Zinc metal is considered a promising anode material for aqueous zinc ion batteries. However, it suffers from dendrite growth, corrosion, and low coulombic efficiency (CE) during plating/stripping. ...Herein, a concentrated hybrid (4 m Zn(CF3SO3)2 + 2 m LiClO4) aqueous electrolyte (CHAE) to overcome the challenges facing the Zn anode is reported. The developed electrolyte achieves dendrite‐free Zn plating/stripping and obtains an excellent CE of ≈100%, surpassing the previously reported values. The combination of synchrotron‐based in operando transmission X‐ray microscopy, X‐ray diffraction, and ex situ X‐ray photoelectron spectroscopy analyses indicate that the denser, anion‐derived passivation layer formed using the CHAE facilitates homogeneous current distribution and better prevents freshly deposited Zn from directly contacting the electrolyte than the looser, solvent‐derived layers formed from a dilute hybrid aqueous electrolyte (DHAE). The beneficial effects of the CHAE on the compact, dense, and stable salt‐anion‐derived passivation layer can be attributed to its unique solvation structure, which suppresses the water‐related side reactions and widens the electrochemical potential window. In the hybrid Zn||LiFePO4 configuration, the CHAE‐based cell delivered a stable performance of CE >99% and capacity retention >90% after 285 cycles. In contrast, the DHAE‐based cell exhibits capacity retention of <65% after 170 cycles.
A concentrated hybrid aqueous electrolyte (CHAE) (4 m Zn(CF3SO3)2 + 2 m LiClO4) is developed to address the dendrite formation and low coulombic efficiency upon Zn deposition/stripping. The Zn growth behavior and the formation mechanism of dense anion‐derived passivation layer are unveiled by synchrotron‐based in operando imaging and spectroscopy techniques. The CHAE shows excellent cell performance in Zn||LiFePO4 dual‐ion battery.
Anode‐free lithium‐metal batteries employ in situ lithium‐plated current collectors as negative electrodes to afford optimal mass and volumetric energy densities. The main challenges to such ...batteries include their poor cycling stability and the safety issues of the flammable organic electrolytes. Here, a high‐voltage 4.7 V anode‐free lithium‐metal battery is reported, which uses a Cu foil coated with a layer (≈950 nm) of silicon–polyacrylonitrile (Si‐PAN, 25.5 µg cm−2) as the negative electrode, a high‐voltage cobalt‐free LiNi0.5Mn1.5O4 (LNMO) as the positive electrode and a safe, nonflammable ionic liquid electrolyte composed of 4.5 m lithium bis(fluorosulfonyl)imide (LiFSI) salt in N‐methyl‐N‐propyl pyrrolidiniumbis(fluorosulfonyl)imide (Py13FSI) with 1 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as additive. The Si‐PAN coating is found to seed the growth of lithium during charging, and reversibly expand/shrink during lithium plating/stripping over battery cycling. The wide‐voltage‐window electrolyte containing a high concentration of FSI− and TFSI− facilitates the formation of stable solid‐electrolyte interphase, affording a 4.7 V anode‐free Cu@Si‐PAN/LiNi0.5Mn1.5O4 battery with a reversible specific capacity of ≈120 mAh g−1 and high cycling stability (80% capacity retention after 120 cycles). These results represent the first anode‐free Li battery with a high 4.7 V discharge voltage and high safety.
4.7 V Cu@Si‐PAN/LiNi0.5Mn1.5O4 anode‐free Li batteries with a reversible specific capacity of ≈120 mAh g−1 and high capacity retention of 80% after 120 cycles are reported. With the nonflammable F‐rich ionic liquid electrolyte and the seeding Si‐PAN layer (950 nm), an enhanced safety and high‐voltage anode‐free Li battery without dendritic Li growth is demonstrated.
