531934 五、發明說明（1) 發明背景 本發明大致揭示一種在氧化還原流之電池系統（redox flow battery system)中之可再更新電化學能量儲存器， 更明確地即所謂全釩氧化還原二次電池（al 1 -vanadium redox secondary batteries) ° 釩氧化還原流電池也稱爲全釩氧化還原電池室或簡稱釩 氧化還原電池室或電池，使用v(n)/v(m)及ν(ιν)/ν(ν) 分別做爲在負（有時稱爲陽極電解液）及正（有時稱爲陰極 電解液）半電池室之電解質溶液中的兩種氧化還原電偶 (couples)。 在釩電池中所使用典型電解質是由具有+3氧化狀態之 50%釩離子及具有+4氧化狀態之5%釩離子的混合物來構成 〇 電解質通常分成兩等份，其分別地放置在電池之正及負 隔間或更精確地在對流電路內。在開始條件中，電池具有 通常爲零之開路電壓。 當外部充分高輸出電壓源強制性電流經過電池時，在負 電解質中之V + 4(50%)將還原成V + 3，同時在正電解質中之 V + 3(50%)將氧化成V + 4。 在某一時間時，以負電解質循環泵（pump)使得連續地循 環經過電池之個別電極隔間的負電解質將僅含V + 3，而以 正電解質循環泵來循環經過電池個別電極隔間的正電解質 將僅含V + 4。 531934 五、發明說明（2) 在此情況下，所述電池將具有零充電狀態（nu 1 1 s t a t e of charge, SOC)，而電池之開路電壓將約1 . IV(伏特）。 以繼續強制性地”充電”電流經過電池，在負電極之V + 3 將還原成V + 2，而在正電極之V + 4將氧化成V + 5。當此轉換 完成時（在充電過程結束時），電池將具有開路電壓約1 . 8V 而所稱電池將具有S0C等於100%。 釩是市售之五氧化二釩（或爲釩酸銨）。總之，其通常以 + 5氧化狀態來市售。 全釩氧化還原電池設備之儲存容量是以酸性電解質中所 溶解之釩量來設定。對於預定電解質溶液之莫耳濃度，儲 存量和兩種電解質之體積係成正比。 顯然地，有需要使用市售五氧化二釩（或釩酸銨）做爲開 始（進料）材料，來生產釩之酸性溶液可適用爲電解質，以 首先充塡氧化還原電池系統之兩個電路，及/或用於擴充 現有電池裝置之儲存容量。 因此釩電解質之製備方法是包含在硫酸（或其他酸）中溶 解V205 &使得其還原成所需要V + 3(約50%)及V + 4(約50%) 之混合物的一種方法。 細微硏磨（粉末）之固體的五氧化二釩僅微溶在水中或酸 ，例如硫酸以溶解V205在酸中來製備電解質之簡單方法是 不可能。 爲了溶解V205，其必需先將其還原成較低（更可溶解）氧 化狀態。 -4- 531934 五、發明說明（3) 已有各種方法提議，主要地利用還原混合物或複雜電解 質及化學加工方法用於v+5之溶解及還原。 歐洲專利第ΕΡ-Α- 0 566 0 1 9號發表一種方法，用於以 五氧化二釩或釩酸銨在濃縮硫酸中化學還原，跟著沈澱物 之熱處理，來產生釩電解質溶液。 世界專利第WO 95 / 1 22 1 9號及第WO 96 / 35239號發表一 種電化學-化學過程，自固體的五氧化二釩來製備釩電解 質溶液及一種使其穩定之方法。五氧化二釩是在一種特殊 百葉窗式板陰極之離子交換膜電池上，使得五氧化二釩漿 向下流動地接觸百葉窗板式陰極以實施溶解。 至今所開發用於製備適當釩電解質之方法及技術係很複 雜及昂貴。另一方面，對全釩流氧化還原電池系統之總經 濟結算而言，低成本之釩電解質溶液在成本效益評價中爲 氧化還原電池較其他能量儲存系統具可用性的重要因素。 符合這需求的基礎在利用很便宜固體五氧化二釩做爲進 給材料。 發明之目的及槪述 現在已發現一種在酸性電解質中立即溶解及還原五氧化 二釩之特別簡單且便宜的方法。 本發明尤其可使用於自五氧化二釩（或釩酸銨），進料來 製備釩電解質，而且使用極簡單及低成本電解池來實施同 時降低溶液輔助處理到最少。 即使如此，本發明之方法即使自能量消耗之觀點，也保 531934 五、發明說明（4) 持十分地有效率。 本發明之方法本質上是一種連續性方法，因而對循環釩 電解質溶液之某一容積是以細微硏磨或粉末形式來連續地 進料固體五氧化二釩（v2o5)、酸及水來保持溶液之特定莫 耳濃度，同時連續地排放大致相同或不同於一期望濃度之 含V + 3及V + 4的相等容積之電解質溶液。 電解質溶液之流出表示製程之產出。 基本上，本發明之方法在於： 重力式地使得電解質溶液通過接觸串聯之複數電解室之 陰極，而逐步地使得進入第一電池室之溶液的部份或全部 之V+4含量還原成v+3，而最後地即使自串聯的複數電池室 之最後一個之電解池的電解質溶液流出口，其電解質溶液 中也微量地轉成爲V+2 ; 使得自最後一個之電解池流出口的電解質溶液，其所如 此還原之釩含量和於提供具攪拌裝置之溶解槽中，以化學 計量比例之五氧化二釩反應而獲得電解質溶液’包含可幾 乎完全地在V+4狀態之所對應之溶解釩量； 添加酸、硫酸或任何其他同等酸及水到釩電解質溶液中 (即接近v+4)以保持其某特定之莫耳濃度； 使得電解質溶液循環通過串聯電解池’同時在串聯複數 電池室中之電池室出口處，排放較佳地包含V + 3及V + 4大致 相同濃度的電解質溶液。 電解質電池室之基本態樣，是在其陰極及陽極個別地具 531934 五、發明說明（5) 有表面形態、幾何形狀及相互排列，使得在陽極表面上建 立電流密度以5至20倍比在陰極表面上之電流密度更大 ，而且自陽極表面來析出氧。 實際上，陰極可以提碳毛氈或活性碳之毛氈或相同材料 來提供很大表面面積，而且可具有管狀或甚至通道形狀形 式；而陽極可以是細圓棒形式，沿著管狀或通道形狀陰極 之幾何軸線來配置。 比較地，陰極之大比活性面積，比較陽極之比活性面積 及其突起的面積比例，致使決定在活性陽極表面之電流密 度以5至20倍大於在幾何形狀突起的陰極表面上之電流 密度。 以在突起的面積約一至數百安培/平方公尺（A/m2)之尺 寸的陰極電流密度來作業，及以對管狀或同等地至少局部 包圍陰極所同心地配置之陽極圓棒直徑的尺寸，可建立陽 極之電流密度超過l〇〇〇A/m2或甚至更高。 在具有明顯地不成比例之電流密度及相當高之陽極電流 密度的條件下，雖然強制式電解池之電流調整，使得確保 V + 4之陰極幾乎完全地還原成V + 3以保持陰極半電池室反應 (即限制最大電流密度使得防止寄生反應諸如氫析出），陽 極半電池室反應變成主要地由氧之析出（水電解）反應來支 援。 事實上，具V + 3氧化成V + 4之熱力學優勢之陽極半電池室 反應，實際上及效力上會受到遷移率及最後地由電解質主 531934 五、 發明說明（6) 體 去充塡在陽極及電池 室 所對著陽極表面之陰 極 表 面 間 之 間 隙的V + 3離子擴散率的大大地不足所阻礙。 進一步對於釩離子對 陽 極表面之遷移及或擴 散 的 重 要 阻 礙 ，係出現在是以在很 局 電流密度下由陽極表 面 所 劇 烈 地 析出的氧氣泡而產生。 在電氣串聯中所強制 地 經過重力式地串聯之 複 數 電 解 池 的 電流，可用電解質通 過 串聯電池室之流動速 的 函 數 來 調 整，使得在離開最後 —^ 個串聯電池室之電解 質 中 而 產 生 全 部V + 4實際地被完全還原成V + 3。 當然，其保有理想條 件 ，事實上所強制地經 過 電 池 室 在 電 流不足情形中會出現 最 小（殘餘）V + 4量，或 反之亦 然 ’ 在 電流超過之情形中， 會 發生V + 3開始還原成 V + 2 使 得 在 離 開最後電池室之電解 質 中微量之V + 2會和V + 3 — 齊 出現 0 陽極具有低氧超電勢 之 電催化劑表面來促成 氧 析出 而 總 之可在陽極極化及氧 排放之條件下耐得酸性' 電) 賛 〇 例如，陽極可以是圓 棒 閥型金屬，可耐得陽 極 衝 擊 9 諸 如 鈦、鉅或其合金，提 供 有氧排放電催化劑之非 鈍 化活性 塗 層。 塗層可以具有混合氧 化 物或至少具有一種貴 金 屬 ， 諸 如 銥 、铑及釕之氧化物混 合 物，及具有至少一種 閥 型 金 屬 諸 如 鈦、鉬及銷。活性塗 層 替代性地可包含貴金 屬 塗 層 諸 如 散 置在導電氧化物基體（ conductive oxide mat r i X) 之 餡 銥或铑或相同金屬。 -8- 531934 五、發明說明 ( 7) 在 提供 有 —^ 般機械攪拌裝置之溶解槽中，離 開 最後 電 池 室之 電解 質 溶 液接觸細微（粉末）形式之化學計 量 比例 之 固 體五 氧化 二 釩 (依在還原電解質溶液中所含之 v+ 3( V + 2 )1 1 ) ，以 硏磨 及 /或篩選固體之五氧化二釩，使得 導 入粒 子 具 有不 大於 100 微米之最大尺寸。 於貯槽 中 回 收傾析或過濾之溶液，而任何未 溶 解之 五 氧 化二 釩微 粒可再循環回到溶解槽內。 如此之 高 含 量溶液大致含V+4狀態之釩，雖 然 很少 量 以 V + 5存在之未溶解之釩。 最 普通 及 最 佳的酸，是硫酸、及水，被添加 到 高含 量 之 釩及 過濾 之 電 解質溶液，以保持特定莫耳濃度 及 電解 質 溶 液。 當然 > 釩 之莫耳含量愈高，電解質之功率/ 總容 積 的 比値 愈局 然 而，溶液在臨界溫度條件下之穩 定性的 問 題 ，會 在相 當 高 莫耳濃度時遭遇。最佳地，在硫 酸 溶液 之 情 形中 ，釩 之 莫 耳濃度含量範圍在2至5莫耳濃 度 〇 溶 液以 泵 打 回到串聯電池室之第一電池室中 的 入口 9 經 v+4(及任何 V + 5之殘餘）之電化學還原成V + 3,而甚至成’ V + 2 電 解質 製 造 設備之生產，是含約相同量之V + 3 及 V+4 的 溶 液， 其可在 串 聯電池室其中之一電池室的出口 處 排放再 循 環溶 液之主 要 流線。 陽 極表 面 之 大到不成比例之電流密度使得大 量 之氧 析出 及相 對應 地少 數V + 3氧化成V + 4，其爲一種令人 -9- 蠻 奇地用 以 531934 五、發明說明（8) 足夠保持加工過程之總效率大於可接收程度的條件；而且 也認爲在釩酸性電解質製備之任何加工過程之總經濟結算 ，其電能量成本佔很微小之比重。 在實施例之替代方案中可以利用包括在圓棒陽極及環包 之圓柱陰極之間之屏篩或甚至微孔性分離器以增加效率。 屏篩或微孔性分離器產生有效的限制，在使在電解質中 以浮力來上升之氧氣泡，因爲其等繼續地生出及離開陽極 表面，而如此使得在屏篩及陰極間之空間中所包含電解質 主體的對流運動達最小，而進一步減少所還原釩離子（V + 3) 漂移及最後到達陽極之能力。 最有效微孔性分離器，可以是多孔性玻璃管，其底部封 閉而包圍圓棒陽極（在本案情形中係自頂部來進入電池室） ，因而所析出氧氣泡一旦到達電解質之表面，可立即經通 風口以自電池室中排放出去。替代性地，適當微孔性分離 器可以是約1毫米厚度之聚丙二醇纖維（poly propylene f i b e r )之毛賣毛。 附圖之簡單說明 第1圖說明根據本發明用於自固體之V205進料來製備釩 電解質溶液的設備； 第2圖是本發明之釩還原電池室的橫剖面圖； 第3圖是釩還原電池室實施例替代方案之橫剖面圖；及 第4圖是全部釩流氧化還原電池系統之基本示意圖，包 括本發明在正電解質之電路中用於重新平衡作用的釩還原 -10- 531934 五、發明說明（9) 電池室。 發明較佳實施例之詳細說日日 參照第1圖之功能示意圖，根據本發明之釩電解質製備 設備，是由複數電解質釩還原電池室Cl、C2、C3、· . .C6 以重力式串聯地連接，且其由適當直流（DC)供給R1以電 氣串聯方式來供給電力。 離開串聯之最後一個電池室C6之溶液，被收集在具有 攪拌裝置S1之溶解槽，T1。 五氧化二釩以適當量藉由習用例之供料漏斗及利用馬達 驅動以控制供料之機械來導入溶解槽T1內。 高釩量之溶液，其最後地包含未溶解之五氧化二釩殘餘 固體微粒，可經由其液面排放口之高於溶解槽T1而流出 ，而且在沈澱槽T2中被傾析。 泵P2循環最後回到溶解槽T1之五氧化二釩分離殘留的 固體微粒，並在澄淸槽T2之底部收集。 高釩量及過濾溶液最後被收集在儲槽T 3。 在儲槽T3中所收集之高釩量溶液，大致包含在V + 4狀態 之釩。含量對應出現在流出串聯之最後一個還原電池室C6 之電化學還原溶液中及已溶解及已還原V + 5之還原量，與 V + 3及最後地V + 2之和相等。事實上，殘留未反應量V + 5也 可在T3中所被收集，如此高釩量溶液之V + 4亦一起出現。 在已添加酸，通常相當量H2S04及水H20來保持釩電解 質溶液之在一期望莫耳濃度後，溶液以泵P1來連續地循 -11- 531934 五、發明說明（1〇) 環經過串聯之釩還原電解池。 因此，進入第一還原電池室C 1之釩電解質溶液大致含 V + 4及可能地爲V + 5殘留量。 在還原電池室Cl、C2、C3...C6之負電極（陰極）處，主 反應是： V“ + e、= = V + 3 (或更精確地 V0 + 2 + e>2H + = = = V + 3 + H20) 如果具有+5氧化狀態之釩出現，另一反應是： V + 5 + e^ = = V + 4(或更精確地 V02 + + e- + 2H + = = = V + 2 + H20) 在負電極處沒有其他反應。氫析出（熱力學上傾向之半 電池室反應）不會發生，因爲碳毛氈電極具有很高氫過電 壓，而且在陰極表面之有效電流密度保持在充分低値。 在正電極處，理論上主反應必需是所出現具有較低氧化 狀態（+4、+3、+2)之任何釩離子被氧化成五氧化二釩（熱 力學上傾向之半電池室反應）。 事實上，接近陽極表面之釩離子將立即氧化成V + 5，如 此任何低氧化狀態之釩離子最後將漂移及擴散到陽極去。 然而，因爲鄰近正電極之釩離子轉換成V + 5(被消耗掉）， 所以陽極半電池室反應將開始受到其他唯一的半電池反應 愈來愈多的支持，即氧氣根據下述反應之釋出及所結果的 析出： H20= = = 02 + 2H + + 2e' 在本發明之非對稱電池室中，沒有排除實際上釩之氧化 如在使用離子交換膜及含陰極電解質之釩及支援酸陽極電 -12- 531934 五、發明說明（11) 解液之分離電路的習用系統。實際上，可以到達電池室之 陽極表面的釩離子，將立即地氧化成v+5。 