Significance of ferroelectric polarization in poly (vinylidene difluoride) binder for high-rate Li-ion diffusion

Song, Woo-Jin,Joo, Se Hun,Kim, Do Hyeong,Hwang, Chihyun,Jung, Gwan Yeong,Bae, Sohyeon,Son, Yeonguk,Cho, Jaephil,Song, Hyun-Kon,Kwak, Sang Kyu,Park, Soojin,Kang, Seok Ju Elsevier 2017 Nano energy Vol.32 No.-

<P><B>Abstract</B></P> <P>An interesting and effective route for improving battery performance using ferroelectric poly(vinylidene difluoride) (PVDF) polymer as a binder material is demonstrated in this work. A ferroelectric PVDF phase developed under the appropriate thermal annealing process enables generation of suitable polarization on active materials during the discharge and charge process, giving rise to longer capacity with lower overpotential at a high current rate. Electrochemical analysis including <I>in situ</I> galvanostatic electrochemical impedance spectroscopy and a galvanostatic intermittent titration measurement revealed that the ferroelectric binder effectively reduced Li-ion diffusion resistance and supported fast migration in the vicinity of active electrodes. Computational results further support that the binding affinity of the ferroelectric PVDF surface is much higher than that of the paraelectric PVDF, confirmed by ideally formed ferroelectric and paraelectric PVDF conformations with Li-ions. Furthermore, we consistently achieved high Li-ion battery (LIB) performance in full cell architecture consisting of a LTO/separator/LFP with a ferroelectric PVDF binder in the anode and cathode materials, revealing that the polarization field is important for fabricating high-performance LIBs, potentially opening a new design concept for binder materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The ferroelectric polarization in PVDF binder enhances Li-ions diffusion. </LI> <LI> Excellent rate performance is demonstrated by β-phase of PVDF binder </LI> <LI> In depth computational study exhibits the polarization effect of ferroelectric binder in LIB cell. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>We demonstrate the effect of PVDF polarization in lithium ion battery system. The strong polarization of ferroelectric PVDF binder on the active material enhances the transport of Li-ion during charge and discharge. As results, the Li-ion diffusion by ferroelectric phase leads to excellent rate performance and cycling stability compared to paraelectric PVDF binder.</P> <P>[DISPLAY OMISSION]</P>

Co/Ti co-substituted layered LiNiO₂ prepared using a concentration gradient method as an effective cathode material for Li-ion batteries

Ko, Hyoung Shin,Kim, Jea Han,Wang, Juan,Lee, Jong Dae Elsevier Sequoia 2017 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>The design of Li-ion batteries with high energy storage capacities and efficiencies is a subject of increased research interest, being of key importance for their large-scale applications and further commercialization. However, conventional Li-ion batteries are expensive and have stability-related concerns, which limit their practical applications. In our search for cheaper and safer Li-ion batteries, we use a concentration gradient method to prepare LiNi<SUB>0.9</SUB>Co<SUB>0.1–<I>x</I> </SUB>Ti<SUB> <I>x</I> </SUB>O<SUB>2</SUB> (0.02 ≤ <I>x</I> ≤ 0.05) cathode materials surface-enriched with Co and Ti that exhibit decreased oxygen loss and improved structural stability. The corresponding crystal structures and morphologies are analyzed by X-ray diffraction and field emission scanning electron microscopy, with the Ni, Co, and Ti concentration distributions determined by energy-dispersive X-ray spectroscopy. The material with the best performance (<I>x</I> = 0.04) exhibits a discharge capacity of 214 mAh g<SUP>−1</SUP> in a charge/discharge voltage range of 3.0–4.3 V (vs. Li/Li<SUP>+</SUP>), and possesses an excellent 50-cycle capacity retention of 98.7%. Thermogravimetric analysis shows that partial substitution of Ni with the strongly oxophilic Ti solves the problem of oxygen loss observed in Ni-rich cathode materials such as LiNiO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Concentration-gradient LiNi<SUB>0.9</SUB>Co<SUB>0.1–<I>x</I> </SUB>Ti<SUB> <I>x</I> </SUB>O<SUB>2</SUB> cathode materials were prepared. </LI> <LI> These materials exhibit decreased oxygen loss and improved structural stability. </LI> <LI> Best performance observed for <I>x</I> = 0.04. </LI> <LI> LiNi<SUB>0.9</SUB>Co<SUB>0.06</SUB>Ti<SUB>0.04</SUB>O<SUB>2</SUB> exhibits a discharge capacity of 214 mAh g<SUP>−1</SUP>. </LI> <LI> LiNi<SUB>0.9</SUB>Co<SUB>0.06</SUB>Ti<SUB>0.04</SUB>O<SUB>2</SUB> exhibits an excellent 50-cycle capacity retention of 98.7%. </LI> </UL> </P>

