Halide Layer Cathodes for Compatible and Fast-Charged Halides-Based All-Solid-State Li Metal Batteries

Insertion-type compounds based on oxides and sulfides have been widely identified and well-studied as cathode materials in lithium-ion batteries. However, halides have rarely been used due to their high solubility in organic liquid electrolytes. Here, we reveal the insertion electrochemistry of VX₃ (X=Cl, Br, I) by introducing a compatible halide solid-state electrolyte with a wide electrochemical stability window. X-ray absorption near-edge structure analyses reveal a two-step lithiation process and the structural transition of typical VCl₃. Fast Li⁺ insertion/extraction in the layered VX₃ active materials and favorable interface guaranteed by the compatible electrode-electrolyte design enables high rate capability and stable operation of all-solid-state Li-VX₃ batteries. The findings from this study will contribute to developing intercalation insertion electrochemistry of halide materials and exploring novel electrode materials in viable energy storage systems.     

Polymers with Intrinsic Microporosity as Solid Ion Conductors for Solid-State Lithium Batteries

Solid-state electrolytes (SSEs) with high ionic conductivity and superior stability are considered to be a key technology for the safe operation of solid-state lithium batteries. However, current SSEs are incapable of meeting the requirements for practical solid-state lithium batteries. Here we report a general strategy for achieving high-performance SSEs by engineering polymers of intrinsic microporosity (PIMs). Taking advantage of the interconnected ion pathways generated from the ionizable groups, high ionic conductivity (1.06×10⁻³ S cm⁻¹ at 25 °C) is achieved for the PIMs-based SSEs. The mechanically strong (50.0 MPa) and non-flammable SSEs combine the two superiorities of outstanding Li⁺ conductivity and electrochemical stability, which can restrain the dendrite growth and prevent Li symmetric batteries from short-circuiting even after more than 2200 h cycling. Benefiting from the rational design of SSEs, PIMs-based SSEs Li-metal batteries can achieve good cycling performance and superior feasibility in a series of withstand abuse tests including bending, cutting, and penetration. Moreover, the PIMs-based SSEs endow high specific capacity (11307 mAh g⁻¹) and long-term discharge/charge stability (247 cycles) for solid-state Li−O₂ batteries. The PIMs-based SSEs present a powerful strategy for enabling safe operation of high-energy solid-state batteries.     

Influencing Factors on Li-ion Conductivity and Interfacial Stability of Solid Polymer Electrolytes,Exampled by Polycarbonates,Polyoxalates and Polymalonates

The application of solid polymer electrolytes (SPEs) in all-solid-state(ASS) batteries is hindered by lower Li⁺-conductivity and narrower electrochemical window. Here, three families of ester-based F-modified SPEs of poly-carbonate (PCE), poly-oxalate (POE) and poly-malonate (PME) were investigated. The Li⁺-conductivity of these SPEs prepared from pentanediol are all higher than the counterparts made of butanediol, owing to the enhanced asymmetry and flexibility. Because of stronger chelating coordination with Li⁺, the Li⁺-conductivity of PME and POE is around 10 and 5 times of PCE. The trifluoroacetyl-units are observed more effective than −O−CH₂−CF₂−CF₂−CH₂−O− during the in situ passivation of Li-metal. Using trifluoroacetyl terminated POE and PCE as SPE, the interfaces with Li-metal and high-voltage-cathode are stabilized simultaneously, endowing stable cycling of ASS Li/LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cells. Owing to an enol isomerization of malonate, the cycling stability of Li/PME/NCM622 is deteriorated, which is recovered with the introduce of dimethyl-group in malonate and the suppression of enol isomerization. The coordinating capability with Li⁺, molecular asymmetry and existing modes of elemental F, are all critical for the molecular design of SPEs.     

Enabling the Operation of Highly Compatible LiI-3-Hydroxypropionitrile Small-Molecule Solid-State Electrolytes in Lithium Metal Batteries via Stepped-Amorphization Strategy

Integrating the advantages of both inorganic ceramic and organic polymer solid-state electrolytes, small-molecule solid-state electrolytes represented by LiI-3-hydroxypropionitrile (LiI-HPN) inorganic–organic hybrid systems possess good interfacial compatibility and high modulus. However, their lack of intrinsic Li⁺ conduction ability hinders potential application in lithium metal batteries until now, despite containing LiI phase composition. Herein, inspired by evolution tendency of ionic conduction behaviors together with first-principles molecular dynamics simulations, we propose a stepped-amorphization strategy to break the Li⁺ conduction bottleneck of LiI-HPN. It involves three progressive steps of composition (LiI-content increasing), time (long-time standing), and temperature (high-temperature melting) regulations, to essentially construct a small-molecule-based composite solid-state electrolyte with intensified amorphous degree, which realizes efficient conversion from an I⁻ to Li⁺ conductor and improved conductivity. As a proof, the stepped-optimized LiI-HPN is successfully operated in lithium metal batteries cooperated with Li₄Ti₅O₁₂ cathode to deliver considerable compatibility and stability over 250 cycles. This work not only clarifies the ionic conduction mechanisms of LiI-HPN inorganic–organic hybrid systems, but also provides a reasonable strategy to broaden the application scenarios of highly compatible small-molecule solid-state electrolytes.     

