Articles and Comments 52

2023年8月19日 16:28

本文はこちら：Articles and Comments 52 | LinkedIn

Preface

Even under the difficult relationship between the two countries, i.e., Japan and China, the two countries are going to be neighbouring countries from the viewpoint of plate techtonics.

China is showing its strength on "Lithium-ion Battery" business, however, it is in a tight spot in terms of "Semiconductor" business. Well, it has brought it on itself, though.

OK, then, let's think about these two matters.

I. Lithium-ion Battery

China is now leading the global lithium-ion battery business from a quantity perspective, e.g., Lithium ion batteries - main manufacturers 2022 | Statista

The quality and the marketing strategy are also good, e.g., BYD’s New Blade Battery Set to Redefine EV Safety Standards - BYD USA

Although I guess that the (-) graphite (Gr) | liquid electrolyte | LiFePO4 (LFP) (+) battery will survive even after the emerge of the sulfide-based all-solid-state lithium-ion battery (ASSLIB), which is the only promissing candidate in order to replace the currently ubiquitous (-) Gr | liquid electrolyte | Li(Ni,Co,Mn)O2 (NCM) or Li(Ni,Co,Al)O2 (NCA) (+) batteries from a view point of rate capability (e.g., Electrochemical Impedance Analysis for Li-ion Batteries (2018).), a point of concern can be the ASSLIB shift in China, i.e., the on-going researches has stayed focused on argyrodite-based solid-state electrolyte. What’s not enough on argylodite is its not-so-high ion conductivity. Even so, the patent matter perhaps restricts the researches toward the argyrodite-based ASSLIB.

Then, the ASSLIB shift in China would have to focus on argyrodite. The followings are the suggestions for the ASSLIB shift in China.

China has large-sized enough single-crystal NCM particles that are suitable for ASSLIB, however, the not-so-high ion conductivity of argyrodite can weaken the competitivity in the market. Thus, it must be sold at a lower price compared to Japanese products.
Then, in spite of the fact that small-sized particles are difficult to prepare the active material/solid-state electrolyte composite electrode, the preparation of LFP (or Li(Mn,Fe)PO4 (LMFP) would be better than LFP)/argyrodite composite electrode must be tried in order to keep the competitivity in the market. Perhaps, the LFP-particle pulverization should be accepted even in the case that the LFP filling factor is lowered.
Anode-free battery, which means it uses the lithium metal depostied on the anode current collector (the quantity of the lithium deposit is based on the lithium ions de-intercalated from the cathode), is meaningful in order to decrease the cost. A problem is the lithium dendrite formation.
The lithium-tellurium cap layer deposited on the anode current collector has so far exhibited the best performance in order to suppress the lithium dendrite formation, however, tellurium is costly. The cheaper alloy is preferable, if possible.
Three-dimensional (3D) current collector is not a perfect solution particularly at a high C-rate. At a high C-rate, the immediate vicinity next to the solid electrolyte layer tends to be used for the redox (= lithium metal deposition at the anode in this case) no matter how the deposition easiness on the 3D current collector is controlled particularly when the ion conductivity in the electrolyte filled in the 3D current collector is low. The lithium dendrite can grow even through the tiny crack in the solid electrolyte layer, thus, the safety matter should not be underestimated.

