Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to −130 °C

Open AccessCCS ChemistryRESEARCH ARTICLE1 Apr 2021Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to −130 °C Wei Zhang, Huarong Xia, Zhiqiang Zhu, Zhisheng Lv, Shengkai Cao, Jiaqi Wei, Yifei Luo, Yao Xiao, Lin Liu and Xiaodong Chen Wei Zhang Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Huarong Xia Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Zhiqiang Zhu Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Zhisheng Lv Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Shengkai Cao Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Jiaqi Wei Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Yifei Luo Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Yao Xiao Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author , Lin Liu Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Google Scholar More articles by this author and Xiaodong Chen *Corresponding author: E-mail Address: [email protected] Innovative Centre for Flexible Devices (iFLEX), School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 Singapore-HUJ Alliance for Research and Enterprise, Campus for Research Excellence and Technological Enterprise, Singapore 138602 Google Scholar More articles by this author https://doi.org/10.31635/ccschem.020.202000341 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Freezing and crystallization of commercial ethylene carbonate-based binary electrolytes, leading to irreversible damage to lithium-ion batteries (LIBs), remain a significant challenge for the survival of energy storage devices at extremely low temperatures (<−40 °C). Herein, a decimal solvent-based high-entropy electrolyte is developed with an unprecedented low freezing point of −130 °C to significantly extend the service temperature range of LIBs, far superior to −30 °C of the commercial counterpart. Distinguished from conventional electrolytes, this molecularly disordered solvent mixture greatly suppresses the freezing crystallization of electrolytes, providing good protection for LIBs from possible mechanical damage at extremely low temperatures. Benefiting from this, our high-entropy electrolyte exhibits extraordinarily high ionic conductivity of 0.62 mS·cm−1 at −60 °C, several orders of magnitude higher than the frozen commercial electrolytes. Impressively, LIBs utilizing decimal electrolytes can be charged and discharged even at an ultra-low temperature of −60 °C, maintaining high capacity retention (∼80% at −40 °C) as well as remarkable rate capability. This study provides design strategies of low-temperature electrolytes to extend the service temperature range of LIBs, creating a new avenue for improving the survival and operation of various energy storage systems under extreme environmental conditions. Download figure Download PowerPoint Introduction Over the past three decades, lithium-ion batteries (LIBs) have gained great success in a large spectrum of portable electronic devices that operate at room temperatures.1–12 Driven by the rapid growth of newly emerging applications, the demand for energy storage to survive and operate at subzero temperatures is surging.13–19 Electric vehicles might be parked at −30 °C in the winter of high-latitude regions. LIBs for telecom base station in mountains and high-altitude drones need to work at temperatures as low as −50 °C. Astrovehicles for space exploration may experience temperatures below −120 °C on Martian surfaces.20–24 Current commercial LIBs cannot survive under these harsh environmental conditions, considering the service temperature range is only −20 to 60 °C.15,25–27 Although thermal management systems can to some extent help batteries maintain a relatively favorable and stable temperature in short-term operation,28–32 long-term storage at these extremely low temperatures will cause irreversible mechanical damage to current LIBs.33–36 A major bottleneck for the narrow service temperature range of LIBs is the freezing crystallization of electrolytes (Scheme 1a).37–41 For almost all LIB electrolytes, high melting point (35–38 °C) ethylene carbonate (EC) is an indispensable solvent component, which plays an essential role in forming stable solid-electrolyte interphase (SEI) on the anode.42–44 This high melting point solvent tends to precipitate from electrolytes first when the temperature drops below 0 °C. Then the decreased solvation ability of the remaining