Electron Redistribution Enables Redox-Resistible Li6PS5Cl towards High-Performance All-Solid-State Lithium Batteries

Sulfide electrolytes with high ionic conductivity hold great promise for all-solid-state lithium batteries. However, the parasitic redox reactions between sulfide electrolyte and Li metal result in interfacial instability and rapid decline of the battery performance. Herein, a redox-resistible Li₆PS₅Cl (LPSC) electrolyte is created by regulating the electron distribution in LPSC with Mg and F incorporation. The introduction of Mg triggers the electron agglomeration around S atom, inhibiting the electron acceptance from Li, and F generates the self-limiting interface, which hinders the redox reactions between LPSC and Li metal. This redox-resistible Li₆PS₅Cl-MgF₂ electrolyte therefore presents a high critical current density (2.3 times that of pristine electrolyte). The LiCoO₂/Li₆PS₅Cl-MgF₂/Li cell shows an outstanding cycling stability (93.3 %@100 cycles at 0.2 C). This study highlights the electronic structure modulation to address redox issues on sulfide-based lithium batteries.     

Impact of the Chlorination of Lithium Argyrodites on the Electrolyte/Cathode Interface in Solid-State Batteries

Lithium argyrodite-type electrolytes are regarded as promising electrolytes due to their high ionic conductivity and good processability. Chemical modifications to increase ionic conductivity have already been demonstrated, but the influence of these modifications on interfacial stability remains so far unknown. In this work, we study Li₆PS₅Cl and Li_5.5PS_4.5Cl_1.5 to investigate the influence of halogenation on the electrochemical decomposition of the solid electrolyte and the chemical degradation mechanism at the cathode interface in depth. Electrochemical measurements, gas analysis and time-of-flight secondary ion mass spectrometry indicate that the Li_5.5PS_4.5Cl_1.5 shows pronounced electrochemical decomposition at lower potentials. The chemical reaction at higher voltages leads to more gaseous degradation products, but a lower fraction of solid oxygenated phosphorous and sulfur species. This in turn leads to a decreased interfacial resistance and thus a higher cell performance.     

Achieving the High Capacity and High Stability of Li-Rich Oxide Cathode in Garnet-Based Solid-State Battery

Solid-state batteries (SSBs) based on Li-rich Mn-based oxide (LRMO) cathodes attract much attention because of their high energy density as well as high safety. But their development was seriously hindered by the interfacial instability and inferior electrochemical performance. Herein, we design a three-dimensional foam-structured GaN−Li composite anode and successfully construct a high-performance SSB based on Co-free Li_1.2Ni_0.2Mn_0.6O₂ cathode and Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) solid electrolyte. The interfacial resistance is considerably reduced to only 1.53 Ω cm² and the assembled Li symmetric cell is stably cycled more than 10,000 h at 0.1–0.2 mA cm⁻². The full battery shows a high initial capacity of 245 mAh g⁻¹ at 0.1 C and does not show any capacity degradation after 200 cycles at 0.2 C (≈100 %). The voltage decay is well suppressed and it is significantly decreased from 2.96 mV/cycle to only 0.66 mV/cycle. The SSB also shows a very high rate capability (≈170 mAh g⁻¹ at 1 C) comparable to a liquid electrolyte-based battery. Moreover, the oxygen anion redox (OAR) reversibility of LRMO in SSB is much higher than that in liquid electrolyte-based cells. This study offers a distinct strategy for constructing high-performance LRMO-based SSBs and sheds light on the development and application of high-energy density SSBs.     

