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As an olivine‐based cathode with high discharge platform and theoretical capacity, Li3V2(PO4)3's (LVP's) low conductivity and excessive grain size are the important factors hindering its development in the battery field. Halloysite nanotubes (HNTs) is a natural and cheap nanotube‐like material with large specific surface area and abundant surface nucleation sites, which can cooperate with conductive carbon layer to solve the deficiency of LVP. In this paper, we design a cathode material for in‐situ growth of LVP on HNTs (LVP@HNTs) and demonstrate that it has the appropriate particle size and the excellent specific surface area in the mass ratio of LVP to HNTs is 2:1. The capacity retention rate of LVP@HNTs‐2 reached almost 100% (97.0 mAh g−1) after 100 cycles at a low rate of 0.5 C. Moreover, its specific discharge capacity is 89.3 mAh g−1 at a high rate of 20 C and its capacity retention rate is as high as 90.1% (80.5 mAh g−1) after 5,000 cycles, showing that the LVP@HNTs‐2 has marvelous rate capability and cycle stability. This study provides an innovative strategy for the development of the high‐performance cathode materials with low‐cost, excellent rate capability, and cycle stability of lithium ion batteries. [ABSTRACT FROM AUTHOR]

Due to the assets such as adequate discharge capacity and rational cost, LiNi0.8Co0.15Al0.05O2 (NCA), a high-nickel ternary layered oxide, is regarded to be a favorable cathode contender for lithium-ion batteries. However, the superior commercial application is restricted by the surface residual alkaline lithium salt (LiOH or/and Li2CO3) of nickel-rich cathode materials, which will expedite the disintegration of the structure and the engendering of gas (CO2). Therefore, in this paper, we devise and fabricate a Y(PO3)3 modified LiNi0.8Co0.15Al0.05O2 (NCA), intending to optimize the surface residual alkaline lithium salt (antecedent deportation of H2O and CO2) while forming an in situ triple composite Li-ion conductor coating (Y(PO3)3-Li3PO4-YPO4) to enhance the electrochemical behavior. Under this method, the 2 mol% Y(PO3)3 modified NCA electrode reveals exceptional rate capability (5 C/156.3 mAh gâˆ'1) and extraordinary cycle stability after 200 cycles (2 C/88.3%), whereas the original sample is only 5 C/123.1 mAh gâˆ'1 and 2 C/71.2% after 200 cycles. Conspicuously, even under the draconian circumstances of the high temperature and the high rate at 55 °C/1 C, the 2 mol% Y(PO3)3 modified NCA electrode sustains a high reversible capacity, with an admirable capacity retention rate of 89.4% after 100 cycles. These contented results signify that the surface remodeling tactic presents a viable scheme for ameliorating high-nickel materials’ performance and appropriateness. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.15Al0.05O2 (NCA), a promising ternary cathode material of lithium-ion batteries, has widely attracted attention due to its high energy density and excellent cycling performance. However, the presence of residual alkali (LiOH and Li2CO3) on the surface will accelerate its reaction with HF from LiPF6, resulting in structural degradation and reduced safety. In this work, we develop a new coating material, LiH2PO4, which can effectively optimize the residual alkali on the surface of NCA to remove H2O and CO2 and form a coating layer with excellent ion conductivity. Under this strategy, the coated sample NCA@0.02Li3PO4 (P2-NCA) provides a capacity of 147.8 mAh gâˆ'1 at a high rate of 5 C, which is higher than the original sample (126.5 mAh gâˆ'1). Impressively, the cycling stabilities of P2-NCA under 0.5 C significantly improved from 85.2% and 81.9% of pristine-NCA cathode to 96.1% and 90.5% at 25 °C and 55 °C, respectively. These satisfied findings indicate that this surface modification method provides a feasible strategy toward improving the performance and applicability of nickel-rich cathode materials. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.15Al0.05O2 (NCA), a promising ternary cathode material of lithium-ion batteries, has widely attracted attention due to its high energy density and excellent cycling performance. However, the presence of residual alkali (LiOH and Li2CO3) on the surface will accelerate its reaction with HF from LiPF6, resulting in structural degradation and reduced safety. In this work, we develop a new coating material, LiH2PO4, which can effectively optimize the residual alkali on the surface of NCA to remove H2O and CO2 and form a coating layer with excellent ion conductivity. Under this strategy, the coated sample NCA@0.02Li3PO4 (P2-NCA) provides a capacity of 147.8 mAh gâˆ'1 at a high rate of 5 C, which is higher than the original sample (126.5 mAh gâˆ'1). Impressively, the cycling stabilities of P2-NCA under 0.5 C significantly improved from 85.2% and 81.9% of pristine-NCA cathode to 96.1% and 90.5% at 25 °C and 55 °C, respectively. These satisfied findings indicate that this surface modification method provides a feasible strategy toward improving the performance and applicability of nickel-rich cathode materials. [ABSTRACT FROM AUTHOR]