solvents leads to further deposition of lithium salts.45–48 These precipitates not only lower the ionic conductivity of electrolytes via the increased viscosity, but also cover the surface of electrodes, leading to the dramatically increased interfacial impedance. What is worse, crystals formed during freezing can damage the SEI film, separator, and electrodes due to volume change and mechanical stress.49–51 The precipitation and crystallization of electrolytes at low temperatures cause irreversible mechanical damage to cell internals, hindering the proper functioning of LIBs at extreme temperatures. Therefore, lowering the freezing point of electrolytes is of great importance to extending the service temperature range of LIBs. Thermodynamically, the liquidus temperature of electrolytes is determined by the value of Gibbs free energy (G) of liquid and solid (Scheme 1b). When assuming that the eutectic point corresponds to the freezing point of electrolytes (Tf), decreasing Gibbs free energy of liquid is an attractive strategy to lower the freezing point of electrolyte, which can be realized by increasing entropy of mixing, according to the following equation52–55 (Scheme 1c), G = H − T S (1)where T, H, and S represent the temperature, enthalpy, and entropy, respectively. This is why EC, existing as solid at room temperature, still can be used in electrolytes when mixed with linear carbonate solvents, such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC).56,57 Conventional approaches mainly focus on using esters as cosolvents with lower melting points and viscosities (e.g., ethyl acetate [EA], −84 °C, ∼0.46 cP) to promote lithium diffusion in electrolytes at subzero temperatures.58–61 Unfortunately, current electrolytes are mostly based on binary, ternary, and quaternary solvent mixtures, whose freezing point still cannot satisfy the requirement of extremely low temperatures, especially <−40 °C.62–67 There are few reports on the study of electrolytes with more components. However, introducing more kinds of miscible solvents into electrolytes to further increase the entropy is probably the key to extending the service temperature range for LIBs (Scheme 1d). Scheme 1 | (a) Schematic illustration of the freezing crystallization of electrolytes with decreasing temperature, causing possible damage to separator and SEI films in LIBs. The red shape represents the precipitates and crystals formed during freezing. (b) Decreasing Gibbs free energy of liquid is an attractive strategy to lower the freezing point. (c) The eutectic point of the mixture is lower than the melting point of each solvent. MPA and MPB mean the melting point of component A and B, respectively. (d) Lowering the freezing point of electrolytes via increasing the number of components due to entropy of mixing. R is the gas constant. xA and xB represent the mole fraction of A and B, respectively. Download figure Download PowerPoint Herein, high-entropy EC-based electrolyte with an unprecedented low freezing point of −130 °C is developed for the survival of LIBs at extremely low temperatures by the usage of decimal solvent mixture, far superior to −30 °C of conventional binary solvent-based electrolytes. This decimal solvent-based electrolyte exhibits extraordinarily high ionic conductivity of 0.62 mS·cm−1 at −60 °C, several orders of magnitude higher than the frozen commercial counterparts. Meanwhile, this more disordered solvent mixture prevents electrolytes from freezing crystallization, protecting LIBs from the irreversible damage at ultra-low temperatures. Benefiting from this, LIBs with our designed electrolytes can be impressively charged at even −60 °C, maintain high capacity retention (∼80% at −40 °C), and show remarkable rate capability at low temperatures. This study provides a strategy to design low-temperature electrolytes for the survival and operation of LIBs under extreme temperature conditions. Experimental Methods Chemicals LiMn2O4 (LMO) microparticles, acetylene black, and electrolytes of 1.0 M LiPF6 in EC:DMC (1∶1) and EC:DEC (1∶1) were purchased from MTI Corp (Richmond, CA, USA). with metal impurity ≤25 ppb. Li4Ti5O12 (LTO) powders were purchased from Xing Neng New Materials Co., Ltd. (Guang Yuan, Sichuan, China). Poly(vinylidene fluoride) (PVDF) was purchased from Arkema KYNAR 761 (Colombes, Hauts-de-Seine, France). EC, propylene carbonate (PC), DMC, DEC, EMC, ethyl propionate (EP), EA, methyl