Dendritic growth of lithium upon charging is a leading failure mode of batteries with lithium metal anodes coupled with solid-state electrolytes. With the development of stabilizing interlayers between the Li metal anode and LLZO solid electrolyte, high critical current densities (>2.5 mA cm(-2)) can be realized. However, achieving similar current densities consistently across a large number of cells with thin LLZO membranes (<100 mu m thick) has proven challenging. The origin of variation in the rate of success is generally attributed to manufacturing defects in the LLZO separator. Here, with the aid of the dendrite location detection method and other characterization techniques, we report shape defects on an otherwise flat surface as an additional origin for crack formation and concomitant dendrite growth. A combination of experimental work and simulations reveals that shape defects act as a stress riser during the operation of the cell. Once the stress on LLZO reaches a critical threshold, it is expected that LLZO will fracture, with rapid growth of lithium dendrites along the crack, leading to rapid shorting of the cell. This finding has shed light on a defect which is critical for the commercial manufacturing of LLZO separators.

Lithium-metal batteries with solid electrolyte separators promise improvements in energy density, fast charge capability, and safety. However, the lack of control of the solid electrolyte-lithium-metal interface continues to impede development. Interlayers between lithium-metal and the solid electrolyte are reported to improve performance but have limitations due to stability, rate limitations, and the use of undesirable elements (e.g., Ag, Au). Here, we show that a thin layer of the abundant metal Sn provides the required stability and transport properties to enable commercially relevant current densities (5 mA cm(-2)) and external pressures (0.3 MPa) at room temperature in Li7La3Zr7O12 (LLZO) hybrid cells. Moreover, these Sn interlayer full cells constructed with NMC cathodes (areal capacity of similar to 2.5 mAh cm(-2)) show no capacity loss for over 500 cycles under symmetric C/3 cycling. Both the interlayer phase behavior and Li transport properties are proposed to underpin the performance of metal-alloy interlayers as indicated by electrochemical and in situ and ex situ characterization techniques.

The solid-state batteries (SSBs) with Li anode present one of the most promising energy storage systems due to their enhanced energy density and safety. However, interfacial problems between Li anode and solid-state electrolyte hinder the advancement of SSBs. Among them, insufficient solid-solid interfacial contact is the main issue, which causes large resistance and hinders Li+ diffusion, leading to current distribution unevenness and lithium dendrites growth. To meet these challenges, a silver/carbon interlayer composed of ultrafine Ag nanoparticles (approximate to 5 nm) grown on COOH-CNTs (nano-Ag@COOH-CNTs) is constructed. In which, nano-Ag is designed to guide homogeneous Li deposition, while CNTs substrate bonds with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte by reactions between & horbar;COOH groups and LLZTO alkaline surface, thus transforming loose physical solid-solid contact to chemical bonding contact. In addition, nano-Ag is immobilized by CNTs, avoiding the migration of Li+ implanted nano-Ag during cycling. Therefore, nano-Ag@COOH-CNTs interlayer can boost Li+ transport at LLZTO/Li interface and inhibit Li dendrites, achieving an ultra-low interfacial resistance of 0.25 Omega cm(2), a high critical current density of 1.7 mA cm(-2) and a long cycling over 2155 h at 0.5 mA cm(-2). The modified SSBs with LiNi0.83Co0.12Mn0.05O2 cathode cycles stably over 500 cycles. Moreover, high-loading SSBs operate stably for 85 cycles.

Solid-state electrolyte separators play a critical role in improving energy density, charging rate, and safety in next-generation batteries; however, controlling the interface between Li-metal and the separator continues to be challenging. Here, using a garnet-type Li7La3Zr2O12 (LLZO) ceramic solid electrolyte, we show that sputter-coated thin metallic interlayers (similar to 300 nm of gold) in combination with controlled discharge rates (0.3 mA/cm(2)) and practical levels of external pressure (0.7 MPa) play vital roles in mitigating void formation during discharge. These metallic-interlayer, Li-metal full cells achieve a high charging rate capability (up to 2.5 mA/cm(2)) and stable long-term cycling of 97.4% capacity retention at 500 cycles for similar to 12 mu m of Li-metal (2.5 mAh/cm(2)). We report progressive changes in the metallic-interlayer morphology measured with ex situ and in situ methods, revealing that a discontinuous metal interlayer can facilitate hundreds of repeated electrochemical cycles without significant loss in cell energy. Our proposed mechanism suggests that the Li-gold alloy particles act as pinning and/or rewetting points for the Li-metal during discharge.