Origin of excellent rate and cycle performance of Na⁺-solvent cointercalated graphite vs. poor performance of Li⁺-solvent case

Jung, Sung Chul,Kang, Yong-Ju,Han, Young-Kyu Elsevier 2017 Nano energy Vol.34 No.-

<P><B>Abstract</B></P> <P>Despite its high reversibility for Li<SUP>+</SUP> intercalation, graphite is known to be electrochemically inactive for Na<SUP>+</SUP> intercalation. On the contrary, recent studies have demonstrated that graphite is active and shows excellent rate and cycle performance for Na<SUP>+</SUP>-solvent cointercalation but it exhibits poor performance for Li<SUP>+</SUP>-solvent cointercalation. Herein, we elucidate the mechanism of Li<SUP>+</SUP>- and Na<SUP>+</SUP>-solvent cointercalation into graphite and the origin of the strikingly different electrochemical performance of Li<SUP>+</SUP>- and Na<SUP>+</SUP>-solvent cointercalation cells. Na<SUP>+</SUP> intercalation into graphite is thermodynamically unfavorable, but Na<SUP>+</SUP>-diglyme cointercalation is very favorable. The diglyme–graphene van der Waals interaction reinforces the interlayer coupling strength and thereby improves the resistance of graphite to exfoliation. The transport of solvated Na ions is so fast that the diffusivity of Na<SUP>+</SUP>-diglyme complexes is markedly faster (by five orders of magnitude) than that of Li<SUP>+</SUP>-diglyme complexes. The very fast Na<SUP>+</SUP>-diglyme conductivity is attributed to facile sliding of flat diglyme molecules, which completely solvate Na ions in the interlayer space of graphite. The slow Li<SUP>+</SUP>-diglyme conductivity is ascribed to steric hindrance to codiffusion caused by bent diglyme molecules that incompletely solvate Li ions. The bent and flat diglyme molecules surrounding Li and Na ions, respectively, are highly associated with the strong Li<SUP>+</SUP>–graphene and weak Na<SUP>+</SUP>–graphene interactions, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Li<SUP>+</SUP>- and Na<SUP>+</SUP>-solvent cointercalations into graphite were examined. </LI> <LI> Solvent cointercalation enables Na<SUP>+</SUP> intercalation into graphite thermodynamically. </LI> <LI> Na<SUP>+</SUP>-solvent transport is strikingly faster than Li<SUP>+</SUP>-solvent transport. </LI> <LI> Weak Na<SUP>+</SUP> ion–graphene interaction significantly enhances rate capability. </LI> <LI> Slow Li<SUP>+</SUP>-diglyme conductivity is ascribed to steric hindrance to codiffusion. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

패턴전사 프린팅을 활용한 리튬이온 배터리 양극 기초소재 Li₂CO₃의 나노스케일 패턴화 방법

강영림,박태완,박은수,이정훈,왕제필,박운익,Kang, Young Lim,Park, Tae Wan,Park, Eun-Soo,Lee, Junghoon,Wang, Jei-Pil,Park, Woon Ik 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.4