然而’所產生之電極電流密度使得陽極處在很高電流密 度中工作，其高於釩離子在電解質溶液中往陽極表面之漂 移及擴散過程的數量大小所支援，係爲特別地不成比例。 結果，在陽極表面上促成大量之氧氣析出，而且氧氣泡劇 烈地析出而出現產生v+3離子漂移到陽極之”機械”障礙。 藉由使用屏篩或可滲透（微孔性）隔膜來限定氧氣泡群靠 近陰極可大幅地提昇對陰極所還原釩離子擴散到陽極的介 入阻礙，且因而防止了在氣體限定屏篩及高量還原釩離子 之陰極表面間的空間所包含之電解質群域中所引起之強烈 對流移動。 低氧過電壓陽極之使用僅促成氧之析出。 當使用相當緊密的微孔性分離器來替代更可滲透屏篩或 隔膜時，總感應效率明顯地增加，然而，電池室電壓也增 加。因此，只要能量消耗和電流及電壓之乘積成比例，可 以找出其最佳折衷點。 已發現欲確保感應效率超過40%，可容易地以陰極/陽極 電流比約5來達成；而且以增加電流/電壓之比達20，則 效率可到達80%而甚至更高水準。使用氣體限定屏篩及更 甚地以使用相當緊密微孔性分離器來獲得數字之明顯提昇 〇 在溶解槽T1中，電解還原釩電解質溶液中所含V+3和固 •13- 531934 五、發明說明（12) 體五氧化二釩v2o5(或釩酸銨）來反應，而根據下述反應來 將其還原成V+4 : (V+5+ V + 3 = = 2V + 4)或更精確地 V205 + 2V + 3 + 2H + = = = 4V0 + 2 + H2〇（1 ) 及（如果V + 2也出現） (2V + 5+ V + 2 = = 3V + 4)或更精確地 V205 + V + 2 + 4H + = = = = 3V0 + 2 + 2H20 根據本發明之非對稱電池室的交叉作用（cross act ion) ，使用在本發明之釩電解質製備設備，如第2圖所示。 第2圖所示實驗室測試電池室包含：圓柱管狀體1，通 常是金屬；插塞2，化學性耐電解質之非導電性耐酸塑膠 諸如PVC，封閉在管狀體的底部；在管狀體丨之下部具有 入口 3，及上溢流口 4。 由具有數厘米厚度之碳毛氈5所構成圓柱形陰極可配置 在及適當地錨定在管1之內圓柱表面。毛氈陰極可提供有 用於DC電源電路之電池室的電氣連接之適當端子6。 第2圖所示實驗室測試電池室中，陰極之內圓柱表面面 積具有約50毫米直徑及高度接觸電解質溶液約250mm。 陽極7是具有6.3mm(l/4英吋）直徑之鈦圓棒，具有銥 及鉅之混合氧化物的塗層，而且浸在電解質內之長度約 250毫米。 塗層欽圓棒陽極7沿著圓柱形碳毛氈陰極之軸線來配置 -14- 531934 五、發明說明（13) 在如此所定實驗室電池室中，碳毛氈陰極之突起之面積 約3 5 3厘米平方，而鈦圓棒陽極表面約4 7厘米平方。 以強制性電流通過7A之電池室，在鈦陽極表面之電流 密度約具有〇.1485A/cm2 = 1 500A/m2，而且碳毛氈之突起之 面積的電流密度具有0.022A/cm2 = 220A/m2。然而，由於碳 纖維毛氈形式之陰極的開放及立即滲透形態，在碳上之實 際或有效之陰極電流密度依估計比較在碳毛氈陰極之幾何 突起之圓柱面積上所計算電流密度以2至1 0倍小於。 第3圖所示是根據替代性實施例之釩還原電池室的交互 作用。 唯一差異的是以流體滲透屏篩或隔膜或微孔性分離器出 現來呈現，其插置在圓柱陰極表面及同軸配置圓棒陽極間 而界定在圓棒陽極7周圍之空間，其中大致保持繼續生出 及最後脫離陽極表面之浮出氧氣泡限制在周圍電解質內。 屏篩隔膜8在接近其中產生V + 4變成V + 3而最後V + 2之在 期望還原的陰極表面處，大致防止了在電解質群域內感應 強烈之對流移動。 具有小而密緻且均勻分佈孔隙之塑膠管可以作爲令人滿 意之氣泡限制屏篩，然而，氧氣泡限制屏篩8，其替代性 也可以是耐用材料，諸如例如鈦線網或塑膠纖維織品的細 網。更佳地是，氣體限制屏篩8可以爲多孔性或微多孔性 管體，例如多孔性玻璃管或諸如燒結後鈦之耐金屬微粒管 -15- 531934 五、發明說明（14) 實例 具有內徑8公分之1 / 2公升玻璃燒杯以用來證明本發明 技術之有效性。 具有約6毫米（1/4英吋）厚度之碳毛氈放置在燒杯的內 壁，而且電氣連接到DC電源供給之負極。 具有約6毫米（1 / 4英吋）外徑之I rOx-ZrOy混合氧化物 塗層鈦圓棒，沿著燒杯之幾何軸線來垂直地定位，而且電 氣地連接到DC電源供給之正極。 在突起之陰極面積及陽極面積間之比値約1 0.7。 約1毫米厚度之聚乙烯氈來形成圓管形狀，底部封閉， 具有約1 2毫米內直徑且放置在燒杯內，同心圓地在塗層 鈦圓棒陽極周圍。 燒杯充塡5莫耳硫酸溶液473毫升，及五氧化二釩粉末 90.9公克（0 . 5摩爾），混合物之總體積是0 . 5 1。 理論上，需要26.8Ah(安培小時）以自氧化+5狀態成爲 氧化+4狀態還原1莫耳之釩。 混合物以電磁攪拌器來攪拌，且黃色粉末之五氧化二釩 大致數天不溶解。 接通DC之電源供給且調整其輸出之電壓且強制8A(安培） 之 DC電流流經電池室。正電極（陽極）電流密度約 501 3A/m2，而在碳毛氈之突起之面積上的負電極（陰極）電 流密度約468A/m2。 電池室電壓大致保持固定在約3 . 8 - 4.0伏特。 -16- 531934 五、發明說明（15) 懸浮體以電磁攪拌器輕微地攪泮，而且在通過電流5 . 2 6 小時之後，黃色粉末似乎可完全地溶解。 如此所獲得之藍色溶液經分析而發現含有釩（2克分子溶 液）2莫耳而釩之氧化狀態爲+3.55。 其過程之感應（電流）效率預估爲92.28%。 用降低之電流5A來重覆測試，而所需要時間爲9 . 87小 時。感應（電流）效率已降低到約78 · 74%，但是所具有電池 室電壓約2.8V。 以薄聚乙烯織布來替代毛氈，電流效率減小到約47%， 如沒有任何可滲透限制元素，則到約20〜25%。 即使不是在最佳實驗室設定測試條件（具有攪拌之玻璃 燒杯）中，所產生之釩電解質具每公升之電力消耗在0.2 至0_5kWh(仟瓦小時）左右，表示其在製備釩電解質之總經 濟結算中爲很低的成本數字。 爲有效率地及便宜地修改酸性電解質溶液中所分解釩含 量之氧化狀態，本發明之非對稱釩電解池的能力，獲得本 發明之相當簡單及低成本、可大致未微細分之非對稱電池 室，可理想地適用於重新平衡作業中之電池之正及負釩電 解質的充電狀態，而不用於氧化還原電池設備沒有使用條 件中其實施昂貴及耗時過程，每次到達電池所不再可容許 之不平衡。 爲了更理解在操作釩電池能量儲存系統可能發生問題之 性質，對於簡單回應導致累積明顯不平衡之主要機構應會 -17- 531934 五、發明說明（16 ) 有幫助。 理論上，假設在釩氧化還原電池之充電及放電期間所發 生唯一過程爲電化學氧化及釩之還原，而且沒有其也副反 應正在發生，則釩電池充電及放電之過程係對稱之過程。 在充電期間，流經電池之電流使得在正電解質隔間內之 v+4氧化成v+5,而且同時及同速率地在負電解質隔間內使 得V + 3成爲V + 2。相對氧化及還原反應在放電期間係發生在 正及負電解質隔間。 不幸地，實際上情形並不同。 釩之電化學氧化及還原不是唯一正在發生之過程。下述 副反應可能在作業之臨界條件下發生： 1) 在負電極處氫氣之電化學析出； 2) 在正電極處氧氣之電化學析出（*); 3) V + 2化學氧化成V + 3 ; 4) V + 5化學還原成V + 4。 (* )如果正電極是由碳製成，則氧之析出局部地或全部 由二氧化碳之析出來取代。 一旦到達充電100%狀態時，反應1)及2)變成唯一之反 應。實際上，在正隔間之電解質中出現之全部V + 4氧化成 V + 5後，在可支援電流之正極上唯一反應是氧之析出（或二 氧化碳）。同樣地，當在正隔間之電解質中所出現全部V + 3 還原成V + 2時，可支援電流之負極上唯一反應是氫之析出 。當充電狀態變成高於90%時，在電池充電雖然在很小量 -18- 531934 五、發明說明（17) 之期間，這些反應將開始發生。 在釩氧化或還原時之電壓隨所產生種類及所消耗種類間 之比値比例地遞增（Nern st方程式），因此，在充電之高狀 態時，電池室電壓上升到約1 . 5伏特之氫及氧（水電解）析 出的電壓。如果充電以過度高速率（電流）來發生，在電池 放電雖然相當小量期間反應1及2 )也發生。 因爲電流密度接近極限電流，所以氫及氧之析出開始發 生爲副（寄生）電極反應。 極限電流是在電極表面上釩之氧化或還原速率等於釩離 子自電解質之群域經空乏層來擴散到電極表面的電流。 反應3)之V + 2氧化成V + 3是在釩電池作業期間最常再發 生之副反應。V + 2在空氣出現時立即氧化成V + 3。因此，除 非可嚴密地防止大氣空氣接觸負電解質（以氮氣阻斷或以 蠟來覆蓋電解質之表面），否則此副反應將立即發生。 因爲上述副反應，在電池作業經許多循環後，對稱會開 始明顯地喪失。 電解質變成不平衡之另一原因，是因爲所使用隔膜不是 完美之分離器。陰離子隔膜也無可避免地受到小數量正離 (H +及V + n)所滲透。 陽離子隔膜通常較佳地爲電池之電池室分離器，因爲比 較陰離子隔膜時，其有更高耐機械及化學性。 事實上，陽離子隔膜主要地可滲透氫離子（H+之擴散速 率十分高於釩離子）。 -19- 531934 五、發明說明（18) 在電池充電期間，在正隔間內根據下述反應所產生氫離 子： V〇 + 2 + H20 = = = = = V〇 + 2 + 2H + + e- 立即和少數較不流動釩離子一起經由隔膜來遷移到負隔 釩離子之漂移將使得在負隔間內所出現相對應量之還原 釩離子來氧化（V + 3及V + 2)，但是過程沒有完全地可逆，因 爲不同氧化狀態之釩離子自己不同地配位溶劑分子（水、 硫酸），而且在隔膜之陽離子交換樹脂中具有不同之流動 性。事實上，在後續放電階段期間，在相反方向中通過隔 膜之釩離子數量將不完全地等同於在充電階段期間已經漂 移的數量。 在電極間累積之不平衡將造成許多問題，其中： 1 )電池容量（照電解質之kWh/ 1 i ter(仟瓦小時/公升））比 例地遞減； 2)在充電期間，兩種電解質中其一可變成完全地充電，而 另一種則保持局部未充電。 實際上，尤其通常不完美之小電池自負隔間來消除空氣 ，在正隔間內之釩離子可完全地氧化成V + 5，而在負隔間 內保持相當量之V + 3。本情形十分重要，因爲如果在個別 電解質內沒有小心地控制氧化狀態’但僅量測開路電壓， 則充電將繼續到達V + 4完全氧化成V + 5之點。本情形中，在 碳電極上氧之大量析出將氧化及損壞電極。 -20- 531934 五、發明說明（19) 根據普通情形，在數次之充電及放電循環後，兩種電解 質（負及正）混合，量測氧化狀態，如果發現不同於+3 . 5， 則化學性地調整到+3.5。 事實上，當停止電池及混合電解質在一起時，總是發現 釩氧化狀態高於+3 · 5 (主要地因爲副反應3之優勢作用的 影響）。 電解質係以添加還原劑（草酸、亞硫酸鹽等）來重新調整 到+3 . 5之釩氧化狀態。 然後，相當量之能量必需消耗來使得系統回到零充電之 狀態（在負電解質內之V + 3及在正電解質內之V+4)。 週期地所消耗能量之量表示能量儲存過程之淨損失。 根據本發明之架構，此不可忽略之損失可以在負或更佳 地在正電解質電路中，以安裝本發明之很小型釩還原非對 稱電池室而大幅地降低，如第4圖之示意圖所示。 如圖示，正電解質可全部地或部份地循環（在後者情形 中例如使用可調整三通閥或以任何裝置）通過很小型非對 稱還原電池室來氧化還原。 電池室氧化還原可根據需要而連續地或斷續地來作業， 以便保持非對稱電fL氧化狀態構造。 因爲此輔助還原電池室氧化還原之出現所提供的可能性 ，所以混合兩種電解質在一起、調整氧化狀態到約+3.5且 使得電池預先充電以便回復零充電之狀態的需求，可以消 除或僅在例外地需要才實施。 -21- 531934 五、發明說明（20) 符號之說明 C1 〜C6 電解質釩還原電池室 T1 溶解槽 S1 攪拌裝置 T2 澄淸槽 T3 儲槽 1 圓柱管狀體 2 插塞 3 流入口 4 上溢流口 5 碳毛氈 6 端子 7 陽極 8 微孔性分離器 8 屏篩隔膜 -22-531934 V. Description of the invention (1) Background of the invention The present invention generally discloses a renewable electrochemical energy storage device in a redox flow battery system. More specifically, the so-called all-vanadium redox secondary Batteries (al 1 -vanadium redox secondary batteries) ° Vanadium redox flow batteries are also called all-vanadium redox battery rooms or abbreviated vanadium redox battery rooms or batteries, using v (n) / v (m) and ν (ιν) / ν (ν) are two types of redox couples in the electrolyte solution of the negative (sometimes called anolyte) and positive (sometimes called catholyte) half-cell compartments. A typical electrolyte used in a vanadium battery is a mixture of 50% vanadium ions with a +3 oxidation state and 5% vanadium ions with a +4 oxidation state. The electrolyte is usually divided into two equal parts, which are placed separately in the battery. The positive and negative compartments are more precisely within the convection circuit. In the starting conditions, the battery has an open circuit voltage of usually zero. When an external sufficiently high output voltage source forces a current through the battery, V + 4 (50%) in the negative electrolyte will be reduced to V + 3, and V + 3 (50%) in the positive electrolyte will be oxidized to V + 4. At a certain time, the negative electrolyte circulating pump (pump) makes the negative electrolyte continuously circulating through the individual electrode compartments of the battery will only contain V + 3, while the positive electrolyte circulating pump will circulate through the individual electrode compartments of the battery. The positive electrolyte will only contain V + 4. 