Plastic Crystal Electrolytes Research Articles

Poly(carbonate)-based ionic plastic crystal fast ion-conductor for solid-state rechargeable lithium batteries

Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate (EC), propylene carbonate (PC), and ethyl methyl carbonate (EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries (LIBs) due to their outstanding dissociation ability to lithium salts. However, volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs. Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers. To this aim, a series of carbonate substituted imidazole ionic plastic crystals (G-NTOC) with different polymerization degrees have been synthesized. The resulting G-NTOC shows an excellent solid-state temperature window (R.T.-115 °C). More importantly, the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10−3 S cm−1 and 0.523 at 30 °C, respectively. Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte. The fabricated Li|G-NTOC|LiFePO4 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g−1 at the discharge rate of 0.1C. After charging-discharging the cell for 60 times, Coulombic efficiency of the solid-state cell still exceeds 97%. Notably, the Li|G-NTOC|LiFePO4 cell can stably light a commercial LED with a rated power of 0.06 W for more than 1 h at 30 °C, and the output power nearly maintains unchanged with the charging-discharging cycling test, implying a sizeable potential application in the next generation of solid-state LIBs.

Fast Charge and High Stability of Solid‐State Graphite Organic Ionic Plastic Crystal Composite Anodes

AbstractInvited for this month's cover picture is the group of Dr. Hiroyuki Ueda and Prof. Patrick C. Howlett at Deakin University (Australia) jointly working with Toyota Motor Corporation (Japan). The cover picture shows the fast lithium‐ion conduction pathways in the graphite anode of all‐solid‐state batteries (ASSBs) enabled by the incorporation of an organic ionic plastic crystal (OIPC) electrolyte. Read the full text of the Research Article at 10.1002/batt.202200057.

Cover Picture: Fast Charge and High Stability of Solid‐State Graphite Organic Ionic Plastic Crystal Composite Anodes (Batteries & Supercaps 7/2022)

The Front Cover shows a solid-state graphite composite anode containing an organic ionic plastic crystal electrolyte as a multifunctional lithium-ion conductor by which the electrolyte/electrode and electrode/current collector contacts are improved, enabling fast lithiation and stable cycling. More information can be found in the Research Article by H. Ueda, P. C. Howlett and co-workers.

Janus Electrolyte with Modified Li+ Solvation for High‐Performance Solid‐State Lithium Batteries

AbstractSolid‐state lithium‐metal batteries attract great attention due to their high energy density and superior safety. However, the sluggish Li+ kinetics of solid electrolyte and poor interface compatibility between electrolyte and lithium anode lead to unsatisfied performance at room temperature, which severely limit their practical application. Herein, a Janus quasi‐solid electrolyte (JSE) design is reported, which modifies the Li+ solvation environment in succinonitrile (SN) plastic crystal electrolyte and creates 1D Li+ transportation channels. Density functional theory calculations and Raman results reveal that Li1.3Al0.3Ti1.7(PO4)3 changes the Li+ solvation environment from SN units to aggregated ion pairs, which accelerates the diffusion rate of Li+. As a result, JSE presents excellent ionic conductivity (0.73 mS cm−1) and high lithium transference number (0.72). With this efficient JSE, Li symmetric cells deliver excellent cycle stability over 600 h with a low over potential of 60 mV. LiFePO4|JSE|Li solid‐state battery delivers an impressive performance with a specific discharge capacity of 152 mAh g−1 after 100 cycles at room temperature under 0.5 C. Moreover, the corresponding pouch cell also shows outstanding performance (140 mAh g−1 under 0.5 C) and withstands abuse tests such as bending and cutting, demonstrating its superior safety for future utilization.

