In-situ formation of liquid crystal interphase in electrolytes with soft templating effect for batteries

Abstract

A battery with an anode, a cathode, and an electrolyte in contact with the anode and cathode has an anode-electrolyte interface and a cathode-electrolyte interface where the electrolyte includes a surfactant in sufficient concentration to generate a gradient liquid crystal interphase layer at the anode-electrolyte interface and / or at the cathode- electrolyte interface. The battery may use various battery chemistries including Zn / MnO2, Cu / MnO2, Fe / MnO2, LiTFSI, or NaPF6.

Description

Embodiments of the present invention overcome longstanding challenges in battery design. Aqueous batteries have valuable safety advantages compared to widespread lithium-ion batteries. However, there is a need to enhance their energy density and cycle life. A promising aqueous cell chemistry, for example, features the reactive pair of Zn2+ / Zn at the anode and Mn2+ / MnO2 at the cathode. This chemical pairing enables an operating cell voltage of approximately 2 V and a two-electron transfer reaction with high specific capacity. To further enhance the energy density, an initial-anode / cathode-free design is beneficial. Initially, only implementing current collectors enhances energy density by reducing weight / volume. The dual-electrode-free design avoids the excessive use of Zn / MnO2, and the complex electrode preparation process with convenient assembly and thus reduces the cost. However, ensuring a prolonged cycling life for dual-electrode-less batteries becomes an essential hurdle, given the insufficient reversibility of Zn / MnO2 deposition / stripping. The deposited ɛ-phase MnO2 exhibits low conductivity, and Mn3+ dissolution results in the depletion of active species. The competitive oxygen evolution reaction (OER) also speeds up water consumption. Furthermore, Zn plating faces challenges such as dendrite growth and hydrogen evolution reaction (HER), which are exacerbated in full cells due to proton-induced corrosion and byproduct accumulation. Thus, adopting a cell design that is simultaneously anode-free and cathode-free is logically viable but still presents a considerable challenge.Controlling the crystal structure of electrodeposited materials improves plating / stripping efficiency and increases cycle life. Even though both Zn and e-MnO2 belong to the hexagonal crystal system, as illustrated in Fig. 1A, no unified regulation strategy exists which could regulate the structures of both materials simultaneously in the same electrochemical cell. To address this challenge, herein is disclosed the use of liquid crystals as an interfacial layer (or interphase) in batteries. The self-assembly of surfactant molecules can initiate the creation of liquid crystal templates with diverse ordered structures. Aqueous batteries often lack an inherent and effective interphase and we demonstrated that in-situ formation of liquid crystal interphase affords a soft template to induce textured deposition behavior in aqueous batteries. In addition, in-situ formation of a liquid crystal interphase from a surfactant is a low-cost and facile strategy, which can be used in the battery manufacturing process.Herein is disclosed a liquid crystal interphase formed in situ by the addition of a trace non-ionic surfactant. Fig. 1B illustrates one example surfactant, t-Oct-C6H4-(OCH2CH2)nOH, n=9-10, with typical surfactant structure including one hydrophobic tail 100 and hydrophilic head 102. The liquid crystal interphase aligns both Zn and MnO2 deposition along the c-axis, significantly enhancing electrochemical cycling stability. This highly reversible dual-deposition enables the development of dual-electrode-free batteries (DEFBs) with anode- free and cathode-free configurations. Soft matter characterizations revealed a dynamic switching process from an aligned surfactant molecular bilayer 120 before deposition to a gradient liquid crystal interphase 122 after deposition, as shown in Fig. 1C. The gradient liquid crystal interphase includes lamellar liquid crystal 124 (close to the deposited electrode), hexagonal liquid crystal 126 (intermediate state) and micelle clusters 128 (close to the electrolyte) after deposition. The formation of this interphase guides templated growth of Zn and MnO2 and explains highly reversible plating / stripping that leads to long cycle life. Specifically, Zn-MnO2 batteries with 0.1 mM surfactant show the most extended cycling life with 80% capacity retention after ~950 cycles.Fig. 1D shows a schematic diagram of a battery according to an embodiment of the invention, including two electrodes / collectors 130, 138 having two corresponding liquid crystal interphase layers 132, 136. An electrolyte 134 contains a small