531934 V. Description of the invention (2) In this case, the battery will have a state of zero charge (nu 1 1 s t a of charge, SOC), and the open circuit voltage of the battery will be about 1. IV (volts). To continue forcibly "charging" the current through the battery, V + 3 at the negative electrode will be reduced to V + 2 and V + 4 at the positive electrode will be oxidized to V + 5. When this conversion is complete (at the end of the charging process), the battery will have an open circuit voltage of about 1.8V and the so-called battery will have S0C equal to 100%. Vanadium is commercially available vanadium pentoxide (or ammonium vanadate). In short, it is usually commercially available in the +5 oxidation state. The storage capacity of all-vanadium redox battery equipment is set by the amount of vanadium dissolved in the acid electrolyte. For the molar concentration of a predetermined electrolyte solution, the storage amount is directly proportional to the volume of the two electrolytes. Obviously, there is a need to use commercially available vanadium pentoxide (or ammonium vanadate) as the starting (feeding) material. The acid solution used to produce vanadium can be used as an electrolyte to first charge the two circuits of the redox battery system. , And / or used to expand the storage capacity of existing battery devices. Therefore, the preparation method of the vanadium electrolyte is a method comprising dissolving V205 & in sulfuric acid (or other acid) so as to reduce it to the required V + 3 (about 50%) and V + 4 (about 50%) mixture. A finely milled (powdered) solid vanadium pentoxide is only slightly soluble in water or an acid, such as sulfuric acid to dissolve V205 in an acid to prepare an electrolyte. To dissolve V205, it must first be reduced to a lower (more soluble) oxidation state. -4- 531934 V. Description of the invention (3) Various methods have been proposed, mainly using reduction mixtures or complex electrolytes and chemical processing methods for the dissolution and reduction of v + 5. European Patent No. EP-A-0 566 0 1 9 discloses a method for chemical reduction of vanadium pentoxide or ammonium vanadate in concentrated sulfuric acid, followed by heat treatment of the precipitate to produce a vanadium electrolyte solution. World Patent Nos. WO 95/1 2219 and WO 96/35239 disclose an electrochemical-chemical process for preparing a vanadium electrolyte solution from solid vanadium pentoxide and a method for stabilizing it. Vanadium pentoxide is on a special louvered plate cathode ion exchange membrane battery, so that the vanadium pentoxide slurry flows down to contact the louvered plate cathode to dissolve. The methods and techniques developed to date for the preparation of suitable vanadium electrolytes are complex and expensive. On the other hand, for the overall economic settlement of an all-vanadium redox battery system, the low-cost vanadium electrolyte solution is an important factor in the availability of redox batteries over other energy storage systems in the cost-benefit evaluation. The basis for meeting this need is the use of very cheap solid vanadium pentoxide as the feed material. OBJECTS AND DESCRIPTION OF THE INVENTION A particularly simple and inexpensive method has now been discovered for the immediate dissolution and reduction of vanadium pentoxide in an acidic electrolyte. The present invention can be particularly used for preparing vanadium electrolyte from vanadium pentoxide (or ammonium vanadate) feed, and using an extremely simple and low-cost electrolytic cell to implement simultaneous reduction of solution auxiliary treatment to a minimum. Even so, the method of the present invention guarantees 531934 from the viewpoint of energy consumption. 5. Description of the Invention (4) is highly efficient. The method of the present invention is essentially a continuous method, so a certain volume of the circulating vanadium electrolyte solution is continuously fed with solid vanadium pentoxide (v2o5), acid and water in the form of fine honing or powder to maintain the solution At a specific Mohr concentration, an electrolyte solution containing V + 3 and V + 4 with an equal volume that is substantially the same or different from a desired concentration is continuously continuously discharged. The outflow of electrolyte solution indicates the output of the process. Basically, the method of the present invention is: Gravitationally passing the electrolyte solution through the cathodes of a plurality of electrolytic cells connected in series, and gradually reducing part or all of the V + 4 content of the solution entering the first battery cell to v + 3, and finally, even if the electrolyte solution flows out from the last electrolytic cell of the plurality of battery cells connected in series, the electrolyte solution is slightly changed to V + 2; so that the electrolyte solution flows out from the last electrolytic cell outlet, The vanadium content thus reduced and the electrolytic solution obtained by reacting vanadium pentoxide in a stoichiometric proportion in a dissolution tank provided with a stirring device include an equivalent amount of dissolved vanadium which can be almost completely in the V + 4 state. ; Add acid, sulfuric acid or any other equivalent acid and