Lithium dendrite (filament) propagation through ceramic electrolytes, leading to short circuits at high rates of charge, is one of the greatest barriers to realizing high-energy-density ...all-solid-state lithium-anode batteries. Utilizing in situ X-ray computed tomography coupled with spatially mapped X-ray diffraction, the propagation of cracks and the propagation of lithium dendrites through the solid electrolyte have been tracked in a Li/Li
PS
Cl/Li cell as a function of the charge passed. On plating, cracking initiates with spallation, conical 'pothole'-like cracks that form in the ceramic electrolyte near the surface with the plated electrode. The spallations form predominantly at the lithium electrode edges where local fields are high. Transverse cracks then propagate from the spallations across the electrolyte from the plated to the stripped electrode. Lithium ingress drives the propagation of the spallation and transverse cracks by widening the crack from the rear; that is, the crack front propagates ahead of the Li. As a result, cracks traverse the entire electrolyte before the Li arrives at the other electrode, and therefore before a short circuit occurs.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
A critical current density on stripping is identified that results in dendrite formation on plating and cell failure. When the stripping current density removes Li from the interface faster than it ...can be replenished, voids form in the Li at the interface and accumulate on cycling, increasing the local current density at the interface and ultimately leading to dendrite formation on plating, short circuit and cell death. This occurs even when the overall current density is considerably below the threshold for dendrite formation on plating. For the Li/Li
PS
Cl/Li cell, this is 0.2 and 1.0 mA cm
at 3 and 7 MPa pressure, respectively, compared with a critical current for plating of 2.0 mA cm
at both 3 and 7 MPa. The pressure dependence on stripping indicates that creep rather than Li diffusion is the dominant mechanism transporting Li to the interface. The critical stripping current is a major factor limiting the power density of Li anode solid-state cells. Considerable pressure may be required to achieve even modest power densities in solid-state cells.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
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•EC electrolyte additive substantially improved performance and stability of ZIBs.•Capacity was improved to 207 mAh g−1 at 0.1 A g−1, sustained for >200 cycles.•EC presence had a ...positive effect on the Zn anode and MnO2 cathode of ZIBs.•EC can form an interface film on Zn anode, suppressing dendrites and side reactions.•EC decreases and stabilizes the polarization of a Zn–Zn battery.
Rechargeable zinc-ion batteries (ZIBs) have recently received tremendous attention for large-scale electrochemical energy storage, but their poor cyclic stability and reversibility and low coulombic efficiency, which are mainly caused by dendrite issues and parasitic reactions of zinc (Zn) anode, prevent them from achieving their full potential. Herein, we investigated the use of ethylene carbonate (EC) as an electrolyte additive to improve the performance of ZIBs. The addition of 6% (w/v) EC substantially enhanced the first-cycle discharge capacity from 115 to 203 mAh g−1 at 0.1 A g−1, while retaining this high discharge capacity (102% retention of the initial capacity) after 200 cycles, and from 43 to 54 mAh g−1 at 1 A g−1 with 85% capacity retention after 1,000 cycles. The ex-situ characterizations and electrochemical impedance spectroscopy analysis before and after Zn–MnO2 and Zn–Zn battery cycling suggested that the addition of EC could effectively suppress dendrite formation and parasitic reactions on the Zn anode, possibly via electrolyte/Zn anode interface film formation in the presence of EC. Moreover, the presence of EC made the MnO2 morphology more open and accessible. These led to substantial improvements in the rate performance and cyclability compared to the additive-free electrolyte.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sulfide‐based Li+ conducting solid electrolytes, such as argyrodite, Li6PS5Cl, for all‐solid‐state batteries can have comparable ionic conductivities with liquid electrolytes. However, the interface ...between sulfide containing solid electrolytes and Li metal and Li‐ion positive electrodes has been found to be unstable, leading to poor cell performance and cycling. Understanding the in situ evolution of interfacial layers between the electrolyte and both electrodes is of paramount importance for designing stable and long‐life solid‐state batteries. Here, in situ Raman microscopy was used to study the interface between Li6PS5Cl electrolyte and metallic Li and LiCoO2. Under potential control, Raman microscopy identified the appearance of degradation products (Li2S, P2Sx and polysulfides) at the electrode/solid electrolyte interface.
Under potential control: In situ Raman microscopy is used to study the interfacial evolution between Li6PS5Cl and Li metal and LiCoO2 during charge and discharge processes for all‐solid‐state batteries applications.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Operando optical microscopy enables imaging at the interface between the Zn electrode and the electrolyte of 1 M ZnSO4(aq) in the symmetrical Zn/Zn cells assembled as the pouch cells with the ...mechanical load of 0.8 MPa. The imaging was executed during cycling of Zn plating and stripping at the different current densities of 0.5, 1.0, 2.0, and 4.0 mA cm−2, and the areal capacity of 2 mAh·cm−2. When the current densities are below 4.0 mA cm−2, no intense Zn dendrites are observed. However, at 4.0 mA cm−2, the severe Zn dendrites can penetrate through the separator and cause short-circuiting. From the electrochemical perspective, the voltage profile of such system drops to almost zero volt. Both operando optical and ex-situ synchrotron X-ray imaging further prove the appearance of the Zn dendrites. By Raman spectroscopy and X-ray diffraction, the cycled Zn electrode surface contains passivation species of Zn4(OH)6SO4, ZnO, and Zn(OH)2 that could limit the active surface area for the Zn plating/stripping, accelerating the localized current density and favoring the growth of Zn dendrites. With the SiO2 additive of 0.5% w/v in 1 M ZnSO4(aq), the severe Zn dendrites disappear, as well as the cycled Zn/electrolyte interface becomes close to the pristine state; low degree of the Zn electrode roughness and the Zn surface passivation is noticed. The appearance of the claimed Zn surface morphology was also confirmed by Scanning Electron Microscopy (SEM). In turn, too low or too high SiO2 content in the electrolyte does not generate desirable effects. A high level of Zn dendrites and short circuiting are still recognized. Hence, both the operando and ex-situ characterizations can mutually validate the phenomena at the Zn/electrolyte interface.