Lithium metal batteries (LMBs) with inorganic solid-state electrolytes are considered promising secondary battery systems because of their higher energy content than their Li-ion counterpart. However, the LMB performance remains unsatisfactory for commercialization, primarily owing to the inability of the inorganic solid-state electrolytes to hinder lithium dendrite propagation. Here, using an Ag-coated Li6.4La3Zr1.7Ta0.3O12 (LLZTO) inorganic solid electrolyte in combination with a silver-carbon interlayer, we demonstrate the production of stable interfacially engineered lab-scale LMBs. Via experimental measurements and computational modelling, we prove that the interlayers strategy effectively regulates lithium stripping/plating and prevents dendrite penetration in the solid-state electrolyte pellet. By coupling the surface-engineered LLZTO with a lithium metal negative electrode, a high-voltage positive electrode with an ionic liquid-based liquid electrolyte solution in pouch cell configuration, we report 800 cycles at 1.6 mA/cm2 and 25 °C without applying external pressure. This cell enables an initial discharge capacity of about 3 mAh/cm2 and a discharge capacity retention of about 85%.

Promoting the interfacial Li + transport and suppressing detrimental lithium dendrites are the main challenges for developing practical solid‐state lithium metal batteries. In this respect, interface rationalizing to synergize the enhancement of ion transport and suppression of lithium dendrites is of paramount significance. Herein, a novel strategy is demonstrated to address those issues by a designed multifunctional composite interlayer. The photocrosslinkable polymer is introduced in a scalable elastic skeleton, which promotes the migration and diffusion of Li + . Moreover, adding perfluoropolyether in the interlayer benefits to regulating the formation of LiF‐rich interface, sufficiently suppress the growth of lithium dendrites. Benefitting from the elasticity, high Li + conductivity and the lithium dendrites suppression capability, the interlayer can significantly improve the interfacial performance of the solid electrolyte/lithium interface, thus leading to the greatly enhanced electrochemical performance of solid‐state lithium metal batteries. A high critical current density of 3.6 mA cm −2 and a long cycling life at 1.0 mA cm −2 for >400 h are achieved for the symmetric cells. Besides, when used in a pouch‐type full cell coupled with LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode, a high charged capacity of 3.25 mAh cm −2 can be maintained through 20 cycles, demonstrating its great potentials for practical application.

Garnet-type electrolyte have received a lot of attention due to its high ionic conductivity, wide electro-chemical window, excellent thermal stability and lithium metal stability, which can match high-voltage cathode and lithium metal anode to promote the safety and energy density of the batteries. The preparation of solid electrolytes frequently necessitates high-temperature solid-state reaction method. However, this method would cause volatile lithium compounds, restricting the practical preparation and application of electrolytes. Herein, the impact of Li2CuO2 (LCO) as a sintering additive on the sintering behavior of Ta-doped garnet-type electrolyte (Li6.5La3Zr1.5Ta0.5O12, LLZT) is investigated. LCO plays an auxiliary sintering role to reduce the sintering temperature, and the internal Li2O atmosphere that is provided by LCO helps densification of LLZT. The relative density of LLZT-0.5 LCO is 96.07 %, and its Li-ion conductivity is 3.6 x 10-4 S cm-1. Li symmetric and full batteries show excellent cycling performance. This facile and effective strategy of utilizing sintering additive for low temperature sintering could offer useful ideas for the low-cost fab-rication of LLZT. (c) 2022 Elsevier B.V. All rights reserved.

Solid-state lithium metal batteries (SSLMBs) have caught research interest for their desirable safety and energy density. However, low density, poor uniformity of the solid-state electrolytes (SSEs), and dendrite penetration through the SSEs are the major problems that hinder the progress in SSLMB's development. Herein, a co-doping strategy is proposed for garnet-type electrolyte by utilizing a well-designed lithium rich additive Li2WO4 (LWO) doping into Li6.5La3Zr1.5Ta0.5O12 (LLZT). LWO addition yields a denser and more uniform material by acting as a sintering aid and providing an inner Li2O atmosphere. W substitutes the Zr element and forms Ta and W-doped LLZO, and second phase, which broadens the sintering temperature range of LLZT and avoids abnormal grain growth (AGG). With 2 wt% LWO, LLZT-2LWO has an ionic conductivity of 0.6 mS/cm and a relative density of 98.67%. Moreover, the critical current density (CCD) of LLZT-2LWO reaches 1.0 mA cm2. LLZT-2LWO achieves long cycling stability for 300 h at 0.5 mA cm-2 , showing an excellent dendrite-suppression capability. The full cell matched with LiNi0.6Co0.2Mn0.2O2 and sulfur cathode displays high discharge capacity and cycling stability. This modification strategy has high efficiency and is conducive to large-scale production, which opens a new opportunity for SSLMBs.(c) 2022 Elsevier Ltd. All rights reserved.