Unveiling and Alleviating Chemical “Crosstalk” of Succinonitrile Molecules in Hierarchical Electrolyte for High‐Voltage Solid‐State Lithium Metal Batteries

Succinonitrile‐based plastic crystal electrolytes have emerged for high‐energy‐density Li metal batteries in terms of their superior ambient ionic conductivity, low flammability, and benign compatibility with high voltage cathode, but are hampered by inherent instabilities toward Li anodes. Constructing hierarchical solid electrolytes structure is a fundamental approach to protect Li anode from succinonitrile attacks, with succinonitrile‐based oxidation‐resistance layer facing high voltage cathode and reduction‐tolerant layer contacting Li anode. However, free succinonitrile molecules in succinonitrile‐based electrolyte layer can diffuse across the electrolyte/electrolyte interface and further reach Li anode surface during the battery cycle. This chemical “crosstalk” cause reduction‐tolerant electrolyte layer to fail to protect the Li anode from the attacks of free succinonitrile molecules. Nano Li6.4La3Zr1.4Ta0.6O12 is introduced creatively into succinonitrile‐based electrolyte layer. By taking advantage of the complexation between La atoms in Li6.4La3Zr1.4Ta0.6O12 and N atoms in succinonitrile, the free succinonitrile molecules are successfully immobilized in succinonitrile‐based electrolyte layer. The resulting low resistance and highly durable solid electrolyte interphase and cathode electrolyte interphase endow NCM622||Li batteries with remarkable cycle stability. Our research provides a new idea for the real application of plastic crystal electrolytes in high voltage solid‐state lithium metal batteries.

In Situ Cross‐Linked Plastic Crystal Electrolytes for Wide‐Temperature and High‐Energy‐Density Lithium Metal Batteries

AbstractThe development of high‐energy‐density lithium metal batteries has been significantly hampered mainly due to the poor electrolyte–electrode compatibility, narrow operating temperature range, and stringent safety concerns of conventional electrolytes. Here, an in situ cross‐linked plastic crystal‐based electrolyte (CPCE) with an optimized composition design is proposed. Based on the interaction of succinonitrile (SN) and ethoxylated trimethylolpropane triacrylate (ETPTA) with polar carbonyl groups, CPCE delivers well‐tuned energy levels and a concentrated coordination structure, leading to an improved electrochemical window and stable electrode–electrolyte interface. In addition, the crystallization of SN molecules is also inhibited, ensuring suitable ion migration in bulky CPCE over a wide temperature range. Moreover, both the nonleakage of cross‐linked ETPTA and the nonflammability of the plastic crystal electrolyte (PCE) further reinforce the safety of CPCE. As a result, the well‐designed CPCE achieves high ion conductivity with a wide electrochemical window (≈5.4 V vs Li+/Li) and a broad operating temperature range (−20 to 100 °C). It also delivers dendrite‐free lithium plating with high Coulombic efficiency of up to ≈99.1%. The Cu|CPCE|LiNi0.8Co0.1Mn0.1O2 anode‐free pouch cell exhibits high energy density (≈1520 Wh L‐1) and high safety during abuse tests. This study paves a new pathway to realize the practical application of high‐energy‐density lithium metal battery energy storage systems.

Effect of UV light polymerization time on the properties of plastic crystal composite polyacrylate polymer electrolyte for all solid‐state lithium‐ion batteries

AbstractTo solve the issues of low ionic conductivity, poor interfacial stability, and weak mechanical strength in the current polymer electrolytes, herein, the UV curing method is proposed to in‐situ polymerize the plastic crystal composite solid polymer electrolyte (S‐PCCE). By using ethoxylated trimethylolpropane triacrylate (ETPTA) as polymerization monomer, in conjunction with the butadiene nitrile and other additives, the S‐PCCE is prepared under ultraviolet light. The S‐PCCE shows improved ionic conductivity than other solid electrolyte materials. The ionic conductivity at room temperature can reach 0.98 × 10−3 S/cm, and it can reach 2.8 × 10−3 S/cm at 55°C, which is beneficial to achieve high battery performance. The LiFePO4/S‐PCCE/Li battery has a high initial discharge specific capacity of 150.4 mAh/g at 0.2C, and the highest discharge specific capacity can reach 162.5 mAh/g. Moreover, after 100 cycles, the battery can still maintain a high discharge specific capacity of 154.2 mAh/g, with a Coulomb efficiency of 98.4%. At the same time, the electrolyte has excellent high‐temperature adaptability, and can still work stably at 55°C with improved ionic conductivity. The superior performance of this material indicates that the plastic crystal composite polyacrylate solid electrolyte based on UV curing method can be used to prepare a high‐performance lithium‐ion battery, and this technology can also be compatible with existing lithium‐ion battery equipment.