•Operando optical spectroscopy reveals real time Zn/electrolyte interfacial changes.•Ex-situ synchrotron X-ray imaging confirms penetration of Zn dendrites.•Raman spectroscopy and X-ray diffraction prove existence of passivation species on Zn electrode surface.•A specific SiO2 quantity in 1 M ZnSO4(aq) effectively suppress Zn dendritic growth and formation.•Zn dendrites and Zn corrosion are influenced by SiO2 content & current density.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
All-solid-state batteries potentially offer safe, high-energy-density electrochemical energy storage, yet are plagued with issues surrounding Li microstructural growth and subsequent cell death. We ...use 7Li NMR chemical shift imaging and electron microscopy to track Li microstructural growth in the garnet-type solid electrolyte, Li6.5La3Zr1.5Ta0.5O12. Here, we follow the early stages of Li microstructural growth during galvanostatic cycling, from the formation of Li on the electrode surface to dendritic Li connecting both electrodes in symmetrical cells, and correlate these changes with alterations observed in the voltage profiles during cycling and impedance measurements. During these experiments, we observe transformations at both the stripping and plating interfaces, indicating heterogeneities in both Li removal and deposition. At low current densities, 7Li magnetic resonance imaging detects the formation of Li microstructures in cells before short-circuits are observed and allows changes in the electrochemical profiles to be rationalized.
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IJS, KILJ, NUK, PNG, UL, UM
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•Carboxymethyl cellulose (CMC) was studied as an artificial solid electrolyte interphase (SEI) for zinc anode.•CMC-SEI effectively mitigated the migration of zinc on the anode ...surface.•CMC-SEI anode exhibited reduced overpotential, improved coulombic efficiency and prolonged cycling.•At 5 mA cm−2, the Zn-iodine battery having CMC-ASEI can cycle up to 2,000 cycles.
Zinc (Zn) is viewed as a promising anode material for large-scale secondary batteries. However, due to parasitic reactions and uneven Zn distribution during repeated stripping/plating cycles, Zn anodes show inferior performance and stability. To overcome such drawbacks, carboxymethyl cellulose (CMC) as an artificial solid electrolyte interphase (ASEI) is fabricated on a Zn sheet and Zn-graphite composite anode. The roles of CMC-ASEI are examined using X-ray tomography, X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Results show that the carboxyl group in CMC can regulate the flux and local concentration of Zn ions at the surface, allowing uniform Zn dissolution/deposition, and can suppress corrosion by reducing water activities on the anode’s surface. At 5 mA cm−2, the Zn-iodine battery having CMC-ASEI can cycle up to 2,000 cycles. This work provides a simple and scalable solution for advanced Zn anodes for Zn-based batteries.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
All-solid-state batteries, which utilise a solid electrolyte in place of liquid electrolytes, have the potential for higher energy densities and greater safety than current lithium-ion batteries. ...However they still face many challenges before the technology is ready to be commercialised.
This short report summarises the current state of knowledge in all-solid-state batteries including the electrical, electrochemical and mechanical properties of the electrolytes, and the challenges that remain to be overcome in their development and processing.
In this work, the composite materials of cellulose and poly(ethylene oxide) (PEO) materials as the solid-electrolyte separator was electrochemically and mechanically characterized before being ...incorporated into solid-state Zn-ion batteries (SSZIBs) with LiFePO4 cathode and Zn anode. As understanding fading mechanisms and operational settings is essential to developing long lasting batteries, we further investigated the mechanisms of LiFePO4 lithiation and de-lithiation in SSZIBs. The capacity fading mechanism was elucidated using ex-situ high energy synchrotron XANES measurements on our developed Zn-ion devices at varying charge rates. Long-term cycling was the focus of these investigations, which tracked and assessed chemical and structural changes. The results show that an increase in inactive FePO4 proportional to the loss of active lithium is the primary driver of capacity fading once the lithium source is depleted. XRD confirm that LiFePO4 exists in an olivine phase and reveal that the insertion and deinsertion behaviour of lithium ions in LiFePO4 changes with cycling. The two phases (LiFePO4, FePO4) and the loss of the lithium source may contribute to the reduced rate capability and capacity fading of LiFePO4 cells during prolonged cycling.
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•High-strength composite cellulose-PEO polymer electrolyte gives the Young's modulus more than 30 MPa.•Improved electrical conductivity of composite cellulose-PEO polymer electrolyte is observed.•Solid-state Zn-ion batteries are developed based on composite cellulose-PEO.•Zn/LiFePO4-based Zn-ion battery capacity fading mechanism is investigated.•A investigation of lithium ion behaviour in the LiFePO4 cathode during insertion and deinsertion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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