concentration of surfactant.Achieving preferential orientation of deposition via surfactant additiveDeposition morphology is strongly influenced by the electrolyte choice. Balancing cost and voltage output, a DEFB prefers a sulfate electrolyte with 1 M ZnSO4 and 1 M MnSO4 formulation (denoted as the pristine electrolyte). The initial charging process will increase the concentration of proton and lower the pH value from 4.3 to 2.6. While this enhances MnO2 reactivity, this shift could disrupt Zn deposition. To address this intricate challenge, our investigation initially focuses on the Zn side. We first examine the morphology of plated Zn. Scanning electron microscopy (SEM) images in Fig. 2A reveal a mossy, flower-like morphology on bare Cu substrate after cycling using the pristine electrolyte. These micro-flowers, ranging from 1 µm to 10 µm, are disordered metallic zinc sheets or zinc hydroxide sulfate (ZHS) formed through corrosion reactions. These unevenly distributed corrosion products can easily lead to dendrite growth due to non-uniform electric fields.To counteract corrosion, we developed a new aqueous "surfactant electrolyte” by adding 0.1 mM surfactant, t-Oct-C6H4-(OCH2CH2)nOH, n=9-10, into the pristine electrolyte. Surprisingly, Fig. 2B shows relatively uniform and small Zn flakes around 1 µm in size. These Zn flakes predominantly exhibit a hexagonal shape, corresponding to the (002) crystal face of Zn22, which further contributes to a macroscopically flat surface topography.Additionally, X-ray diffraction (XRD) shows comparable intensities of the (002) and (100) Zn crystal planes prepared in the pristine electrolyte while the intensity of the (002) plane is substantially enhanced by 600% in the surfactant electrolyte. To confirm their texture, XRD (002) pole figures of Zn are measured. Pole figure of Zn deposited in the pristine electrolyte is shown in Fig. 2C, and Pole figure of Zn deposited in the surfactant electrolyte is shown in Fig. 2D. q is the angle of rotation that measures the azimuth of the sample in the surface plane and ψ is the tilt angle that defines the amount of tilting of the sample with respect to the normal to the sample surface. Both investigated Zn samples are disassembled from the DEFB in the fully charged state (constant voltage of 2.3 V to the charged capacity of 0.5 mAh / cm²) after 10 cycles. In Fig. 2C, the pristine electrolyte leads to a radially uneven diffraction intensity with a broad ring shape, implying a less pronounced Zn texture. Conversely, using the surfactant electrolyte, the Zn (002) pole figure in Fig. 2D shows concentrated intensity at the center, indicating a (002) out-of-plane preferred orientation of these hexagonal Zn flakes.Zn / Cu half-cells were assembled to evaluate plating / stripping reversibility. Fig. 2E is a graph of Coulombic efficiency (CE) for Zn plating / stripping as a function of cycle number of Zn / Cu cells at 2 mA and 2 mAh / cm². It reveals Zn / Cu cell using the pristine electrolyte experiences fluctuating Coulombic efficiency (CE) that steeply drops after ~50 cycles. In contrast, the surfactant electrolyte maintains a high average CE over 99.9% for 200 cycles. Fig. 2F shows representative charge / discharge curves of Zn / Cu cells at different cycles. The voltage profiles highlight pristine electrolyte's instability and irreversible behavior after 50 cycles. However, the surfactant electrolyte demonstrates favorable reversibility with a small voltage hysteresis, which can be attributed to the (002) plane growth, since the (002) plane promotes flat, compact Zn deposition and limits HER activity through enhanced corrosion resistance.Identifying the alignment of surfactant molecules before depositionTo understand how the surfactant facilitates Zn (002) plane emergence, we first investigate the surfactant molecule alignment on the current collector before deposition, which is pivotal for Zn atom nucleation. We immersed Cu foil in the pristine electrolyte and surfactant electrolyte. Contact angle tests unveiled the hydrophilic nature (~48° contact angle) of pristine electrolyte-covered Cu and the super-hydrophilic nature (~0° contact angle) of surfactant electrolyte-covered Cu. This super-hydrophilic surface suggests that the outward-facing segment of the surfactant is indeed the hydrophilic head due to the hydrophobic interactions between the nonpolar tails of neighboring surfactant molecules, forming a bilayer structure 120 as shown in Fig. 1C.To discern whether the arrangement of surfactants is organized or disordered, we designed a chemical titration experiment on the coated Cu by introducing an alkaline solution and inferring alignment from ZHS formation. The pristine electrolyte resulted in randomly-oriented ZHS sheets while the surfactant electrolyte