Solid-state lithium (Li) metal battery is promising for next-generation battery systems due to its high safety and expected high energy density. Li7La3Zr2O12 (LLZO) with superior ionic conductivity and excellent stability with Li stands out among numerous solid electrolytes, yet the poor interfacial contact and the growth of dendrites hinder its application. Herein, a lithium-salt lithiophilic layer with nano-porous structure is constructed on the garnet surface by using H3BO3 aqueous solution and HF vapor. The violent reaction of lithium-salt layer with Li coupled with capillary force from nano-porous layer give rise to superior lithiophilicity, which greatly improves the wettability of LLZO with molten Li, thereby reducing the interfacial impedance to & SIM;9 omega cm(2). The interfacial reaction induces bi-functional interphase with electronically insulation and high surface energy, which can block the electron transport at the interface and guide the horizontal deposition of lithium, thus effectively suppressing the Li dendrites. With above effects, a stable LLZO/Li interface is obtained with an improved critical current density (CCD) of & SIM;2 mA cm(-2) and excellent cycling stability for 1200 h at 0.5 mA cm(-2) at 25 ?. And the solid batteries with LiFePO4 or LiNi0.5Co0.2Mn0.3O2 cathode display excellent long-term cycling performance and can work normally at 1.2 mA cm(-2) at 25 ?.

Solid‐state lithium metal batteries (SSLMBs) are attracting increasing attentions as one of the promising next‐generation technologies due to their high‐safety and high‐energy density. Their practical application, however, is hindered by lithium dendrite growth and propagation in solid‐state electrolytes (SSEs). Herein, an in situ grain boundary modification strategy relying on the reaction between Li 2 TiO 3 (LTO) and Ta‐substituted garnet‐type electrolyte (LLZT) is developed, which forms LaTiO 3 along with lesser amounts of LTO/Li 2 ZrO 3 at the grain boundaries (GBs). The second phases of LTO/Li 2 ZrO 3 inhibit abnormal grain growth. The presence of LaTiO 3 at the GBs reduces electronic conductivity and improves mechanical strength, which can hinder dendrite formation and block lithium dendrite penetration through the LLZT. Moreover, the adjacent grains by LaTiO 3 build a continuous Li + transport path, providing a homogeneous Li + flux throughout the whole LLZT‐4LTO. As a result, symmetric cells of Li | LLZT‐4LTO | Li shows a high critical current density of 1.8 mA cm −2 and a long cycling stability up to 2000 h at 0.3 mA cm −2 . Moreover, the high‐voltage full cells demonstrate remarkable cycling stability and rate performance. It is believed that this novel grain boundary modification strategy can shed light on the constructing of high‐performance SSEs for practical SSLMBs.