지난 수십년간 인류에게 핵심적인 에너지 자원이었던 화석연료가 갈수록 고갈되고 있고, 산업발전에 따른 오염이 심해지고 있는 환경을 보호하기 위한 노력의 일환으로, 친환경 이차전지, 수소발생 에너지 장치, 에너지 저장 시스템 등과 관련한 새로운 에너지 기술들이 개발되고 있다. 그 중에서도 리튬이온 배터리 (Lithium ion battery, LIB)는 높은 에너지 밀도와 긴 수명으로 인해, 대용량 배터리로 응용하기에 적합하고 산업적 응용이 가능한 차세대 에너지 장치로 여겨진다. 하지만, 친환경 전기 자동차, 드론 등 증가하는 배터리 시장을 고려할 때, 수명이 다한 이유로 어느 순간부터 많은 양의 배터리 폐기물이 쏟아져 나올 것으로 예상된다. 이를 대비하기 위해, 폐전지에서 리튬 및 각종 유가금속을 회수하는 공정개발이 요구되는 동시에, 이를 재활용할 수 있는 방안이 사회적으로 요구된다. 본 연구에서는, 폐전지의 재활용 전략소재 중 하나인, 리튬이온 배터리의 대표적 양극 소재 Li2CO3의 나노스케일 패턴 제조 방법을 소개하고자 한다. 우선, Li2CO3 분말을 진공 내 가압하여 성형하고, 고온 소결을 통하여 매우 순수한 Li2CO3 박막 증착용 3인치 스퍼터 타겟을 성공적으로 제작하였다. 해당 타겟을 스퍼터 장비에 장착하여, 나노 패턴전사 프린팅 공정을 이용하여 250 nm 선 폭을 갖는, 매우 잘 정렬된 Li2CO3 라인 패턴을 SiO2/Si 기판 위에 성공적으로 형성할 수 있었다. 뿐만 아니라, 패턴전사 프린팅 공정을 기반으로, 금속, 유리, 유연 고분자 기판, 그리고 굴곡진 고글의 표면에까지 Li2CO3 라인 패턴을 성공적으로 형성하였다. 해당 결과물은 향후, 배터리 소자에 사용되는 다양한 기능성 소재의 박막화에 응용될 것으로 기대되고, 특히 다양한 기판 위에서의 리튬이온 배터리 소자의 성능 향상에 도움이 될 것으로 기대된다. For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.

CFD 해석을 적용한 18650 리튬-이온 배터리 팩의 열 해석 신뢰도 기초 분석

심창휘,김한상 한국수소및신에너지학회 2020 한국수소 및 신에너지학회논문집 Vol.31 No.5

The Li-ion battery is considered to be one of the potential power sources for electric vehicles. In fact, the efficiency, reliability, and cycle life of Li-ion batteries are highly influenced by their thermal conditions. Therefore, a novel thermal management system is highly required to simultaneously achieve high performance and long life of the battery pack. Basically, thermal modeling is a key issue for the novel thermal management of Li-ion battery systems. In this paper, as a basic study for battery thermal modeling, temperature distributions inside the simple Li-ion battery pack (comprises of nine 18650 Li-ion batteries) under a 1C discharging condition were investigated using measurement and computational fluid dynamics (CFD) simulation approaches. The heat flux boundary conditions of battery cells for the CFD thermal analysis of battery pack were provided by the measurement of single battery cell temperature. The temperature distribution inside the battery pack were compared at six monitoring locations. Results show that the accurate estimation of heat flux at the surface of single cylindrical battery is paramount to the prediction of temperature distributions inside the Li-ion battery under various discharging conditions (C-rates). It is considered that the research approach for the estimation of temperature distribution used in this study can be used as a basic tool to understand the thermal behavior of Li-ion battery pack for the construction of effective battery thermal management systems.

F-doped Li_1.15Ni_0.275Ru_0.575O₂ cathode materials with long cycle life and improved rate performance

Choi, Sojeong,Kim, Min-Cheol,Moon, Sang-Hyun,Kim, Hyeona,Park, Kyung-Won Elsevier 2019 ELECTROCHIMICA ACTA Vol.326 No.-