Build a High-Performance All-Solid-State Lithium Battery through Introducing Competitive Coordination Induction Effect in Polymer-Based Electrolyte

Polymer-inorganic composite electrolytes (PICE) have attracted tremendous attention in all-solid-state lithium batteries (ASSLBs) due to facile processability. However, the poor Li⁺ conductivity at room temperature (RT) and interfacial instability severely hamper the practical application. Herein, we propose a concept of competitive coordination induction effects (CCIE) and reveal the essential correlation between the local coordination structure and the interfacial chemistry in PEO-based PICE. CCIE introduction greatly enhances the ionic conductivity and electrochemical performances of ASSLBs at 30 °C. Owing to the competitive coordination (Cs^{+ …} TFSI^{− …} Li⁺, Cs^{+ …} C−O−C ^… Li⁺ and 2,4,6-TFA ^… Li ^… TFSI⁻) from the competitive cation (Cs⁺ from CsPF₆) and molecule (2,4,6-TFA: 2,4,6-trifluoroaniline), a multimodal weak coordination environment of Li⁺ is constructed enabling a high efficient Li⁺ migration at 30 °C (Li⁺ conductivity: 6.25×10⁻⁴ S cm⁻¹; t_Li ⁺ =0.61). Since Cs⁺ tends to be enriched at the interface, TFSI⁻ and PF₆⁻ in situ form LiF-Li₃N-Li₂O-Li₂S enriched solid electrolyte interface with electrostatic shielding effects. The assembled ASSLBs without adding interfacial wetting agent exhibit outstanding rate capability (LiFePO_4: 147.44 mAh g⁻¹@1 C and 107.41mAhg⁻¹@2 C) and cycling stability at 30 °C (LiFePO₄:94.65 %@200cycles@0.5 C; LiNi_0.5Co_0.2Mn_0.3O₂: 94.31 %@200 cycles@0.3 C). This work proposes a concept of CCIE and reveals its mechanism in designing PICE with high ionic conductivity as well as high interfacial compatibility at near RT for high-performance ASSLBs.     

Covalent Organic Framework with Multi-Cationic Molecular Chains for Gate Mechanism Controlled Superionic Conduction in All-Solid-State Batteries

Although solid-state batteries (SSBs) are high potential in achieving better safety and higher energy density, current solid-state electrolytes (SSEs) cannot fully satisfy the complicated requirements of SSBs. Herein, a covalent organic framework (COF) with multi-cationic molecular chains (COF-MCMC) was developed as an efficient SSE. The MCMCs chemically anchored on COF channels were generated by nano-confined copolymerization of cationic ionic liquid monomers, which can function as Li⁺ selective gates. The coulombic interaction between MCMCs and anions leads to easier dissociation of Li⁺ from coordinated states, and thus Li⁺ transport is accelerated. While the movement of anions is restrained due to the charge interaction, resulting in a high Li⁺ conductivity of 4.9×10⁻⁴ S cm⁻¹ and Li⁺ transference number of 0.71 at 30 °C. The SSBs with COF-MCMC demonstrate an excellent specific energy density of 403.4 Wh kg⁻¹ with high cathode loading and limited Li metal source.     

无机钠离子电池固体电解质研究进展

地球上钠资源储量丰富、成本低廉,使得钠电池吸引了越来越多研究者的关注。传统的基于有机溶剂电解液体系的钠电池在安全方面存在不足。固态钠离子电池能够有效解决安全的问题,增加电池的安全性能。固态钠离子电池是一种很有前景的储能方式。钠离子固体电解质主要有Na-β-Al_2O_3、钠超离子导体(NASICON)、硫化物、聚合物以及硼氢化物这几类。无机固体电解质相对于聚合物固体电解质,离子电导率有优势。本文总结了三种常见的无机钠离子固体电解质:Na-β-Al_2O_3、NASICON、硫化物的研究进展,从离子电导率和界面稳定性等方面阐述了近年来的发展。     

A Systematic Study on the Effects of Solvating Solvents and Additives in Localized High-Concentration Electrolytes over Electrochemical Performance of Lithium-Ion Batteries

Localized high-concentration electrolytes (LHCEs) based on five different types of solvents were systematically studied and compared in lithium (Li)-ion batteries (LIBs). The unique solvation structure of LHCEs promotes the participation of Li salt in forming solid electrolyte interphase (SEI) on graphite (Gr) anode, which enables solvents previously considered incompatible with Gr to achieve reversible lithiation/delithiation. However, the long cyclability of LIBs is still subject to the intrinsic properties of the solvent species in LHCEs. Such issue can be readily resolved by introducing a small amount of additive into LHCEs. The synergetic decompositions of Li salt, solvating solvent and additive yield effective SEIs and cathode electrolyte interphases (CEIs) in most of the studied LHCEs. This study reveals that both the structure and the composition of solvation sheaths in LHCEs have significant effect on SEI and CEI, and consequently, the cycle life of energetically dense LIBs.     