butanoate (MB), butyl acetate (BA), methyl propionate (MP), propyl butyrate (PB), fluoroethylene carbonate (FEC), and electrolyte of 1.0 M LiPF6 in EC∶DMC∶DEC (1∶1∶1) were purchased from Sigma-Aldrich Inc (St. Louis, Missouri, USA). Electrolyte preparation For multicomponent electrolytes, the amount of EC is fixed at 10% by volume and the volume ratio of other solvents is maintained at 1∶1. After the homogeneous mixing of these solvents, LiPF6 (1 M) is further dissolved in these solvents. FEC was used as an additive for electrolytes. Characterization Differential scanning calorimetry (DSC) was used to investigate the freezing point of the electrolytes through a DSC 2010 differential scanning calorimeter (TA Instruments, New Castle, Delaware, USA). During measurement, the sealed pan with electrolyte was first cooled down to −170 °C at the rate of 10 °C min−1 by a liquid nitrogen cooling system, then equilibrated at −170 °C and held isothermally for another 20 min, finally followed by scanning from −170 to 25 °C at the rate of 5 °C min−1. The freezing point of the electrolyte can be acquired by taking the temperature at the onset of endothermic change from the thermal baseline. The apparent viscosity of the electrolyte at various temperatures was obtained with a DV3T viscometer (Brookfield AMETEK, Middleboro, Massachusetts, USA). The ionic conductivity of electrolytes at various temperatures was measured with electrochemical impedance spectroscopy (EIS) (Solartron, Farnborough, Hampshire, UK). The heat production of solvent mixing was monitored by Nano isothermal titration calorimetry (Nano ITC) (TA Instruments). PC-to-EA titration was conducted at 25 °C with per injection volume of 2 µL and the titration interval of 300 s. The molar density of PC and EA is 0.010588 and 0.009214 mol·mL−1, respectively. Electrode fabrication LMO and LTO were used as the active materials of the cathode and anode, respectively. Binder and conductive agent were used without further treatment. For the preparation of working electrodes, active materials (80 wt %) and conductive agent (10 wt %) were thoroughly mixed with binders (10 wt %). The homogenous slurry was pasted on aluminum or copper foil and dried in air at 60 °C for 2 h, and then dried in vacuum at 100 °C overnight to remove residual solvent. Electrochemical testing Electrochemical properties were investigated using CR2032 coin-type cells. All cells were assembled inside an argon-filled glovebox with oxygen and water contents below 0.6 ppm. Commercial electrolytes and our designed electrolytes with the varied number of solvents were used as the battery electrolyte. The discharging/charging tests of batteries were performed on a NEWARE battery analyzer (Shenzhen, Guangdong, China) at different current rates. For the measurement of low-temperature performance, the batteries were placed in a climatic chamber (ESPEC, Kita-ku, Osaka, Japan) and rested to reach thermal equilibrium. Linear sweep voltammetry was carried out on an electrochemical station (Solartron). Results and Discussion To systematically evaluate the impact of the number of solvents on the properties of electrolytes, we designed a series of electrolytes with a varied number of solvents (denoted as n mix) and three commercial electrolytes were used for comparison (Figure 1a). These solvents are commonly used components for low-temperature electrolytes in LIBs ( Supporting Information Table S1). For multicomponent electrolytes, the amount of EC is fixed at 10% in volume and the volume ratio of others is maintained at 1∶1. To ensure a good cyclability of battery, the total fraction of EC and PC is kept no <20%, considering these two components play a vital role in the formation of a stable SEI.68–71 The freezing point, explored by DSC (Figure 1b), decreased greatly with an increase in the number of solvents from binary to decimal (Figure 1c). When the component number increases to decimal, the freezing point of electrolyte is significantly decreased to −130 °C, far superior to ~−30 °C of commercial binary electrolytes. Benefiting from this, the decimal solvent-based electrolyte still existed as a liquid in an environmental chamber at −85 °C, while commercial binary (C1, C2) and ternary solvent-based electrolytes (C3) were totally frozen at −60 °C (Figure 1d). The mixture of EC:EMC (1∶9) and EC:EA (1∶9) was utilized as control samples, and the DSC results demonstrated that the