technologies are still far from satisfaction to meet the increasingly diverse range of applications. For instance, the use of lithium-ion cells in large scale applications, such as electric vehicles, demands high charge/discharge cycling performance and an inherent high thermal stability.3,4 Micro-lithium-ion batteries which can be applied to human body require in first instance the considerations of safety issue and cycling performance. 5,6 For the development of a novel type of lithium-ion battery like all-solid-state lithium-ion battery, one of the urgent needs to be addressed is to improve the ionic and electronic conductivity among the whole battery system. 7,8 Additionally, high rate performance and long cycle life are required for lithium-ion battery as stationary application for power management. To advance the battery technologies according the desired applications, it is important to explore the cathode and anode materials, and match them reasonably and to investigate their electrochemical performances. [10][11][12] have attracted much attention because more than two formula units of Li-ions can possibly intercalate/deintercalate into/from their host crystal structure during discharge/charge at a moderate working potential. On the basis of the crystal structure in these cathode materials, the use of phosphate polyanions (PO 4 ) 3− is considered as a potential alternative to oxide-based cathodes. The strong P−O bonds and the framework of (PO 4 ) 3− anions can guarantee both the dynamic and thermal stabilities required to fulfill the safety requisites in high-power applications.18 More than that, phosphate materials are also believed to be superior candidates of an...

Monolithic All-Phosphate Solid-State Lithium-Ion Battery with Improved Interfacial Compatibility

“…Particularly, LTP anode material and LATP electrolyte powder XRD patterns show rhombohedral structure with space group R 3̅ c . The structure of LVP cathode material is monoclinic with space group P 2 1 / n . − The specimens are further characterized by TEM, from which the lattice fringes of the LTP, LATP, and LVP can be seen, demonstrating the high degree of crystallinity of the electrode and electrolyte particles. The TEM images are thus supporting the information obtained by XRD with respect to the crystallization of the electrochemical active materials.…”

“…For purpose of improving of the interfacial connection the approach of designing the morphology by solvothermal synthesis is applied to establish highly defined microstructures with comparatively large specific surface areas of the electrode materials (12.7 ± 0.4 g m –2 for LTP and 14.4 ± 0.4 g m –2 for LVP) . As shown in the TEM images in the figure above and the SEM images in Figure S1a and b, the LTP materials exhibit a regular spindle-shape with lengths at the long-side of about 6 μm.…”

Self-standing NASICON-type electrodes with high mass loading for fast-cycling all-phosphate sodium-ion batteries

“…Hence, the NTP/CNFs and NVP/CNFs electrodes contained surface and bulk particles in a weight ratio of roughly 1 : 1. The morphological features of the as-prepared electrodes could effectively benet their electrochemical performance because (i) the full use of the space in the CNFs for mass loading in such a way that particles of the active material are located on the surface and in the bulk of CNT bunches results in a large specic capacity of the electrodes; (ii) the carbon phases can help to circumvent the intrinsic poor electronic conductivity of phosphate electrode materials and improve the binding between the active materials and CNFs; [34][35][36][37] (iii) the carbon layers can protect the NTP and NVP particles against erosion by the electrolyte and thus increase the cycling life of the electrodes; (iv) the small particle size of the NTP and NVP materials guarantees short diffusion pathways for Na + in the active materials, as well as relatively large specic surface areas of the electrodes (50.5 m 2 g À1 for NTP/CNFs and 49.4 m 2 g À1 for NVP/CNFs), which provides excellent kinetics for the intercalation/deintercalation of Na + and reduces polarization during cycling; [38][39][40][41][42] and (v) the high porosity of the electrodes, which was about 69% for the NTP/CNFs and NVP/CNFs electrodes as calculated from the relative and theoretical densities of the materials, could reduce the wetting issue of the electrolyte. Therefore, the as-prepared NTP/CNFs and NVP/ CNFs electrodes are expected to be capable of providing high exibility, high rate capability and stable cycling performance for SIBs in practical applications.…”

Insights into a layered hybrid solid electrolyte and its application in long lifespan high-voltage all-solid-state lithium batteries

“…S6a †) consistent with previous reports. 40,44,45 The tiny reversible plateau at about 3.3 V is the LiFePO 4 impurity, whose capacity is less than 5% of the total discharge capacity. The specic discharge capacity is around 130 mA h g À1 , corresponding to 98% of its theoretical capacity (131.5 mA h g À1 ) based on two lithium extractions.…”