An All-Solid-State Lithium Metal Battery Based on Electrodes-Compatible Plastic Crystal Electrolyte

Solid-state plastic crystal electrolytes (SPCEs) have attracted much attention due to their high ionic conductivity at room temperature and polymer-like plasticity. Herein, we made a LiFePO4||Li solid state battery based on SPCEs. A SPCE film is made up of glass fiber, succinonitrile (SN), lithium bis (triflu-romethanesulphonyl) imid (LiTFSI), and LiNO3. Glass fiber is introduced to improve the mechanical property, and LiNO3 served as an additive to stabilize electrolyte/Li interface. The SPCE film delivers a high ionic conductivity of 7.3 × 10−4 S cm−1 at room temperature and has excellent stability with Li-metal anode. SPCE is also infused into cathode electrode and used as the interface with cathode particles, which can access a large interface contact area and deform reversibly with volume change. The LiFePO4||Li solid state battery based on SPCE can work well at ambient temperature, which shows a high initial specific capacity of 121.4 mAh g−1 and has 86.9% retention after 90 cycles at 0.5 C.

All-Solid-state Lithium Battery with Sulfide Electrolyte: From Interface Design to Full Cell

All-solid-state lithium batteries (ASSLBs) have gained intensive attention because of their intrinsic safety and high energy density.1 However, significant interfacial challenges such as detrimental interfacial reactions, poor solid-solid ionic contact, and lithium dendrite growth have stymied the development of ASSLBs. Besides that, the large gap between fundamental research and practical engineering design has slowed down ASSLBs commercialization. Over the past five years, our group has been dedicated to the research and development of ASSLBs, with the aims of overcoming the interfacial challenges and pushing ASSLBs closer to commercialization. First, we have regulated the interfacial ion and electron transport via increasing the ionic conductivity of interfacial buffer layers,2 manipulating interfacial nanostructures,3, 4 using single-crystal cathodes,5 deciphering interfacial reaction mechanisms,6 and constructing artificial solid electrolyte interphases (SEI).7 Based on these advanced and innovative strategies, the large interfacial resistance was successfully eliminated. As a result, ASSLBs with sulfide electrolytes demonstrated both ultra-long cycling stability and high-rate performance. To transfer these viable technologies into practical application and bridging the large gap between laboratory research and practical full cells, we are committed to engineering solid-state pouch cells with competitive energy density and low cost. Recently, a solvent-free and cost-effective process was developed for fabricating ultra-thin inorganic solid electrolyte membranes as well as solid-state thick electrodes. Furthermore, a solid-liquid interface and a plastic crystal electrolyte were engineered to enable practical solid-state pouch cells with high energy density and excellent safety.8, 9 These works not only provide an in-depth understanding of interfacial mass and charge transport but also offer feasible strategies to commercialize practical solid-state pouch cells. References C. Wang, J. Liang, Y. Zhao, M. Zheng, X. Li, X. Sun*, Energy Environ. Sci. , 2021, doi:10.1039/d1ee00551k.C. Wang, J. Liang, S. Hwang, X. Li, Y. Zhao, K. Adair, C. Zhao, X. Li, S. Deng, X. Lin, X. Yang, R. Li, H. Huang, L. Zhang, S. Lu, D. Su and X. Sun*, Nano Energy , 2020, 72, 104686.C. Wang, X. Li, Y. Zhao, M. N. Banis, J. Liang, X. Li, Y. Sun, K. R. Adair, Q. Sun, Y. Liu, F. Zhao, S. Deng, X. Lin, R. Li, Y. Hu, T.-K. Sham, H. Huang, L. Zhang, R. Yang, S. Lu and X. Sun*, Small Methods , 2019, 3, 1900261.C. Wang, J. Liang, M. Jiang, X. Li, S. Mukherjee, K. Adair, M. Zheng, Y. Zhao, F. Zhao, S. Zhang, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, C. V. Singh and X. Sun*, Nano Energy, 2020, 76, 105015.C. Wang, R. Yu, S. Hwang, J. Liang, X. Li, C. Zhao, Y. Sun, J. Wang, N. Holmes, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, D. Su and X. Sun*, Energy Storage Mater ., 2020, 30, 98-103.C. Wang, S. Hwang, M. Jiang, J. Liang, Y. Sun, K. Adair, M. Zheng, S. Mukherjee, X. Li, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, J. Wang, C. V. Singh, D. Su, X. Sun*. Adv. Energy Mater., 2021, 2100210. doi:10.1002/aenm.202100210.C. Wang, Y. Zhao, Q. Sun, X. Li, Y. Liu, J. Liang, X. Li, X. Lin, R. Li, K. R. Adair, L. Zhang, R. Yang, S. Lu and X. Sun*, Nano Energy, 2018, 53, 168-174.C. Wang, Q. Sun, Y. Liu, Y. Zhao, X. Li, X. Lin, M. N. Banis, M. Li, W. Li, K. R. Adair, D. Wang, J. Liang, R. Li, L. Zhang, R. Yang, S. Lu and X. Sun*, Nano Energy, 2018, 48, 35-43.C. Wang, K. R. Adair, J. Liang, X. Li, Y. Sun, X. Li, J. Wang, Q. Sun, F. Zhao, X. Lin, R. Li, H. Huang, L. Zhang, R. Yang, S. Lu and X. Sun*, Adv. Funct. Mater. , 2019, 29, 1900392.