produced well-ordered ZHS structures tied to the preferred (002) plane orientation, induced by the methodically arranged surfactant molecules. The above difference resembles the Zn morphology difference prepared in the pristine electrolyte / surfactant electrolyte, attributed to the same hexagonal system of ZHS and Zn.Addressing the number of surfactant molecular layers, spectroscopic ellipsometry was conducted to investigate the polarization change upon reflection from the coated Cu. The measurements determine that the average thickness of the surfactant layer is approximately 5 nm, indicating a singular bilayer. The above experiments confirmed the aligned surfactant-bimolecular structure on Cu surface before deposition, which facilitates uniform Zn atom nucleation and reduces "dead Zn" accumulation on Cu foil during cycling, possibly through decreased interfacial tension.In-situ formation of liquid crystal interphase for templated depositionWhile the organized arrangement of surfactants in the initial state has been elucidated, we also investigated the mechanism by which the surfactants guide Zn deposition with a preferred orientation. The key to comprehending this issue lies in understanding the interphase between Zn and the surfactant electrolyte. We examined the interphase composition using X-ray photoelectron spectroscopy (XPS). XPS depth profiling of the Zn surface after plating in pristine electrolyte and surfactant electrolyte reveals that the surfactant additive restricts the formation of ZHS, as evidenced by suppressed S 2p spectra. Moreover, in comparison to the pristine electrolyte, XPS analysis of the Zn surface exhibited an additional peak in the O 1s spectra for the surfactant electrolyte, which is ascribed to carbon-oxygen single bond, indicating the existence of organic-rich interphase due to the self-assembled surfactant. Additionally, as the etching depth increases, the intensity of the carbon- oxygen bond strengthens. This implies that the interphase structure, comprised of surfactants, thickens after deposition, possibly becoming more complex than the structure formed by a bilayer of the surfactant molecules.Considering the interphase structure commonly extends from the electrode surface into the bulk phase of the electrolyte, we investigated differences in the surfactant arrangement at different points in the interphase. We commence our investigation from the side closest to the bulk electrolyte. Surfactant molecules, when dissolved in water, typically form clusters known as micelles. We utilize dynamic laser scattering (DLS) to capture the size of these micelles, by focusing its laser beam at the center of the cuvette. Given that the laser does not capture signals from the bottom, we specially designed the experiment in which we place Zn metal at the bottom of the cuvette, targeting to provide an approximation of how the bulk electrolyte structure changes following zinc deposition. Fig. 3A is a graph of results of a dynamic laser scattering (DLS) test of the surfactant aqueous solution without Zn metal. Fig. 3B is a graph of results of a dynamic laser scattering (DLS) test of the surfactant aqueous solution without Zn metal. Insets of the figures illustrate that the size of a micelle cluster would be larger after putting the Zn metal at the bottom of cuvette considering that laser only focuses on the center of cuvette. In comparisons between surfactant solutions with and without added Zn, the effective micelle cluster diameter was observed to increase to 745 nm (with, Fig. 3B) from 223 nm (without, Fig. 3A). We hypothesize that the self-assembly of surfactant molecules at the Zn electrode interface contributes to lower surfactant concentration in the bulk phase. Dilute surfactant concentrations in water usually results in the forming of larger micelles.Referring to the water-surfactant binary phase diagram, higher surfactant concentrations induce the formation of lyotropic liquid crystals. We utilized a polarized optical microscope (POM), a tool for studying liquid crystals and other transparent crystalline structures, to further characterize the interphase structure. Fig. 3C shows a polarized optical microscope image of Zn surface prepared in the pristine electrolyte. By retaining a thin electrolyte film after disassembling cells, the Zn prepared using the pristine electrolyte exhibited no interference colors, signifying the absence of a transparent crystal structure on its surface. In contrast, Fig. 3D shows a polarized optical microscope image of Zn surface prepared in the surfactant electrolyte. The surfactant electrolyte sample POM image shows an irregular display of radial (rainbow-like and fan-like) interference colors. This optical pattern corresponds to the characteristics of the hexagonal