It is essential to decouple the interfacial reactions taking place at the anode and cathode in rechargeable batteries. However, due to the reactive nature of Li, it is challenging to use Li‐metal ...batteries (LMBs) protocol to decouple the interfacial reactions. The by‐products from the anode or cathode become mixed in Li/NMC111 cells, which make decoupling interfacial reactions difficult. Here, reactions at electrodes are successfully decoupled and demystified using a protocol combining anode‐free LMB (AFLMB) with online electrochemical mass spectroscopy. LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) and EC/ethyl methyl carbonate (1:1 v/v%) electrolytes are used to compare interfacial reactions in Li/NMC111 and Cu/NMC111 cells. In Cu/NMC111, the evolution of CO2, CO, and C2H4 gases at the initial stage of first charging is due to interfacial reactions at Cu surface due to solid–electrolyte‐interphase formation. However, the evolution of CO2 and CO gases at high voltage in the entire cycles is associated with chemical and/or electrochemical electrolyte oxidation at the cathode. This work paves a new concept to decouple interfacial reactions at electrodes for developing electrochemically stable electrolytes to improve the performance with the long‐cycling life of AFLMBs and LMBs.
Reductive and oxidative gases evolving at the anode and cathode in Li/NMC111 and Cu/NMC111 are independently studied using a protocol combining EL‐Cell and GC‐MS. Understanding the decoupled interfacial reactions at both electrodes help elucidate the solid–electrolyte‐interphase formation mechanism and develop stable and high‐performance electrolytes.
Using lightweight and inexpensive aluminum foil as a current collector in aqueous batteries is still very challenging due to its serious corrosion effects, which impede the practical applications of ...aqueous batteries. In this study, Pc is proposed as a corrosion inhibitor for aluminum current collectors. Interestingly, the corrosion current density (0.013 μA) in an aqueous electrolyte with the Pc additive is 23 times less than that (0.302 μA) without Pc. Furthermore, a Zn/LVPF cell was used to assess the corrosion impact on its battery performance in an aqueous electrolyte. Zn|LVPF cells at a 0.2C rate with the Pc additive demonstrated a higher capacity retention of 75% and 50.12% after 100 and 200 cycles, respectively. The battery without Pc showed a substantially worse cycle life with only 27.57% capacity retention after 40 cycles. Furthermore, Pc prevents aluminum corrosion in an organic electrolyte-based battery. The Pc additive can protect aluminum from corrosion by a dual-secure passivation mechanism, including its physical adsorption on the Al surfaces and electrochemically formed AlPc-F passivation layer. This work opens a new avenue for developing corrosion inhibitors of aluminum not only in aqueous electrolytes but also for organic-based electrolytes.
The Pc (phthalocyanine) additive prevents Al corrosion by dual-secure mechanisms: electrochemical formation of an AlPc-F layer and physical adsorption of Pc on Al surfaces. Pc contains an N-lone pair, adsorbing on the Al current collector preferentially.
Argyrodite sulfide-based solid electrolyte Li6PS5Cl (LPSC) is considered to have great potential in solid-state battery applications due to its ion conductivity being comparable to that of liquid ...electrolytes. However, interfacial instability between LPSC and Li during cycling, resulting in battery polarization, is an ongoing problem. Here, we report that CO2 adsorption can play a crucial role in improving both interfacial and electrochemical stability between lithium and LPSC. Investigating the formation of the new S–CO2 bond, examined here using various analytical techniques, is pivotal to modifying interfacial behavior. It enhances the interfacial stability between lithium and LPSC and reduces cell resistance. Moreover, the Li|CO2@LPSC|LTO shows an amazing result, with 62% capacity retention and ultra-high coulombic efficiency of 99.91% after 1000 cycles. Interestingly, the same concept was also applied to the high ionic conductivity sulfide-based superionic conductor Li10GeP2S12 (LGPS) system, which also has the PS43− moiety. It also enhanced the stability at the lithium and LGPS interface. This work offers a new direction toward reducing the interfacial resistance of sulfide-based solid electrolytes; it increases the possibility of realizing sulfide-based all-solid-state lithium metal batteries.
Lithium-ion batteries (LIBs) are widely used in applications ranging from electric vehicles to wearable devices. Before the invention of secondary LIBs, the primary lithium-thionyl chloride ...(Li-SOCl2) battery was developed in the 1970s using SOCl2 as the catholyte, lithium metal as the anode and amorphous carbon as the cathode1-7. This battery discharges by lithium oxidation and catholyte reduction to sulfur, sulfur dioxide and lithium chloride, is well known for its high energy density and is widely used in real-world applications; however, it has not been made rechargeable since its invention8-13. Here we show that with a highly microporous carbon positive electrode, a starting electrolyte composed of aluminium chloride in SOCl2 with fluoride-based additives, and either sodium or lithium as the negative electrode, we can produce a rechargeable Na/Cl2 or Li/Cl2 battery operating via redox between mainly Cl2/Cl- in the micropores of carbon and Na/Na+ or Li/Li+ redox on the sodium or lithium metal. The reversible Cl^NaCl or Cl2/LiCl redox in the microporous carbon affords recharge-ability at the positive electrode side and the thin alkali-fluoride-doped alkali-chloride solid electrolyte interface stabilizes the negative electrode, both are critical to secondary alkali-metal/Cl2 batteries.