water to the vanadium electrolyte solution (ie close to v + 4) to maintain a certain Mohr concentration; make the electrolyte solution circulate through the series electrolytic cells' while in the multiple battery cells in series At the outlet of the battery chamber, the electrolyte solution preferably containing V + 3 and V + 4 is approximately the same concentration. The basic appearance of the electrolyte battery chamber is that the cathode and anode are individually equipped with 531934. V. Description of the invention (5) The surface morphology, geometry and mutual arrangement make the current density on the anode surface to be 5 to 20 times the ratio. The current density on the cathode surface is greater, and oxygen is precipitated from the anode surface. In fact, the cathode can provide carbon felt or activated carbon felt or the same material to provide a large surface area, and can have a tubular or even channel shape; while the anode can be in the form of a thin round rod, along the tube or channel shape of the cathode Geometric axis. In comparison, the large specific active area of the cathode and the ratio of the specific active area of the anode and the area of its protrusions result in a current density on the surface of the active anode that is 5 to 20 times greater than the current density on the surface of the cathode with geometric protrusions. Work with a cathode current density of a size of about one to several hundred amperes per square meter (A / m2) over the area of the protrusion, and a diameter of an anode round rod arranged concentrically to a tube or equivalently at least partially surrounding the cathode It is possible to establish anode current density in excess of 1000A / m2 or even higher. Under the condition that the current density is significantly disproportionate and the anode current density is quite high, although the current of the forced electrolytic cell is adjusted, it is ensured that the cathode of V + 4 is almost completely reduced to V + 3 to maintain the cathode half-cell chamber reaction. (I.e., limiting the maximum current density to prevent parasitic reactions such as hydrogen precipitation), the anode half-cell chamber reaction becomes mainly supported by the precipitation of oxygen (water electrolysis) reaction. In fact, the anode half-cell chamber reaction with the thermodynamic advantage of V + 3 oxidation to V + 4 will actually be affected by mobility and finally by the electrolyte host 531934 V. Description of the invention (6) The V + 3 ion diffusivity in the gap between the anode surface and the cathode surface facing the anode surface is greatly deficient. Further important obstacles to the migration and / or diffusion of vanadium ions to the surface of the anode arise from the occurrence of oxygen bubbles that are strongly precipitated from the surface of the anode at a very local current density. The current forced in the electrical series through the multiple electrolytic cells connected by gravity in series can be adjusted by the electrolyte through the function of the flow rate of the series battery chambers, so that all V is generated in the electrolyte leaving the last ^ series battery chambers. +4 is actually completely reduced to V + 3. Of course, it maintains ideal conditions. In fact, the minimum (residual) V + 4 amount will occur in the case of insufficient current when forced to pass through the battery chamber, or vice versa. In the case where the current exceeds, V + 3 will begin to reduce. V + 2 makes a small amount of V + 2 and V + 3 appear in the electrolyte leaving the final battery compartment. 0 The anode has a low oxygen overpotential on the surface of the electrocatalyst to promote the precipitation of oxygen. In short, it can be polarized and oxygen in the anode. Resistant to acidic conditions under discharge conditions.) For example, the anode can be a round rod valve-type metal that can withstand anode impacts such as titanium, giant, or its alloys, providing a non-passivated active coating with an oxygen-emission electrocatalyst. The coating may have a mixed oxide or at least one precious metal, such as an oxide mixture of iridium, rhodium, and ruthenium, and at least one valve-type metal such as titanium, molybdenum, and pins. The reactive coating may alternatively comprise a precious metal coating such as a filler interspersed with a conductive oxide matrix (Ix) or iridium or rhodium or the same metal. -8-531934 V. Description of the invention (7) In a dissolution tank provided with a general mechanical stirring device, the electrolyte solution leaving the last battery chamber contacts a fine (powder) stoichiometric proportion of solid vanadium pentoxide (according to V + 3 (V + 2) 1 1) contained in the reducing electrolyte solution, and the solid vanadium pentoxide is honed and / or screened so that the introduced particles have a maximum size of not more than 100 microns. The decanted or filtered solution is recovered in the storage tank, and any undissolved vanadium pentoxide particles can be recycled back to the dissolution tank. Such a high content solution contains approximately V + 4 vanadium, although very little undissolved vanadium exists at V + 5. The most common and best acids are sulfuric acid, and water, which are added to high levels of vanadium and filtered electrolyte solutions to maintain specific mole concentrations and electrolyte solutions. Of course > The higher the molar content of vanadium, the more the power / total volume ratio of the electrolyte becomes more serious. However, the stability of the solution under critical temperature conditions will be encountered at relatively high molar concentrations. Optimally, in the case of a sulfuric acid solution, the molar content of vanadium is in the range of 2 to 5 molar. The solution is pumped back to the inlet 9 in the first battery compartment of the series battery compartment via v + 4 (and Any residue of V + 5) is electrochemically reduced to V + 3, and even to the production of 'V + 