phase of liquid crystals. To further eliminate the influence of inherent colors under the POM, we focused on a specific zinc particle with a preferred orientation of (002) plane. By keeping the sample stationary and rotating the POM stage, we observed the interference color disappearing and reappearing. This phenomenon, known as extinction, is a characteristic of liquid crystalline structures. It is worth noting that the interference color of a single (002) surface remains consistent, providing evidence of a uniform orientation of the hexagonal phase on the surface. Based on these observations, we conclude that a hexagonal liquid crystal interphase exists on the surface of the electrode.Given that surfactants are organic components sensitive to electron beams, we employ cryogenic transmission electron microscopy (cryo-TEM) for exploring the electrode-adjacent interphase. To study the interphase between Zn (002) and the surfactant electrolyte, we conducted Zn deposition on a Cu grid mesh assembled in a DEFB using the surfactant electrolyte. The highly porous mesh can induce Zn sheets to deposit into the pores, creating cross-sections with various orientations, which facilitates our observation of the Zn / surfactant electrolyte interface. Fig. 3E is a high-resolution cryo-TEM image of the interface between Zn (002) and liquid crystal. The dotted lines are used to distinguish Zn (002) and liquid crystal. Note that the interface between Zn and liquid crystal is not very clear or ordered because there may be a buffer layer. The image reveals the lower portion of Zn (002), characterized by thin lattice fringes. In stark contrast, the upper thicker layer represents the interphase, displaying a substantial layer spacing of 4.67 nm. When we compare our findings with previous research, we observe a striking resemblance to a lamellar phase of liquid crystal, notably due to the similarity in layer spacing. Fig. 3F illustrates the periodic structure of lamellar liquid crystal based on the Cryo-TEM results in Fig. 3E and previous literature. The thickness of the amphiphilic bilayer in lamellar phase is ~4.67 nm. As a soft template, the lamellar liquid crystal packing on the surface of Zn (002) can guide its textured growth. Fig. 3G illustrates that the liquid crystal interphase can guide Zn (002) growth via templated deposition. The probable mechanism behind this templated deposition involves the layer-by-layer-type induction of Zn growth by the lamellar liquid crystal, elucidating our observation of an interphase with a thickness approaching ~400 nm. Some of the observed lamellar liquid crystal phases might stem from the hexagonal phase transition at lower temperatures. However, due to the operational limitations of cryo-TEM, accurately discerning the boundary between the hexagonal and lamellar phases poses challenges.To gain atomic-level insights into the interfaces closer to the electrode, we conducted density functional theory (DFT) simulations of Zn-surfactant and Zn-H2O interactions. We found that the most stable configuration of the surfactant molecule is the hydrophilic end vertically bonded to the Zn (002) surface. This suggests that surfactant molecules in close proximity to the Zn surface are more likely to adopt a lamellar phase arrangement rather than a hexagonal phase (relatively parallel state). Compared to the (100) and (101) planes, the adsorption is stronger between the (002) plane and the surfactant molecule, indicating that surfactant molecules can easily adsorb on Zn (002), promoting the surfactant aggregation and formation of the liquid crystal interphase, thus leading to the enlargement of textured Zn (002) during cycling. The preferred bonding interaction may help to stabilize the deposition structure, even if the lattice parameters between Zn and liquid crystal may be not perfectly matched (similar to van der Waals epitaxy). In contrast, water only forms weakly bound overlayers on Zn (002). Adsorption of surfactant molecules is strongly preferred over water molecules, causing a local water-poor region near to the electrode. Thus, it is evident that we verified an in situ formed gradient liquid crystal interphase structure (micelle-hexagonal-lamellar), which is closely linked to the local concentration gradient of the surfactant, acting as the driving force behind liquid crystal formation.General strategy through liquid crystal interphase for MnO2 deposition and beyondRecognizing that e-MnO2 shares the same hexagonal crystal system as Zn, we aimed to implement the in situ liquid crystal phase strategy to the MnO2 cathode in the DEFB. MnO2 formed in the pristine electrolyte exhibits an uneven morphology with partly exposed graphite felt substrate. Conversely, the addition of surfactant facilitates a more uniform