<P><B>Abstract</B></P> <P>In this study, Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> cathode material for lithium-ion batteries is synthesized using a facile solid-state reaction. In particular, the Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> cathode material with a layered structure, despite its high initial capacity, deteriorates in both stability and rate performance. In order to overcome the drawbacks, F-doped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> cathode structures (LNROF-x, 0 < x < 0.1) are prepared with varying contents of F as a dopant and characterized. For the F-doped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> samples, if the O<SUP>2−</SUP> sites in the structure are replaced by F<SUP>−</SUP>, the transition metal ions of Ni<SUP>2+</SUP> and Ru<SUP>4+</SUP> can be partially reduced to Ni<SUP>+</SUP> and Ru<SUP>3+</SUP> with larger ionic radii for charge compensation. Thus, the increased interspace between the transition metal ions caused by their reduction increases the lattice parameter in the F-doped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> structure. Compared to the undoped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB>, the improved electrochemical properties, i.e., long life cycle and rate performance, of the F-doped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> samples can result from the improved structural stability caused by a stronger bond of metal-F than that of metal-O and an increased Li<SUP>+</SUP>-ion diffusion motion caused by an increased Li slab distance. Furthermore, the Li<SUP>+</SUP>-ion diffusion coefficients for the samples are measured by cyclic voltammetry and galvanostatic intermittent titration. However, with increasing F-doping amount, the diffusion coefficients for LNROF-0.02, LNROF-0.04, and LNROF-0.06 increase, whereas the diffusion coefficient for LNROF-0.08 with the excessive F-doping decreases because of the increased resistance to Li<SUP>+</SUP> ion motion caused by the Li/Ni anti-site defect. Thus, the amount of F as a dopant in the F-doped Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> samples for the LIBs needs to be optimized.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Li<SUB>1.15</SUB>Ni<SUB>0.275</SUB>Ru<SUB>0.575</SUB>O<SUB>2</SUB> (LNRO) cathodes were synthesized using a solid-state reaction. </LI> <LI> F-doped LNRO cathodes were prepared with varying contents of F as a dopant. </LI> <LI> F-doped LNRO cathodes showed the improved electrochemical properties. </LI> <LI> The improved performance is due to a strong bond of metal-F and an increased Li + -ion diffusion motion. </LI> <LI> The amount of F as a dopant in the F-doped LNRO samples for the LIBs was optimized. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrochemical lithium intercalation chemistry of condensed molybdenum metal cluster oxide: LiMo₄O₆

Lim, Sung-Chul,Chae, Munseok S.,Heo, Jongwook W.,Hong, Seung-Tae Elsevier 2017 Journal of solid state chemistry Vol.254 No.-

<P><B>Abstract</B></P> <P>The electrochemical lithium-ion intercalation properties of molybdenum metal-cluster oxide Li<SUB> <I>x</I> </SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> (0.33 ≤ <I>x</I> ≤ 1.0) in an organic electrolyte of 1.0M LiPF<SUB>6</SUB> in ethylene carbonate/dimethyl carbonate (1:2v/v) were characterized for the first time. Li<SUB>0.66</SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> (tetragonal, <I>P4/mbm</I>, <I>a</I> = 9.5914(3) Å, <I>c</I> = 2.8798(1) Å, <I>V</I> = 264.927(15) Å<SUP>3</SUP>, <I>Z</I> = 2) was prepared via ion-exchange of indium and lithium ions from InMo<SUB>4</SUB>O<SUB>6</SUB> (tetragonal, <I>P4/mbm</I>, <I>a</I> = 9.66610(4) Å, <I>c</I> = 2.86507(2) Å, <I>V</I> = 267.694(2) Å<SUP>3</SUP>, <I>Z</I> = 2), which was first synthesized from a stoichiometric mixture of In, Mo, and MoO<SUB>3</SUB> via a solid-state reaction for 11h at 1100°C. Then, Li<SUB>0.33</SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> was obtained via electrochemical charge of the electrode at 3.4V vs. Li. The electrochemical lithium-ion insertion into Li<SUB>0.33</SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> occurs stepwise: three separate peaks were observed in the cyclic voltammogram and three quasi-plateaus in the galvanostatic profile, indicating a complicated intercalation mechanism. However, examination of the structural evolution of Li<SUB> <I>x</I> </SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> during the electrochemical cycle indicated a reversible reaction over the measured voltage range (2.0–3.2V) and <I>x</I> range (0.33 ≤ <I>x</I> ≤ 1.00). Despite the excellent electrochemical reversibility, Li<SUB> <I>x</I> </SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> showed poor rate performance with a low capacity of 36.3mAhg<SUP>−1</SUP> at a rate of 0.05C. Nonetheless, this work demonstrates a new structural class of lithium cathode materials with condensed metal clusters and 1D tunnels, and provides a host material candidate for multivalent-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An electrochemical Li-ion intercalation into Mo metal-cluster oxide is demonstrated. </LI> <LI> Reversible structural changes are observed during the electrochemical cycle. </LI> <LI> A new structural class of lithium cathode materials is provided. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The electrochemical lithium-ion intercalation properties of a molybdenum metal-cluster oxide of Li<SUB> <I>x</I> </SUB>Mo<SUB>4</SUB>O<SUB>6</SUB> (0.33 ≤ <I>x</I> ≤ 1.0) in an organic electrolyte of 1.0M LiPF<SUB>6</SUB> in EC/DMC (1:2v/v) were characterized for the first time.</P> <P>[DISPLAY OMISSION]</P>