2 electrolyte manufacturing equipment, which is a solution containing approximately the same amount of V + 3 and V + 4, which can be used in series batteries The main streamline of the recirculated solution is discharged at the outlet of one of the battery compartments. The large and disproportionate current density on the anode surface causes a large amount of oxygen to precipitate and correspondingly a small number of V + 3 to oxidize to V + 4, which is a kind of -9- quite strangely used 531934 V. Description of the invention (8) It is sufficient to maintain the condition that the total efficiency of the processing process is greater than the acceptable level; and it is also believed that the total economic settlement of any processing process in the preparation of vanadium acid electrolytes has a very small proportion of its electrical energy costs. In alternatives to the embodiments, screen screens or even microporous separators included between the round rod anode and the cylindrical cathode of the ring wrap may be used to increase efficiency. Screen sieves or microporous separators effectively limit the oxygen bubbles that rise with buoyancy in the electrolyte, because they continue to produce and leave the anode surface, and thus make the space between the screen and the cathode Convective motion containing the electrolyte body is minimized, which further reduces the ability of the reduced vanadium ion (V + 3) to drift and eventually reach the anode. The most effective microporous separator can be a porous glass tube whose bottom is closed to surround the round rod anode (in the case, it enters the battery chamber from the top), so once the precipitated oxygen bubbles reach the surface of the electrolyte, they can immediately Pass the vent to drain from the battery compartment. Alternatively, a suitable microporous separator may be wool of polypropylene propylene fiber (poly propylene fiber) having a thickness of about 1 mm. Brief Description of the Drawings Fig. 1 illustrates a device for preparing a vanadium electrolyte solution from a solid V205 feed according to the present invention; Fig. 2 is a cross-sectional view of a vanadium reduction battery chamber of the present invention; and Fig. 3 is a vanadium reduction A cross-sectional view of the alternative embodiment of the battery chamber; and Figure 4 is a basic schematic diagram of all vanadium flow redox battery systems, including the vanadium reduction of the present invention for rebalancing in a positive electrolyte circuit -10- 531934 V. Description of the invention (9) Battery room. The detailed description of the preferred embodiment of the invention refers to the functional schematic diagram of Fig. 1. According to the vanadium electrolyte preparation device of the present invention, a plurality of electrolyte vanadium reduction battery chambers Cl, C2, C3, ... C6 are connected in series by gravity. It is connected and it is supplied with electricity by an appropriate direct current (DC) supply R1 in an electrical series manner. The solution leaving the last battery chamber C6 in the series is collected in a dissolving tank T1 with a stirring device S1. The vanadium pentoxide is introduced into the dissolution tank T1 in an appropriate amount by a feeding funnel of the conventional use case and a machine driven by a motor to control the feeding. The high vanadium solution, which finally contains undissolved vanadium pentoxide residual solid particles, can flow out through its liquid level discharge port higher than the dissolution tank T1, and is decanted in the sink lake T2. Pump P2 finally returns to dissolving vanadium pentoxide in the dissolution tank T1 to separate the remaining solid particles, and collects it at the bottom of the clear tank T2. The high vanadium content and the filtration solution are finally collected in storage tank T 3. The high vanadium solution collected in storage tank T3 contains approximately vanadium in the V + 4 state. The content corresponds to the amount of reduction that has appeared in the electrochemical reduction solution flowing out of the last reduction cell chamber C6 in series and that has been dissolved and reduced V + 5, and is equal to the sum of V + 3 and finally V + 2. In fact, the residual unreacted amount V + 5 can also be collected in T3, and V + 4 of such a high vanadium amount solution also appears together. After acid has been added, usually equivalent amounts of H2S04 and water H20 to keep the vanadium electrolyte solution at a desired molar concentration, the solution is continuously pumped by pump P1-11-531934 V. Description of the invention (1) The ring is connected in series Vanadium reduction electrolytic cell. Therefore, the vanadium electrolyte solution entering the first reduction battery chamber C 1 contains approximately V + 4 and possibly V + 5 residues. At the negative electrodes (cathode) of the reduction cell compartments Cl, C2, C3 ... C6, the main reaction is: V "+ e, = = V + 3 (or more precisely V0 + 2 + e > 2H + = = = V + 3 + H20) If vanadium with +5 oxidation state appears, another reaction is: V + 5 + e ^ = = V + 4 (or more precisely V02 + + e- + 2H + = = = V + 2 + H20) There is no other reaction at the negative electrode. Hydrogen evolution (the half-cell reaction that is thermodynamically preferred) does not occur because the carbon felt electrode has a high hydrogen overvoltage and the effective current density on the cathode surface is maintained at It is sufficiently low. At the positive electrode, in theory, the main reaction must be that any vanadium ion that has a lower oxidation state (+4, +3, +2) appears to be oxidized to vanadium pentoxide (half cell that is thermodynamically preferred) Chamber reaction). In fact, vanadium ions near the anode surface will immediately oxidize to V + 5, so any low-oxidation vanadium ions will eventually drift and diffuse to the anode. However, because the vanadium ions adjacent to the positive electrode are converted to V + 5 (consumed), so the anode