固体聚合物电解质在肉桂醇电解氧化中的应用(II)——后续化学反应在电催化反应中的地位及其影响因素

对影响肉桂醇电极氧化的各种因素作了进一步的讨论. 实验结果表明固体聚合物电解质内水的含量、pH 以及浸入离子交换膜中的二价锰离子的浓度均对该电极反应的电位以及后续化学反应的速度有很大的影响, 在较高的温度下反应时, 有利手提高生成肉桂醛的电流效率.     

Regulating Steric Hindrance of Porous Organic Polymers in Composite Solid-State Electrolytes to Induce the Formation of LiF-Rich SEI in Li-Ion Batteries

Lithium fluoride (LiF) at the solid electrolyte interface (SEI) contributes to the stable operation of polymer-based solid-state lithium metal batteries. Currently, most of the methods for constructing lithium fluoride SEI are based on the design of polar groups of fillers. However, the mechanism behind how steric hindrance of fillers impacts LiF formation remains unclear. This study synthesizes three kinds of porous polyacetal amides (PAN-X, X=NH₂, NH-CH₃, N-(CH₃)₂) with varying steric hindrances by regulating the number of methyl substitutions of nitrogen atoms on the reaction monomer, which are incorporated into polymer composite solid electrolytes, to investigate the regulation mechanism of steric hindrance on the content of lithium fluoride in SEI. The results show that bis(trifluoromethanesulfonyl)imide (TFSI⁻) will compete for the charge without steric effect, while excessive steric hindrance hinders the interaction between TFSI⁻ and polar groups, reducing charge acquisition. Only when one hydrogen atom on the amino group is replaced by a methyl group, steric hindrance from the methyl group prevents TFSI⁻ from capturing charge in that direction, thereby facilitating the transfer of charge from the polar group to a separate TFSI⁻ and promoting maximum LiF formation. This work provides a novel perspective on constructing LiF-rich SEI.     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2在不同电解液中的性能研究

应用低热固相合成法制备锂离子电池正极材料L iCo1/3N i1/3Mn1/3O2.研究该材料的结构与形貌,并比较它在商品L iPF6盐和在实验室合成的L iBOB(L iB(C2O4)2)盐电解液中的电化学性能.在L iPF6/EC+DMC+DEC电解液中,该材料表现出优良的电化学性能,其于0.5C、1C、1.5C、2C、3C放电倍率的初始比容量依次为167、163、163、157、147mAh/g,电池的循环性能也较好,说明低热固相合成的材料的有较好的高倍率性能.在L iBOB/EC+DEC+DE电解液中,0.5C倍率下比容量为160 mAh/g,较之L iPF6盐电解液的相差不大,但在高倍率下的比容量有所下降.     

The Temperature-Composition Phase Equilibria in the HgTe–HgI2 Pseudobinary System

The temperature-composition phase diagram of the HgTe—HgI₂ pseudobinary system was determined between 25 and 670°C using differential scanning calorimetry, differential thermal analysis, Debye-Scherrer powder X-ray diffraction techniques, and metallographic analysis methods. Solid solutions of HgTe and HgI₂ with the cubic, zinc blende-type structure exist above 300°C, having a maximum solubility of 11.7±0.8 Mol-% HgI₂ in HgTe at 501±5°C. The monoclinic intermediate phase Hg₃Te₂I₂ is formed by a peritectic reaction upon cooling at 501±5°C, with the peritectic point at approximately 37±4 Mol-% HgI₂. The previously unknown cubic phase Hg₃TeI₄ (a = 6.240±0.003 Å) is formed by a eutectoid reaction at 238±3°C and is stable up to 273±3°C, where it melts by a peritectic reaction with the peritectic point at approximately 79±3 Mol-% HgI₂. Between Hg₃TeI₄ and HgI₂ is a eutectic point at 82±3 Mol-% HgI₂ and 250±3°C. The α to β transition of HgI₂ at 133±3°C is independent of sample composition between 33.3 and 100 Mol-% HgI₂.     

The homogeneity range of lyonsite-type phase existing in the CrVO4 - Co3V2O8 system

In the work presented here, the way of obtaining the phase with general formula Co_3+1.5xCr_2–x(VO₄)₄ (0 ≤ × < 0.4) is demonstrated. A new phase is detected in CrVO₄ - Co₃V₂O₈ that is formed in one of the intersection of the ternary CoO - V₂O₅ - Cr₂O₃ system. Monophasic Co₃Cr₂(VO₄)₄ (Co_3+1.5xCr_2−x(VO₄)₄, where × = 0) was obtained from both a mixture comprising CrVO₄ and Co₃V₂O₈ as well as from the mixture of CoV₂O₆ with CoCr₂O₄. The Co_3+1.5xCr_2−x(VO₄)₄ is isotypic with the those demonstrating the lyonsite-type structure. The temperature of melting for the new compound was established using the DTA methods.