deposition, driven by favorable nucleation conditions.Fig. 4A is a TEM image of MnO2 deposition using the pristine electrolyte. The image reveals the (100) and (102) planes of e-MnO2, showing a tunnel structure formed in the pristine electrolyte. Fig. 4B is a TEM image of MnO2 deposition using the surfactant electrolyte. Following surfactant incorporation, this image highlights a noticeably increased lattice plane spacing of 0.72 nm, aligning well with the (002) planes of 8-MnO2. Insets illustrate the crystal structure of e-MnO2 (Fig. 4A) and 8-MnO2 (Fig. 4B) with the same hexagonal crystal system. XRD analysis using Mo radiation corroborates the presence of e-MnO2 and 6-MnO2 in the pristine electrolyte and surfactant electrolyte, respectively. Both share the hexagonal crystal system, but the 8-phase has a layered structure with a dominant (002) plane and enhanced electronic conductivity. Hence, the introduction of surfactant results in a similar preferential orientation (c-axis) in both Zn and MnO2 and even causes MnO2 to form as a different phase. Fig. 4C is a POM image of MnO2 deposited on carbon fiber using the surfactant electrolyte. The POM image with interference color confirms the in situ formed liquid crystal interphase on MnO2, guiding the 8-phase growth. Further DFT calculations elucidate the surfactant aggregation mechanisms on the 8-MnO2 (002) plane and surfactant adsorption occurs via C-O bond formation. Additionally, we noted restricted ZHS formation and a reduction in defects concerning trivalent manganese, potentially due to the protective and coordinating function of the liquid crystal interphase.We conducted Cu deposition experiments to further investigate the influence of liquid crystal interphase on different crystal systems. Fig. 4D is an SEM image of Cu deposition on bare Cu with surfactant additive, where the inset illustrates the cubic crystal system of Cu. Interestingly, while Cu formed in the pristine electrolyte presents uneven and irregular octahedral morphology, this image shows that Cu formed in the surfactant electrolyte demonstrates a uniform cubic shape. Additional XRD assessments indicate a prominent enhancement in the (200) plane of Cu developed in the surfactant electrolyte, suggesting a similar preferred c-axis orientation in the cubic system as well. Furthermore, this universal deposition strategy of texture control, mediated by liquid crystal phase, is independent of substrates, as evidenced by consistent deposition outcomes. Zn deposition on both titanium and graphite foils preserves the preferred (002) crystal plane orientation. This approach surpasses traditional substrate-controlled epitaxial growth, maintaining efficacy even at increasing distances from the substrate, as validated by grazing incidence XRD (GIXRD) analysis.Electrochemical performances of dual-electrode-free Zn / MnO2 batteriesFor the design of a battery based on the discoveries discussed above, first we aimed to identify preferred surfactant additive concentrations for the electrochemical performance of DEFBs (Cu foil||Carbon felt). Fig. 4E is a graph showing the results of cycling tests using the electrolytes with different surfactant concentrations (charging at 2.3 V up to 0.5 mAh / cm² and discharging at 5 mA / cm² down to 1 V). The inset details the 10th cycle curve. The graph demonstrates that, among the concentrations tested, a 0.1 mM surfactant concentration ensures the most extended cycling life (80% capacity retention for ~950 cycles) with a higher discharge capacity compared to the lower output and notable capacity decay of the pristine-electrolyte-based DEFB after ~250 cycles. Since the charging is at a fixed capacity, the CEs can be easily calculated. It can be observed that the cell with the liquid crystal interphase (0.1 mM) maintains high CEs close to 100% for 200 cycles, whereas the maximum CE of the pristine one is less than 90%. The 1 mM concentration, however, hastens battery degradation. This concentration seems to foster a complete lamellar liquid crystal interphase, rather than the gradient interphase observed in the 0.1 mM surfactant electrolyte. Conversely, the 0.01 mM surfactant electrolyte falls short in forming liquid crystals. A thicker lamellar phase might hinder transport, contrasted by the potentially more dynamic-enhancing hexagonal phase with extensive 1-D channels. Further simulations indicate that liquid crystalline phases with anisotropic diffusion coefficients can drastically reduce zinc dendrite growth by fostering better transport kinetics. The double-layer theory and our findings suggest that the lamellar phase, functioning as a Helmholtz layer, may facilitate textured growth thermodynamically, while the hexagonal phase as a diffusion layer promotes uniform ion flux, enhancing