lowered freezing point of the multicomponent electrolyte was not because of the low content of EC ( Supporting Information Figure S1). In addition, the freezing crystallization of electrolytes, commonly observed in commercial samples, is greatly suppressed after the introduction of more types of solvents, protecting LIBs from irreversible damage at extremely low temperatures (Figure 1e). Figure 1 | (a) Solvent compositions of representative commercial electrolytes and the designed multicomponent high-entropy electrolytes with 1 M LiPF6 and FEC as additive. (b) DSC measurement for electrolytes with a varied number of solvents at heating from −170 to 20 °C. The dashed light blue line indicates the onset temperature of melting. (c) The experimental and calculated freezing point of these electrolytes. The insets are optical images of commercial and decimal solvent-based electrolytes at −60 °C. (d) Optical images of commercial and decimal solvent-based electrolytes at −60 and −85 °C. (e) DSC curves of C1 and 10 mix electrolytes with decreasing temperature. Download figure Download PowerPoint The feasibility of these solvents for LIBs is ensured by the calculated energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) (Figure 2a), as well as linear scanning voltammetry (Figure 2b). Considering that some solvents possess lower LUMO compared with EC, FEC was used as an additive to promote the formation of a stable SEI.72–74 Then, the ionic conductivity of commercial and multicomponent electrolytes was studied over a range of temperatures. At room temperature (25 °C), these electrolytes showed comparable Li diffusivity (Figure 2c and Supporting Information Figure S2). With the decrease of temperature, especially when it dropped below −40 °C, the ionic conductivity of commercial binary and ternary solvent-based electrolytes decreased significantly, whereas multicomponent electrolytes displayed improved Li+ mobility compared to binary and ternary systems. In particular, decimal solvent-based high-entropy electrolyte exhibited an unprecedented high conductivity of 0.62 mS·cm−1 at −60 °C, several orders of magnitude greater than the frozen commercial binary counterpart. Such high ionic conductivity might be attributed to the decreased viscosity of multicomponent electrolyte (Figure 2d). Meanwhile, the activation energy of Li+ diffusion in electrolytes, obtained from the slope of the σ versus 1/T plot (Figure 2e), was significantly reduced by ∼30% when the solvent number increased to six (Figure 2f). In terms of both liquidus temperature and lithium diffusion capability at −40 °C, our designed decimal solvent-based high-entropy electrolytes are much superior to the reported electrolytes (Figure 2g). Therefore, the introduction of decimal solvent endows electrolytes with both an ultra-low freezing point and high low-temperature ionic conductivity. Figure 2 | (a) Molecular structure, HOMO, and LUMO energies of EC, PC, EMC, DEC, EA, BA, MP, EP, MB, PB, and FEC. (b) Linear sweep voltammetry study of commercial C2 and our designed decimal electrolytes in a voltage range from 0 to 5.5 V. (c) Ionic conductivity vs temperature of commercial and multicomponent electrolytes with a varied solvent number. (d) Viscosity of commercial and multicomponent electrolytes at varied temperatures. (e) Arrhenius plot for ionic conductivity (σ), and (f) activation energy (Ea) for Li+ diffusion of these electrolytes. (g) Comparison of freezing point and ionic conductivity (at −40 °C) among reported electrolytes and our decimal solvent-based electrolytes. Download figure Download PowerPoint Using LMO/LTO full cell as a model system, these electrolytes were used for LIBs operating at low temperatures, we assembled full cells with LMO as cathode and LTO as anode as a model system. For batteries with commercial binary and ternary solvent-based electrolytes, both capacity and discharging voltage greatly decreased with the temperature, and the battery can hardly be discharged below −40 °C (Figure 3a). For high-entropy decimal solvent-based electrolyte, the capacity retention at low temperatures is significantly enhanced and the battery can maintain 80% capacity at −40 °C and ∼37% at −60 °C at 0.1 C (1 C = 140 mA·g−1) (Figures 3b and 3c and Supporting Information Figure S3). Notably, our batteries are charged and discharged at the same low temperatures, instead of the conventional testing routine, charging at a