Two types of racemic rodlike Schiff base mesogens with –CN– (type I ) and –NC– (type III ) linkages were prepared. These mesogens possessed either difluoro substitutions at the inner-core position ...of the phenyl ring or hydroxy group to form intramolecular hydrogen bonding with an ester or/and imine linkage. When the appropriate concentration of chiral additive is doped into them, the incorporation of two fluoro substituents is more useful for blue phase (BP) stabilization than that of a hydroxy group near the ester linkage in Schiff base mesogens. BPI and BPII can be identified by reflectance spectra and polarized optical microscope images. BPII emerges easily on cooling when the appropriate chiral dopant ISO(6OBA)2 or chiral dopant S811 is doped into the Schiff base mesogen having only a hydroxy group near the ester linkage. Interestingly, BPI can be observed when 10–15 wt% ISO(6OBA)2 was doped into the difluoro substituted Schiff base mesogen III during a heating process. The experimental and molecular modeling results indicate that most of the difluorinated Schiff base mesogens with larger dipole moments exhibit wider BP ranges than their corresponding non-fluorinated homologues under the same chirality condition. In addition, wide BPs can be induced for racemic rodlike Schiff base mesogens I in the chiral system and this is easier than that for racemic rodlike Schiff base mesogens III . In Schiff base mesogens I , the dipole moment is dominant for BP stabilization. However, the fluorine substituent effect is the main factor in Schiff base mesogens III .
Conspectus Lithium (Li) metal is the ultimate negative electrode due to its high theoretical specific capacity and low negative electrochemical potential. However, the handling of lithium metal ...imposes safety concerns in transportation and production due to its reactive nature. Recently, anode-free lithium metal batteries (AFLMBs) have drawn much attention because of several of their advantages, including higher energy density, lower cost, and fewer safety concerns during cell production compared to LMBs. Pushing the reversible Coulombic efficiency (CE) of AFLMBs up to 99.98% is key to achieving their 80% capacity retention over more than 1000 cycles. However, interfacial irreversible phenomena such as electrolyte decomposition reactions on both electrodes, dead Li formation, and Li dendrite formation result in poor capacity retention and short circuits in LMBs and AFLMBs. Therefore, it is of great importance and scientific interest to explore those interfacial irreversible phenomena to improve the cell’s cycle life. Although significant contributions toward mitigating electrolyte decomposition, dead lithium, and dendritic lithium formation have been reported at the lithium anode, real irreversible phenomena are usually hidden or difficult to discover due to excess lithium employed in LMBs and simultaneous events taking place in both electrodes or at the interfaces. An integrated protocol is suggested to include Li||Cu, cathode||Li, and cathode||Cu configurations to provide overall quantification and determination of various sources of irreversible Coulombic efficiency (irr-CE) in AFLMBs and LMBs. Combining Li||Cu, cathode||Li, and cathode||Cu configurations is essential for separating the root sources of the capacity loss and irr-CE in LMBs and AFLMBs. Remarkably, integrating an anode-free cell with various analytical techniques can serve as a powerful protocol to decouple and quantify those interfacial irreversible phenomena according to our recent reports. In this Account, we focus on the protocol based on an anode-free cell combined with various analytical methods to investigate interfacial irreversible phenomena. Complementary advanced tools such as transmission X-ray microscopy (visualizing Li plating/stripping mechanism), nuclear magnetic resonance spectroscopy (quantifying dead lithium), and gas chromatography–mass spectroscopy (decoupling interfacial reactions) were employed to extract the intrinsic reasons and sources of individual irreversible reactions in LMBs and AFLMBs. Quantitative evaluation of nucleation and growth of Li metal deposition are addressed, along with solid electrolyte interphase (SEI) fracture, visualization of lithium dendrite growth, decoupling of oxidative and reductive electrolyte decomposition mechanisms, and irreversible efficiency (i.e., dead Li and SEI formation) to reveal the intrinsic causes of individual irr-CE in AFLMBs. Meanwhile, an anode-free protocol can also be utilized as a powerful and multifunctional tool to develop electrolyte formulations or artificial layers for LMBs and AFLMBs. Therefore, we also suggest that the anode-free configurations with significant irreversible phenomena can effectively screen and develop new electrolytes. Finally, the concepts of the protocol with an anode-free cell combined with various advanced analytical tools can be extended to provide an in-depth understanding of other metal batteries and solid-state anode-free metal batteries.