PEO based polymer in plastic crystal electrolytes for room temperature high-voltage lithium metal batteries

Lithium metal coupled with high voltage cathodes has been extensively investigated to meet the demand for higher energy density batteries. However, only a few electrolytes are compatible with both lithium anode and high voltage LiNi 0.5 Mn 0.3 Co 0.2 O 2 . Pure poly(ethylene oxide) electrolyte shows high-stability against lithium metal but has limited oxidation stability (typically < 3.8 V). Nitrile-based electrolyte with -C≡N groups exhibits excellent electrochemical stability against high voltage electrodes. Here, a novel type of poly(ethylene oxide) based polymer in plastic crystal (succinonitrile) electrolyte is designed to achieve stable cathode/electrolyte and anode/electrolyte interfaces simultaneously through strong intermolecular interactions. Li-Li symmetric cells with the polymer in plastic crystal electrolyte runs stably for 700 h at 1 mA cm −2 . Even with a high cut-off voltage of 4.4 V, the Li// LiNi 0.5 Mn 0.3 Co 0.2 O 2 cell delivers a high discharge capacity of 169 mA h g −1 and a capacity retention of 80% after 120 cycles. Our work highlights development of PEO-based electrolytes with higher energy density by inter-molecular design. • PIPCE shows a high ionic conductivity, wide electrochemical window and low flammability. • Improved electrochemical stability of PIPCE originates from the inter-molecule interaction. • NMC532/PIPCE/Li delivers a capacity of 169 mA h g -1 with 4.4 V cut-off voltage. • Stable SEI and CEI are formed at the electrolyte/electrode interface.

Organic fast ion-conductor with ordered Li-ion conductive nano-pathways and high ionic conductivity for electrochemical energy storage

Solid electrolyte (SE) is the most crucial factor to fabricate safe and high-performance all-solid-state lithium-ion batteries. However, the most commonly reported SE, including solid polymer electrolyte (SPE) and inorganic oxides and sulfides, suffer problems of low ionic conductivity at room temperature for SPE and large interfacial impedance with electrodes for inorganic electrolytes. Here we for the first time demonstrate a novel ionic plastic crystal lithium salt solid electrolyte (OLiSSE) fast ion-conductor dilithium (1,3-diethyl-4,5-dicarboxylate) imidazole bromide with ordered Li-ion conductive nanopathways and an exceptional ionic conductivity of 4.4 × 10−3 S cm−1 at 30 °C. The prepared OLiSSE exhibits apparent characters of typical ionic plastic crystals in the temperature range of −20 to 70 °C, and shows remarkable thermal stability and electrochemical stability below 150 °C and 4.7 V, respectively. No lithium dendrite or short circuit behavior is detected for the Li|OLiSSE|Li cell after the galvanostatic charge-discharge test for 500 h. The fabricated Li|OLiSSE|LiFePO4 all-solid-state cell without using any separator and liquid plasticizer directly delivers an initial discharge capacity of 151.4 mAh g−1 at the discharge rate of 0.1 C, and shows excellent charge-discharge cycle stability, implying large potential application in the next generation of safe and flexible all-solid-state lithium batteries.