higher temperature followed by discharging at a lower temperature. Meanwhile, the batteries with decimal solvent-based electrolyte displayed significantly enhanced rate performances at subzero temperatures ( Supporting Information Figure S4) and this high-entropy electrolyte can also be applied with other electrode materials ( Supporting Information Figure S5). Even after storage at ultra-low temperatures, for example, −85 °C, the battery with decimal solvent-based electrolyte can still works well and lights up a wristband at −60 °C (Figure 3d and Supporting Information Movie S1). These should be attributed to the unprecedented low freezing point of −130 °C and the suppressed freezing crystallization of the high-entropy electrolyte, according to the control experiments (Figure 3e). Moreover, the greatly improved low-temperature performance is not at the cost of cyclability at low and elevated temperatures (Figure 3f and Supporting Information Figure S6), although the Jahn–Teller distortion of the LMO cathode and gassing of the LTO anode need to be further addressed via doping and coating, as well as additional electrolyte formulation for practical applications. Therefore, our designed decimal solvent-based electrolytes well extend the survival and operation temperature range for LIBs. Figure 3 | (a, b) Discharging curves of LMO/LTO full cell with commercial (a) and decimal solvent-based electrolytes (b) at 0.1 C at various temperatures. (c) Capacity retention of batteries based on commercial and decimal solvent-based electrolytes with decreasing temperature from 25, 0, −20, −40, and −60 °C. (d) Optical images of wristband powered by batteries with commercial and our decimal solvent-based electrolytes operating at −60 °C in an environmental chamber. (e) Comparison of capacity retention of batteries at −60 °C with electrolytes based on a varied number of solvents. (f) Cycling performance of LMO/LTO cell with C2 and decimal solvent-based electrolyte at 0.2 C at −40 °C. Download figure Download PowerPoint The underlying mechanism was investigated by ITC (TA Instruments, New Castle, Delaware, USA),75 taking the mixing of PC and EA as an example (Figure 4a). The heat production during mixing includes two contributions: the change of enthalpy and entropy. The enthalpy contribution was calculated from the measured heat of ideal mixing in the stirring mode from Redlich–Kister polynomial equations (Figure 4b), while the entropy change could be computed based on the deviations of heat production in the nonstirring mode from ideal mixing (Figure 4c and Supporting Information Figure S7).76 These results demonstrated that the introduction of more kinds of miscible solvents increased the system entropy, which is the underlying reason for the greatly depressed freezing point of multicomponent electrolytes. Based on these observations, we can get a comprehensive picture of the whole process (Figure 4d and Supporting Information Figure S8). For commercial binary solvent-based electrolytes, the system is more ordered. The higher melting point component of EC is more inclined to precipitate first with the decrease of temperature, followed by lithium salt and other solvents, in the form of orderly crystals. This freezing crystallization may cause irreversible mechanical damage to the separator and SEI film of LIBs. The molecular ordering also limits the lowering of the liquidus temperature of commercial electrolytes (~−30 °C). For decimal solvent-based high-entropy electrolytes, the mixture is more disordered. EC molecules are more separated from each other. Therefore, the transition temperature at which electrolytes turn from liquid into solid can be lowered to −130 °C. Meanwhile, freezing of this decimal solvent-based electrolyte favors the formation of amorphous solid, which is less damaging to LIB internal structures. As a result, the lowered freezing point and suppressed crystallization of decimal solvent-based high-entropy electrolyte extend the survival temperature range of LIBs significantly. Figure 4 | (a) Isothermal titration calorimetry data for the mixing of PC and EA in both stirring and nonstirring mode, and (b) the corresponding heat production of titration. (c) The calculated entropy contribution during the mixing process. (d) Schematic illustrations of the changes in commercial binary and our designed decimal high-entropy electrolytes with the decrease in temperature. Download