Japan is OK because of TOYOTA, by the way.
前回、記事抜粋51 | LinkedInも「アルジロダイトはイオン伝導度が低いと散々指摘してきたが、中国にはイオン伝導度の高い硫化物固体電解質を開発するのは無理そうだし、中国はもうアルジロダイトでいいや！」と書いたが、日本からもこんな奴が出てくるしな（笑）：脱炭素の切り札は「全固体電池」だ！三井金属を買ったワケ（同志社大学 SYさん）【企業分析バトル】: J-CAST 会社ウォッチ【全文表示】／・・・さて、今回は「脱炭素」という点に注目して銘柄を選定しました。「国策に売りなし」という格言があるように、「脱炭素」は世界的にも取り組まれています。そこで注目したのが、東証一部上場企業である「三井金属」です。非鉄大手。銅箔は世界首位級の企業です。ここはいいとして・・・。この全個体電池の実用化を2020年以降と早い時期に三井金属は設定している。ESG投資という面からみても非常に優れていることがわかる。三井金属がやっているのがアルジロダイトなんだわ。イオン伝導度が電解液に比して高くないから日本では小型電池のMaxellが使っているくらいなんだが。この手の「自称投資家」は「間違って儲ける」しかないのである（笑）。こいつらが儲けようが損しようが知ったことではないが、中国には車両電動化をさらに推進してもらい、原油消費量を削減してもらわなければならない。リチウムイオン電池、BEVを世界中に輸出している中国ならなおさら貢献度は高い。ということで、「①LFPを使ってコストを下げる（LFPは粒径が小さいし、リチウムイオンチャネルが1次元なので、厄介なところは有るが。）；②LFPとアルジロダイトのコンポジットをつくる際にLFPが粉砕されることも許容し（活物質／硫化物固体電解質比率は下がるのでエネルギー密度は下がる。）、粉砕されて粒径が小さくなることでアルジロダイトとの接触面積・電極内リチウムイオン量も増やし、アルジロダイトのイオン伝導度が低いことをカバーする；③幸運なことにブレードバッテリーはバイポーラ型にしやすい構造だから、全固体にシフトする際は最初からバイポーラ型にしてアルジロダイトの低いイオン伝導度をカバーする。」といったことを提唱しているわけな。にしても、関関同立ってホント頭が悪い。
で、問題はLFP／アルジロダイト界面である。まともにやればもれなく高抵抗層ができ上がってしまう。中国はこれを嫌って正極には塩化物固体電解質を使うことも検討しているが、これがアルジロダイトに輪をかけてイオン伝導度が低い。日本の場合は正極活物質に粒径の大きい三元系を使い、活物質粒子表面を保護層（リチウムイオン伝導体だが電子絶縁体）で被覆している。被覆活物質粒子が粉砕されないように硫化物固体電解質とのコンポジット電極をつくる。これでいいのは硫化物固体電解質に電解液よりもはるかにイオン伝導度の高いものを使っているからなのである。LFPでこれをやっても小粒径のため活物質充填率が低くなるし（比表面積が大きくなる→接触する硫化物固体電解質を増やす必要が有る）、イオン伝導度の低いアルジロダイトを使っても日本の全固体電池のような高速充放電はできない。
ということで、LFP／アルジロダイトのコンポジットをつくる際に「ひょっとしてLFPが粉砕されるかも」ってくらいのせん断応力がかかって仮に粉砕されても「あれ？保護膜が残ってる？」ってくらいの「LFP含有粒子」がおそらく良いのである。
ここまで書いてやったんだからあとは自分で考えてね♡

II. Semiconductor

Among the following technologies, ② Two-Dimensional Semiconductor (perhaps partially with the printed electronics) and ③ ReRAM, for which not-so-high degree of integrity would suffice the needs, have become availble for China.

Regarding ① Ferroelectric Tunneling Junction, the research in China is still focusing on perovskite materials, however, the practical choice is (Hf,Zr)O2 (HZO). Thus, the research on HZO should be conducted. The lateral size is not a big deal, for now.