Toward Low‐Temperature Lithium Batteries: Advances and Prospects of Unconventional Electrolytes

Lithium batteries have been widely used in various fields such as portable electronic devices, electric vehicles, and grid storages devices. However, the low temperature‐tolerant performances (−70 to 0 °C) of lithium batteries are still mainly hampered by low ionic conductivity of bulk electrolyte and interfacial issues. In general, there are four threats in developing low‐temperature lithium batteries when using traditional carbonate‐based electrolytes: 1) low ionic conductivity of bulk electrolyte, 2) increased resistance of solid electrolyte interphase (SEI), 3) sluggish kinetics of charge transfer, 4) slow Li diffusion throughout bulk electrodes. Meanwhile, conventional electrolytes have been close to the upper limit of optimum low‐temperature performance owing to their intrinsic molecular structural properties. As a result, it is urgent to design unconventional electrolytes with lower melting point and higher ionic conductivity. Herein, the recent key advances in regard to unconventional electrolytes including fluorinated ester, ethyl acetate, gamma‐butyrolactone, liquefied gas, ether, plastic crystal, and aqueous electrolytes are overviewed. Solvation structure modification and SEI optimization of unconventional electrolytes for low‐temperature lithium batteries are focused. Finally, aiming at the deficiencies in current understanding, the inherent limitations and envision the future prospects of low‐temperature lithium batteries are explored.

Cellulose‐Based Plastic Crystal Electrolyte Membranes with Enhanced Interface for Solid‐State Lithium Batteries

Fabricating robust succinonitrile‐based plastic crystal electrolyte (PCE) membranes with abundant and sustainable polymer skeleton and reinforcing the stability of the PCE–lithium anode interface are essential for adopting PCE in all‐solid‐state lithium metal batteries (ASSLMBs). Herein, renewable and low‐cost cellulose is utilized as the mechanical support framework to prepare the self‐standing cellulose‐based PCE (C‐PCE) through the facile tape‐casting method. The cellulose matrix provides excellent robustness to the hybrid C‐PCE system. The fabricated C‐PCE shows an ionic conductivity of about 2.1 × 10−4 S cm−1 and a tensile strength of over 0.5 MPa at room temperature. Solid‐state lithium batteries assembled with the Li4Ti5O12 cathode, lithium metal anode, and the prepared electrolyte films exhibit an initial capacity surpassing 155 mAh g−1 at 0.2 C and room temperature. This work presents a new attempt to use low‐cost cellulose and common additives to prepare high‐performance PCE membranes for lithium‐battery applications.

Na–CO2 battery with NASICON-structured solid-state electrolyte

Abstract Utilizing CO2 as cathode gas, Na–CO2 battery has been intensively studied due to its potential application in the exploration of Mars, where CO2 takes up 96% of the atmosphere. However, evaporation of the flammable liquid electrolyte restricts the practical application of the Na–CO2 battery. Herein, a solid-state Na–CO2 battery has been fabricated with the help of a plastic crystal electrolyte and kinetically stable interphase. The succinonitrile-based plastic crystal electrolyte interphase makes an intimate contact between Na3Zr2Si2PO12(NZSP) and cathode, thereby promotes the interfacial charge transfer. Simultaneously, the kinetically stable interphase on the anode side is revealed by the cooperation of theoretical calculation and experiments. The kinetically stable interphase protects the NZSP from the continuous interfacial parasitic reaction. The as-proposed solid-state Na–CO2 battery delivers a life span of 50 cycles at 100 mA g−1 with a potential gap of 1.4 V. This study makes solid-state electrolyte Na–CO2 battery an attractive prospect in future applications.