figure Download PowerPoint Conclusion In summary, we developed a new type of decimal solvent-based high-entropy electrolyte with an unprecedented low freezing point of −130 °C to significantly extend the survival temperature range of LIBs. The freezing crystallization, commonly observed in commercial binary electrolytes, is greatly suppressed after the introduction of decimal solvents, enabling this high-entropy electrolyte to provide effective protection for the survival of LIBs under extreme thermal conditions. This decimal solvent-based electrolyte exhibited remarkably high ionic conductivity of 0.62 mS·cm−1 even at −60 °C and endowed batteries with a high capacity retention of ∼80% at −40 °C, far superior to that of commercial counterparts. This study not only provides new insights into designing electrolytes for LIBs working at ultra-low temperatures, but also opens up an avenue for extending the environmental frontiers of current battery systems. Supporting Information Supporting Information is available. Conflict of Interest There is no conflict of interest to report. Funding Information This study was supported by the National Research Foundation, Prime Minister’s Office, Singapore under the Nanomaterials for Energy and Water Management CREATE Programme, and the Energy Innovation Research Programme (EIRP) administered by the Energy Market Authority (no. NRF2015EWT-EIRP002-008). References References 1. Tarascon J. M.; Armand M.Issues and Challenges Facing Rechargeable Lithium Batteries.Nature2001, 414, 359–367. Google Scholar 2. Whittingham M. S.Lithium Batteries and Cathode Materials.Chem. Rev.2004, 104, 4271–4302. Google Scholar 3. Li H.; Wang Z.; Chen L.; Huang X.Research on Advanced Materials for Li-Ion Batteries.Adv. Mater.2009, 21, 4593–4607. Google Scholar 4. Goodenough J. B.; Park K. S.The Li-Ion Rechargeable Battery: A Perspective.J. Am. Chem. Soc.2013, 135, 1167–76. Google Scholar 5. Li M.; Lu J.; Chen Z.; Amine K.30 Years of Lithium-Ion Batteries.Adv. Mater.2018, 30, 1800561. Google Scholar 6. Lopez J.; Mackanic D. G.; Cui Y.; Bao Z.Designing Polymers for Advanced Battery Chemistries.Nat. Rev. Mater.2019, 4, 312–330. Google Scholar 7. Bruce P. G.; Scrosati B.; Tarascon J.-M.Nanomaterials for Rechargeable Lithium Batteries.Angew. Chem. Int. Ed.2008, 47, 2930–2946. Google Scholar 8. Nitta N.; Wu F.; Lee J. T.; Yushin G.Li-Ion Battery Materials: Present and Future.Mater. Today2015, 18, 252–264. Google Scholar 9. Zheng J.; Myeong S.; Cho W.; Yan P.; Xiao J.; Wang C.; Cho J.; Zhang J. G.Li- and Mn-Rich Cathode Materials: Challenges to Commercialization.Adv. Energy Mater.2017, 7, 1601284. Google Scholar 10. Nayak P. K.; Erickson E. M.; Schipper F.; Penki T. R.; Munichandraiah N.; Adelhelm P.; Sclar H.; Amalraj F.; Markovsky B.; Aurbach D.Review on Challenges and Recent Advances in the Electrochemical Performance of High Capacity Li- and Mn-Rich Cathode Materials for Li-Ion Batteries.Adv. Energy Mater.2018, 8, 1702397. Google Scholar 11. Zhou L.; Zhang K.; Hu Z.; Tao Z.; Mai L.; Kang Y.-M.; Chou S.-L.; Chen J.Recent Developments on and Prospects for Electrode Materials with Hierarchical Structures for Lithium-Ion Batteries.Adv. Energy Mater.2018, 8, 1701415. Google Scholar 12. Schmuch R.; Wagner R.; Hörpel G.; Placke T.; Winter M.Performance and Cost of Materials for Lithium-Based Rechargeable Automotive Batteries.Nat. Energy2018, 3, 267–278. Google Scholar 13. Wang C.-Y.; Zhang G.; Ge S.; Xu T.; Ji Y.; Yang X.-G.; Leng Y.Lithium-Ion Battery Structure That Self-Heats at Low Temperatures.Nature2016, 529, 515–518. Google Scholar 14. Li Q.; Jiao S.; Luo L.; Ding M. S.; Zheng J.; Cartmell S. S.; Wang C.-M.; Xu K.; Zhang V.; Xu W.Wide-Temperature Electrolytes for Lithium-Ion Batteries.ACS Appl. Mater. Interfaces2017, 9, 18826–18835. Google Scholar 15. Fan J.; Tan S.Studies on Charging Lithium-Ion Cells at Low Temperatures.J. Electrochem. Soc.2006, 153, A1081–A1092. Google Scholar 16. Scrosati B.; Hassoun J.; Sun Y.-K.Lithium-Ion Batteries. A Look into the Future.Energy Environ. Sci.2011, 4, 3287–3295. Google Scholar 17. Xiong D. J.; Petibon R.; Nie M.; Ma L.; Xia J.; Dahn J. R.Interactions Between Positive and Negative Electrodes in Li-Ion Cells Operated at High Temperature and High Voltage.J. Electrochem. Soc.2016, 163, A546–A551. Google Scholar 18. You Y.; Yao H. R.; Xin S.; Yin Y. X.; Zuo T. T.; Yang C. P.; Guo Y. G.; Cui Y.; Wan L. J.; Goodenough J. B.Subzero-Temp