The characterization of dynamic behavior of Li-ion battery packs for enhanced design and states identification

Nam, Woochul,Kim, Ji-Young,Oh, Ki-Yong Elsevier 2018 Energy conversion and management Vol.162 No.-

<P><B>Abstract</B></P> <P>The dynamic responses of a Li-ion battery pack deployed on hybrid electric vehicles are studied with a high fidelity finite element model and a parametric reduced-order model. The effects of microstructure transformation in the electrode materials caused by lithium-ion intercalation/deintercalation on the evolution of dynamic responses are investigated including the effects of the state of charge, aging, and cell-to-cell variations. The dynamic responses obtained from a finite element analysis show two interesting phenomena. First, the high modal density is controllable with the design modification of a pack component. Second, dynamic responses, especially the evolution of the natural frequencies of the fixed-boundary modes, of a Li-ion battery pack provide useful information to estimate the dynamic states or health states of the battery. A probabilistic analysis is also carried out considering stochastic operational conditions of hybrid electric vehicles with a parametric reduced-order model. The probabilistic analysis not only suggests appropriate modes and locations for monitoring its dynamic responses, but also determines the maximum response level of every cell in the battery pack. The proposed modeling approach can improve the safety and reliability of the structural design of battery cells and packs. Furthermore, it can be useful for the identification of the battery states during the operation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dynamics of the battery pack are characterized for various operational conditions. </LI> <LI> Statistical structural variations are analyzed using an order reduction technique. </LI> <LI> Proper design of the spacers can eliminate concerns on high modal density. </LI> <LI> Fixed-boundary modes are sensitive to the evolution of structural dynamics. </LI> <LI> Probabilistic analysis defines sensitive locations for monitoring a battery pack. </LI> </UL> </P>

SOH and RUL prediction of Li‑ion batteries based on improved Gaussian process regression

Hailin Feng,Guoling Shi 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12

Accurately predicting the state of health (SOH) and remaining useful life (RUL) of Li-ion batteries is the key to Li-ion battery health management. In this paper, a novel GPR-based method for SOH and RUL prediction is proposed. First, fivefeatures are extracted from the cyclic charging currents of batteries, and a grey correlation analysis (GRA) shows that these five features are highly correlated with battery capacity. A novel Li-ion battery SOH prediction model is established byimproving a basic Gaussian process regression model. Meanwhile, a polynomial regression model is developed to update the feature values in the future. Then the RUL of a battery is predicted by combining the SOH prediction model. Finally,the prediction effect of the proposed model is compared with other models using four Li-ion battery degradation data. The obtained results show that the model proposed in this paper has the highest accuracy. The robustness of the proposed model is verified by random walk battery data.

Effect of Li₃BO₃ Additive on Densification and Ion Conductivity of Garnet-Type Li₇La₃Zr₂O₁₂ Solid Electrolytes of All-Solid-State Lithium-Ion Batteries

Shin, Ran-Hee,Son, Sam-Ick,Lee, Sung-Min,Han, Yoon Soo,Kim, Yong Do,Ryu, Sung-Soo The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.6

In this study, we investigate the effect of the$Li_3BO_3$ additive on the densification and ionic conductivity of garnet-type $Li_7La_3Zr_2O_{12}$ solid electrolytes for all-solid-state lithium batteries. We analyze their densification behavior with the addition of $Li_3BO_3$ in the range of 2-10 wt.% by dilatometer measurements and isothermal sintering. Dilatometry analysis reveals that the sintering of $Li_7La_3Zr_2O_{12}-Li_3BO_3$ composites is characterized by two stages, resulting in two peaks, which show a significant dependence on the $Li_3BO_3$ additive content, in the shrinkage rate curves. Sintered density and total ion conductivity of the system increases with increasing $Li_3BO_3$ content. After sintering at $1100^{\circ}C$ for 8 h, the $Li_7La_3Zr_2O_{12}-8$ wt.% $Li_3BO_3$ composite shows a total ionic conductivity of $1.61{\times}10^{-5}Scm^{-1}$, while that of the pure $Li_7La_3Zr_2O_{12}$ is only $5.98{\times}10^{-6}Scm^{-1}$.