kinetics. Therefore, achieving the appropriate gradient liquid crystal interphase structure (lamellar-hexagonal) is vital and the key lies in the concentration of surfactant in the electrolyte. For example, if the concentration is too high, liquid crystals may not be obtained, but rather possibly zinc oxide.The 0.1 mM surfactant electrolyte is used for further electrochemical testing. Further analysis under more realistic conditions affirmed the liquid crystal interphase's positive impact on the practical application of DEFBs. Fig. 4F is a graph showing results of cycling tests using the pristine electrolyte or surfactant electrolyte (charging at 2.3 V up to 3 mAh / cm² and discharging at 15 mA / cm² down to 1 V). Inset: the 10th curve. The graph sets a higher charging capacity (3 mAh / cm²) for DEFBs, highlighting a widened cycle life gap between pristine electrolyte and surfactant electrolyte (50 vs. 225 cycles). Concurrently, surfactant electrolyte yields higher voltage and capacity output with reduced polarization, attributed to minimized blockage from ZHS and augmented 8-MnO2 conductivity under the liquid crystal interphase. Fig. 4G is a graph of cycling tests at -10°C (top) and 60°C (bottom) using the pristine electrolyte or surfactant electrolyte (charging at 2.3 V up to 1 mAh / cm² and discharging at 5 mA / cm² down to 1 V), where the inset shows the 10th cycle curves. Enhanced kinetic performance is evident in this test, where surfactant electrolyte maintains stable cycling at -10°C, in remarkable contrast to the rapid degradation experienced by pristine electrolyte. At higher temperatures, focusing on thermodynamic stability becomes pivotal. Utilizing surfactant electrolyte, which reduces the self-discharge rate, allows for longer cycling life at 60°C, owing to greater corrosion resistance and less hydrogen evolution reaction / oxygen evolution reaction (HER / OER) activity. Applying separator-free or sealing-free structures could further streamline components, maximizing battery energy density and cost-effectiveness, albeit with a decreased cycle life due to the dissolution-shuttle effect of inactive Zn / MnO2 and expedited water evaporation. Fig. 4H is a graph of cycling tests using the pristine electrolyte or surfactant electrolyte (charging at 2.3 V up to 1 mAh / cm² and discharging at 5 mA / cm² down to 1 V) without separator and sealing component under lean electrolyte amount (100 µL vs. 1 mL), where the inset shows the 10th cycle curve. The graph presents capacity results of a surfactant-electrolyte-based DEFB without separator and sealing components, sustaining ~50 cycles with a lean electrolyte volume (100 µL). This design allows capacity recovery through water refilling, mitigating capacity fading due to water evaporation. However, the pristine-electrolyte-based DEFB cannot regain capacity through refilling, as it lacks the liquid crystal interphase structure, resulting in a significant amount of irreversible deposition products associated with irreversible capacity loss. This kind of component-free DEFB has an ultrahigh energy density of up to 213 Wh / kg based on the entire cell without external packaging, which is nearly six times that of traditional insertion-type Zn-MnO2 batteries. Although its cycle life is shorter due to lower CE under extreme conditions, it is still a promising choice for high-energy-density aqueous batteries because it has the potential to break through grid applications and move towards scenarios such as electric vehicles. In fact, a shorter cycle life is a common issue for electrode-less batteries, and further optimization is expected in the future under extreme conditions such as lean electrolyte states.We have disclosed a liquid crystal interphase chemistry and general strategy to regulate preferred deposition orientation for stable and high-energy-density aqueous batteries. In-depth soft matter characterizations reveal the in-situ formation of a gradient liquid crystal interphase from a single surfactant molecular bilayer during charging. This surfactant-aggregation-induced interphase structure facilitates the templated growth of the hexagonal crystal system's (002) plane, enhancing deposition reversibility. Extending the long-established soft templating approach, from colloid chemistry, we present a solution to the irreversible deposition issue in aqueous batteries. The full cells based on Zn / MnO2 dual deposition with ultrahigh energy density exhibit significantly enhanced cycling life using this local liquid crystal interphase, even under stringent and component-less conditions. Furthermore, this facile approach may extend to other electrode systems like cubic Cu, encouraging the customization of liquid crystal interphase structures to foster advancements in energy storage.