half-cell chamber reaction will begin to be countered by the other half-cells There should be more and more support, that is, the release of oxygen and the resulting precipitation according to the following reaction: H20 = = = 02 + 2H + + 2e 'In the asymmetric battery cell of the present invention, the actual vanadium is not ruled out. Oxidation, such as the use of ion exchange membranes and vanadium containing cathode electrolytes and supporting acid anodes-12-531934 V. Description of the invention (11) Conventional system for the separation circuit of solution. In fact, vanadium can reach the anode surface of the battery room Ions will immediately oxidize to v + 5. However, the generated electrode current density makes the anode work at a very high current density, which is higher than the number of vanadium ions drifting and diffusing in the electrolyte solution to the anode The support is particularly disproportionate. As a result, a large amount of oxygen precipitation is promoted on the surface of the anode, and the oxygen bubbles are violently precipitated to cause a "mechanical" obstacle that causes v + 3 ions to drift to the anode. By using a screen or A permeable (microporous) membrane to limit the group of oxygen bubbles close to the cathode can greatly increase the barrier to the diffusion of vanadium ions reduced by the cathode to the anode, and thus prevent the The strong convective movement caused by the electrolyte group contained in the space between the screen and the cathode surface of the high-reduction vanadium ions. The use of low-oxygen over-voltage anodes only promotes the precipitation of oxygen. When using very tight microporosity When a separator is used to replace a more permeable screen or diaphragm, the total induction efficiency increases significantly, however, the battery chamber voltage also increases. Therefore, as long as the energy consumption is proportional to the product of current and voltage, the best compromise can be found It has been found that to ensure the induction efficiency exceeds 40%, it can be easily achieved with a cathode / anode current ratio of about 5; and by increasing the current / voltage ratio to 20, the efficiency can reach 80% or even higher. The use of gas-limited screens and, more importantly, the use of fairly compact microporous separators, has resulted in a significant increase in numbers. In the dissolution tank T1, the V + 3 and solids contained in the electrolytically reduced vanadium electrolyte solution. 13-531934 V. Description of the invention (12) The reaction is based on the reaction of vanadium pentoxide v2o5 (or ammonium vanadate), and it is reduced to V + 4 according to the following reaction: (V + 5 + V + 3 = = 2V + 4) or more Precisely V205 + 2V + 3 + 2H + = = = 4V0 + 2 + H2〇 (1) and (if V + 2 also appears) (2V + 5+ V + 2 = = 3V + 4) or more precisely V205 + V + 2 + 4H + = = = = 3V0 + 2 + 2H20 The cross act ion of the asymmetric battery cell according to the present invention is used in the vanadium electrolyte preparation device of the present invention, as shown in FIG. 2. The laboratory test battery chamber shown in Figure 2 includes: a cylindrical tubular body 1, usually a metal; a plug 2, a chemically and electrolyte-resistant non-conductive acid-resistant plastic such as PVC, sealed at the bottom of the tubular body; The lower part has an inlet 3 and an overflow outlet 4. A cylindrical cathode composed of a carbon felt 5 having a thickness of several centimeters can be disposed on and appropriately anchored to the cylindrical surface inside the tube 1. The felt cathode can be provided with suitable terminals 6 for the electrical connection of the battery compartment of the DC power circuit. In the laboratory test battery chamber shown in Fig. 2, the area of the inner cylindrical surface of the cathode has a diameter of about 50 mm and a height of about 250 mm in contact with the electrolyte solution. The anode 7 is a titanium round rod having a diameter of 6.3 mm (1/4 inch), has a coating of iridium and a giant mixed oxide, and is immersed in the electrolyte for a length of about 250 mm. Coated round rod anode 7 is arranged along the axis of the cylindrical carbon felt cathode -14-531934 V. Description of the invention (13) In the laboratory battery room so defined, the area of the protrusion of the carbon felt cathode is about 3 5 3 cm Square, while the surface of the titanium round rod anode is about 47 cm square. Passing a forced current through a 7A battery chamber, the current density on the surface of the titanium anode is about 0.1485A / cm2 = 1 500A / m2, and the current density of the area of the carbon felt protrusions is 0.022A / cm2 = 220A / m2. However, due to the open and immediate infiltration form of the cathode in the form of carbon fiber felt, the actual or effective cathode current density on carbon is estimated to be 2 to 10 times the calculated current density on the cylindrical area of the geometric protrusion of the carbon felt cathode Less than. Figure 3 shows the interaction of a vanadium reduction cell according to an alternative embodiment. The only difference is the appearance of a fluid-permeable screen or diaphragm or a microporous separator, which is inserted between the surface of the cylindrical cathode and the coaxially arranged round rod anode and defines the space around the round rod anode 7, which generally remains continued The floating oxygen bubbles that are generated and finally detached from the anode surface are confined within the surrounding electrolyte. The screen diaphragm 8 generates V + 4 in the vicinity of V + 3 and V + 2 is finally at the surface of the cathode desired to be reduced, which substantially prevents induction of strong convective movement in the electrolyte group domain. Plastic tubes with small, dense and uniformly distributed pores can be used as satisfactory bubble-restricting screens. However, the oxygen-bubble-restricting screens 8 can alternatively be durable materials such as, for