Infiltrated and Isostatic Laminated NCM and LTO Electrodes with Plastic Crystal Electrolyte Based on Succinonitrile for Lithium-Ion Solid State Batteries

We report a new process technique for electrode manufacturing for all solid-state batteries. Porous electrodes are manufactured by a tape casting process and subsequently infiltrated by a plastic crystal polymer electrolyte (PCPE). With a following isostatic lamination process, the PCPE was further integrated deeply into the porous electrode layer, forming a composite electrode. The PCPE comprises the plastic crystal succinonitrile (SN), lithium conductive salt LiTFSI and polyacrylonitrile (PAN) and exhibits suitable thermal, rheological (ƞ = 0.6 Pa s @ 80 °C 1 s−1) and electrochemical properties (σ &gt; 10−4 S/cm @ 45 °C). We detected a lowered porosity of infiltrated and laminated electrodes through Hg porosimetry, showing a reduction from 25.6% to 2.6% (NCM infiltrated to laminated) and 32.9% to 4.0% (LTO infiltrated to laminated). Infiltration of PCPE into the electrodes was further verified by FESEM images and EDS mapping of sulfur content of the conductive salt. Cycling tests of full cells with NCM and LTO electrodes with PCPE separator at 45 °C showed up to 165 mAh/g at 0.03C over 20 cycles, which is about 97% of the total usable LTO capacity with a coulomb efficiency of between 98 and 99%. Cycling tests at 0.1C showed a capacity of ~128 mAh/g after 40 cycles. The C-rate of 0.2C showed a mean capacity of 127 mAh/g. In summary, we could manufacture full cells using a plastic crystal polymer electrolyte suitable for NCM and LTO active material, which is easily to be integrated into porous electrodes and which is being able to be used in future cell concepts like bipolar stacked cells.

In situ fabricated ceramic/polymer hybrid electrolyte with vertically aligned structure for solid-state lithium batteries

The succinonitrile (SN) plastic crystal electrolyte with high ionic conductivity and wide electrochemical window has been a promising room-temperature solid electrolyte. In this work, the ice-templated Li1.5Al0.5Ge1.5(PO4)3 (LAGP) with vertically aligned channels is applied to improve the mechanical properties of SN, in which the LAGP particles of the ceramic skeleton are tightly bonded and form continuous connected ion transport pathways. The SN-based electrolyte is firmly locked in the microchannels of LAGP through in-situ thermal polymerization. Compared with commercial Celgard, LAGP exhibits better affinity to SN-based electrolyte, which is further confirmed by DFT calculation. The excellent affinity can be expected to provide sufficient electrolyte diffusion pathways and benefit the cycling stability of batteries. Due to the structural design, LAGP/SN hybrid electrolyte displays high ionic conductivity of 1.17 × 10−3 S•cm–1 at 30°C, superior Li+ transference number (0.77), and wide electrochemical window (0∼5.0 V vs. Li+/Li). In addition, the Li symmetric cells with this hybrid electrolyte show excellent interfacial stability over 200 h at 0.2 mA•cm−2 and high critical current density (CCD) of 1.0 mA•cm−2. The solid-state lithium batteries (LiNi0.5Co0.2Mn0.3O2/Li) provide excellent room-temperature rate capability (1 C) and stable cycling performance at 0.2 C with a retention of 90.0% after 100 cycles.

High−Performance organic lithium−ion battery with plastic crystal electrolyte

Organic quinone compounds are expected to become the main cathode materials for the next generation of energy storage devices due to their high capacity. However, they would soluble in conventional organic electrolytes, causing a reduction in electrochemical performance. Interestingly, the plastic crystal electrolyte (PCE) based on succinonitrile (SN) not only has high ionic conductivity, but also can alleviate the solubility problem of quinone compounds. In this study, the 5 mol% LiTFSI (lithium bis(trifluoromethane)sulfonimide)/SN PCE was firstly chosen to match with quinone compound calix[4]quinone (C4Q) to assemble lithium−ion batteries (LIBs). The SN−based electrolyte system greatly boosting batteries life and achieving good rate performance. With SN−based electrolyte, LIBs displayed an initial discharge specific capacity of 424 mAh g −1 (95% of theoretical specific capacity) at 0.1 C, and the capacity retention rate was still as high as 60% after 1000 cycles with the coulombic efficiency always around 100%. At 2 C, the capacity maintained around 140 mAh g −1 . Our work has great application value in LIBs due to the low cost and the excellent electrochemical performance of C4Q in LiTFSI/SN PCE. Succinonitrile (SN) plastic crystal electrolyte (PCE) has excellent electrical conductivity, and can effectively alleviate the dissolution problem of organic electrode materials in traditional electrolytes. The use of SN PCE greatly improves the cycle performance and rate capability of calix[4]quinone (C4Q) in lithium ion batteries.