Claims

1. A battery comprising:an anode;a cathode; andan electrolyte in contact with the anode and cathode such that an anode-electrolyte interface and a cathode-electrolyte interface are present;wherein the electrolyte includes a surfactant in sufficient concentration to generate a gradient liquid crystal interphase layer at the anode-electrolyte interface and / or at the cathode-electrolyte interface.

2. The battery of claim 1 wherein the battery has a Zn / MnO2 battery chemistry having an aqueous electrolyte and a non-ionic surfactant.

3. The battery of claim 1 wherein the battery has battery chemistry selected from the group consisting of Cu / MnO2, Fe / MnO2, Li, and Na.

4. The battery of claim 1 wherein the electrolyte is a non-aqueous electrolyte, wherein the non-aqueous electrolyte is an organic solvent that can form a liquid crystal interphase layer by adding a surfactant.

5. The battery of claim 1 wherein the electrolyte is a sulfate electrolyte.

6. The battery of claim 1 wherein the surfactant is anion-type.

7. The battery of claim 1 wherein the surfactant is cation-type.

8. The battery of claim 1 wherein the surfactant has 0.1 mM concentration in the electrolyte.

9. The battery of claim 1 wherein the surfactant is t-Oct-C6H4-(OCH2CH2)nOH, n=9-10.

10. The battery of claim 1 wherein the battery is a dual-electrode-free battery (DEFB) without separator or sealing components.

11. A method of making a battery, the method comprising:disposing a first current collector and a second current collector in an electrolyte containing a surfactant that forms a gradient liquid crystal interphase under electric field influence;passing current through the electrolyte, wherein molecules of the surfactant are adsorbed onto surfaces of the first and second current collectors, thereby facilitating in-situ deposition of a battery anode at the first current collector and in-situ deposition of a battery cathode at the second current collector;wherein the gradient liquid crystal phase is formed at electrode surfaces during the in-situ deposition, which stabilizes the electrochemical reactions to facilitate reversible operation of the battery.

12. The method of claim 11 wherein the battery has a Zn / MnO2 battery chemistry, an aqueous electrolyte, and a non-ionic surfactant.

13. The method of claim 11 wherein the battery has battery chemistry selected from the group consisting of Cu / MnO2, Fe / MnO2, Li, and Na.

14. The method of claim 11 wherein the electrolyte is a non-aqueous electrolyte, wherein the non-aqueous electrolyte is an organic solvent that can form a liquid crystal interphase layer by adding a surfactant.

15. The method of claim 11 wherein the electrolyte is a sulfate electrolyte.

16. The method of claim 11 wherein the surfactant is anion-type.

17. The method of claim 11 wherein the surfactant is cation-type.

18. The method of claim 11 wherein the surfactant has 0.1 mM concentration in the electrolyte.

19. The method of claim 11 wherein the surfactant is t-Oct-C6H4-(OCH2CH2)nOH, n=9-10.

20. The method of claim 11 wherein the battery is a dual-electrode-free battery (DEFB) without separator or sealing components.

Images