One of the viable options to significantly augment the energy density of lithium-ion batteries (LIBs) is to adopt lithium metal anode in the cell, which offers the highest theoretical capacity (3,860 mAh g-1) among anode materials.1 However, the practical obstacles such as dendrite growth, low Coulombic efficiency, and safety issues still remain unresolved, despite the extensive efforts to employ the lithium metal anode in LIBs.2 Recent progress in solid-state electrolyte development has granted a new promising opportunity for the utilization of lithium metal anodes, whose mechanical rigidity and non-flammable nature are supposed to effectively suppress lithium dendrite short-circuiting, thereby securing battery safety. Nevertheless, there has been no report thus far that demonstrates acceptable levels of electrochemical performance of solid-state lithium metal batteries for real-world applications.3,4 In our research, a lithium-metal-battery employing tailored garnet-type Li7-xLa3-aZr2-bO12 (LLZO) solid-electrolytes that can meet the lifespan requirements of both electric vehicles and stationary applications has been achieved, affording remarkable stability and energy density over 2,000 cycles. It is demonstrated that the compatibility between LLZO and lithium metal is crucial for the long-term stability, which can be accomplished by regulating bulk dopants and the corresponding dopant-specific interfacial treatment using protonation/etching. The appropriate selection of dopant and dopant-specific protonation/etching agent for LLZO leads to (i) the formation of a stable passivation layer at the interface with lithium metal, (ii) effective release of residual stress in LLZO, and (iii) intact contact at the interface. The lithium-metal cell with 2 mAh cm-2 cathode (12 mg cm-2) delivers a cumulative capacity of over 4,000 mAh cm-2 at 3 mA cm-2, which to the best of our knowledge, is the highest long-term cycle value reported for lithium metal batteries with LLZO electrolytes. Moreover, even with the thin 110-µm-LLZO electrolyte and 20-µm lithium metal, a high-loading-capacity cell (3.2 mAh cm-2) exhibits a superior cycle life (>600 cycles) at 2 mA cm-2 without short-circuiting, affording a basis for the high-energy-cell design with ultra-thin electrolyte. In addition, an all-solid-state-battery, excluding the ionic liquid electrolyte, was successfully demonstrated using the composite cathode, which could cycle over 1,000 times at a high current density of 3 mA cm-2 without short-circuiting. To the best of our knowledge, this is the first all-solid-state battery that can operate over 1,000 cycles, enabled by the garnet-type electrolytes and cathode with a commercially acceptable capacity. These findings are expected to open a new avenue for developing long-lasting solid-state lithium metal batteries by highlighting the efficacy of the coupled bulk and interface doping of solid electrolytes.

Abstract Lithium metal batteries (LMBs) are considered the most promising next-generation battery system because of their high energy density and safety. Significant research effort has been devoted to developing more stable and energy-dense LMBs than the state-of-the-art Li-ion batteries. However, the LMB performance remains unsatisfactory for commercialization, primarily owing to the inability of solid electrolytes to block Li dendrite propagation. Herein, we demonstrate highly stable LMB employing garnet-type oxide electrolyte by introducing a carbon-based interlayer with careful interface engineering. We theoretically and experimentally demonstrate that our design effectively regulated Li deposition away from the solid electrolyte, preventing dendrite penetration. We further demonstrated that the interface condition between the interlayer and solid electrolyte is critical and present an effective strategy to achieve an optimal interface. Overall, our garnet-type oxide-based LMB exhibited a high energy density of ~ 680 Wh/L for over 800 cycles at room temperature without using external pressure.

Solid‐state batteries (SSBs) promise high energy density and strong safety due to using nonflammable solid‐state electrolytes (SSEs) and high‐capacity Li metal anode. Ta‐substituted Li7La3Zr2O12 (LLZT) SSE possesses superior ionic conductivity and stability with Li metal, yet the interfacial compatibility and lithium dendrite hazards still hinder its applications. Herein, an interfacial engineering is demonstrated by facile acid‐salt (AS) treatment on LLZT, constructing a 3D cross‐linking LiF‐LiCl (CF) network. Such structure facilitates Li wetting via capillary permeation. Notably, CF as electronically insulting phases block the electrons through the interface and ulteriorly suppress the dendrite formation. The assembled Li symmetric cell exhibited a low interfacial impedance (11.6 Ω cm2) and high critical current densities (CCDs) in the time‐constant mode, 1.8 mA cm−2 at 25 °C and 3.6 mA cm−2 at 60 °C, respectively. Meanwhile, by exploring the capacity‐constant mode of CCD measurement, the concept of critical areal capacity (CAC) is first proposed, obtaining its values of ≈0.5 mAh cm−2 at 25 °C and 1.2 mAh cm−2 at 60 °C. Moreover, the safety‐enhanced hybrid SSBs matched with LiFePO4 and LiNi0.6Co0.2Mn0.2O2 deliver a remarkable rate and cycling performances, validating the feasibility of this interfacial engineering in various SSB systems.

Solid-state batteries (SSBs) have attracted many attentions due to its higher energy density and improved safety. As one of the most promising solid electrolytes, garnet Li7La3Zr2O12 (LLZO) has achieved significant advances in its cell performance, however, its application in Li-metal batteries is still hindered by lithium dendrite growth at voids or grain boundaries inside the solid electrolyte. Herein, a novel grain-boundary enhancement strategy was demonstrated by introducing Li6Zr2O7 (LZO), which can be decomposed into Li2O in situ, into Ta-doped LLZO (LLZT). The Li2O provides a sufficient inner Li2O atmosphere, achieving none mother powder sintering. The Li2ZrO3 stays at garnet grain boundaries or fills up the pores, which have been shown to effectively suppress the lithium dendrite growth. More importantly, the critical current density (CCD) of the Li | LLZT-LZO | Li symmetric cell achieved as high as 1.4 mA cm(-2) at 25 degrees C and 2.0 mA cm(-2) at 60 degrees C, and the long-term lithium cycling remained stable over 2000 h at 0.3 mA cm(-2). Moreover, the Li-S battery maintained high discharge capacity of 816 mAh g(-1) after 200 cycles at 0.5C. Therefore, our work provides a facile and effective strategy to prepare a safety-enhanced electrolyte for future applications of SSBs.

