Solid Electrolyte Lithium Phosphous Oxynitride as a Protective Nanocladding Layer for 3D High-Capacity Conversion Electrodes

Self Cite

batteries (e.g., Li-S battery and Li-air battery) due to the low electrochemical potential and high theoretical specific capacity of Li metal (3861 mAh g −1 ). The battery industry expended considerable effort to commercialize Li metal anodes via electrolyte additive engineering in the late 1980s. [4][5][6] However due to the instability of the Li-metal/electrolyte interface, and the formation of dangerous dendrites on Li metal surface, the use of lithium anodes decreased in popularity.The low electrochemical potential of Li metal makes it highly reactive, readily forming thin native surface layers during manufacturing. In principle, the insulating native surface layer could suppress or block electron transfer to the electrolyte, serving as a self-limiting protection layer on the Li surface to prevent solvent decomposition. However, the chemical/electrochemical instability of the interface leads to significant battery degradation through Li metal corrosion, solvent/electrolyte consumption, and flammable gas generation, largely associated with formation of a solid electrolyte interphase (SEI) layer by chargetransfer-initiated decomposition of the organic solvent. [7,8] The technology potential of Li anodes provides strong incentive to understand and prevent these Li surface degradation mechanisms at the surface of Li foils that would be employed in high energy Li anode storage systems. [9][10][11][12][13][14][15][16][17] Solvent Decomposition on Li Metal FoilsFoils of Li-metal are commonly used as negative electrode in pursuit of Li-metal batteries. Because of Li's exceptionally high reactivity, the surface is always covered with an oxide layer. We characterize the as-prepared Li foil surface by the in situ X-ray Photoelectron Spectroscopy (XPS) results in Figure 1a, where a Li metal foil was directly transferred from a purified Arfilled glovebox through ultrahigh vacuum to the XPS system, thus avoiding air exposure ( Figure S1, Supporting Information). The Li (1s) XPS spectrum indicates a mixture of Li 2 O, Li 2 CO 3 , and LiOH on the Li surface. Since prior investigations using our in situ XPS capabilities revealed no measurable carbon or carbonate following growth of Li 2 O by atomic layer deposition (ALD), [18] the presence of a carbonate feature Chemical and electrochemical instability of the Li metal interface with organic solvent has been a major impediment to use of Li-metal anodes for next-generation batteries. Here the character of Li surface degradation and the application of atomic layer deposition (ALD) as a protection layer to suppress the degradation are addressed. Using standard Li foil samples in organic solvent with and without in situ deposited ALD Al 2 O 3 protective layers, results from in situ atomic force microscopy, mass spectrometry (including differential electrochemical mass spectrometry), X-ray Photoelectron Spectroscopy (XPS), and ex situ scanning electron microscopy/energy dispersive X-ray spectroscopy are reported. Despite the presence of a thin oxide/hydroxide/carbonate layer on th...

Section: In Situ Afm: Solvent Decomposition On Ald‐protected LI Metalmentioning

confidence: 99%

ALD Protection of Li‐Metal Anode Surfaces – Quantifying and Preventing Chemical and Electrochemical Corrosion in Organic Solvent

Lin

Kozen

Noked

et al. 2016

Self Cite

“…Furthermore, Li et al found that even a coating of 2 ALD cycles of Al 2 O 3 introduces a significant voltage hysteresis, which results in a worsened rate capability. Other ALD coatings are also investigated, such as TiN, ZrO 2 , HfO 2 , TiO 2 , ZnO, hybrid metal‐organic films, and ALD solid electrolytes . While the focus of the investigation is mostly to improve the lifetime of the electrodes, the kinetics are an often‐overlooked and very important battery characteristic.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Ultrathin Amorphous ALD Alumina and Titania on the Rate Capability of Anatase TiO₂ and LiMn₂O₄ Lithium Ion Battery Electrodes