The achievement of high ionic conductivity for solid‐state electrolyte and low interface resistance between electrodes and electrolyte are keys to successful solid‐state lithium ion batteries. In this paper, an efficient solid‐state electrolyte with dual‐layer structure for dendrite‐free lithium metal battery is designed. A Li metal‐friendly poly(ethylene oxide) (PEO) can serve as low‐voltage stable polymer electrolyte and ceramic‐dominating poly(vinylidene fluoride)–lithium aluminum titanium phosphate (PVDF–LATP) composite solid electrolyte is able to resist higher voltage facing cathode. More importantly, bistrifluoroacetamide (BTFA), as a polar molecular plasticizer, can simultaneously inhibit polymer crystallization, coordinate the delocalization of negative charges, and facilitate the solvation of lithium salts, providing absorption sites for lithium ion migration. The obtained BTFA‐activated PEO/PVDF–LATP double‐layer solid electrolyte exhibits satisfied ionic conductivity (4.4 × 10−4 S cm−1 at 25 °C), high Li+‐transfer number (0.68), and wide electrochemical stable windows (0–5.092 V vs Li/Li+). Moreover, both the assembled full cells with LiFePO4 and high‐voltage LiNi0.8Co0.1Mn0.1O2 cathodes show high initial discharge capacities (163.3 and 219.5 mAh g−1 at 0.1 C, respectively), excellent cycling, and rate performance. [ABSTRACT FROM AUTHOR]

Solid‐state lithium batteries will revolutionize the lithium‐ion battery and energy storage applications if certain key challenges can be resolved. The formation of lithium‐protrusions (dendrites) that can cause catastrophic short‐circuiting is one of the main obstacles, and progresses by a mechanism that is not yet fully understood. By utilizing X‐ray computed tomography with nanoscale resolution, the 3D morphology of lithium protrusions inside short‐circuited solid electrolytes has been obtained for the first time. Distinguishable from adjacent voids, lithium protrusions partially filled cracks that tended to propagate intergranularly through the solid electrolyte, forming a large waved plane in the shape of the grain boundaries. Occasionally, the lithium protrusions bifurcate into flat planes in a transgranular mode. Within the cracks themselves, lithium protrusions are preferentially located in regions of relatively low curvature. The crack volume filled with lithium in two samples is 82.0% and 83.1%, even though they have distinctly different relative densities. Pre‐existing pores in the solid electrolyte, as a consequence of fabrication, can also be part‐filled with lithium, but do not have a significant influence on the crack path. The crack/lithium‐protrusion behavior qualitatively supports a model of propagation combining electrochemical and mechanical effects. [ABSTRACT FROM AUTHOR]

In this work, amorphous silica was uniformly embedded at the nano-scale in the tunnel wall of mesoporous carbon, with no free or aggregated silica or carbon particles in the cavity of the tunnels. The tunnel provides sufficient space for the volume expansion of SiO 2 , while the carbon skeleton forms electric conducting paths for the electrochemical reaction/activation of the silica. Therefore, impregnation of inactive and insulating SiO 2 particles in active and conducting mesoporous carbon (SiO 2 -MC) is beneficial for improving the electrochemical activity and cycling performance of the former as an LIB anode. As a result, the SiO 2 -MC composite delivers a reversible capacity of 670 mAh g − 1 , much higher than that of the composite (SiO 2 + MC) containing SiO 2 aggregates (~ 300 mAh g − 1 ). This impregnation concept can be applied in the structural design of composite electrodes for other secondary batteries and preparation of high-efficiency catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] High-nickel LiNi 0.9 Co 0.1 O 2 cathode shows an enormous potential in next-generation high energy density lithium-ion batteries. However, its cation mixing and the second hexagon to the third hexagonal of phase transition (H2 − H3) pose severe challenges to its practical and commercial applications. In this work, zirconium metaphosphate is applied to optimize the microstructure near surface zone of LiNi 0.9 Co 0.1 O 2 cathode material to suppress its cation mixing and the H2 − H3 phase transformation during long cycling process. It is found that single-atom or atomic group plays different roles in doping strategy due to their different thermodynamic properties. Specifically, Zr4+ tends to form a uniform doping to optimize crystal structure, while PO 4 3- group presents a gradient distribution near the surface area and generates Li 3 PO 4 coating layer to enhance the Li+ mass transfer. As a result, the modified LiNi 0.9 Co 0.1 O 2 cathode shows an improved cycling stability with a high capacity retention of 93.7% after 100 cycles, whereas the bare LiNi 0.9 Co 0.1 O 2 cathode only delivers a low capacity retention of 81.7%. This work highlights the critical role of thermodynamic properties of doped atoms toward the electrochemical performance and can be extended to other layered cathode materials. [ABSTRACT FROM AUTHOR]

Achieving a highly stabilized surface structure is the key to successfully enhancing the cycling stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM) cathode material for Li-ion batteries at high cut-off voltage (4.5 V). In this work, we report a highly surface-stabilized NCM material via a high-valent titanium ion (Ti4+)-induced nanostructured hybrid surface with a core-shell structure. Consequently, the Ti-modified LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode provides an excellent cycling stability with 92.3% capacity retention (100 cycles, 0.5C, 2.7–4.5 V). This proposed hybrid core-shell nanostructure prominently mitigates the surface structural degradations, continuous microcracking and parasitic reactions, effectively improving the surface structural stability. This efficient strategy provides a step towards further commercial application of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 material and can be extended to other layered cathode materials. • Here, we reported a highly surface-stabilized NCM material with Ti4+-induced hybrid surface with a core-shell structure. • The as-proposed epitaxial protective coating layer effectively alleviates side reactions and microcracking of NCM cathode. • The capacity attenuation mechanism of NCM cathode material is revealed from the perspective of structural degradations. • The T2-NCM electrode exhibits a superior cycling stability with 92.3% capacity retention (100 cycles, 2.7–4.5 V). [ABSTRACT FROM AUTHOR]