Garnet-type Li7La3Zr2O12 (LLZO) Li+ ion solid electrolyte is a promising candidate for next generation high-safety solid-state batteries. Ga-doped LLZO exhibits excellent Li+ ion conductivity, higher than 1 x 10(-3) S cm(-1). In this research, the doping amount of Ga, the calcination temperature of Ga-LLZO primary powders, the sintering conditions and the evolution of grains are explored to demonstrate the optimum parameters to obtain a highly conductive ceramics reproducibly via conventional solid-state reaction methods under ambient air sintering atmosphere. Cubic LLZO phase is obtained for Li6.4Ga0.2La3Zr2O12 powder calcined at low temperature 850 degrees C. In addition, ceramic pellets sintered at 1100 degrees C for 320 min using this powder have relative densities higher than 94% and conductivities higher than 1.2 x 10(-3) S cm(-1) at 25 degrees C.

Although garnet-type LLZO has been considered one of the most promising solid electrolyte for solid-state batteries (SSB), the instability of electrode/LLZO interface has been obstacle for the practical application of LLZO into the batteries.[1] Thus, a fundamental understanding of the lithium deposition behavior in the interface would aid in elucidating the underlying mechanisms of the short circuit failure due to unstable interface and designing the interface in SSBs. Herein, we successfully used an in operando microscopy technique to probe Li deposition through the LLZO electrolyte in an anode-free solid-state battery setup. More importantly, we carefully examined the interface with artificial interlayers, which revealed that Li plating is strongly dominated by the kinetics of alloying and precipitation through the metal interlayer. In addition, we confirmed that the interlayer also affects the sequential stripping process, influencing the electrochemical performance of the cell. Supported by these intriguing observations, we propose the dynamic roles of the interlayer during battery operation: as a buffer layer and a seed layer. The in-house cell and microscope system shown in Figure 1a were used for the in operando observations of Li deposition on LLZO. Li foil was attached to the bottom of the LLZO pellet and the top surface was pre-coated with the selected interlayer metal. We investigated electrochemical Li deposition behavior in the absence of an interlayer metal. Li metal begins to appear in island shapes under an applied galvanostatic current (0.1 mA cm-2) and continues to grow over time as shown in Figure 1b. It is worth noting that all of the small Li-metal islands first form at pre-existing defects on the pristine LLZO surface during initial lithiation and Li grows preferably at these islands during the subsequent plating. When the metal interlayer was introduced, the deposition behavior was significantly altered. With 30-nm-thick Au layer, we observed that Au interlayer changed color under electrochemical bias, which is indicative of the formation of a Li-Au alloy. These color changes are followed by the formation of island-type small precipitations. From this observation, we propose that Au interlayer plays the unexpected role of a “buffer layer”, which dynamically functions as a medium for Li redistribution by propagating alloying reactions. Given the proposed new role of the interlayer, we expected the Li-metal deposition behavior to critically depend on the thermodynamic and kinetic properties of the interlayer metal and its alloying nature with Li. Si and Ag were chosen in this study, considering the availability of various alloys and the appreciable Li diffusivities in their alloys. When Si layer is applied (Figure 2a), the color changed during the early stages as gold, but subsequent behavior was noticeably different from that of the Au; Li metal preferentially precipitates at only a few sites, and whisker-shaped Li metal rapidly grows at these sites. On the other hand, in Ag interlayer (Figure 2b), the alloying reaction occurs first, followed by the uniform formation of numerous small nuclei. Interestingly, the two reactions occur nearly simultaneously, implying that both the alloying reaction and precipitation in the alloy are so fast that the sequential processes are unable to be distinguished. Regarding on this, the metal interlayers can be regarded as seed matrix for lithium precipitation. Further, Ag interlayer is more reversible upon Li stripping than Au or Si. The better efficacy of the lithium deposition/stripping process with Ag interlayer was further validated by comparative electrochemical testing of two electrode cells constructed with ‘100-nm-thick metal layer│LLZO │Li’ configuration. The results show that the coulombic efficiencies of cells using the various interlayers are closely related to the Li deposition and stripping behavior. The cell with Ag layer, which induces the most-uniform and reversible Li deposition among the tested metals, exhibits the highest efficiency of 71%, while that with Si layer shows 28%. Thus, it indicates that the interlayer can significantly affect the electrochemical performance of anode-free SSBs that employ solid electrolytes by regulating lithiation and de-lithiation behavior at the interface. Considering the ease of interlayer deposition on the LLZO surface and its wide applicability, we expect that our findings will provide useful guidelines for securing optimal interfaces for SSBs. REFERENCES [1] Aguesse, F.; Manalastas, W.; Buannic, L.; Lopez del Amo, J. M.; Singh, G.; Llordés, A.; Kilner, J., ACS Applied Materials & Interfaces 9, 3808-3816. (2017) Figure 1