example, titanium wire mesh or plastic fiber fabrics. Fine net. More preferably, the gas confinement screen 8 may be a porous or microporous tube body, such as a porous glass tube or a metal-resistant particle tube such as sintered titanium. -15-531934 V. Description of the invention (14) Examples have internal A 1 / 2-liter glass beaker with a diameter of 8 cm is used to demonstrate the effectiveness of the technology of the present invention. A carbon felt having a thickness of about 6 mm (1/4 inch) was placed on the inner wall of the beaker and was electrically connected to the negative electrode of the DC power supply. An I rOx-ZrOy mixed oxide coated titanium round bar with an outer diameter of about 6 mm (1/4 inch) is positioned vertically along the geometric axis of the beaker and is electrically connected to the positive pole of the DC power supply. The ratio between the area of the cathode of the protrusion and the area of the anode is approximately 10.7. Polyethylene felt with a thickness of about 1 mm to form a round tube shape, closed at the bottom, having an inner diameter of about 12 mm and placed in a beaker, concentrically around the coated titanium round rod anode. The beaker was filled with 473 ml of a 5 mol sulfuric acid solution and 90.9 g (0.5 mol) of vanadium pentoxide powder, and the total volume of the mixture was 0.5 1. Theoretically, it takes 26.8Ah (ampere-hours) to reduce 1 mole of vanadium from the auto-oxidized +5 state to the oxidized +4 state. The mixture was stirred with an electromagnetic stirrer and the yellow powder of vanadium pentoxide did not dissolve for several days. Turn on the DC power supply and adjust its output voltage to force a DC current of 8A (amperes) to flow through the battery compartment. The current density of the positive electrode (anode) is about 501 3A / m2, and the current density of the negative electrode (cathode) on the area of the protrusions of the carbon felt is about 468A / m2. The battery compartment voltage remains approximately fixed at approximately 3.8-4.0 volts. -16- 531934 V. Description of the invention (15) The suspension was slightly stirred with an electromagnetic stirrer, and after passing the current for 5.26 hours, the yellow powder seemed to be completely dissolved. The blue solution thus obtained was analyzed and found to contain 2 moles of vanadium (2 mol solution) and the oxidation state of vanadium was +3.55. The inductive (current) efficiency of the process is estimated to be 92.28%. Repeat the test with a reduced current of 5A, and the time required is 9.87 hours. Inductive (current) efficiency has been reduced to approximately 78.74%, but the battery compartment voltage is approximately 2.8V. Using thin polyethylene woven fabrics instead of felts reduces the current efficiency to about 47%, or about 20 to 25% if there is no permeable limiting element. Even if it is not in the best laboratory setting test conditions (glass beaker with agitation), the vanadium electrolyte produced has a power consumption of about 0.2 to 0_5 kWh (仟 Wh) per liter, indicating its total economy in preparing vanadium electrolytes. Low cost figures in settlement. In order to efficiently and inexpensively modify the oxidation state of the vanadium content decomposed in the acidic electrolyte solution, the ability of the asymmetric vanadium electrolytic cell of the present invention to obtain a relatively simple and low-cost asymmetric battery of the present invention that can be substantially undivided The chamber can be ideally used for rebalancing the positive and negative vanadium electrolyte charge status of the battery during operation. It is not used for redox battery equipment. It is expensive and time-consuming to implement in the absence of use conditions. Allow for imbalance. In order to better understand the nature of the problems that may occur when operating a vanadium battery energy storage system, the main mechanism for a simple response that results in a significant cumulative imbalance should be -17-531934 V. Description of the Invention (16) is helpful. Theoretically, assuming that the only processes that occur during the charging and discharging of vanadium redox batteries are electrochemical oxidation and reduction of vanadium, and no side reactions are taking place, the charging and discharging processes of vanadium batteries are symmetrical. During charging, the current flowing through the battery oxidizes v + 4 in the positive electrolyte compartment to v + 5, and simultaneously and at the same rate makes V + 3 into V + 2 in the negative electrolyte compartment. Relative oxidation and reduction reactions occur in the positive and negative electrolyte compartments during discharge. Unfortunately, the situation is actually different. The electrochemical oxidation and reduction of vanadium is not the only process that is taking place. The following side reactions may occur under critical conditions of operation: 1) electrochemical precipitation of hydrogen at the negative electrode; 2) electrochemical precipitation of oxygen at the positive electrode (*); 3) chemical oxidation of V + 2 to V + 3; 4) V + 5 is chemically reduced to V + 4. (*) If the positive electrode is made of carbon, the precipitation of oxygen is partially or entirely replaced by the precipitation of carbon dioxide. Once the 100% charge state is reached, reactions 1) and 2) become the only reactions. In fact, after all V + 4 appearing in the electrolyte in the positive compartment is oxidized to V + 5, the only reaction on the positive electrode that can support the current is the precipitation of oxygen (or carbon dioxide). Similarly, when all V + 3 appearing in the electrolyte in the positive compartment is reduced to V + 2, the only reaction on the negative electrode that can support the current is the precipitation of hydrogen. When the state of charge becomes higher than 90%, these reactions will begin to occur during the charging of the battery, although in a small amount -18-531934 