The decent ductileness, high ionic conductivity, low cost, and versatility over synthesis methods make Li-argyrodite a promising for all-solid-state lithium batteries. However, its serious ...interfacial incompatibility with Li anode, dendrite growth, and intrinsic air instability impedes its practicability. Herein, we report a CuCl dual doped Li-argyrodite sulfide superb-conductor (Li6+3xP1−xCuxS5−xCl1+x) prepared to overcome these issues via ball-mill free synthesis approach. The maximum Li+ conductivity of 4.34 mS cm−1 at room temperature with ultrawide voltage stability up to 8 V vs. Li/Li+ was achieved in Li6.3P0.9Cu0.1S4.9Cl1.1 (LPSC-1) via a both composite and planar electrode system and can suppress dendrite formation at a current density of 3 mA cm−2 at 50 оC. The symmetrical cell cycled at 0.1 and 1 mA cm−2 also demonstrates remarkable reversibility with negligible overpotential alteration for more than 2400 h and 400 h. An ex-situ XPS and AC impedance analysis proved enhanced interfacial compatibility at Li | SE and achieved a critical current density of 3 mA cm−2. More interestingly, incorporating soft acid Cu in LPSC-1 boosts the air stability and suppresses H2S generation by two-folds. The XRD for the LPSC-1 before and after air exposure proves the decrease in the oxophilicity of the sulfide solid electrolyte.
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•Doping soft acid Cu in LPSC boosts the air stability and suppresses H2S generation.•Ultra-high Li metal capability at 0.1 mA cm−2, 1 mA cm−2 and 3 mA cm−2.•Ionic conductivity of 4.34 mS cm−1 at RT with extended voltage stability, 8 V.•Superior dendrite suppression capability with CCD 3 mA cm−2 at 50 оC.•Decrease in oxophilicity with structural stability confirmed via XRD.
Lithium metal is considered as an ideal anode material for lithium-ion batteries, because of its highest theoretical specific capacity, energy density, low reduction potential, and lightweight. ...However, its practical application is being hindered by factors such as the presence of uncontrolled interfacial reactions with liquid electrolytes, unstable solid electrolyte interphase (SEI), dendrite formation due to inhomogeneous lithium-deposition and poor cycle life. Herein, Lithium ion conducting composite film comprising of cubic garnet (Li7La2.75Ca0.25Zr1.75Nb0.25O12) (LLCZN), polyvinylidene fluoride (PVDF) and lithium perchlorate (LiClO4) salt is prepared by electrospinning. The composite film induces inorganic-rich solid electrolyte interphase which is mechanically stable to suppress the formation of lithium dendrites. The Li‖Cu@LLCZN/PVDF(84:16)LiClO4 cell exhibits negligible polarization compared to a bare copper one (Li‖Cu) performed in 1 M LiPF6 ethylene carbonate (EC) diethyl carbonate (DEC) (1:1 v/v ratio) electrolyte at a current density of 0.2 mA cm−2. Moreover, the anode free full cell configuration (Cu@LLCZN/PVDF‖NMC) demonstrates improved capacity retention of 58.66% and average coulombic efficiency of 97.6% after 30th cycles. The as-synthesized composite film induces inorganic rich (LiF and LiCl) SEI and gives required mechanical strength to suppress the lithium dendrite formation. These features endow the Cu anode with stable interface chemistry which is essential to the realization of anode-free lithium metal batteries.
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•Cubic garnet composite film modified copper.•Film-induced SEI obtained during in situ charge-discharge process.•Mechanical strength of the composite strong enough to suppress dendrite.•Inorganic-rich SEI improves the electrochemical stability of the anode free battery.