The mechanism of Li dendrite formation for Ta-doped LLZO (LLZTO) was investigated by examining the electronic structure and the laser annealing of LLZTO was performed as a bandgap engineering method to suppress the Li dendrite formation.

Securing the chemical and physical stabilities of electrode/solid-electrolyte interfaces is crucial for the use of solid electrolytes in all-solid-state batteries. Directly probing these interfaces during electrochemical reactions would significantly enrich the mechanistic understanding and inspire potential solutions for their regulation. Herein, the electrochemistry of the lithium/Li 7 La 3 Zr 2 O 12 -electrolyte interface is elucidated by probing lithium deposition through the electrolyte in an anode-free solid-state battery in real time. Lithium plating is strongly affected by the geometry of the garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) surface, where nonuniform/filamentary growth is triggered particularly at morphological defects. More importantly, lithium-growth behavior significantly changes when the LLZO surface is modified with an artificial interlayer to produce regulated lithium depositions. It is shown that lithium-growth kinetics critically depend on the nature of the interlayer species, leading to distinct lithium-deposition morphologies. Subsequently, the dynamic role of the interlayer in battery operation is discussed as a buffer and seed layer for lithium redistribution and precipitation, respectively, in tailoring lithium deposition. These findings broaden the understanding of the electrochemical lithium-plating process at the solid-electrolyte/lithium interface, highlight the importance of exploring various interlayers as a new avenue for regulating the lithium-metal anode, and also offer insight into the nature of lithium growth in anode-free solid-state batteries.

Li-garnet Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for lithium metal batteries owing to its excellent stability and high ionic conductivity. However, there exists serious lithium dendrite problem in LLZO electrolyte under elevated current density, easily leading to internal short-circuit and poor cycling performance. In this work, we demonstrated that Ta-doped LLZO with 4 wt% MgO additive delivered superior endurance to lithium dendrite due to its improved mechanical properties and lower electronic conductivity. The critical current density (CCD) of LLZTO-MgO composite electrolyte reached as high as 1.95 mA.cm(-2) at room temperature (RT). It also realized stable lithium plating/stripping performance for 1000h under 0.5 mA.cm(-2). Moreover, the full cell paired with LiNi0.6Co0.2Mn0.2O2 cathode exhibited better cycling stability especially at a high rate. Our work provided an alternative strategy for dendrite-suppression in solid electrolyte besides interfacial modification. (C) 2020 Elsevier B.V. All rights reserved.

Ni-rich NCM (LiNixCoyMnzO2, 0.6 < x < 1, 0 < y < 1, 0 < z 1) are up-and-coming cathode materials with high working voltage (similar to 3.8 V) for usage in lithium ion batteries. In order to achieve higher capacity through lithium extraction, higher cutoff voltages (>4.3 V) are applied on these materials. Consequently, the batteries will suffer from aggravated side reactions at the cathode/electrolyte interface and the inherent instabilities of Ni-rich NCM cathodes, and thus exhibit rapid capacity fading and voltage decay. Herein, we report a facile and scalable strategy that employs Zr doping concurrent with LixZryOz surface coating, contributing to outstanding capacity retentions of 97.8% at 0.2C and 91.6% at 2C after 100 cycles over 2.8-4.5 V. The improved cycling stability can be attributed to the enhanced bulk stability and suppressed nonequilibrium diffusion reactions, which are further ascribed to the reduced oxygen vacancies and optimized microstructure.