Matchmaker of Marriage between a Li Metal Anode and NASICON-Structured Solid-State Electrolyte: Plastic Crystal Electrolyte and Three-Dimensional Host Structure.

The marriage between a Li metal anode and the solid-state electrolyte is expected to limit the safety risk of secondary batteries. However, dendrites and interfacial stability hinder the combination of Li metal anode and solid-state electrolyte. Herein, a plastic crystal electrolyte (PCE) and three-dimensional (3D) host structure played the role of a matchmaker in combining the solid-state electrolyte and Li metal anode. Succinonitrile cooperated with Li salt and Li6.4La3Zr1.4Ta0.6O12 nanosize powder and built a PCE interphase, which enhanced the interfacial stability between Li1.5Al0.5Ge1.5(PO4)3 and Li metal anode. To protect the soft PCE from the dendrite penetration, commercially sold Super P, carbon nanotube, KS6, and Ketjen black were co-heated with the melted Li metal. However, only KS6 built a 3D host in Li metal successfully because of its high graphitization and layered structure. Benefitting from the matchmakers, the solid-state batteries exhibited enhanced cycling stability.

Interface Engineering of Sulfide-Based All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) have gained intensive attention worldwide because of their intrinsic safety and potential high energy density.1 As a critical component in ASSLBs, various solid-state electrolytes have been extensively studied over the past decade. So far, the ionic conductivity of solid-state electrolytes, particularly sulfide electrolytes (SEs, i.e. Li10GeP2S12) is close to that of conventional liquid electrolytes. However, the electrochemical performance of SE-based ASSLBs is hindered by the large interfacial resistance between electrodes and sulfide electrolytes. The underlying reasons are detrimental interfacial reactions and insufficient solid-solid contact between electrodes and SEs in ASSLBs.2 In our research, taking the advantages of atomic/molecular layer deposition techniques, an interfacial layer with designed functionalities can be conformably interposed between the electrodes and solid-state sulfide electrolytes, aiming at overcoming the interfacial resistance. At the anode interface, a artifical solid electrolyte interphase (SEI) has been engineered to suppress the interfacial rections and lithium dendrite growth, sucessfully enabling the use of Li metal in SE-based ASSLBs.3 At the cathode interface, a dual-shell interfacial nanostructure was rationally designed, in which the inner shell LiNbO3 suppressing the interfacial reactions, while the outer shell Li10GeP2S12 providing an intimate electrode-electrolyte contact.4 As a result, the dual-shell strucutured LGPS@LNO@LCO cathode exhibits a high initial specific capacity of 125.8 mAh.g-1 (1.35 mAh.cm-2) with an initial Coulombic efficiency of 90.4% at 0.1 C and 87.7 mAh.g-1 even at 1C. Furthermore, a plastic crystal electrolyte has been developed, which can simultaneously suppress the interfacial reactions and lithium dendrite growth in ASSLBs.5 The above work not only demonstrates various strategies to enable high-energy-density ASSLBs but also provides new insights into the interfacial challenges of ASSLBs.

An Adjustable-Porosity Plastic Crystal Electrolyte Enables High-Performance All-Solid-State Lithium-Oxygen Batteries.

The limited triple-phase boundaries (TPBs) in solid-state cathodes (SSCs) and high resistance imposed by solid electrolytes (SEs) make the achievement of high-performance all-solid-state lithium-oxygen (ASS Li-O2 ) batteries a challenge. Herein, an adjustable-porosity plastic crystal electrolyte (PCE) has been fabricated by employing a thermally induced phase separation (TIPS) technique to overcome the above tricky issues. The SSC produced through the in-situ introduction of the porous PCE on the surface of the active material, facilitates the simultaneous transfer of Li+ /e- , as well as ensures fast flow of O2 , forming continuous and abundant TPBs. The high Li+ conductivity, softness, and adhesion of the dense PCE significantly reduce the battery resistance to 115 Ω. As a result, the ASS Li-O2 battery based on this adjustable-porosity PCE exhibits superior performances with high specific capacity (5963 mAh g-1 ), good rate capability, and stable cycling life up to 130 cycles at 32 °C. This novel design and exciting results could open a new avenue for ASS Li-O2 batteries.