① Ferroelectric Tunneling Junction (FTJ) by W. Xiao et al.: Greatly enhanced tunneling electroresistance in ferroelectric tunnel junctions with a double barrier design | npj Computational Materials (nature.com ) We propose that the double barrier effect is expected to enhance the tunneling electroresistance (TER) in the ferroelectric tunnel junctions (FTJs). To demonstrate the feasibility of this mechanism, we design a model structure of Pt/BaTiO3/LaAlO3/Pt/BaTiO3/LaAlO3/Pt double barrier ferroelectric tunnel junction (DB-FTJ), which can be considered as two identical Pt/BaTiO3/LaAlO3/Pt single barrier ferroelectric tunnel junctions (SB-FTJs) connected in series. Based on density functional calculation, we obtain the giant TER ratio of 2.210 × 10^8% in the DB-FTJ, which is at least three orders of magnitude larger than that of the SB-FTJs of Pt/BaTiO3/LaAlO3/Pt, together with an ultra-low resistance area product (0.093 KΩum^2) in the high conductance state of the DB-FTJ. Moreover, it is possible to control the direction of polarization of the two single ferroelectric barriers separately and thus four resistance states can be achieved, making DB-FTJs promising as multi-state memory devices.
Assume that the tunneling probability through the single layer (SL) is 0.01 at the OFF state and 0.05 at the ON state, respectively. Then, ON/OFF ratio (SL) becomes 5.
Obviously, the tunneling probability through the double layer (DL) is 1*10^-4 at the OFF state and 25*10^-4, respectively. Then, ON/OFF ratio (DL) becomes 25.
A point of concern would be the increase in the resitivity.
② Two-Dimensional Semiconductor (2D Semiconductor): Low-temperature growth of MoS2 on polymer and thin glass substrates for flexible electronics | Nature Nanotechnology Recent advances in two-dimensional semiconductors, particularly molybdenum disulfide (MoS2), have enabled the fabrication of flexible electronic devices with outstanding mechanical flexibility. Previous approaches typically involved the synthesis of MoS2 on a rigid substrate at a high temperature followed by the transfer to a flexible substrate onto which the device is fabricated. A recurring drawback with this methodology is the fact that flexible substrates have a lower melting temperature than the MoS2 growth process, and that the transfer process degrades the electronic properties of MoS2. Here we report a strategy for directly synthesizing high-quality and high-crystallinity MoS2 monolayers on polymers and ultrathin glass substrates (thickness ~30 µm) at ~150 °C using metal–organic chemical vapour deposition. By avoiding the transfer process, the MoS2 quality is preserved. On flexible field-effect transistors, we achieve a mobility of 9.1 cm2 V−1 s−1 and a positive threshold voltage of +5 V, which is essential for reducing device power consumption. Moreover, under bending conditions, our logic circuits exhibit stable operation while phototransistors can detect light over a wide range of wavelengths from 405 nm to 904 nm.
So, the road to mass production has been paved: e.g., (1) BN/Fe-Ni is placed onto the polyimide film (PI). (2) The 2D materials are deposited onto the BN/Fe-Ni/PI. (3) Patterning etc.
③ ReRAM: Analysis of the Electrical ReRAM Device Degradation Induced by Thermal Cross‐Talk - Al‐Mamun - 2023 - Advanced Electronic Materials - Wiley Online Library A switching of resistive memory cells leads to a local accumulation of Joules heat in the device. In resistive RAM (ReRAM) arrays, the heat generated in one cell spreads via common electrode metal lines to the neighboring cells and may cause their performance degradation. The performance degradation results in reduced number of switching cycles and, in extreme cases, even in a loss of a bit, caused by the rupture of the nanofilament. The authors propose a thermal analysis of the thermal cross-talk, describe its impact on cells’ electric performance, and identify three major mechanisms for the ReRAM reliability: (i) thermal conductivity, (ii) the specific heat capacity, and (iii) geometry of the electrodes. Several ReRAM arrays are manufactured to vary thermal conductivity, specific heat and geometry of the electrodes by depositing eight different inert electrodes: Pt(50 nm)/Ti(30 nm), Ru(50 nm)/Ti(30 nm), Co(50 nm)/Ti(30 nm), Pt(50 nm/Cu(100 nm)/Ti(30 nm), Pt(50 nm)/ Cu(200 nm)/Ti(30 nm), Ru(50 nm/Cr(30 nm), Ru(50 nm)/Ti(50 nm), and Rh(50 nm)/Cr(30 nm). The experimentally found differences of the degradation of electric performance of the array cells performed under identical circumstances can be correctly predicted by the proposed thermal analysis using the material properties and geometry parameters of the electrodes.
It means that the degree of integrity of ReRAM has been improved enough.

Japan is OK because of TSMC, Micron, and perhaps Rapidus hopefully, by the way.