Lithium Battery Cathode Composite for Energy Density and Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries with conventional cathode active materials face challenges in meeting the high energy density and output requirements for electric vehicles (EVs) and hybrid electric vehicles (HEVs), as they suffer from safety issues due to volume changes and low discharge potential, respectively.
Innovation Solution
A high energy density lithium secondary battery is developed, incorporating a cathode with a layered lithium transition metal oxide and a spinel lithium manganese oxide, combined with crystalline graphite anode active materials, optimized for specific surface area and conductivity, and a separator with high ion permeability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt composite oxide with layered structure is used as cathode active material, then discharge voltage and energy density are improved, but safety deteriorates due to volume changes and structural collapse during Li ion intercalation and deintercalation
Solution Approach 1:
The patent uses a composite cathode active material consisting of lithium cobalt composite oxide (layered structure) and lithium manganese composite oxide (spinel structure). The layered structure provides high discharge voltage and energy density, while the spinel structure provides structural stability and safety during Li ion cycling, thus resolving the contradiction between energy density and safety.
2Reliability
If lithium manganese composite oxide with spinel structure is used as cathode active material, then safety is improved, but energy density deteriorates
Solution Approach 1:
The patent combines lithium manganese composite oxide (spinel structure, providing safety) with lithium cobalt composite oxide (layered structure, providing high energy density). This composite approach allows the battery to achieve both safety and high energy density, resolving the contradiction between these two parameters.
3Duration of action of stationary object
If crystalline graphite is used as anode active material, then cycle lifespan is improved due to reversible charge/discharge behavior, but output properties deteriorate
Solution Approach 1:
The patent applies local quality by using crystalline graphite with specific surface area control (0.005 to 0.013 m2/mAh). By optimizing the surface area, the anode maintains the reversible charge/discharge behavior of crystalline graphite for good cycle lifespan while improving output properties through enhanced surface reactivity and ion transport.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The battery achieves enhanced energy density and output characteristics suitable for EVs and HEVs, with improved cycle lifespan and safety, enabling effective power storage for electric vehicles and hybrid systems.
Implementation Method 1
the layered structure thereof undergoes changes in volume according to repeated intercalation and deintercalation of Li ions
Implementation Method 2
a separator
Data Source
AI summary
Disclosed is a high energy density lithium secondary battery including a cathode. The cathode contains, as cathode active materials, a first cathode active material having a layered structure and a second cathode active material having a spinel structure. The amount of the first cathode active material is between 40 and 100 wt % based on the total weight of the cathode active materials. The high density lithium secondary battery further comprises an anode, including crystalline graphite having a specific surface area (with respect to capacity) of 0.005 to 0.013 m2/mAh as an anode active material, as well as a separator.