Mattelaer

Vereecken

Dendooven

et al. 2017

Interface modification is a heavily investigated method of extending the lifetime of lithium ion batteries. While many studies have explored the effect of interface coating on the lifetime, the rate capability is often overlooked. In this study, the authors investigated the influence of ultrathin (<10 nm) atomic layer deposition (ALD) coatings of amorphous Al2O3 and amorphous TiO2. It is found that, on thin‐film anatase TiO2, the rate capability is unaffected by an amorphous TiO2 coating since it does not pose an additional impedance on the system, while Al2O3 coatings are detrimental for the rate performance due to the 1.5 × 1012 Ω cm resistivity toward lithium ions. A thicker than 2 nm ALD Al2O3 film is found to block lithium transfer completely, resulting in a purely capacitive film. Solvent oxidation is studied on thin‐film LiMn2O4. The authors demonstrate that both coatings can partially solve the solvent decomposition. However, the kinetic bottleneck posed by 1 nm Al2O3 is still greater than the uncoated LiMn2O4, leading to worsened rate capability. ALD TiO2 on the other hand can prevent most of the solvent decomposition, resulting in smoother electrodes. The absence of the decomposition layer and lithium conducting properties of the ALD TiO2 films results in an improved rate capability for the ALD TiO2 coated electrode.

“…The present result suggests that the formation of undesirable LiF in the SEI layer is another contributor to the decreased performance in the cathode, in addition to metal dissolutions by HF. Another recent work by Lin and co‐workers showed that ALD‐LiPON coating enhanced the cyclability of CNTs@RuO 2 conversion electrodes, due to the high Li ion conductivity at the electrode/electrolyte interface and constrained RuO 2 electrodes by LiPON coating . Both work on LiPON and Li 3 PO 4 coatings indicate that the solid‐state electrolyte is critical for transporting Li ions through the electrode/electrolyte interface, regardless of on the anode or cathode.…”

Section: Resultsmentioning

confidence: 98%

Atomic Layer Deposition of Hierarchical CNTs@FePO₄ Architecture as a 3D Electrode for Lithium‐Ion and Sodium‐Ion Batteries

Liu

Wang

Sun

et al. 2016

materials in the same footprint, while still deliver good power densities as a result of short Li + diffusion paths. [1,2] In order to realize 3D microbatteries, there is a great need for thin film deposition techniques that can precisely produce thin film electrode and electrolyte materials on high-aspect-ratio substrates. Recently, atomic layer deposition (ALD) appears as a powerful technique for depositing uniform and conformal thin films on such high-aspect-ratio substrates. [3] ALD is based on sequential exposure of gaseous precursors on the target substrates where saturated surface reactions allow deposition of high-quality thin films in a layerby-layer manner, and the film thickness is controlled in submonolayer accuracy. [4,5] These advantages of ALD promise it great potential for the fabrication of 3D all-solidstate microbatteries. To achieve this ultimate goal, it is essential to develop ALD processes specifically for battery active materials, including the anode, cathode, and solid-state electrolyte.During the past few years, great progresses have been made to produce these electrochemically active materials by ALD for lithium-ion battery (LIB) applications. [6][7][8][9] On one hand, the anode materials that can be synthesized by ALD have been extended from metal oxides (such as TiO 2 , SnO 2 ) to metal sulfides (such as GaS x ). [9,10] Meanwhile, several glass-type solid-state electrolytes, i.e., LiTaO 3 , [11] Li 3 PO 4 , [12,13] Li x Al y Si z O, [14] and LiPON, [15,16] have been deposited via ALD by using a sub-cycle strategy, and exhibited ionic conductivities of ≈10 −9 -10 −7 S cm −1 at room temperature (RT). Lithium-containing cathode materials (LiCoO 2 , LiMnO 2 , and LiFePO 4 ) [17][18][19] have also been synthesized using ALD, by carefully designing the surface chemistry employed. More recently, an organic lithium anode, Li-terephthalate, has also been successfully made by using Li(thd) and terephthalic acid as precursors and pairing ALD with molecular layer deposition. [20] With these ALD-deposited electrode materials in place, the next key step toward 3D microbatteries would be the integration of these active materials onto 3D structures to build 3D microelectrodes, which is yet to be demonstrated. Besides LIBs, sodium-ion batteries (SIBs) are recently attracting increasing attention as a low-cost energy storage system. [21][22][23] Similarly, development of 3D electrode 3D microbatteries hold great promise as on-board energy supply systems for microelectronic devices. The construction of 3D microbatteries relies on the development of film deposition techniques that can enable coatings of uniform electrode and electrolyte materials in high-aspect-ratio substrates. Here, a 3D FePO 4 on carbon nanotubes (CNTs@FePO 4 ) structure is fabricated by coating FePO 4 on CNTs/carbon paper substrate using atomic layer deposition. Compared to FePO 4 on a planar substrate, the 3D CNTs@FePO 4 electrode exhibits significantly increased areal capacity and excellent rate capability for lithium-ion and sodium...