V. Invention Description (17). When the vanadium is oxidized or reduced, the voltage increases proportionally with the ratio between the species produced and the species consumed (Nern st equation), so when the state of charge is high, the battery chamber voltage rises to about 1.5 volts of hydrogen And the voltage of oxygen (water electrolysis) precipitation. If charging occurs at an excessively high rate (current), reactions 1 and 2) also occur during the battery discharge although a relatively small amount. Because the current density is close to the limit current, the precipitation of hydrogen and oxygen begins to occur as a secondary (parasitic) electrode reaction. The limiting current is the current on the electrode surface where the oxidation or reduction rate of vanadium is equal to the vanadium ions diffuse from the electrolyte domain to the electrode surface through the empty layer. The oxidation of V + 2 to V + 3 in reaction 3) is the most common side reaction that occurs again during the operation of a vanadium battery. V + 2 is oxidized to V + 3 immediately when air appears. Therefore, unless the atmospheric air can be strictly prevented from coming into contact with the negative electrolyte (blocked with nitrogen or the surface of the electrolyte covered with wax), this side reaction will occur immediately. Because of the above-mentioned side reactions, after many cycles of battery operation, symmetry will start to be noticeably lost. Another reason the electrolyte becomes unbalanced is because the diaphragm used is not a perfect separator. Anionic membranes are also inevitably penetrated by small amounts of positive ion (H + and V + n). Cationic separators are usually preferred as battery cell separators because they have higher mechanical and chemical resistance than anionic separators. In fact, cationic membranes are mainly permeable to hydrogen ions (the diffusion rate of H + is much higher than vanadium ions). -19- 531934 V. Description of the invention (18) During battery charging, hydrogen ions are generated in the positive compartment according to the following reaction: V〇 + 2 + H20 = = = = = V〇 + 2 + 2H + + e -Immediate migration with a few less mobile vanadium ions through the diaphragm to the negatively separated vanadium ions will cause a corresponding amount of reduced vanadium ions to oxidize in the negative compartment (V + 3 and V + 2), but The process is not completely reversible, because vanadium ions of different oxidation states themselves coordinate the solvent molecules (water, sulfuric acid) differently, and have different fluidity in the cation exchange resin of the membrane. In fact, the number of vanadium ions passing through the membrane in the opposite direction during the subsequent discharge phase will not exactly equal the amount that has drifted during the charge phase. The imbalance accumulated between the electrodes will cause many problems, among them: 1) the battery capacity (decreasing in proportion to the kWh / 1 i ter (仟 watt hour / liter) of the electrolyte); 2) during charging, One can become fully charged, while the other remains partially uncharged. In fact, especially imperfect small cells self-negative compartments to eliminate air, vanadium ions in the positive compartment can be completely oxidized to V + 5, and a considerable amount of V + 3 is maintained in the negative compartment. This situation is very important because if the oxidation state is not carefully controlled in individual electrolytes but only the open circuit voltage is measured, the charge will continue to reach the point where V + 4 is completely oxidized to V + 5. In this case, a large amount of precipitation of oxygen on the carbon electrode will oxidize and damage the electrode. -20- 531934 V. Description of the invention (19) According to the general situation, after several charge and discharge cycles, the two electrolytes (negative and positive) are mixed and the oxidation state is measured. If it is found to be different from +3.5, then Chemically adjusted to +3.5. In fact, when the battery and the mixed electrolyte are stopped together, it is always found that the vanadium oxidation state is higher than + 3 · 5 (mainly because of the effect of the predominant effect of side reaction 3). The electrolyte is readjusted to a vanadium oxidation state of +3.5 by adding a reducing agent (oxalic acid, sulfite, etc.). Then, a considerable amount of energy must be consumed to return the system to a state of zero charge (V + 3 in the negative electrolyte and V + 4 in the positive electrolyte). The amount of energy consumed periodically represents the net loss of the energy storage process. According to the structure of the present invention, this non-negligible loss can be greatly reduced in the negative or better in the positive electrolyte circuit by installing the very small vanadium reduction asymmetric battery cell of the present invention, as shown in the schematic diagram of FIG. 4 . As shown, the positive electrolyte can be fully or partially circulated (in the latter case, for example using an adjustable three-way valve or by any device) through a very small asymmetric reduction cell compartment for redox. The battery cell redox can be operated continuously or intermittently as needed to maintain the asymmetric electrical fL oxidation state structure. Because of the possibility provided by the appearance of redox in this auxiliary reduction battery compartment, the need to mix two electrolytes together, adjust the oxidation state to about +3.5, and make the battery pre-charged in order to restore the state of zero charge can be eliminated or only Exceptional implementation is required. -21- 531934 V. Description of the invention (20) Explanation of symbols C1 ～ C6 Electrolyte vanadium reduction battery chamber T1 Dissolving tank S1 Stirring device T2 Clear tank T3 Storage tank 1 Cylindrical tube 2 Plug 3 Inlet 4 Overflow port 5 carbon felt 6 terminal 7 anode 8 microporous separator 8 screen sieve diaphragm -22-